Estimating Acute Cardiorespiratory Effects of Ambient Volatile Organic Compounds

Identifying cardiovascular disease risk in the U.S. population using environmental volatile organic compounds exposure: A machine learning predictive model based on the SHAP methodology

BACKGROUND

Cardiovascular disease (CVD) remains a leading cause of mortality globally. Environmental pollutants, specifically volatile organic compounds (VOCs), have been identified as significant risk factors. This study aims to develop a machine learning (ML) model to predict CVD risk based on VOC exposure and demographic data using SHapley Additive exPlanations (SHAP) for interpretability.

METHODS

We utilized data from the National Health and Nutrition Examination Survey (NHANES) from 2011 to 2018, comprising 5098 participants. VOC exposure was assessed through 15 urinary metabolite metrics. The dataset was split into a training set (70 %) and a test set (30 %). Six ML models were developed, including Random Forest (RF), Light Gradient Boosting Machine (LightGBM), Decision Tree (DT), Extreme Gradient Boosting (XGBoost), Multi-Layer Perceptron (MLP), and Support Vector Machines (SVM). Model performance was evaluated using the Area Under the Receiver Operating Characteristic Curve (AUROC), accuracy, balanced accuracy, F1 score, J-index, kappa, Matthew's correlation coefficient (MCC), positive predictive value (PPV), negative predictive value (NPV), sensitivity (sens), specificity (spec) and SHAP was applied to interpret the best-performing model.

RESULTS

The RF model exhibited the highest predictive performance with an ROC of 0.8143. SHAP analysis identified age and ATCA as the most significant predictors, with ATCA showing a protective effect against CVD, particularly in older adults and those with hypertension. The study found a significant interaction between ATCA levels and age, indicating that the protective effect of ATCA is more pronounced in older individuals due to increased oxidative stress and inflammatory responses associated with aging. E-values analysis suggested robustness to unmeasured confounders.

CONCLUSIONS

This study is the first to utilize VOC exposure data to construct an ML model for predicting CVD risk. The findings highlight the potential of combining environmental exposure data with demographic information to enhance CVD risk prediction, supporting the development of personalized prevention and intervention strategies.

Identifying effects of volatile organic compounds exposure on kidney stone prevalence in U.S. adults: a cross-sectional analysis of NHANES 2007-2020

OBJECTIVE

Our aim was to comprehensively investigate the relationship between blood volatile organic compounds (VOCs) and kidney stone prevalence for U.S. adults.

METHODS

In this cross-sectional study, 10,052 participants from the 2007-2020 National Health and Nutrition Examination Survey (NHANES) were included. Multivariate logistic regression model was employed to investigate the association between 9 blood VOCs and kidney stones. We explored the dose-response relationship between blood VOCs and kidney stones using restricted cubic spline (RCS) analysis. Additionally, weighted quantile sum (WQS) regression model was performed to assess the overall association of 9 blood VOCs with kidney stones. Finally, subgroup analyses were conducted to identify the findings in different populations at high prevalence.

RESULTS

Logistic regression analysis and dose-response risk curves revealed that blood benzene (aOR = 1.308, 95% CI: 1.118-1.530, P = 0.001), blood ethylbenzene (aOR = 1.280, 95% CI: 1.054-1.554, P = 0.013), blood m-/p-xylene (aOR = 1.187, 95% CI: 1.008-1.398, P = 0.040), blood 2,5-dimethylfuran (aOR = 1.319, 95% CI: 1.135-1.533, P < 0.001) and blood furan (aOR = 1.698, 95% CI: 1.305-2.209, P < 0.001) were positively associated with the prevalence of kidney stones. WQS regression analysis revealed that exposure to mixed blood VOCs was positively correlated with kidney stone prevalence (OR = 1.34, 95% CI: 1.14-1.57), with furans carrying the greatest weight. Subgroup analyses suggested that kidney stones were more susceptible to the effects of blood VOCs in young and middle-aged, female, overweight and obese, non-hypertensive, and non-diabetic populations.

CONCLUSIONS

In this study, the results indicated that high VOC exposure was positively and independently associated with kidney stones in U.S. adults. This finding highlighted the need for public health strategies to reduce VOC exposure and its role in kidney stone prevention and treatment.

Health effects of air pollutant mixtures (volatile organic compounds, particulate matter, sulfur and nitrogen oxides) - a review of the literature

The health risks associated with individual air pollutant exposures have been studied and documented, but in real-life, the population is exposed to a multitude of different substances, designated as mixtures. A body of literature on air pollutants indicated that the next step in air pollution research is investigating pollutant mixtures and their potential impacts on health, as a risk assessment of individual air pollutants may actually underestimate the overall risks. This review aims to synthesize the health effects related to air pollutant mixtures containing selected pollutants such as: volatile organic compounds, particulate matter, sulfur and nitrogen oxides. For this review, the PubMed database was used to search for articles published within the last decade, and we included studies assessing the associations between air pollutant mixtures and health effects. The literature search was conducted according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. A number of 110 studies were included in the review from which data on pollutant mixtures, health effects, methods used, and primary results were extracted. Our review emphasized that there are a relatively small number of studies addressing the health effects of air pollutants as mixtures and there is a gap in knowledge regarding the health effects associated with these mixtures. Studying the health effects of air pollutant mixtures is challenging due to the complexity of components that mixtures may contain, and the possible interactions these different components may have.

Maternal Exposure to Per- and Polyfluoroalkyl Substances and Offspring Chromosomal Abnormalities: The Japan Environment and Children's Study

BACKGROUND

Although recent in vitro experimental results have raised the question of whether maternal exposure to per- and polyfluoroalkyl substances (PFAS) may be a potential environmental risk factor for chromosomal abnormalities, epidemiological studies investigating these associations are lacking.

OBJECTIVES

This study examined whether prenatal PFAS exposure is associated with a higher prevalence of chromosomal abnormalities among offspring.

METHODS

We used data from the Japan Environment and Children's Study, a nationwide birth cohort study, and employed logistic regression models to examine the associations between maternal plasma PFAS concentrations in the first trimester and the diagnosis of chromosomal abnormalities in all births (artificial abortions, miscarriages, stillbirths, and live births) up to 2 years of age. In addition, we examined associations with mixtures of PFAS using multipollutant models.

RESULTS

The final sample consisted of 24,724 births with singleton pregnancies, of which 44 confirmed cases of chromosomal abnormalities were identified (prevalence: 17.8/10,000 births). When examined individually, exposure to perfluorononanoic acid (PFNA) and perfluorooctane sulfonic acid (PFOS) showed positive associations with any chromosomal abnormalities with age-adjusted odds ratios of 1.81 (95% CI: 1.26, 2.61) and 2.08 (95% CI: 1.41, 3.07) per doubling in concentration, respectively. These associations remained significant after Bonferroni correction, although they did not reach the adjusted significance threshold in certain sensitivity analyses. Furthermore, the doubling in all PFAS included as a mixture was associated with chromosomal abnormalities, indicating an age-adjusted odds ratio of 2.25 (95% CI: 1.34, 3.80), with PFOS as the predominant contributor, followed by PFNA, perfluoroundecanoic acid (PFUnA), and perfluorooctanoic acid (PFOA).

DISCUSSION

The study findings suggested a potential association between maternal exposure to PFAS, particularly PFOS, and chromosomal abnormalities in offspring. However, the results should be interpreted cautiously, because selection bias arising from the recruitment of women in early pregnancy may explain the associations. https://doi.org/10.1289/EHP13617.

Emission characteristics of volatile organic compounds from consumer spray products based on product type, spray method, and distance

Consumer spray products (CSPs) are widely used in daily life, yet it is challenging to find products that fully disclose all components posing health risks. Existing studies primarily focus on product components or VOC quantities emitted during use. Therefore, this study aimed to measure the VOC concentrations emitted by CSPs at varying distances. 47 CSPs available in the Korean market were selected, spanning three spray groups: antiseptics/insecticides (11), aromatic deodorants (16), and coating/polishing agents (20). VOC in air samples were collected using Tenax TA tube at a distance of 1 and 3 m from the sprayed CSPs and then analyzed by thermal desorption-gas chromatography-mass spectrometry system. Discrepancies were found between labeled and actual product components. Aromatic deodorants exhibited the highest total VOCs (TVOCs), while antiseptic/insecticide sprays exhibited the lowest. In the antiseptic/insecticide group and coating/polishing agent group, benzene as a propellant had a maximum concentration (30.9 ± 25.6 ppb), and as trigger, its concentration was 33.7 ± 30.7 ppb. Quantitative analysis using advanced analytical instruments only explained 26.1 ± 20.4% of toluene-equivalent TVOCs, suggesting the presence of additional substances. Concentrations varied by distance due to substance volatility and usage. Maintaining a distance of at least 1 m from CSPs is recommended.

A review of disrupted biological response associated with volatile organic compound exposure: Insight into identification of biomarkers

Volatile organic compounds (VOCs) are widespread harmful atmospheric pollutants, which have long been concerned and elucidated to be one of the risks of acute and chronic diseases for human, such as leukemia and cancer. Although numerous scientific studies have documented the potential adverse outcomes caused by VOC exposure, the mechanisms which biological response pathways of these VOC disruption remain poorly understood. Therefore, the identification of biochemical markers associated with metabolism, health effects and diseases orientation can be an effective means of screening biological targets for VOC exposure, which provide evidences to the toxicity assessment of compounds. The current review aims to understand the mechanisms underlying VOCs-elicited adverse outcomes by charactering various types of biomarkers. VOCs-related biomarkers from three aspects were summarized through in vitro, animal and epidemiological studies. i) Unmetabolized and metabolized VOC biomarkers in human samples for assessing exposure characteristics in different communities; ii) Adverse endpoint effects related biomarkers, mainly including (anti)oxidative stress, inflammation response and DNA damage; iii) Omics-based molecular biomarkers alteration in gene, protein, lipid and metabolite aspects associated with biological signaling pathway disorders response to VOC exposure. Further research, advanced machine learning and bioinformation approaches combined with experimental results are urgently needed to ascertain the selection of biomarkers and further illuminate toxic mechanisms of VOC exposure. Finally, VOCs-induced disease causes can be predicted with proven results.

Benzene: A critical review on measurement methodology, certified reference material, exposure limits with its impact on human health and mitigation strategies

Benzene is a carcinogenic pollutant with significant emission sources present in the atmosphere. The need for accurate and precise measurement of benzene in the atmosphere has become increasingly evident due to its toxicity and the adverse health effects associated with exposure to different concentrations. Certified reference material (CRM) is essential to establish the traceability of measurement results. The present review compiles the available national and international measurement methods, certified reference materials (CRMs) for benzene and the limit of benzene in fuel composition (v/v) worldwide. Overall, the review indicates the benzene level in the atmosphere and the resulting impacts on the environment and human health, which frequently exceed the exposure limits of different environment regulatory agencies. An extensive literature review was conducted to gather information on monitoring and analysis methods for benzene, revealing that the most preferred method, i.e. Gas Chromatography- Flame Ionization Detector and Mass Spectrometry, is neither cost-effective nor suitable for real-time continuous monitoring. By analysing existing literature and studies, this review will shed light on the understanding of the importance of benzene pollution monitoring in ambient air and its implications for public health. Additionally, it will reflect the mitigation strategies applied by regulators & need for future revisions of air quality guidelines.

Associations between specific volatile organic chemical exposures and cardiovascular disease risks: insights from NHANES

Introduction

An increasing body of research has demonstrated a correlation between pollutants from the environment and the development of cardiovascular diseases (CVD). However, the impact of volatile organic chemicals (VOC) on CVD remains unknown and needs further investigation.

Objectives

This study assessed whether exposure to VOC was associated with CVD in the general population.

Methods

A cross-sectional analysis was conducted utilizing data from five survey cycles (2005-2006, 2011-2012, 2013-2014, 2015-2016, and 2017-2018) of the National Health and Nutrition Examination Survey (NHANES) program. We analyzed the association between urinary VOC metabolites (VOCs) and participants by multiple logistic regression models, further Bayesian Kernel Machine Regression (BKMR) models and Weighted Quantile Sum (WQS) regression were performed for mixture exposure analysis.

Results

Total VOCs were found to be positively linked with CVD in multivariable-adjusted models (p for trend = 0.025), independent of established CVD risk variables, such as hypertension, diabetes, drinking and smoking, and total cholesterol levels. Compared with the reference quartile of total VOCs levels, the multivariable-adjusted odds ratios in increasing quartiles were 1.01 [95% confidence interval (CI): 0.78-1.31], 1.26 (95% CI: 1.05-1.21) and 1.75 (95% CI: 1.36-1.64) for total CVD. Similar positive associations were found when considering individual VOCs, including AAMA, CEMA, CYMA, 2HPMA, 3HPMA, IPM3 and MHBMA3 (acrolein, acrylamide, acrylonitrile, propylene oxide, isoprene, and 1,3-butadiene). In BKMR analysis, the overall effect of a mixture is significantly related to VOCs when all chemicals reach or exceed the 75th percentile. Moreover, in the WQS models, the most influential VOCs were found to be CEMA (40.30%), DHBMA (21.00%), and AMCC (19.70%).

Conclusion

The results of our study indicated that VOC was all found to have a significant association with CVD when comparing results from different models. These findings hold significant potential for public health implications and offer valuable insights for future research directions.

Cardiovascular health and proximity to urban oil drilling in Los Angeles, California

BACKGROUND

Although ~18 million people live within a mile from active oil and gas development (OGD) sites in the United States, epidemiological research on how OGD affects the health of nearby urban residents is sparse. Thousands of OGD sites are spread across Los Angeles (LA) County, California, home to the largest urban oil production in the country. Air pollution and noise from OGD may contribute to cardiovascular morbidity.

OBJECTIVE

We examined the association between proximity to OGD and blood pressure in a diverse cohort of residents in LA.

METHODS

We recruited residents in South LA who lived <1 km from an OGD site. We collected three blood pressure measurements for each participant and used the second and third measurements to calculate averages for systolic blood pressure (SBP) and diastolic blood pressure (DBP) separately. We conducted multivariable linear regression to examine the relationship between distance to OGD sites and continuous SBP and DBP, adjusting for BMI, smoking status, distance to freeway, sex, age, and use of antihypertension medications, with a random effect for household. We examined effect measure modification by BMI category and smoking category.

RESULTS

Among the 623 adult participants, we found that for every 100 meter increase in distance from the OGD site, DBP was reduced by an average of 0.73 mmHg (95% CI: -1.26, -0.21) in this population. We observed stronger effects of proximity to OGD site on DBP among never smokers and among participants with a healthy BMI. The associations observed between proximity to OGD site and SBP were weaker but followed the same patterns as those for DBP.

IMPACT

Our study suggests that living near urban oil drilling sites is significantly associated with greater diastolic blood pressure in urban Los Angeles communities. This research improves understanding of impacts from living nearby drilling operations on the health and welfare of this community, which is critical to inform public health relevant strategies.

Machine learning-driven identification of air toxic combinations associated with asthma symptoms among elementary school children in Spokane, Washington, USA

Air toxics are atmospheric pollutants with hazardous effects on health and the environment. Although methodological constraints have limited the number of air toxics assessed for associations with health and disease, advances in machine learning (ML) enable the assessment of a much larger set of environmental exposures. We used ML methods to conduct a retrospective study to identify combinations of 109 air toxics associated with asthma symptoms among 269 elementary school students in Spokane, Washington. Data on the frequency of asthma symptoms for these children were obtained from Spokane Public Schools. Their exposure to air toxics was estimated by using the Environmental Protection Agency's Air Toxics Screening Assessment and National Air Toxics Assessment. We defined three exposure periods: the most recent year (2019), the last three years (2017-2019), and the last five years (2014-2019). We analyzed the data using the ML-based Data-driven ExposurE Profile (DEEP) extraction method. DEEP identified 25 air toxic combinations associated with asthma symptoms in at least one exposure period. Three combinations (1,1,1-trichloroethane, 2-nitropropane, and 2,4,6-trichlorophenol) were significantly associated with asthma symptoms in all three exposure periods. Four air toxics (1,1,1-trichloroethane, 1,1,2,2-tetrachloroethane, BIS (2-ethylhexyl) phthalate (DEHP), and 2,4-dinitrophenol) were associated only in combination with other toxics, and would not have been identified by traditional statistical methods. The application of DEEP also identified a vulnerable subpopulation of children who were exposed to 13 of the 25 significant combinations in at least one exposure period. On average, these children experienced the largest number of asthma symptoms in our sample. By providing evidence on air toxic combinations associated with childhood asthma, our findings may contribute to the regulation of these toxics to improve children's respiratory health.

Association between Ambient Volatile Organic Compounds Exposome and Emergency Hospital Admissions for Cardiovascular Disease

The limited research on volatile organic compounds (VOCs) has not taken into account the interactions between constituents. We used the weighted quantile sum (WQS) model and generalized linear model (GLM) to quantify the joint effects of ambient VOCs exposome and identify the substances that play key roles. For a 0 day lag, a quartile increase of WQS index for n-alkanes, iso/anti-alkanes, aromatic, halogenated aromatic hydrocarbons, halogenated saturated chain hydrocarbons, and halogenated unsaturated chain hydrocarbons were associated with 1.09% (95% CI: 0.13, 2.06%), 0.98% (95% CI: 0.22, 1.74%), 0.92% (95% CI: 0.14, 1.69%), 1.03% (95% CI: 0.14, 1.93%), 1.69% (95% CI: 0.48, 2.91%), and 1.85% (95% CI: 0.93, 2.79%) increase in cardiovascular disease (CVD) emergency hospital admissions, respectively. Independent effects of key substances on CVD-related emergency hospital admissions were also reported. In particular, an interquartile range increase in 1,1,1-trichloroethane, methylene chloride, styrene, and methylcyclohexane is associated with a greater risk of CVD-associated emergency hospital admissions [3.30% (95% CI: 1.93, 4.69%), 3.84% (95% CI: 1.21, 6.53%), 5.62% (95% CI: 1.35, 10.06%), 8.68% (95% CI: 3.74, 13.86%), respectively]. We found that even if ambient VOCs are present at a considerably low concentration, they can cause cardiovascular damage. This should prompt governments to establish and improve concentration standards for VOCs and their sources. At the same time, policies should be introduced to limit VOCs emission to protect public health.

Seasonal and diurnal measurement of ambient benzene at a high traffic inflation site in Delhi: Health risk assessment and its possible role in ozone formation pathways

Benzene is the most toxic and hazardous pollutant among volatile organic compounds (VOCs), as it comes under group 1 carcinogens recognized by the International Agency for Research on Cancer (IARC). It also plays a significant role in forming secondary pollutants like ozone. The benzene concentration was measured using a charcoal sorbent tube by active sampling at a traffic junction and analysis was done using GC-FID. The maximum average concentration of benzene in ambient air was found to be 33 μg/m3. A diurnal study of benzene measurement shows higher benzene concentrations in the evening compared to the morning. Seasonal variation of benzene is found to be winter > spring > summer > autumn > monsoon and OFP was found to be 21, 19, 14, 13, and 10 respectively. Cancer (ILCR) and non-cancer (HQ) health risk assessment was done to determine the impact of ambient benzene on the residents of urban areas. The yearly average value of ILCR was found to be 2×10-6 ± 1×10-6 which ranges from acceptable value to three times the WHO acceptable value i.e 1×10-6. The correlation of ozone and its precursor, benzene with meteorological parameters is also evaluated. The correlation of benzene and ozone with solar radiation shows the influence of photochemical reactions on the levels of benzene and ozone at the study site, although it is low.

Comprehensive analysis between volatile organic compound (VOC) exposure and female sex hormones: a cross-sectional study from NHANES 2013-2016

There is growing evidence suggesting that exposure to volatile organic compounds (VOCs) can pose significant health risks, including interference with the function of the reproductive system. However, there has been a lack of research focused on the impact of common environmental VOCs on the levels of sex hormones in the general female population. In this study, we conducted a cross-sectional analysis utilizing the database of the National Health and Nutrition Examination Survey (NHANES, 2013-2016). A total of 2633 participants were included in this study. The Pearson correlation model revealed the potential of co-exposure or co-toxicity between benzene and 2,5-dimethylfuran. According to GLM models, we discovered a significant positive association between blood levels of 2,5-dimethylfuran and benzene with testosterone levels in women. Subgroup analysis further identified that the women with underweight and healthy weight might be the high-risk subgroup. Bayesian kernel machine regression (BKMR) was applied to further assess the univariate and bivariate exposure-response relationships between multiple VOCs. Our research systemically formulated the possible relationship between exposure to VOCs and female sex hormones, indicating the role of VOCs as a risk factor for endocrine disruption, especially benzene and 2,5-dimethylfuran. These findings have important implications for public health and call for further investigation.

Large-scale agricultural burning and cardiorespiratory emergency department visits in the U.S. state of Kansas

BACKGROUND

Prescribed agricultural burning is a common land management practice, but little is known about the health effects from the resulting smoke exposure.

OBJECTIVE

To examine the association between smoke from prescribed burning and cardiorespiratory outcomes in the U.S. state of Kansas.

METHODS

We analyzed a zip code-level, daily time series of primary cardiorespiratory emergency department (ED) visits for February-May (months when prescribed burning is common in Kansas) in the years 2009-2011 (n = 109,220). Given limited monitoring data, we formulated a measure of smoke exposure using non-traditional datasets, including fire radiative power and locational attributes from remote sensing data sources. We then assigned a population-weighted potential smoke impact factor (PSIF) to each zip code, based on fire intensity, smoke transport, and fire proximity. We used Poisson generalized linear models to estimate the association between PSIF on the same day and in the past 3 days and asthma, respiratory including asthma, and cardiovascular ED visits.

RESULTS

During the study period, prescribed burning took place on approximately 8 million acres in Kansas. Same-day PSIF was associated with a 7% increase in the rate of asthma ED visits when adjusting for month, year, zip code, meteorology, day of week, holidays, and correlation within zip codes (rate ratio [RR]: 1.07; 95% confidence interval [CI]: 1.01, 1.13). Same-day PSIF was not associated with a combined outcome of respiratory ED visits (RR [95% CI]: 0.99 [0.97, 1.02]), or cardiovascular ED visits (RR [95% CI]: 1.01 [0.98, 1.04]). There was no consistent association between PSIF during the past 3 days and any of the outcomes.

SIGNIFICANCE

These results suggest an association between smoke exposure and asthma ED visits on the same day. Elucidating these associations will help guide public health programs that address population-level exposure to smoke from prescribed burning.

Impacts of COVID-19's restriction measures on personal exposure to VOCs and aldehydes in Taipei City

The Coronavirus Disease 2019 (COVID-19) pandemic provided an unprecedented natural experiment, that allowed us to investigate the impacts of different restrictive measures on personal exposure to specific volatile organic compounds (VOCs) and aldehydes and resulting health risks in the city. Ambient concentrations of the criteria air pollutants were also evaluated. Passive sampling for VOCs and aldehydes was conducted for graduate students and ambient air in Taipei, Taiwan, during the Level 3 warning (strict control measures) and Level 2 alert (loosened control measures) of the COVID-19 pandemic in 2021-2022. Information on the daily activities of participants and on-road vehicle counts nearby the stationary sampling site during the sampling campaigns were recorded. Generalized estimating equations (GEE) with adjusted meteorological and seasonal variables were used to estimate the effects of control measures on average personal exposures to the selected air pollutants. Our results showed that ambient CO and NO2 concentrations in relation to on-road transportation emissions were significantly reduced, which led to an increase in ambient O3 concentrations. Exposure to specific VOCs (benzene, methyl tert-butyl ether (MTBE), xylene, ethylbenzene, and 1,3-butadiene) associated with automobile emissions were remarkably decreased by ~40-80 % during the Level 3 warning, resulting in 42 % and 50 % reductions of total incremental lifetime cancer risk (ILCR) and hazard index (HI), respectively, compared with the Level 2 alert. In contrast, the exposure concentration and calculated health risks in the selected population for formaldehyde increased by ~25 % on average during the Level 3 warning. Our study improves knowledge of the influence of a series of anti-COVID-19 measures on personal exposure to specific VOCs and aldehydes and its mitigations.

Monitoring vs. modeled exposure data in time-series studies of ambient air pollution and acute health outcomes

BACKGROUND

Population-based short-term air pollution health studies often have limited spatiotemporally representative exposure data, leading to concerns of exposure measurement error.

OBJECTIVE

To compare the use of monitoring and modeled exposure metrics in time-series analyses of air pollution and cardiorespiratory emergency department (ED) visits.

METHODS

We obtained daily counts of ED visits for Atlanta, GA during 2009-2013. We leveraged daily ZIP code level concentration estimates for eight pollutants from nine exposure metrics. Metrics included central monitor (CM), monitor-based (inverse distance weighting, kriging), model-based [community multiscale air quality (CMAQ), land use regression (LUR)], and satellite-based measures. We used Poisson models to estimate air pollution health associations using the different exposure metrics. The approach involved: (1) assessing CM-based associations, (2) determining if non-CM metrics can reproduce CM-based associations, and (3) identifying potential value added of incorporating full spatiotemporal information provided by non-CM metrics.

RESULTS

Using CM exposures, we observed associations between cardiovascular ED visits and carbon monoxide, nitrogen dioxide, fine particulate matter, elemental and organic carbon, and between respiratory ED visits and ozone. Non-CM metrics were largely able to reproduce CM-based associations, although some unexpected results using CMAQ- and LUR-based metrics reduced confidence in these data for some spatiotemporally-variable pollutants. Associations with nitrogen dioxide and sulfur dioxide were only detected, or were stronger, when using metrics that incorporate all available monitoring data (i.e., inverse distance weighting and kriging).

SIGNIFICANCE

The use of routinely-collected ambient monitoring data for exposure assignment in time-series studies of large metropolitan areas is a sound approach, particularly when data from multiple monitors are available. More sophisticated approaches derived from CMAQ, LUR, or satellites may add value when monitoring data are inadequate and if paired with thorough data characterization. These results are useful for interpretation of existing literature and for improving exposure assessment in future studies.

IMPACT STATEMENT

This study compared and interpreted the use of monitoring and modeled exposure metrics in a daily time-series analysis of air pollution and cardiorespiratory emergency department visits. The results suggest that the use of routinely-collected ambient monitoring data in population-based short-term air pollution and health studies is a sound approach for exposure assignment in large metropolitan regions. CMAQ-, LUR-, and satellite-based metrics may allow for health effects estimation when monitoring data are sparse, if paired with thorough data characterization. These results are useful for interpretation of existing health effects literature and for improving exposure assessment in future air pollution epidemiology studies.

Volatile Hydrocarbon Exposures and Incident Coronary Heart Disease Events: Up to Ten Years of Follow-up among Deepwater Horizon Oil Spill Workers

BACKGROUND

During the 2010 Deepwater Horizon (DWH) disaster, response and cleanup workers were potentially exposed to toxic volatile components of crude oil. However, to our knowledge, no study has examined exposure to individual oil spill-related chemicals in relation to cardiovascular outcomes among oil spill workers.

OBJECTIVES

Our aim was to investigate the association of several spill-related chemicals [benzene, toluene, ethylbenzene, xylene, n-hexane (BTEX-H)] and total hydrocarbons (THC) with incident coronary heart disease (CHD) events among workers enrolled in a prospective cohort.

METHODS

Cumulative exposures to THC and BTEX-H across the cleanup period were estimated via a job-exposure matrix that linked air measurement data with self-reported DWH spill work histories. We ascertained CHD events following each worker's last day of cleanup work as the first self-reported physician-diagnosed myocardial infarction (MI) or a fatal CHD event. We estimated hazard ratios (HR) and 95% confidence intervals for the associations of exposure quintiles (Q) with risk of CHD. We applied inverse probability weights to account for bias due to confounding and loss to follow-up. We used quantile g-computation to assess the joint effect of the BTEX-H mixture.

RESULTS

Among 22,655 workers with no previous MI diagnoses, 509 experienced an incident CHD event through December 2019. Workers in higher quintiles of each exposure agent had increased CHD risks in comparison with the referent group (Q1) of that agent, with the strongest associations observed in Q5 (range of HR = 1.14 - 1.44 ). However, most associations were nonsignificant, and there was no evidence of exposure-response trends. We observed stronger associations among ever smokers, workers with ≤ high school education, and workers with body mass index < 30   kg / m 2 . No apparent positive association was observed for the BTEX-H mixture.

CONCLUSIONS

Higher exposures to volatile components of crude oil were associated with modest increases in risk of CHD among oil spill workers, although we did not observe exposure-response trends. https://doi.org/10.1289/EHP11859.

Hospitalisations for cardiovascular and respiratory disease among older adults living near unconventional natural gas development: a difference-in-differences analysis

BACKGROUND

During 2008-15, the Marcellus shale region of the US state of Pennsylvania experienced a boom in unconventional natural gas development (UNGD) or "fracking". However, despite much public debate, little is known about the effects of UNGD on population health in local communities. Among other mechanisms, air pollution from UNGD might affect individuals living nearby through cardiovascular or respiratory disease, and older adults could be particularly susceptible.

METHODS

To study the health impacts of Pennsylvania's fracking boom, we exploited the ban on UNGD in neighbouring New York state. Using 2002-15 Medicare claims, we conducted difference-in-differences analyses over multiple timepoints to estimate the risk of living near UNGD for hospitalisation with acute myocardial infarction (AMI), chronic obstructive pulmonary disease (COPD) and bronchiectasis, heart failure, ischaemic heart disease, and stroke among older adults (aged ≥65 years).

FINDINGS

Pennsylvania ZIP codes that started UNGD in 2008-10 were associated with more hospitalisations for cardiovascular diseases in 2012-15 than would be expected in the absence of UNGD. Specifically, in 2015, we estimated an additional 11·8, 21·6, and 20·4 hospitalisations for AMI, heart failure, and ischaemic heart disease, respectively, per 1000 Medicare beneficiaries. Hospitalisations increased even as UNGD growth slowed. Results were robust in sensitivity analyses.

INTERPRETATION

Older adults living near UNGD could be at high risk of poor cardiovascular outcomes. Mitigation policies for existing UNGD might be needed to address current and future health risks. Future consideration of UNGD should prioritise local population health.

FUNDING

University of Chicago and Argonne National Laboratories.

Triggering of ST-elevation myocardial infarction by ultrafine particles in New York: Changes following Tier 3 vehicle introduction

BACKGROUND

Previously, we found increased rates of ST-elevation myocardial infarction (STEMI) associated with increased ultrafine particle (UFP; <100 nm) concentrations in the previous few hours in Rochester, New York. Relative rates were higher after air quality policies and a recession reduced pollutant concentrations (2014-2016 versus 2005-2013), suggesting PM composition had changed and the same PM mass concentration had become more toxic. Tier 3 light duty vehicles, which should produce less primary organic aerosols and oxidizable gaseous compounds, likely making PM less toxic, were introduced in 2017. Thus, we hypothesized we would observe a lower relative STEMI rate in 2017-2019 than 2014-2016.

METHODS

Using STEMI events treated at the University of Rochester Medical Center (2014-2019), UFP and other pollutants measured in Rochester, a case-crossover design, and conditional logistic regression models, we estimated the rate of STEMI associated with increased UFP and other pollutants in the previous hours and days in the 2014-2016 and 2017-2019 periods.

RESULTS

An increased rate of STEMI was associated with each 3111 particles/cm³ increase in UFP concentration in the previous hour in 2014-2016 (lag hour 0: OR = 1.22; 95% CI = 1.06, 1.39), but not in 2017-2019 (OR = 0.94; 95% CI = 0.80, 1.10). There were similar patterns for black carbon, UFP_11-50nm, and UFP_51-100nm. In contrast, increased rates of STEMI were associated with each 0.6 ppb increase in SO₂ concentration in the previous 120 h in both periods (2014-2016: OR = 1.26, 95% CI = 1.03, 1.55; 2017-2019: OR = 1.21, 95% CI = 0.87, 1.68).

CONCLUSIONS

Greater rates of STEMI were associated with short term increases in concentrations of UFP and other motor vehicle related pollutants before Tier 3 introduction (2014-2016), but not afterwards (2017-2019). This change may be due to changes in PM composition after Tier 3 introduction, as well as to increased exposure misclassification and greater underestimation of effects from 2017 to 2019.

Effects of Benzene: Hematological and Hypersensitivity Manifestations in Resident Living in Oil Refinery Areas

Literature is teeming with publications on industrial pollution. Over the decades, the main industrial pollutants and their effects on human health have been widely framed. Among the various compounds involved, benzene plays a leading role in the onset of specific diseases. Two systems are mainly affected by the adverse health effects of benzene exposure, both acute and chronic: the respiratory and hematopoietic systems. The most suitable population targets for a proper damage assessment on these systems are oil refinery workers and residents near refining plants. Our work fits into this area of interest with the aim of reviewing the most relevant cases published in the literature related to the impairment of the aforementioned systems following benzene exposure. We perform an initial debate between the two clinical branches that see a high epidemiological expression in this slice of the population examined: residents near petroleum refinery areas worldwide. In addition, the discussion expands on highlighting the main immunological implications of benzene exposure, finding a common pathophysiological denominator in inflammation, oxidative stress, and DNA damage, thus helping to set the basis for an increasingly detailed characterization aimed at identifying common molecular patterns between the two clinical fields discussed.

Acute effects of ambient non-methane hydrocarbons on cardiorespiratory hospitalizations: A multicity time-series study in Taiwan

BACKGROUND

Few environmental epidemiological studies and no large multicity studies have evaluated the acute short-term health effects of ambient non-methane hydrocarbons (NMHC), the essential precursors of ground-level ozone and secondary organic aerosol formation.

OBJECTIVE

We conducted this multicity time-series study in Taiwan to evaluate the association between airborne NMHC exposure and cardiorespiratory hospital admissions.

METHODS

We collected the daily mean concentrations of NMHC, fine particulate matter (PM2.5), ozone (O3), weather conditions, and daily hospital admission count for cardiorespiratory diseases between 2014 and 2017 from eight major cities of Taiwan. We applied an over-dispersed generalized additive Poisson model (GAM) with adjustment for temporal trends, seasonal variations, weather conditions, and calendar effects to compute the effect estimate for each city. Then we conducted a random-effects meta-analysis to pool the eight city-specific effect estimates to obtain the overall associations of NMHC exposure on lag0 day with hospital admissions for respiratory and circulatory diseases, respectively.

RESULTS

On average, a 0.1-ppm increase of lag0 NMHC demonstrated an overall 0.9% (95% CI: 0.4-1.3%) and 0.8% (95% CI: 0.4-1.2%) increment of hospital admissions for respiratory and circulatory diseases, respectively. Further analyses with adjustment for PM2.5 and O3 in the multi-pollutant model or sensitivity analyses with restricting the NMHC monitoring from the general stations only confirmed the robustness of the association between ambient NMHC exposure and cardiorespiratory hospitalizations.

CONCLUSION

Our findings provide robust evidence of higher cardiorespiratory hospitalizations in association with acute exposure to ambient NMHC in eight major cities of Taiwan.

Flory-Huggins VOC Photonics Sensor Made of Cellulose Derivatives

As a widespread air pollutant, volatile organic compounds (VOCs) are harmful to the human body's skin, nervous system, and respiratory system. Low-cost, extensive, and continuous detection of VOCs is of great significance to human health. We infiltrated and coated cellulose acetate on the inverse opal photonic crystal skeleton of methylcellulose-polyvinyl alcohol-graphene oxide to construct a degradable, high-toughness cellulose VOC sensor. Cellulose acetate enhances the response to VOCs and achieves a highly selective response to acetone vapor due to the smaller Flory-Huggins parameter with acetone. This work proposes a general, simple, easy-to-use, and highly selective photonic crystal VOC sensor development strategy. Calculated from the Flory-Huggins solution theory, a suitable polymer was selected to modify the inverse opal photonic crystal framework and achieve high selectivity detection.

Environmental exposure to volatile organic compounds is associated with endothelial injury

OBJECTIVE

Volatile organic compounds (VOCs) are airborne toxicants abundant in outdoor and indoor air. High levels of VOCs are also present at various Superfund and other hazardous waste sites; however, little is known about the cardiovascular effects of VOCs. We hypothesized that ambient exposure to VOCs exacerbate cardiovascular disease (CVD) risk by depleting circulating angiogenic cells (CACs).

APPROACH AND RESULTS

In this cross-sectional study, we recruited 603 participants with low-to-high CVD risk and measured 15 subpopulations of CACs by flow cytometry and 16 urinary metabolites of 12 VOCs by LC/MS/MS. Associations between CAC and VOC metabolite levels were examined using generalized linear models in the total sample, and separately in non-smokers. In single pollutant models, metabolites of ethylbenzene/styrene and xylene, were negatively associated with CAC levels in both the total sample, and in non-smokers. The metabolite of acrylonitrile was negatively associated with CD45^dim/CD146⁺/CD34⁺/AC133⁺ cells and CD45⁺/CD146⁺/AC133⁺, and the toluene metabolite with AC133⁺ cells. In analysis of non-smokers (n = 375), multipollutant models showed a negative association with metabolites of ethylbenzene/styrene, benzene, and xylene with CD45^dim/CD146⁺/CD34⁺ cells, independent of other VOC metabolite levels. Cumulative VOC risk score showed a strong negative association with CD45^dim/CD146⁺/CD34⁺ cells, suggesting that total VOC exposure has a cumulative effect on pro-angiogenic cells. We found a non-linear relationship for benzene, which showed an increase in CAC levels at low, but depletion at higher levels of exposure. Sex and race, hypertension, and diabetes significantly modified VOC associated CAC depletion.

CONCLUSION

Low-level ambient exposure to VOCs is associated with CAC depletion, which could compromise endothelial repair and angiogenesis, and exacerbate CVD risk.

Generating Data Visualizations of Longitudinal Cohort Ambient Air Pollution Exposure: Report-Back Intervention Development in Participatory Action Research

A civic engagement and data science design was used to develop a report-back intervention to address stakeholder concerns related to air emissions surrounding a coke oven factory near Buffalo, NY. This factory had historically emitted high levels of benzene pollution and ceased operation in October 2018 because of violations of the US Clean Air Act and US Resource Conservation and Recovery Act. Using publicly available air pollution and weather data, descriptive time series and wind-rose data visualizations were developed using open-source software as part of a two-page report-back brief. Data from two air toxics monitoring sites in this direction suggest that industrial sources were likely the major contributor to the benzene in the air at these locations prior to May 2018, after which traffic emissions became the likely major contributor. Wind-rose visualizations demonstrated that the wind typically blew toward the northeast, which was qualitatively consistent with locations of stakeholder concerns. With the factory closed, collective efforts subsequently shifted to address traffic emission air pollution sources, factory site cleanup, and ground and water pollution mitigation. Because this intervention utilized open-source software and publicly available data, it can serve as a blueprint for future data-driven nursing interventions and community-led environmental justice efforts.

Combined adjuvant effects of ambient vapor-phase organic components and particulate matter potently promote allergic sensitization and Th2-skewing cytokine and chemokine milieux in mice: The importance of mechanistic multi-pollutant research

Although exposure to ambient particulate matter (PM) is linked to asthma, the health effects of co-existing vapor-phase organic pollutants (vapor) and their combined effects with PM on this disease are poorly understood. We used a murine asthma model to test the hypothesis that exposure to vapor would enhance allergic sensitization and this effect would be further strengthened by co-existing PM. We found that vapor and PM each individually exerted adjuvant effects on OVA sensitization. Co-exposure to vapor and PM during sensitization further enhanced allergic lung inflammation and OVA-specific antibody production which was accompanied by pulmonary cytokine/chemokine milieu that favored T-helper 2 immunity (i.e. increased IL-4, downregulation of Il12a and Ifng, and upregulation of Ccl11 and Ccl8). TNFα, IL-6, Ccl12, Cxcl1 and detoxification/antioxidant enzyme responses in the lung were pollutant-dependent. Inhibition of lipopolysaccharide-induced IL-12 secretion from primary antigen-presenting dendritic cells correlated positively with vapor's oxidant potential. In conclusion, concurrent exposure to vapor and PM led to significantly exaggerated adjuvant effects on allergic lung inflammation which were more potent than that of each pollutant type alone. These findings suggest that the effects of multi-component air pollution on asthma may be significantly underestimated if research only focuses on a single air pollutant (e.g., PM).

Machine learning-driven identification of early-life air toxic combinations associated with childhood asthma outcomes

Air pollution is a well-known contributor to asthma. Air toxics are hazardous air pollutants that cause or may cause serious health effects. Although individual air toxics have been associated with asthma, only a limited number of studies have specifically examined combinations of air toxics associated with the disease. We geocoded air toxic levels from the US National Air Toxics Assessment (NATA) to residential locations for participants of our AiRway in Asthma (ARIA) study. We then applied Data-driven ExposurE Profile extraction (DEEP), a machine learning-based method, to discover combinations of early-life air toxics associated with current use of daily asthma controller medication, lifetime emergency department visit for asthma, and lifetime overnight hospitalization for asthma. We discovered 20 multi-air toxic combinations and 18 single air toxics associated with at least 1 outcome. The multi-air toxic combinations included those containing acrylic acid, ethylidene dichloride, and hydroquinone, and they were significantly associated with asthma outcomes. Several air toxic members of the combinations would not have been identified by single air toxic analyses, supporting the use of machine learning-based methods designed to detect combinatorial effects. Our findings provide knowledge about air toxic combinations associated with childhood asthma.

Sensors for Context-Aware Smart Healthcare: A Security Perspective

The advances in the miniaturisation of electronic devices and the deployment of cheaper and faster data networks have propelled environments augmented with contextual and real-time information, such as smart homes and smart cities. These context-aware environments have opened the door to numerous opportunities for providing added-value, accurate and personalised services to citizens. In particular, smart healthcare, regarded as the natural evolution of electronic health and mobile health, contributes to enhance medical services and people's welfare, while shortening waiting times and decreasing healthcare expenditure. However, the large number, variety and complexity of devices and systems involved in smart health systems involve a number of challenging considerations to be considered, particularly from security and privacy perspectives. To this aim, this article provides a thorough technical review on the deployment of secure smart health services, ranging from the very collection of sensors data (either related to the medical conditions of individuals or to their immediate context), the transmission of these data through wireless communication networks, to the final storage and analysis of such information in the appropriate health information systems. As a result, we provide practitioners with a comprehensive overview of the existing vulnerabilities and solutions in the technical side of smart healthcare.

Short-term exposure to fine particulate air pollution and emergency department visits for kidney diseases in the Atlanta metropolitan area

Toxicological evidence has shown that fine particulate matter (PM_2.5) may affect distant organs, including kidneys, over the short term. However, epidemiological evidence is limited.

OBJECTIVES

We investigated associations between short-term exposure to PM_2.5, major PM_2.5 components [elemental carbon (EC), organic carbon (OC), sulfate, and nitrate], and gaseous co-pollutants (O₃, CO, SO₂, NO₂, and NO_x) and emergency department (ED) visits for kidney diseases during 2002-2008 in Atlanta, Georgia.

METHODS

Log-linear time-series models were fitted to estimate the acute effects of air pollution, with single-day and unconstrained distributed lags, on rates of ED visits for kidney diseases [all renal diseases and acute renal failure (ARF)], controlling for meteorology (maximum air and dew-point temperatures) and time (season, day of week, holidays, and long-term time trend).

RESULTS

For all renal diseases, we observed positive associations for most air pollutants, particularly 8-day cumulative exposure to OC [rate ratio (RR) = 1.018, (95% confidence interval [CI]: 1.003, 1.034)] and EC [1.016 (1.000, 1.031)] per interquartile range increase exposure. For ARF, we observed positive associations particularly for 8-day exposure to OC [1.034 (1.005, 1.064)], EC [1.032 (1.002, 1.063)], nitrate [1.032 (0.996, 1.069)], and PM_2.5 [1.026 (0.997, 1.057)] per interquartile range increase exposure. We also observed positive associations for most criteria gases. The RR estimates were generally higher for ARF than all renal diseases.

CONCLUSIONS

We observed positive associations between short-term exposure to fine particulate air pollution and kidney disease outcomes. This study adds to the growing epidemiological evidence that fine particles may impact distant organs (e.g., kidneys) over the short term.

Association of cardiorespiratory hospital admissions with ambient volatile organic compounds: Evidence from a time-series study in Taipei, Taiwan

As important precursors of ozone and secondary organic aerosols, the harmful impact of exposure to ambient volatile organic compounds (VOCs) is of public health interest. However, few studies have investigated the health risks of numerous individual VOC species. This study linked the daily concentrations of 54 C2-C11 VOC species monitored from the Wanhua Photochemical Assessment Monitoring Station and hospital admissions for cardiorespiratory diseases in Taipei, Taiwan, from the National Health Insurance Research Database. A standard time-series approach entailing a series of sensitivity analyses was applied to investigate the short-term health risks of exposure to VOC subgroups and species. Consistent associations of all VOC subgroups and main species with chronic obstructive pulmonary disease (COPD) hospitalizations were demonstrated. In addition, associations of the C5-C6 alkanes, C2-C3 alkenes, toluene, and xylene with asthma hospitalizations were found, as were associations of aromatic hydrocarbons with hospitalizations for heart failure. An interquartile range increase in total VOC exposure at lag0 day (102.6 parts per billion carbon) was associated with increments of 1.84% (95% confidence interval: 0.54%-3.15%), 1.65% (0.71%-2.60%), and 1.21% (0.36%-2.07%) in hospitalizations for asthma, COPD, and heart failure, respectively. The effect estimates were robust with data excluding extreme values, the second pollutant adjustment for PM_2.5 and O₃, and the Bonferroni correction. The associations of ambient VOC exposure with cardiorespiratory hospitalizations in Taipei serve as a reference for VOC regulations and ozone control strategies.

Volatile organic compounds in an e-waste dismantling region: From spatial-seasonal variation to human health impact

The dismantling of electrical and electronic waste (e-waste) can release various Volatile organic compounds (VOCs), impacting the surrounding ambient environment. We investigated the spatio-temporal characteristics and health risks of the ambient VOCs emitted in a typical e-waste dismantling region by conducting multi-site sampling campaigns in four seasons. The pollution of benzene, toluene, ethylbenzene, and xylenes (BTEX) in the e-waste dismantling park has relation to e-waste dismantling by seasonal trend analysis. The highest concentrations of most VOCs occurred in winter and autumn, while the lowest levels were observed in summer and spring. The spatial distribution map revealed the e-waste dismantling park to be a hotspot of BTEX, 1,2-dichloropropane (1,2-DCP), and 1,2-dichloroethane (1,2-DCA), while two major residential areas were also the hotspots of BTEX. The e-waste emission source contributed 20.14% to the total VOCs in the e-waste dismantling park, while it was absent in the major residential and rural areas. The cancer risk assessment showed that six VOCs exceeded 1.0 × 10^-6 in the e-waste dismantling park, while only three or four compounds exceeded this risk in other areas. The noncancer risks of all compounds were below the safety threshold. This study supplements the existing knowledge on VOC pollution from e-waste dismantling and expands the research scope of chemical pollution caused by e-waste.

INTEGRATIVE STATISTICAL METHODS FOR EXPOSURE MIXTURES AND HEALTH

Humans are concurrently exposed to chemically, structurally and toxicologically diverse chemicals. A critical challenge for environmental epidemiology is to quantify the risk of adverse health outcomes resulting from exposures to such chemical mixtures and to identify which mixture constituents may be driving etiologic associations. A variety of statistical methods have been proposed to address these critical research questions. However, they generally rely solely on measured exposure and health data available within a specific study. Advancements in understanding of the role of mixtures on human health impacts may be better achieved through the utilization of external data and knowledge from multiple disciplines with innovative statistical tools. In this paper we develop new methods for health analyses that incorporate auxiliary information about the chemicals in a mixture, such as physicochemical, structural and/or toxicological data. We expect that the constituents identified using auxiliary information will be more biologically meaningful than those identified by methods that solely utilize observed correlations between measured exposure. We develop flexible Bayesian models by specifying prior distributions for the exposures and their effects that include auxiliary information and examine this idea over a spectrum of analyses from regression to factor analysis. The methods are applied to study the effects of volatile organic compounds on emergency room visits in Atlanta. We find that including cheminformatic information about the exposure variables improves prediction and provides a more interpretable model for emergency room visits for respiratory diseases.

Source-Apportioned PM2.5 and Cardiorespiratory Emergency Department Visits: Accounting for Source Contribution Uncertainty

BACKGROUND

Despite evidence suggesting that air pollution-related health effects differ by emissions source, epidemiologic studies on fine particulate matter (PM2.5) infrequently differentiate between particles from different sources. Those that do rarely account for the uncertainty of source apportionment methods.

METHODS

For each day in a 12-year period (1998-2010) in Atlanta, GA, we estimated daily PM2.5 source contributions from a Bayesian ensemble model that combined four source apportionment methods including chemical transport and receptor-based models. We fit Poisson generalized linear models to estimate associations between source-specific PM2.5 concentrations and cardiorespiratory emergency department visits (n = 1,598,117). We propagated uncertainty in the source contribution estimates through analyses using multiple imputation.

RESULTS

Respiratory emergency department visits were positively associated with biomass burning and secondary organic carbon. For a 1 µg/m increase in PM2.5 from biomass burning during the past 3 days, the rate of visits for all respiratory outcomes increased by 0.4% (95% CI 0.0%, 0.7%). There was less evidence for associations between PM2.5 sources and cardiovascular outcomes, with the exception of ischemic stroke, which was positively associated with most PM2.5 sources. Accounting for the uncertainty of source apportionment estimates resulted, on average, in an 18% increase in the standard error for rate ratio estimates for all respiratory and cardiovascular emergency department visits, but inflation varied across specific sources and outcomes, ranging from 2% to 39%.

CONCLUSIONS

This study provides evidence of associations between PM2.5 sources and some cardiorespiratory outcomes and quantifies the impact of accounting for variability in source apportionment approaches.

Source-Specific Volatile Organic Compounds and Emergency Hospital Admissions for Cardiorespiratory Diseases

Knowledge gaps remain regarding the cardiorespiratory impacts of ambient volatile organic compounds (VOCs) for the general population. This study identified contributing sources to ambient VOCs and estimated the short-term effects of VOC apportioned sources on daily emergency hospital admissions for cardiorespiratory diseases in Hong Kong from 2011 to 2014. We estimated VOC source contributions using fourteen organic chemicals by positive matrix factorization. Then, we examined the associations between the short-term exposure to VOC apportioned sources and emergency hospital admissions for cause-specific cardiorespiratory diseases using generalized additive models with polynomial distributed lag models while controlling for meteorological and co-pollutant confounders. We identified six VOC sources: gasoline emissions, liquefied petroleum gas (LPG) usage, aged VOCs, architectural paints, household products, and biogenic emissions. We found that increased emergency hospital admissions for chronic obstructive pulmonary disease were positively linked to ambient VOCs from gasoline emissions (excess risk (ER%): 2.1%; 95% CI: 0.9% to 3.4%), architectural paints (ER%: 1.5%; 95% CI: 0.2% to 2.9%), and household products (ER%: 1.5%; 95% CI: 0.2% to 2.8%), but negatively associated with biogenic VOCs (ER%: -6.6%; 95% CI: -10.4% to -2.5%). Increased congestive heart failure admissions were positively related to VOCs from architectural paints and household products in cold seasons. This study suggested that source-specific VOCs might trigger the exacerbation of cardiorespiratory diseases.

Association of ambient non-methane hydrocarbons exposure with respiratory hospitalizations: A time series study in Taipei, Taiwan

Ambient hydrocarbons are important precursors of ground-level ozone and secondary organic aerosol formation. However, few studies have assessed the health impact of airborne hydrocarbons. We conducted this time series ecological study to evaluate the association of short-term airborne hydrocarbons exposure with hospital admissions for respiratory diseases, while controlling for co-exposure to criteria pollutants. Taipei air pollution and weather data for the period spanning from January 2010 to December 2017 were obtained from Taiwan Air Quality Monitoring Network. Subsequently, daily pollutant concentrations were linked with daily hospital admission counts for respiratory diseases into a time series data frame. The standard generalized additive Poisson model adjusted for temporal trends, seasonal variations, weather conditions, and calendar effects, was applied to examine the short-term associations of acute airborne hydrocarbon exposure with respiratory hospital admissions. Next, the robustness of the associations was tested using two-pollutant models with further adjustment for fine particulate matter (PM_2.5) and gaseous pollutants. The results demonstrated that an interquartile range increase in non-methane hydrocarbon (NMHC) exposure on lag0 day (0.15 ppm) was associated with a 0.86% (95% confidence interval: 0.37%-1.36%), 2.06% (0.77%-3.38%), and 1.25% (0.31%-2.20%) increment in all-respiratory-disease-, asthma-, and chronic-obstructive-pulmonary-disease-linked hospital admissions, respectively. The associations were robust with further adjustment for co-exposure to PM_2.5 and ozone. The acute effect estimate of methane on each respiratory category was sensitive to the co-pollutant adjustment and lost statistical significance in the two-pollutant models. In conclusion, we confirmed that airborne NMHC exposure increased the risk of respiratory-disease-related hospital admissions in Taipei; this information may aid in the regulation of hydrocarbon pollution.

Automobile exhaust-derived PM2.5 induces blood-testis barrier damage through ROS-MAPK-Nrf2 pathway in sertoli cells of rats

Particulate matter with an aerodynamic diameter of less than 2.5 μm (PM_2.5) derived from automobile exhaust can lead to serious male spermatogenesis dysfunction, but its specific molecular mechanism is unclear. In this experiment, we focused on the blood-testis barriers (BTB) and explored the intracellular mechanisms underlying the fertility toxicity of PM_2.5 originating from automobile exhaust in the primary cultured Sertoli cells(SCs) of rats. After PM_2.5 exposure, excessive reactive oxygen species (ROS) and increased apoptosis of SCs were detected. The expression of the BTB related proteins including ZO-1, Occludin, N-cadherin and β-catenin were significantly decreased and the spatial arrangement of F-actin was completely disordered through Immunofluorescence and Western blots tests. The phosphorylation of Jun N-terminal kinase (JNK), extracellular signal regulatory kinase (ERK), p38 mitogen-activated protein kinase (MAPK) were upregulated and nuclear factor (erythroid-derived 2) -like 2-related factor (Nrf2) was downregulated respectively. However, combined utilization of vitamin C and E were observed to prevent the increase of ROS generation, reduce celluar apoptosis, increase the expression of BTB related proteins, reconstructed the spatial arrangement of F-actin as well as improved the Nrf2 expression and attenuated the phosphorylation of the MAPK kinases and cleaved caspase-3 levels. Furthermore, ERK inhibitor (SCH772984), JNK inhibitor (SP600125) and p38 MAPK inhibitor (SB203580) obviously up-regulated BTB-related proteins expression as well as activated Nrf2 expression at varying degrees, indicating that ROS-MAPKs-Nrf2 is involved in the signaling pathway that leads to PM_2.5-induced spermatogenesis dysfunction. These findings indicate that PM_2.5 derived from automobile exhaust causes oxidative stress, which in turn causes cellular apoptosis of SCs and damage of the blood-testis barrier, resulting male spermatogenesis dysfunction, in which ROS-MAPK-Nrf-2 pathways may play a key role.

A randomized, double-blind, crossover intervention study of traffic-related air pollution and airway inflammation in healthy adults

Supplemental Digital Content is available in the text.

Background:

Traffic-related air pollution (TRAP) may increase the risk of respiratory disease. The components of TRAP that are responsible for its respiratory toxicity are largely unknown. The objective was to identify the component(s) of TRAP that cause airways inflammation using fractional exhaled nitric oxide (FE_NO) and randomized interventions.

Methods:

A randomized, double-blind, crossover intervention study was conducted in which 39 healthy university students spent 2 hours next to a busy road. During exposure, participants wore either a powered air-purifying respirator (PAPR) or an N95 facemask. PAPRs were fitted with a fine particle (PM_2.5) filter, a PM_2.5 and volatile organic carbon (VOC) filter, or a sham filter, and were blinded to filter type. The four interventions (three PAPR filters and N95) were assigned randomly for each participant and separated by at least 1 week. FE_NO was measured before and immediately after each roadside exposure, and at 1, 2, 4, and 6 hours after exposure.

Results:

With the sham PAPR filter, the mean postexposure FE_NO increased an average of 2.3 ppb (±4.4) compared with the pre-exposure level. Similar increases in FE_NO were seen with both the PM_2.5 PAPR filter and the N95 mask, but no increase was seen with the combination PM_2.5 and VOC PAPR filter.

Conclusions:

Because PAPR filters do not filter inorganic gases (e.g., NO₂ or carbon monoxide), it is concluded that the VOC component of TRAP rather than either the particulate matter or the inorganic gases component is responsible for the airway inflammation caused by TRAP exposure.

Impact of air pollution control policies on cardiorespiratory emergency department visits, Atlanta, GA, 1999-2013

BACKGROUND

Air pollution control policies resulting from the 1990 Clean Air Act Amendments were aimed at reducing pollutant emissions, ambient concentrations, and ultimately adverse health outcomes.

OBJECTIVES

As part of a comprehensive air pollution accountability study, we used a counterfactual study design to estimate the impact of mobile source and electricity generation control policies on health outcomes in the Atlanta, GA, metropolitan area from 1999 to 2013.

METHODS

We identified nine sets of pollution control policies, estimated changes in emissions in the absence of these policies, and employed those changes to estimate counterfactual daily ambient pollutant concentrations at a central monitoring location. Using a multipollutant Poisson time-series model, we estimated associations between observed pollutant levels and daily counts of cardiorespiratory emergency department (ED) visits at Atlanta hospitals. These associations were then used to estimate the number of ED visits prevented due to control policies, comparing observed to counterfactual daily concentrations.

RESULTS

Pollution control policies were estimated to substantially reduce ambient concentrations of the nine pollutants examined for the period 1999-2013. We estimated that pollutant concentration reductions resulting from the control policies led to the avoidance of over 55,000 cardiorespiratory disease ED visits in the five-county metropolitan Atlanta area, with greater proportions of visits prevented in later years as effects of policies became more fully realized. During the final two years of the study period, 2012-2013, the policies were estimated to prevent 16.5% of ED visits due to asthma (95% interval estimate: 7.5%, 25.1%), 5.9% (95% interval estimate: -0.4%, 12.3%) of respiratory ED visits, and 2.3% (95% interval estimate: -1.8%, 6.2%) of cardiovascular disease ED visits.

DISCUSSION

Pollution control policies resulting from the 1990 Clean Air Act Amendments led to substantial estimated reductions in ambient pollutant concentrations and cardiorespiratory ED visits in the Atlanta area.

Inhalation of Simulated Smog Atmospheres Affects Cardiac Function in Mice

The health effects of individual criteria air pollutants have been well investigated. However, little is known about the health effects of air pollutant mixtures that more realistically represent environmental exposures. The present study was designed to evaluate the cardiac effects of inhaled simulated smog atmospheres (SA) generated from the photochemistry of either gasoline and isoprene (SA-G) or isoprene (SA-Is) in mice. Four-month-old female mice were exposed for 4 h to filtered air (FA), SA-G, or SA-Is. Immediately and 20 h after exposure, cardiac responses were assessed with a Langendorff preparation using a protocol consisting of 20 min of global ischemia followed by 2 h of reperfusion. Cardiac function was measured by index of left-ventricular developed pressure (LVDP) and cardiac contractility (dP/dt) before ischemia. Pre-ischemic LVDP was lower in mice immediately after SA-Is exposure (52.2 ± 5.7 cm H₂O compared to 83.9 ± 7.4 cm H₂O after FA exposure; p = 0.008) and 20 h after SA-G exposure (54.0 ± 12.7 cm H₂O compared to 79.3 ± 7.4 cm H₂O after FA exposure; p = 0.047). Pre-ischemic left ventricular contraction dP/dt_max was lower in mice immediately after SA-Is exposure (2025 ± 169 cm H₂O/sec compared to 3044 ± 219 cm H₂O/sec after FA exposure; p < 0.05) and 20 h after SA-G exposure (1864 ± 328 cm H₂O/sec compared to 2650 ± 258 cm H₂O/sec after FA exposure; p = 0.05). In addition, SA-G reduced the coronary artery flow rate 20 h after exposure compared to the FA control. This study demonstrates that acute SA-G and SA-Is exposures decrease LVDP and cardiac contractility in mice, indicating that photochemically-altered atmospheres affect the cardiovascular system.

Relationships between indicators of cardiovascular disease and intensity of oil and natural gas activity in Northeastern Colorado

BACKGROUND

Oil and natural gas (O&G) extraction emits pollutants that are associated with cardiovascular disease, the leading cause of mortality in the United States.

OBJECTIVE

We evaluated associations between intensity of O&G activity and cardiovascular disease indicators.

METHODS

Between October 2015 and May 2016, we conducted a cross-sectional study of 97 adults living in Northeastern Colorado. For each participant, we collected 1-3 measurements of augmentation index, systolic and diastolic blood pressure (SBP and DBP), and plasma concentrations of interleukin (IL)- 1β, IL-6, IL-8 and tumor necrosis factor alpha (TNF-α). We modelled the intensity of O&G activity by weighting O&G well counts within 16 km of a participant's home by intensity and distance. We used linear models accounting for repeated measures within person to evaluate associations.

RESULTS

Adjusted mean augmentation index differed by 6.0% (95% CI: 0.6, 11.4%) and 5.1% (95%CI: -0.1, 10.4%) between high and medium, respectively, and low exposure tertiles. The greatest mean IL-1β, and α-TNF plasma concentrations were observed for participants in the highest exposure tertile. IL-6 and IL-8 results were consistent with a null result. For participants not taking prescription medications, the adjusted mean SBP differed by 6 and 1 mm Hg (95% CIs: 0.1, 13 mm Hg and -6, 8 mm Hg) between the high and medium, respectively, and low exposure tertiles. DBP results were similar. For participants taking prescription medications, SBP and DBP results were consistent with a null result.

CONCLUSIONS

Despite limitations, our results support associations between O&G activity and augmentation index, SBP, DBP, IL-1β, and TNF-α. Our study was not able to elucidate possible mechanisms or environmental stressors, such as air pollution and noise.

Species and release characteristics of VOCs in furniture coating process

Volatile organic compounds (VOCs) are an important factor affecting ambient air quality, and furniture production is one of the important sources of VOC pollution. High VOC concentrations have adverse effects on the environment and worker welfare in furniture factories. In order to control VOC emissions in a furniture workshop, the VOC species and concentration distributions were examined. Qualitative analysis of VOC species was carried out by headspace gas chromatography/mass spectrometry. The results showed that VOCs from a furniture workshop were mainly 12 substances including acetate, toluene, and xylene compounds. The heights and representative positions of VOCs released during the coating process were determined, and the results showed that VOC concentrations depended on environmental and height factors. The concentration of VOCs decreased with increasing altitude and reached a maximum concentration at 0.4 m above the ground. Because the concentration of VOCs varied with temperature, humidity, air pressure, and amount of spray paint, this paper established functional relationships between VOC concentrations and temperature, humidity, air pressure, and amount of spray paint. These results provide a theoretical basis for furniture workshops to automatically monitor and control VOCs. MAIN FINDING OF THIS WORK: VOCs from the furniture workshop were mainly composed of 10 substances including acetate, toluene, and xylene compounds.

Utilization of the Maryland Environmental Justice Screening Tool: A Bladensburg, Maryland Case Study

Maryland residents' knowledge of environmental hazards and their health effects is limited, partly due to the absence of tools to map and visualize distribution of risk factors across sociodemographic groups. This study discusses the development of the Maryland EJSCREEN (MD EJSCREEN) tool by the National Center for Smart Growth in partnership with faculty at the University of Maryland School of Public Health. The tool assesses environmental justice risks similarly to the U.S. Environmental Protection Agency's (USEPA) EJSCREEN tool and California's tool, CalEnviroScreen 3.0. We discuss the architecture and functionality of the tool, indicators of importance, and how it compares to USEPA's EJSCREEN and CalEnviroScreen. We demonstrate the use of MD EJSCREEN through a case study on Bladensburg, Maryland, a town in Prince George's County (PG) with several environmental justice concerns including air pollution from traffic and a concrete plant. Comparison reveals that environmental and demographic indicators in MD EJSCREEN most closely resemble those in EPA EJSCREEN, while the scoring is most similar to CalEnviroScreen. Case study results show that Bladensburg has a Prince George's environmental justice score of 0.99, and that National Air Toxics Assessment (NATA) air toxics cancer risk is concentrated in communities of color.

A multicity study of air pollution and cardiorespiratory emergency department visits: Comparing approaches for combining estimates across cities

Determining how associations between ambient air pollution and health vary by specific outcome is important for developing public health interventions. We estimated associations between twelve ambient air pollutants of both primary (e.g. nitrogen oxides) and secondary (e.g. ozone and sulfate) origin and cardiorespiratory emergency department (ED) visits for 8 specific outcomes in five U.S. cities including Atlanta, GA; Birmingham, AL; Dallas, TX; Pittsburgh, PA; St. Louis, MO. For each city, we fitted overdispersed Poisson time-series models to estimate associations between each pollutant and specific outcome. To estimate multicity and posterior city-specific associations, we developed a Bayesian multicity multi-outcome (MCM) model that pools information across cities using data from all specific outcomes. We fitted single pollutant models as well as models with multipollutant components using a two-stage chemical mixtures approach. Posterior city-specific associations from the MCM models were somewhat attenuated, with smaller standard errors, compared to associations from time-series regression models. We found positive associations of both primary and secondary pollutants with respiratory disease ED visits. There was some indication that primary pollutants, particularly nitrogen oxides, were also associated with cardiovascular disease ED visits. Bayesian models can help to synthesize findings across multiple outcomes and cities by providing posterior city-specific associations building on variation and similarities across the multiple sources of available information.

Are ambient volatile organic compounds environmental stressors for heart failure?

BACKGROUND

Numerous epidemiological studies have indicated the adverse cardiovascular effects of air pollution on heart failure (HF) risk. However, little data are available directly evaluating the association of ambient volatile organic compounds (VOCs) with HF risk. We aimed to estimate the short-term effects of ambient VOCs on HF emergency hospitalizations in Hong Kong and to evaluate whether the associations were modified by sex and age.

METHODS

We collected the daily VOCs concentrations from the Hong Kong Environmental Protection Department between April 2011 to December 2014. HF emergency hospital admission data were obtained from the Hospital Authority of Hong Kong. Generalized additive model (GAM) integrated with the distributed lag model (DLM) was used to estimate the excess risks of HF emergency hospitalizations with ambient concentrations of each VOCs groups - alkane, alkene, alkyne, benzene and substituted benzene.

RESULTS

We observed short-term effects of alkyne and benzene on an increased risk of HF emergency hospitalizations. The cumulative effect over 0-6 lag days (dlm_0-6) for an IQR increment of alkyne (1.17 ppb) was associated with 4.2% (95% CI: 1.18%-7.26%) increases of HF emergency hospitalizations, while the corresponding effect estimate over dlm_0-2 for benzene per IQR (0.43 ppb) was 2.7% (95% CI: 0.39%-5.04%). Each VOCs groups was significantly associated with HF emergency hospitalizations in men.

CONCLUSIONS

Ambient volatile organic compounds, particularly alkyne and benzene, were associated with increased risks of heart failure in the Hong Kong population.

Toward a panoramic perspective of the association between environmental factors and cardiovascular disease: An environment-wide association study from National Health and Nutrition Examination Survey 1999-2014

OBJECTIVES

An environment-wide association study (EWAS) may be useful to comprehensively test and validate associations between environmental factors and cardiovascular disease (CVD) in an unbiased manner.

APPROACH AND RESULTS

Data from National Health and Nutrition Examination Survey (1999-2014) were randomly 50:50 spilt into training set and testing set. CVD was ascertained by a self-reported diagnosis of myocardial infarction, coronary heart disease or stroke. We performed multiple linear regression analyses associating 203 environmental factors and 132 clinical phenotypes with CVD in training set (false discovery rate < 5%) and significant factors were validated in the testing set (P < 0.05). Random forest (RF) model was used for multicollinearity elimination and variable importance ranking. Discriminative power of factors for CVD was calculated by area under the receiver operating characteristic (AUROC). Overall, 43,568 participants with 4084 (9.4%) CVD were included. After adjusting for age, sex, race, body mass index, blood pressure and socio-economic level, we identified 5 environmental variables and 19 clinical phenotypes associated with CVD in training and testing dataset. Top five factors in RF importance ranking were: waist, glucose, uric acid, and red cell distribution width and glycated hemoglobin. AUROC of the RF model was 0.816 (top 5 factors) and 0.819 (full model). Sensitivity analyses reveal no specific moderators of the associations.

CONCLUSION

Our systematic evaluation provides new knowledge on the complex array of environmental correlates of CVD. These identified correlates may serve as a complementary approach to CVD risk assessment. Our findings need to be probed in further observational and interventional studies.

Short-term effects of ambient benzene and TEX (toluene, ethylbenzene, and xylene combined) on cardiorespiratory mortality in Hong Kong

BACKGROUND

Numerous epidemiological and experimental studies have demonstrated the detrimental effects of the criteria air pollutants on population health, including particulate matters, ozone, and nitrogen dioxide. However, evidence on health effects of benzene, toluene, ethylbenzene, and xylene (BTEX in short) is insufficient.

OBJECTIVES

The present study aimed to assess the exposure-lag-response relations of ambient BTEX components with cardiorespiratory mortality in Hong Kong population.

METHODS

Daily BTEX concentrations from April 2011 to December 2014 were collected from the Hong Kong Environmental Protection Department. Cause-specific mortality records were obtained from the Census and Statistics Department of Hong Kong. Generalized additive model (GAM) integrated with a distributed lag model (DLM) was used to estimate the excess risks of cardiorespiratory mortality associated with the cumulative exposure to benzene and TEX (toluene, ethylbenzene and xylene combined) over 0-9 lag days, while adjusting for time trend, seasonality, weather conditions and calendar effects.

RESULTS

We observed the delayed and distributed lag effects of BTEX components on circulatory mortality. The cumulative exposures over 0-9 lag days for IQR increments of benzene (1.4 μg/m³) and TEX (7.9 μg/m³) were associated with 5.8% (95%CI: 1.0% to 10.8%) and 3.5% (95%CI: 1.0% to 6.1%) increases in circulatory mortality, respectively. The effect estimates of benzene and TEX were more delayed than that of PM_2.5. We didn't observe any significant association of BTEX exposure on total and respiratory deaths.

CONCLUSIONS

Short-term elevations in ambient BTEX concentrations may trigger circulatory mortality in Hong Kong population.

Respiratory health of dust-exposed Congolese coltan miners

PURPOSE

In Democratic Republic of the Congo (DRC), informal coltan mining has been expanding amidst increased insecurity due to armed conflicts. We investigated the impact of occupational dust-exposure on the respiratory health of Congolese coltan miners.

METHODS

In total, 441 Congolese workers participated in this study, including 199 informal coltan miners and 242 office workers (controls). Information on respiratory complaints was collected using two standardized questionnaires. Physical examination (vital signs, auscultation) and lung function test (Peak Flow meter) were performed. In addition, workplace airborne PM2.5 and volatile organic compounds (VOC) concentrations were measured.

RESULTS

Higher airborne PM2.5 (range 180-210 µg/m³) and VOC (range 1.4-2.3 µg/m³) levels were detected at coltan mining work stations as compared with control sites (19-44 and 0.5-0.8 µg/m³, respectively). All respiratory complaints and disorders were more prevalent in informal coltan miners than in controls. Additionally, a markedly lower mean PEFR was observed in coltan miners than in controls (347.93 ± 6.88 vs. 493.23 ± 67.38 L/min, respectively). Moreover, positive associations between informal coltan mining and almost all respiratory complaints were observed, except wheezing at effort and night cough. On the other hand, an inverse association was observed between lung function (PEFR) and PM2.5 exposure, between PEFR and VOC exposure, and also between PEFR and current smoking.

CONCLUSIONS

This study showed high prevalence of respiratory complaints in Congolese informal coltan miners, suggesting the necessity to implement efficient occupational safety measures and regulate this informal mining business.

Impacts of Regulations on Air Quality and Emergency Department Visits in the Atlanta Metropolitan Area, 1999-2013

INTRODUCTION

The United States and Western Europe have seen great improvements in air quality, presumably in response to various regulations curtailing emissions from the broad range of sources that have contributed to local, regional, and global pollution. Such regulations, and the ensuing controls, however, have not come without costs, which are estimated at tens of billions of dollars per year. These costs motivate accountability-related questions such as, to what extent do regulations lead to emissions changes? More important, to what degree have the regulations provided the expected human health benefits?

Here, the impacts of specific regulations on both electricity generating unit (EGU) and on-road mobile sources are examined through the classical accountability process laid out in the 2003 Health Effects Institute report linking regulations to emissions to air quality to health effects, with a focus on the 1999-2013 period. This analysis centers on regulatory actions in the southeastern United States and their effects on health outcomes in the 5-county Atlanta metropolitan area. The regulations examined are largely driven by the 1990 Clean Air Act Amendments (C). This work investigates regulatory actions and controls promulgated on EGUs: the Acid Rain Program (ARP), the NOx Budget Trading Program (NBP), and the Clean Air Interstate Rule (CAIR) - and mobile sources: Tier 2 Gasoline Vehicle Standards and the 2007 Heavy Duty Diesel Rule.

METHODS

Each step in the classic accountability process was addressed using one or more methods. Linking regulations to emissions was accomplished by identifying major federal regulations and the associated state regulations, along with analysis of individual facility emissions and control technologies and emissions modeling (e.g., using the U.S. Environmental Protection Agency's [U.S. EPA's] MOtor Vehicle Emissions Simulator [MOVES] mobile-source model). Regulators, including those from state environmental and transportation agencies, along with the public service commissions, play an important role in implementing federal rules and were involved along with other regional stakeholders in the study. We used trend analysis, air quality modeling, satellite data, and a ratio-of-ratios technique to investigate a critical current issue, a potential large bias in mobile-source oxides of nitrogen (NOx) emissions estimates.

The second link, emissions-air quality relationships, was addressed using both empirical analyses as well as chemical transport modeling employing the Community Multiscale Air Quality (CMAQ) model. Kolmogorov-Zurbenko filtering accounting for day of the year was used to separate the air quality signal into long-term, seasonal, weekday-holiday, and short-term meteorological signals. Regression modeling was then used to link emissions and meteorology to ambient concentrations for each of the species examined (ozone [O3], particulate matter ≤ 2.5 μm in aerodynamic diameter [PM2.5], nitrogen dioxide [NO2], sulfur dioxide [SO2], carbon monoxide [CO], sulfate [SO4-2], nitrate [NO3-], ammonium [NH4+], organic carbon [OC], and elemental carbon [EC]). CMAQ modeling was likewise used to link emissions changes to air quality changes, as well as to further establish the relative roles of meteorology versus emissions change impacts on air quality trends. CMAQ and empirical modeling were used to investigate aerosol acidity trends, employing the ISORROPIA II thermodynamic equilibrium model to calculate pH based on aerosol composition. The relationships between emissions and meteorology were then used to construct estimated counterfactual air quality time series of daily pollutant concentrations that would have occurred in the absence of the regulations. Uncertainties in counterfactual air quality were captured by the construction of 5,000 pollutant time series using a Monte Carlo sampling technique, accounting for uncertainties in emissions and model parameters.

Health impacts of the regulatory actions were assessed using data on cardiorespiratory emergency department (ED) visits, using patient-level data in the Atlanta area for the 1999-2013 period. Four outcome groups were chosen based on previous studies identifying associations with ambient air pollution: a combined respiratory disease (RD) category; the subgroup of RD presenting with asthma; a combined cardiovascular disease (CVD) category; and the subgroup of CVD presenting with congestive heart failure (CHF).

Models were fit to estimate the joint effects of multiple pollutants on ED visits in a time-series framework, using Poisson generalized linear models accounting for overdispersion, with a priori model formulations for temporal and meteorological covariates and lag structures. Several parameterizations were considered for the joint-effects models, including different sets of pollutants and models with nonlinear pollutant terms and first-order interactions among pollutants. Use of different periods for parameter estimates was assessed, as associations between pollutant levels and ED visits varied over the study period. A 7-pollutant, nonlinear model with pollutant interaction terms was chosen as the baseline model and fitted using pollutant and outcome data from 1999-2005 before regulations might have substantially changed the toxicity of pollutant mixtures. In separate analyses, these models were fitted using pollutant and outcome data from the entire 1999-2013 study period. Daily counterfactual time series of pollutant concentrations were then input into the health models, and the differences between the observed and counterfactual concentrations were used to estimate the impacts of the regulations on daily counts of ED visits. To account for the uncertainty in both the estimation of the counterfactual time series of ambient pollutant levels and the estimation of the health model parameters, we simulated 5,000 sets of parameter estimates using a multivariate normal distribution based on the observed variance-covariance matrix, allowing for uncertainty at each step of the chain of accountability. Sensitivity tests were conducted to assess the robustness of the results.

RESULTS

EGU NOx and SO2 emissions in the Southeast decreased by 82% and 83%, respectively, between 1999 and 2013, while mobile-source emissions controls led to estimated decreases in Atlanta-area pollutant emissions of between 61% and 93%, depending on pollutant. While EGU emissions were measured, mobile-source emissions were modeled. Our results are supportive of a potential high bias in mobile-source NOx and CO emissions estimates. Air quality benefits from regulatory actions have increased as programs have been fully implemented and have had varying impacts over different seasons. In a scenario that accounted for all emissions reductions across the period, observed Atlanta central monitoring site maximum daily 8-hour (MDA8h) O3 was estimated to have been reduced by controls in the summertime and increased in the wintertime, with a change in mean annual MDA8h O3 from 39.7 ppb (counterfactual) to 38.4 ppb (observed). PM2.5 reductions were observed year-round, with average 2013 values at 8.9 μg/m3 (observed) versus 19.1 μg/m3 (counterfactual). Empirical and CMAQ analyses found that long-term meteorological trends across the Southeast over the period examined played little role in the distribution of species concentrations, while emissions changes explained the decreases observed. Aerosol pH, which plays a key role in aerosol formation and dynamics and may have health implications, was typically very low (on the order of 1-2, but sometimes much lower), with little trend over time despite the stringent SO2 controls and SO42- reductions.

Using health models fit from 1999-2005, emissions reductions from all selected pollution-control policies led to an estimated 55,794 cardiorespiratory disease ED visits prevented (i.e., fewer observed ED visits than would have been expected under counterfactual scenarios) - 52,717 RD visits, of which 38,038 were for asthma, and 3,057 CVD visits, of which 2,104 were for CHF - among the residents of the 5-county area over the 1999-2013 period, an area with approximately 3.5 million people in 2013. During the final two years of the study (2012-2013), when pollution-control policies were most fully implemented and the associated benefits realized, these policies were estimated to prevent 5.9% of the RD ED visits that would have occurred in the absence of the policies (95% interval estimate: -0.4% to 12.3%); 16.5% of the asthma ED visits (95% interval estimate: 7.5% to 25.1%); 2.3% of the CVD ED visits (95% interval estimate: -1.8% to 6.2%); and -.6% of the CHF ED visits (95% interval estimate: 26.3% to 10.4%). Estimates of ED visits prevented were generally lower when using health models fit for the entire 1999-2013 study period.

Sensitivity analyses were conducted to show the impact of the choice of parameterization of the health models and to assess alternative definitions of the study area. When impacts were assessed for separate policy interventions, policies affecting emissions from EGUs, especially the ARP and the NBP, appeared to have had the greatest effect on prevention of RD and asthma ED visits.

CONCLUSIONS

This study demonstrates the effectiveness of regulations on improving air quality and health in the southeastern United States. It also demonstrates the complexities of accountability assessments as uncertainties are introduced in each step of the classic accountability process. While accounting for uncertainties in emissions, air quality-emissions relationships, and health models does lead to relatively large uncertainties in the estimated outcomes due to specific regulations, overall the benefits of regulations have been substantial.

Estimating Acute Cardiovascular Effects of Ambient PM2.5 Metals

BACKGROUND

Few epidemiologic studies have investigated health effects of water-soluble fractions of PM_2.5 metals, the more biologically accessible fractions of metals, in their attempt to identify health-relevant components of ambient PM_2.5.

OBJECTIVES

In this study, we estimated acute cardiovascular effects of PM_2.5 components in an urban population, including a suite of water-soluble metals that are not routinely measured at the ambient level.

METHODS

Ambient concentrations of criteria gases, PM_2.5, and PM_2.5 components were measured at a central monitor in Atlanta, Georgia, during 1998-2013, with some PM_2.5 components only measured during 2008-2013. In a time-series framework using Poisson regression, we estimated associations between these pollutants and daily counts of emergency department (ED) visits for cardiovascular diseases in the five-county Atlanta area.

RESULTS

Among the PM_2.5 components we examined during 1998-2013, water-soluble iron had the strongest estimated effect on cardiovascular outcomes [R͡R=1.012 (95% CI: 1.005, 1.019), per interquartile range increase (20.46ng/m³)]. The associations for PM_2.5 and other PM_2.5 components were consistent with the null when controlling for water-soluble iron. Among PM_2.5 components that were only measured during 2008-2013, water-soluble vanadium was associated with cardiovascular ED visits [R͡R=1.012 (95% CI: 1.000, 1.025), per interquartile range increase (0.19ng/m³)].

CONCLUSIONS

Our study suggests cardiovascular effects of certain water-soluble metals, particularly water-soluble iron. The observed associations with water-soluble iron may also point to certain aspects of traffic pollution, when processed by acidifying sulfate, as a mixture harmful for cardiovascular health. https://doi.org/10.1289/EHP2182.

Differential exposure and acute health impacts of inhaled solid-fuel emissions from rudimentary and advanced cookstoves in female CD-1 mice

BACKGROUND

There is an urgent need to provide access to cleaner end user energy technologies for the nearly 40% of the world's population who currently depend on rudimentary cooking and heating systems. Advanced cookstoves (CS) are designed to cut emissions and solid-fuel consumption, thus reducing adverse human health and environmental impacts.

STUDY PREMISE

We hypothesized that, compared to a traditional (Tier 0) three-stone (3-S) fire, acute inhalation of solid-fuel emissions from advanced natural-draft (ND; Tier 2) or forced-draft (FD; Tier 3) stoves would reduce exposure biomarkers and lessen pulmonary and innate immune system health effects in exposed mice.

RESULTS

Across two simulated cooking cycles (duration ~ 3h), emitted particulate mass concentrations were reduced 80% and 62% by FD and ND stoves, respectively, compared to the 3-S fire; with corresponding decreases in particles visible within murine alveolar macrophages. Emitted carbon monoxide was reduced ~ 90% and ~ 60%, respectively. Only 3-S-fire-exposed mice had increased carboxyhemoglobin levels. Emitted volatile organic compounds were FD ≪ 3-S-fire ≤ ND stove; increased expression of genes involved in xenobiotic metabolism (COX-2, NQO1, CYP1a1) was detected only in ND- and 3-S-fire-exposed mice. Diminished macrophage phagocytosis was observed in the ND group. Lung glutathione was significantly depleted across all CS groups, however the FD group had the most severe, ongoing oxidative stress.

CONCLUSIONS

These results are consistent with reports associating exposure to solid fuel stove emissions with modulation of the innate immune system and increased susceptibility to infection. Lower respiratory infections continue to be a leading cause of death in low-income economies. Notably, 3-S-fire-exposed mice were the only group to develop acute lung injury, possibly because they inhaled the highest concentrations of hazardous air toxicants (e.g., 1,3-butadiene, toluene, benzene, acrolein) in association with the greatest number of particles, and particles with the highest % organic carbon. However, no Tier 0-3 ranked CS group was without some untoward health effect indicating that access to still cleaner, ideally renewable, energy technologies for cooking and heating is warranted.

Associations between Ambient Fine Particulate Oxidative Potential and Cardiorespiratory Emergency Department Visits

BACKGROUND

Oxidative potential (OP) has been proposed as a measure of toxicity of ambient particulate matter (PM).

OBJECTIVES

Our goal was to address an important research gap by using daily OP measurements to conduct population-level analysis of the health effects of measured ambient OP.

METHODS

A semi-automated dithiothreitol (DTT) analytical system was used to measure daily average OP (OP^DTT) in water-soluble fine PM at a central monitor site in Atlanta, Georgia, over eight sampling periods (a total of 196 d) during June 2012-April 2013. Data on emergency department (ED) visits for selected cardiorespiratory outcomes were obtained for the five-county Atlanta metropolitan area. Poisson log-linear regression models controlling for temporal confounders were used to conduct time-series analyses of the relationship between daily counts of ED visits and either the 3-d moving average (lag 0-2) of OP^DTT or same-day OP^DTT. Bipollutant regression models were run to estimate the health associations of OP^DTT while controlling for other pollutants.

RESULTS

OP^DTT was measured for 196 d (mean=0.32 nmol/min/m³, interquartile range=0.21). Lag 0-2 OP^DTT was associated with ED visits for respiratory disease (RR=1.03, 95% confidence interval (CI): 1.00, 1.05 per interquartile range increase in OP^DTT), asthma (RR=1.12, 95% CI: 1.03, 1.22), and ischemic heart disease (RR=1.19, 95% CI: 1.03, 1.38). Same-day OP^DTT was not associated with ED visits for any outcome. Lag 0-2 OP^DTT remained a significant predictor of asthma and ischemic heart disease in most bipollutant models.

CONCLUSIONS

Lag 0-2 OP^DTT was associated with ED visits for multiple cardiorespiratory outcomes, providing support for the utility of OP^DTT as a measure of fine particle toxicity. https://doi.org/10.1289/EHP1545.