The effects of PM2.5 and its components from indoor and outdoor sources on cough and wheeze symptoms in asthmatic children

Incidence of cough from acute exposure to fine particulate matter (PM2.5) in Madagascar: A pilot study

Prolonged exposure to fine particulate matter (PM2.5) is a known risk to respiratory health, causing chronic lung impairment. Yet, the immediate, acute effects of PM2.5 exposure on respiratory symptoms, such as cough, are less understood. This pilot study aims to investigate this relationship using objective PM2.5 and cough monitors. Fifteen participants from rural Madagascar were followed for three days, equipped with an RTI Enhanced Children's MicroPEM PM2.5 sensor and a smartphone with the ResApp Cough Counting Software application. Univariable Generalized Estimating Equation (GEE) models were applied to measure the association between hourly PM2.5 exposure and cough counts. Peaks in both PM2.5 concentration and cough frequency were observed during the day. A 10-fold increase in hourly PM2.5 concentration corresponded to a 39% increase in same-hour cough frequency (incidence rate ratio (IRR) = 1.40; 95% CI: 1.12, 1.74). The strength of this association decreased with a one-hour lag between PM2.5 exposure and cough frequency (IRR = 1.21; 95% CI: 1.01, 1.44) and was not significant with a two-hour lag (IRR = 0.93; 95% CI: 0.71, 1.23). This study demonstrates the feasibility of objective PM2.5 and cough monitoring in remote settings. An association between hourly PM2.5 exposure and cough frequency was detected, suggesting that PM2.5 exposure may have immediate effects on respiratory health. Further investigation is necessary in larger studies to substantiate these findings and understand the broader implications.

Nickel in ambient particulate matter and respiratory or cardiovascular outcomes: A critical review

Exposure to ambient particulate matter (PM) has been associated with respiratory and cardiovascular outcomes, and nickel has been more frequently associated with these outcomes than other metal constituents of ambient PM. Because of this, we evaluated whether the evidence to date supports causal relationships between exposure to nickel in ambient PM and respiratory or cardiovascular outcomes. We critically reviewed 38 studies in human populations published between 2012 and 2022. Although a large variety of respiratory and cardiovascular outcomes were examined, data were sparse for many. As a result, we focused our evaluation on seven respiratory outcomes and three cardiovascular outcomes that were each examined in ≥3 studies. Of these health outcomes, exposure to nickel in ambient PM has been statistically significantly associated with respiratory mortality, respiratory emergency hospital visits, asthma, lung function (i.e., forced expiratory volume in 1 s, forced vital capacity), cardiovascular mortality, and ischemic heart disease mortality. Studies of the health outcomes of focus are subject to multiple methodological limitations, primarily ecological fallacy (short-term exposure studies), exposure measurement error, confounding, model misspecification, and multiple comparisons issue. While some statistically significant associations were reported, they were not strong, precise, or consistent. Statistically significant findings for long-term exposure to nickel in PM were largely reported in studies that could not establish temporality, despite their cohort study design. Statistically significant findings for short-term exposure to nickel in PM were largely reported in studies that could establish temporality, although this cannot inform causal inference at the individual level due to the aggregate level data used. The biological plausibility of the associations is only supported at high concentrations not relevant to ambient exposures. Overall, the literature to date does not provide adequate support for a causal relationship between nickel in ambient PM and respiratory or cardiovascular outcomes.

Exposure to ambient black carbon and particulate matter during pregnancy in associations with risk of pre-eclampsia: A meta-analysis based on population-based studies

Air pollution control protocols and policies formulated for PM2.5 and PM10 (particulate matter [PM] with an aerodynamic diameter of ≤2.5 and 10 μm), however, such protocols and policies have not been available for black carbon (BC). A growing number of studies have evaluated the association between long-term exposure to ambient air pollution with BC and PM and pre-eclampsia. We applied a meta-analysis to estimate pooled odds ratios (ORs) and 95 % confidence intervals (CIs) based on four exposure windows (first/second/third trimester and entire pregnancy). 24 studies meeting our selection criteria (8 for BC, 21 and 15 for PM2.5 and PM10) were finally included after screening studies published up to June 22, 2023. An increase of 1 μg/m3 BC during the second trimester and entire pregnancy were associated with a 16 % (OR: 1.16, 95 % CI: [1.02, 1.32]) and a 15 % (OR: 1.15, 95 % CI: [1.03, 1.29]) increased risk of pre-eclampsia, respectively. A 10 μg/m3 increase in second-trimester exposure to PM2.5 and PM10 was associated with a 1 % (OR: 1.01, 95 % CI: [1.00, 1.03]) and a 5 % (OR: 1.05, 95 % CI: [1.01, 1.10]) increased risk of pre-eclampsia. An 11 % (OR: 1.11, 95 % CI: [1.03, 1.21]) increased risk of pre-eclampsia was found to be associated with a 10 μg/m3 increase in PM10 exposure during the entire pregnancy. The results support the potential effect of exposure to ambient particulate pollutants on risk of pre-eclampsia and emphasize the necessity of strategies and protocols for controlling BC. Greater efforts in controlling ambient particulate pollution and especially BC are needed in order to prevent pregnant women from developing pre-eclampsia.

Sources of personal PM2.5 exposure during pregnancy in the MADRES cohort

BACKGROUND

Personal exposure to fine particulate matter (PM2.5) is impacted by different sources each with different chemical composition. Determining these sources is important for reducing personal exposure and its health risks especially during pregnancy.

OBJECTIVE

Identify main sources and their contributions to the personal PM2.5 exposure in 213 women in the 3rd trimester of pregnancy in Los Angeles, CA.

METHODS

We measured 48-hr integrated personal PM2.5 exposure and analyzed filters for PM2.5 mass, elemental composition, and optical carbon fractions. We used the EPA Positive Matrix Factorization (PMF) model to resolve and quantify the major sources of personal PM2.5 exposure. We then investigated bivariate relationships between sources, time-activity patterns, and environmental exposures in activity spaces and residential neighborhoods to further understand sources.

RESULTS

Mean personal PM2.5 mass concentration was 22.3 (SD = 16.6) μg/m3. Twenty-five species and PM2.5 mass were used in PMF with a final R2 of 0.48. We identified six sources (with major species in profiles and % contribution to PM2.5 mass) as follows: secondhand smoking (SHS) (brown carbon, environmental tobacco smoke; 65.3%), fuel oil (nickel, vanadium; 11.7%), crustal (aluminum, calcium, silicon; 11.5%), fresh sea salt (sodium, chlorine; 4.7%), aged sea salt (sodium, magnesium, sulfur; 4.3%), and traffic (black carbon, zinc; 2.6%). SHS was significantly greater in apartments compared to houses. Crustal source was correlated with more occupants in the household. Aged sea salt increased with temperature and outdoor ozone, while fresh sea salt was highest on days with westerly winds from the Pacific Ocean. Traffic was positively correlated with ambient NO2 and traffic-related NOx at residence. Overall, 76.8% of personal PM2.5 mass came from indoor or personal compared to outdoor sources.

IMPACT

We conducted source apportionment of personal PM2.5 samples in pregnancy in Los Angeles, CA. Among identified sources, secondhand smoking contributed the most to the personal exposure. In addition, traffic, crustal, fuel oil, fresh and aged sea salt sources were also identified as main sources. Traffic sources contained markers of combustion and non-exhaust wear emissions. Crustal source was correlated with more occupants in the household. Aged sea salt source increased with temperature and outdoor ozone and fresh sea salt source was highest on days with westerly winds from the Pacific Ocean.

Integrated analysis of ATAC-seq and RNA-seq unveils the role of ferroptosis in PM2.5-induced asthma exacerbation

BACKGROUND

PM2.5 exposure increases asthma exacerbation risk and worsens airway inflammation and mucus secretion, but the underlying mechanisms, especially the epigenetic modification changes, are not fully understood.

METHODS

ATAC-seq was conducted in Beas-2B cells to explore the differential chromatin accessibilities before and after exposure to PM2.5. RNA-seq was applied to screen the differentially expressed genes (DEGs) as well. The integrated analysis of ATAC-seq and RNA-seq was performed. The key up-regulated genes in the ferroptosis signaling pathway were identified by combined analysis with the FerrDb database and then verified. Meanwhile, to access the role of PM2.5-induced ferroptosis in asthma mice, house dust mites (HDM) were employed to conduct an allergic asthma mice model, and the ferroptosis-specific inhibitor (Ferrostatin-1, Fer-1) was used. The H&E staining, PAS staining, airway hyperresponsiveness, and bronchoalveolar lavage fluid (BALF) cell counting were used to investigate the impact of PM2.5-induced ferroptosis in asthma mice.

RESULTS

A total of 4,921 regions with differential accessibility were identified, encompassing 4,031 unique genes. Among these, 250 regions exhibited increased accessibility while 4,671 regions displayed reduced accessibility. Through the integrated analysis of ATAC-seq and RNA-seq, ferroptosis was determined as the key enriched pathway based on up-regulated DEGs and increased chromatin accessibilities. Furthermore, the decreased cell viability, accelerated lipid peroxide and morphological changes in mitochondria observed upon PM2.5 exposure were rescued by Fer-1, which are indicative of ferroptosis. By overlapping with ferroptosis-related genes from the FerrDb database, FTH1 and FTL were identified as the prominent up-regulated genes with increased chromatin accessibility in ferroptosis pathway. In addition, ChIP-qPCR analysis indicated that histone modification like H3K4me3 and H3K27ac positively regulated FTH1 and FTL expression. Subsequently, in PM2.5-exposed asthmatic mice, inhibition of ferroptosis effectively attenuated airway inflammation and mucus secretion.

CONCLUSION

These findings shed light on the molecular mechanisms underlying PM2.5-induced asthma exacerbation, with epigenetic modifications playing a pivotal role. Furthermore, it suggests the therapeutic potential of targeting ferroptosis as an intervention strategy.

Geochemical characteristics and socioeconomic associations of carbonaceous aerosols in coal-fueled cities with significant seasonal pollution pattern

Carbonaceous aerosols, comprising organic carbon (OC) and elemental carbon (EC), are critical component of fine particulate matter (PM2.5), with diverse impacts on air quality and human health. This study investigated the concentrations and seasonal patterns of carbonaceous species in PM2.5 during both the heating season (January 2021) and non-heating season (July 2021) in three coal-fueled cities in northern China, as well as the differences in carbonaceous aerosols and their associations with socioeconomic parameters in cities situated on either side of the "Hu Line" in China. The results showed that, owing to intensified coal combustion and unfavorable meteorological conditions, levels of OC, EC, and OC/EC ratios were higher in winter compared to summer. Moreover, the presence of dust (DU) and light pollution (LP) days resulted in elevated OC levels but decreased EC levels. The Char-EC/Soot-EC ratios were highest during LP, followed by CL and DU. A source apportionment analysis demonstrated that coal burning, vehicle exhaust, road dust, and biomass burning were the primary contributors to carbonaceous aerosols, as confirmed by diagnostic ratios, Char-EC/Soot-EC ratios, and PCA analysis. Furthermore, our study found that carbonaceous aerosols concentrations and source apportionment primarily varied with diurnal and seasonal trends and different pollution types. Additionally, at the national scale, population density and urban green space exhibited a positive correlation with OC/EC ratios (p < 0.05), while energy consumption per unit of GDP showed a negative correlation (p < 0.05). The observation that OC/EC ratios were lower in coal-fueled cities than in economy-based cities suggests a more severe pollution scenario. These findings highlight the importance of comprehending of the seasonal variation and chemical characteristics of carbonaceous aerosol for understanding air pollution sources and characteristics, which is essential for both air quality management and human health.

Lias overexpression alleviates pulmonary injury induced by fine particulate matter in mice

Oxidative stress and inflammation are mechanisms underlying toxicity induced by fine particulate matter (PM2.5). The antioxidant baseline of the human body modulates the intensity of oxidative stress in vivo. This present study aimed to evaluate the role of endogenous antioxidants in alleviating PM2.5-induced pulmonary injury using a novel mouse model (LiasH/H) with an endogenous antioxidant capacity of approximately 150% of its wild-type counterpart (Lias+/+). LiasH/H and wild-type (Lias+/+) mice were randomly divided into control and PM2.5 exposure groups (n = 10), respectively. Mice in the PM2.5 group and the control group were intratracheally instilled with PM2.5 suspension and saline, respectively, once a day for 7 consecutive days. The metal content, major pathological changes in the lung, and levels of oxidative stress and inflammation biomarkers were examined. The results showed that PM2.5 exposure induced oxidative stress in mice. Overexpression of the Lias gene significantly increased the antioxidant levels and decreased inflammatory responses induced by PM2.5. Further study found that LiasH/H mice exerted their antioxidant function by activating the ROS-p38MAPK-Nrf2 pathway. Therefore, the novel mouse model is useful for the elucidation of the mechanisms of pulmonary injury induced by PM2.5.

Spatiotemporally continuous estimates of daily 1-km PM2.5 concentrations and their long-term exposure in China from 2000 to 2020

Monitoring long-term variations in fine particulate matter (PM_2.5) is essential for environmental management and epidemiological studies. While satellite-based statistical/machine-learning methods can be used for estimating high-resolution ground-level PM_2.5 concentration data, their applications have been hindered by limited accuracy in daily estimates during years without PM_2.5 measurements and massive missing values due to satellite retrieval data. To address these issues, we developed a new spatiotemporal high-resolution PM_2.5 hindcast modeling framework to generate the full-coverage, daily, 1-km PM_2.5 data for China for the period 2000-2020 with improved accuracy. Our modeling framework incorporated information on changes in observation variables between periods with and without monitoring data and filled gaps in PM_2.5 estimates induced by satellite data using imputed high-resolution aerosol data. Compared to previous hindcast studies, our method achieved superior overall cross-validation (CV) R² and root-mean-square error (RMSE) of 0.90 and 12.94 μg/m³ and significantly improved the model performance in years without PM_2.5 measurements, raising the leave-one-year-out CV R² [RMSE] to 0.83 [12.10 μg/m³] at a monthly scale (0.65 [23.29 μg/m³] at a daily scale). Our long-term PM_2.5 estimates show a sharp decline in PM_2.5 exposure in recent years, but the national exposure level in 2020 still exceeded the first annual interim target of the 2021 World Health Organization air quality guidelines. The proposed hindcast framework represents a new strategy to improve air quality hindcast modeling and can be applied to other regions with limited air quality monitoring periods. These high-quality estimates can support both long- and short-term scientific research and environmental management of PM_2.5 in China.

Using a human bronchial epithelial cell-based malignant transformation model to explore the function of hsa-miR-200 family in the progress of PM2.5-induced lung cancer development

Numerous studies have revealed that ambient long-term exposure to fine particulate matter (PM_2.5) is significantly related to the development of lung cancer, but the molecular mechanisms of PM_2.5 exposure-induced lung cancer remains unknown. As an important epigenetic regulator, microRNAs (miRNAs) play vital roles in responding to environment exposure and various diseases including lung cancer development. Here we constructed a PM_2.5-induced malignant transformed cell model and found that miR-200 family, especially miR-200a-3p, was involved in the process of PM_2.5 induced lung cancer. Further investigation of the function of miR-200 family (miR-200a-3p as a representative revealed that miR-200a-3p promoted cell migration by directly suppressing TNS3 expression. These results suggested that ambient PM_2.5 exposure may increase the expression of miR-200 family and then promote the proliferation and migration of lung cancer cells. Our study provided novel model and insights into the molecular mechanism of ambient PM_2.5 exposure-induced lung cancer.

PM2.5 exposure and lung function impairment among fiber-cement industry workers

Introduction

Numerous studies have reported respiratory impairment by exposure to fine particulate matter (PM_2.5). However, limited studies investigated its effects on fiber cement roof workers. Thus, our study evaluated the impact of PM_2.5 on pulmonary impairments among workers and its risk factors.

Design and Method

A total of 131 fiber cement roof workers have been chosen based on the inclusive criteria. Size-segregated particles were measured in the workplace of workers. Interview and spirometry tests were obtained to determine the respiratory impairments.

Result

The results showed the mean concentrations of PM_2.5 had exceeded the WHO and US-EPA standards. A quarter of workers had lung restriction, lung obstruction, and mixed. Workers are most likely to have shortness of breath and wheezing. A significant correlation was found between smoking, production workers, and a long work period with abnormal lung function. Fiber cement roof workers are significantly at risk of exposure to PM_2.5. They are most likely to acquire abnormal lung function due to PM_2.5 exposure.

Conclusion

Our study recommended the industry constantly maintain its programs. The industry should keep using the wet process to prevent dust generation and water suppression from preventing dust spread, as well as to wear respiratory protection for workers to avoid PM_2.5 exposure. We recommended as well to the industry to implement follow-up programs for workers with abnormal lung function. Further action is needed to protect the workers' occupational health in the fiber cement roof industry.

Associations between outdoor air pollutants and non-viral asthma exacerbations and airway inflammatory responses in children and adolescents living in urban areas in the USA: a retrospective secondary analysis

BACKGROUND

Asthma prevalence and severity have markedly increased with urbanisation, and children in low-income urban centres have among the greatest asthma morbidity. Outdoor air pollution has been associated with adverse respiratory effects in children with asthma. However, the mechanisms by which air pollution exposure exacerbates asthma, and how these mechanisms compare with exacerbations induced by respiratory viruses, are poorly understood. We aimed to investigate the associations between regional air pollutant concentrations, respiratory illnesses, lung function, and upper airway transcriptional signatures in children with asthma, with particular focus on asthma exacerbations occurring in the absence of respiratory virus.

METHODS

We performed a retrospective analysis of data from the MUPPITS1 cohort and validated our findings in the ICATA cohort. The MUPPITS1 cohort recruited 208 children aged 6-17 years living in urban areas across nine US cities with exacerbation-prone asthma between Oct 7, 2015, and Oct 18, 2016, and monitored them during reported respiratory illnesses. The last MUPPITS1 study visit occurred on Jan 6, 2017. The ICATA cohort recruited 419 participants aged 6-20 years with persistent allergic asthma living in urban sites across eight US cities between Oct 23, 2006, and March 25, 2008, and the last study visit occurred on Dec 30, 2009. We included participants from the MUPPITS1 cohort who reported a respiratory illness at some point during the follow-up and participants from the ICATA cohort who had nasal samples collected during respiratory illness or at a scheduled visit. We used air quality index values and air pollutant concentrations for PM2·5, PM10, O3, NO2, SO2, CO, and Pb from the US Environmental Protection Agency spanning the years of both cohorts, and matched values and concentrations to each illness for each participant. We investigated the associations between regional air pollutant concentrations and respiratory illnesses and asthma exacerbations, pulmonary function, and upper airway transcriptional signatures by use of a combination of generalised additive models, case crossover analyses, and generalised linear mixed-effects models.

FINDINGS

Of the 208 participants from the MUPPITS1 cohort and 419 participants from the ICATA cohort, 168 participants in the MUPPITS1 cohort (98 male participants and 70 female participants) and 189 participants in the ICATA cohort (115 male participants and 74 female participants) were included in our analysis. We identified that increased air quality index values, driven predominantly by increased PM2·5 and O3 concentrations, were significantly associated with asthma exacerbations and decreases in pulmonary function that occurred in the absence of a provoking viral infection. Moreover, individual pollutants were significantly associated with altered gene expression in coordinated inflammatory pathways, including PM2·5 with increased epithelial induction of tissue kallikreins, mucus hypersecretion, and barrier functions and O3 with increased type-2 inflammation.

INTERPRETATION

Our findings suggest that air pollution is an important independent risk factor for asthma exacerbations in children living in urban areas and is potentially linked to exacerbations through specific inflammatory pathways in the airway. Further investigation of these potential mechanistic pathways could inform asthma prevention and management approaches.

FUNDING

National Institutes of Health, National Institute of Allergy and Infectious Diseases.

Diesel exhaust PM2.5 greatly deteriorates fibrosis process in pre-existing pulmonary fibrosis via ferroptosis

Fine particulate matter (PM2.5) has been widely reported to contribute to the pathogenesis of pulmonary diseases. The direct hazardous effect of PM2.5 on the respiratory system at high concentrations in vitro and in vivo have been well identified. However, its effect on the pre-existing respiratory diseases of patients at environment-related concentrations remains unclear. Diesel exhaust PM2.5 as a primary representative of ambient PM2.5 fine particles were used to investigated the effect of PM2.5 on the fibrosis progression of existing pulmonary fibrosis disease models. This study reported that PM2.5 could result in the enhanced sensitivity to fibrotic response, which may be ascribed to ferroptosis induced by PM2.5 in damaged lung areas. Proteomic analysis revealed that the upregulation of HO-1 as a key mechanism in the ferroptosis and exacerbation of pulmonary fibrosis induced by PM2.5. As a result, HO-1 degraded heme-containing protein and released iron in fibrotic cells, leading to generation of mitochondrial ROS and impaired mitochondrial function. Transmission electron microscopic assay verified that PM2.5 entered the mitochondria of fibrotic cells and was accompanied by significant mitochondrial morphological changes characterized by increased mitochondrial membrane density and reduced mitochondrial size. The HO-1 inhibitor zinc protoporphyrin and mitochondrion-targeted antioxidant Mito-TEMPO significantly attenuated PM2.5-induced ferroptosis and exacerbation of fibrosis. In addition, AMPK-ULK1 axis-triggered autophagy activation and NCOA4-mediated degradation of ferritin by autophagy were found to be related to the PM2.5-induced ferroptosis of fibrotic cells. As evidenced by the inhibition of autophagy with 3-methyladenine or AMPK inhibitor, NCOA4 knockdown decreased intracellular iron accumulation and lipid peroxidation, thereby relieving PM2.5-induced epithelial-mesenchymal transition and cell death in fibrotic cells. Overall, this study provided experimental support for the idea that PM2.5 greatly deteriorates fibrosis process in pre-existing pulmonary fibrosis, and HO-1-mediated mitochondrial dysfunction and NCOA4-mediated ferritinophagy are jointly required for the PM2.5-induced ferroptosis and enhanced fibrosis effects.

Short-term associations between ambient air pollution and emergency department visits for Alzheimer's disease and related dementias

Dementia is a seriously disabling illness with substantial economic and social burdens. Alzheimer's disease and its related dementias (AD/ADRD) constitute about two-thirds of dementias. AD/ADRD patients have a high prevalence of comorbid conditions that are known to be exacerbated by exposure to ambient air pollution. Existing studies mostly focused on the long-term association between air pollution and AD/ADRD morbidity, while very few have investigated short-term associations. This study aims to estimate short-term associations between AD/ADRD emergency department (ED) visits and three common air pollutants: fine particulate matter (PM_2.5), nitrogen dioxide (NO₂), and warm-season ozone.

Methods

For the period 2005 to 2015, we analyzed over 7.5 million AD/ADRD ED visits in five US states (California, Missouri, North Carolina, New Jersey, and New York) using a time-stratified case-crossover design with conditional logistic regression. Daily estimated PM_2.5, NO_2, and warm-season ozone concentrations at 1 km spatial resolution were aggregated to the ZIP code level as exposure.

Results

The most consistent positive association was found for NO₂. Across five states, a 17.1 ppb increase in NO₂ concentration over a 4-day period was associated with a 0.61% (95% confidence interval = 0.27%, 0.95%) increase in AD/ADRD ED visits. For PM_2.5, a positive association with AD/ADRD ED visits was found only in New York (0.64%, 95% confidence interval = 0.26%, 1.01% per 6.3 µg/m³). Associations with warm-season ozone levels were null.

Conclusions

Our results suggest AD/ADRD patients are vulnerable to short-term health effects of ambient air pollution and strategies to lower exposure may reduce morbidity.

The impact of GPS-derived activity spaces on personal PM2.5 exposures in the MADRES cohort

BACKGROUND

In-utero exposure to particulate matter with aerodynamic diameter less than 2.5 μm (PM_2.5) is associated with low birth weight and health risks later in life. Pregnant women are mobile and locations they spend time in contribute to their personal PM_2.5 exposures. Therefore, it is important to understand how mobility and exposures encountered within activity spaces contribute to personal PM_2.5 exposures during pregnancy.

METHODS

We collected 48-h integrated personal PM_2.5 samples and continuous geolocation (GPS) data for 213 predominantly Hispanic/Latina pregnant women in their 3^rd trimester in Los Angeles, CA. We also collected questionnaires and modeled outdoor air pollution and meteorology in their residential neighborhood. We calculated three GPS-derived activity space measures of exposure to road networks, greenness (NDVI), parks, traffic volume, walkability, and outdoor PM_2.5 and temperature. We used bivariate analyses to screen variables (GPS-extracted exposures in activity spaces, individual characteristics, and residential neighborhood exposures) based on their relationship with personal, 48-h integrated PM_2.5 concentrations. We then built a generalized linear model to explain the variability in personal PM_2.5 exposure and identify key contributing factors.

RESULTS

Indoor PM_2.5 sources, parity, and home ventilation were significantly associated with personal exposure. Activity-space based exposure to roads was associated with significantly higher personal PM_2.5 exposure, while greenness was associated with lower personal PM_2.5 exposure (β = -3.09 μg/m³ per SD increase in NDVI, p-value = 0.018). The contribution of outdoor PM_2.5 to personal exposure was positive but relatively lower (β = 2.05 μg/m³ per SD increase, p-value = 0.016) than exposures in activity spaces and the indoor environment. The final model explained 34% of the variability in personal PM_2.5 concentrations.

CONCLUSIONS

Our findings highlight the importance of activity spaces and the indoor environment on personal PM_2.5 exposures of pregnant women living in Los Angeles, CA. This work also showcases the multiple, complex factors that contribute to total personal PM_2.5 exposure.

Assessing exposure to household air pollution in children under five: A scoping review

Understanding the differences in the approaches used to assess household air pollution (HAP) is crucial for evaluating HAP-related health effects and interpreting the effectiveness of stove-fuel interventions. Our review aims to understand how exposure to HAP from solid fuels was measured in epidemiological studies in children under five. We conducted a search of PubMed, EMBASE, Cochrane Central Register of Controlled Trials, Global Health Library, Web of Science, and CINAHL to identify English-language research articles published between January 1, 2000 and April 30, 2022. Two researchers applied the inclusion and exclusion criteria independently. Study region, type of measurement, study design, health outcomes, and other key characteristics were extracted from each article and analyzed descriptively. Our search strategy yielded 2229 records, of which 185 articles were included. A large proportion was published between 2018 and 2022 (42.1%), applied a cross-sectional study design (47.6%), and took place in low- or lower middle-income countries. Most studies (130/185, 70.3%) assessed HAP using questionnaires/interviews, most frequently posing questions on cooking fuel type, followed by household ventilation and cooking location. Cooking frequency/duration and children's location while cooking was less commonly considered. About 28.6% (53/185) used monitors, but the application of personal portable samplers was limited (particulate matter [PM]: 12/40, 30.0%; carbon monoxide [CO]: 13/34, 38.2%). Few studies used biomarkers or modeling approaches to estimate HAP exposure among children under five. More studies that report household and behavioral characteristics and children's location while cooking, apply personal exposure samplers, and perform biomarker analysis are needed to advance our understandings of HAP exposure among infants and young children, who are particularly susceptible to HAP-related health effects.

Oxidative potential and in vitro toxicity of particles generated by pyrotechnic smokes in human small airway epithelial cells

Pyrotechnic smokes are widely used in civilian and military applications. The major issue arise from the release of particles after smoke combustion but the health risks related to their exposure are poorly documented whereas toxicity of airborne particles on the respiratory target are very well known. Therefore, this study aimed to explore the in vitro toxicity of the particle fraction of different pyrotechnic smokes. Particles from a red signalling smoke (RSS), an hexachloroethane-based obscuring smoke (HC-OS) and an anti-intrusion smoke (AIS) were collected from the cloud. RSS particles displayed the highest organic fraction (quinones and polycyclic aromatic hydrocarbons) of the three samples characterized. AIS particles contained K and cholesterol derivatives. HC-OS particles were mainly metallic with very high concentrations of Al, Fe and Ca. Intrinsic oxidative potential of smoke particles was measured with two assays. Depletions of DTT by RSS particles was greater than depletion obtained with AIS and HC-OS particles but depletion of acid ascorbic (AA) was only observed with HC-OS particles. In vitro toxicity was assessed by exposing human small airway epithelial cells (SAEC) to various concentrations of particles. After 24 h of exposure, cell viability was not affected but significant modifications of mRNA expression of antioxidant (SOD-1 and -2, catalase, HO-1, NQO-1) and inflammatory markers (IL-6, IL-8, TNF-α) were observed and were dependent on smoke type. Particles rich in metal, such as HC-OS, induced a greatest depletion of AA and a greatest inflammatory response, whereas particles rich in organic compounds, such as RSS, induced a greatest DTT depletion and a greatest antioxidant response. In conclusion, the three smoke particles have an intrinsic oxidative potential and triggered a cell adaptive response. Our study improved the knowledge of particle toxicity of pyrotechnic smokes and scientific approach developed here could be used to study other type of particles.

Recent Insights into Particulate Matter (PM2.5)-Mediated Toxicity in Humans: An Overview

Several epidemiologic and toxicological studies have commonly viewed ambient fine particulate matter (PM_2.5), defined as particles having an aerodynamic diameter of less than 2.5 µm, as a significant potential danger to human health. PM_2.5 is mostly absorbed through the respiratory system, where it can infiltrate the lung alveoli and reach the bloodstream. In the respiratory system, reactive oxygen or nitrogen species (ROS, RNS) and oxidative stress stimulate the generation of mediators of pulmonary inflammation and begin or promote numerous illnesses. According to the most recent data, fine particulate matter, or PM_2.5, is responsible for nearly 4 million deaths globally from cardiopulmonary illnesses such as heart disease, respiratory infections, chronic lung disease, cancers, preterm births, and other illnesses. There has been increased worry in recent years about the negative impacts of this worldwide danger. The causal associations between PM_2.5 and human health, the toxic effects and potential mechanisms of PM_2.5, and molecular pathways have been described in this review.

PM2.5 Exposure and Asthma Development: The Key Role of Oxidative Stress

Oxidative stress is defined as the imbalance between reactive oxygen species (ROS) production and the endogenous antioxidant defense system, leading to cellular damage. Asthma is a common chronic inflammatory airway disease. The presence of asthma tends to increase the production of reactive oxygen species (ROS), and the antioxidant system in the lungs is insufficient to mitigate it. Therefore, asthma can lead to an exacerbation of airway hyperresponsiveness and airway inflammation. PM2.5 exposure increases ROS levels. Meanwhile, the accumulation of ROS will further enhance the oxidative stress response, resulting in DNA, protein, lipid, and other cellular and molecular damage, leading to respiratory diseases. An in-depth study on the relationship between oxidative stress and PM2.5-related asthma is helpful to understand the pathogenesis and progression of the disease and provides a new direction for the treatment of the disease. This paper reviews the research progress of oxidative stress in PM2.5-induced asthma as well as highlights the therapeutic potentials of antioxidant approaches in treatment of asthma.

Daily Associations of Air Pollution and Pediatric Asthma Risk Using the Biomedical REAI-Time Health Evaluation (BREATHE) Kit

Background: Exposure to air pollution is associated with acute pediatric asthma exacerbations, including reduced lung function, rescue medication usage, and increased symptoms; however, most studies are limited in investigating longitudinal changes in these acute effects. This study aims to investigate the effects of daily air pollution exposure on acute pediatric asthma exacerbation risk using a repeated-measures design. Methods: We conducted a panel study of 40 children aged 8−16 years with moderate-to-severe asthma. We deployed the Biomedical REAI-Time Health Evaluation (BREATHE) Kit developed in the Los Angeles PRISMS Center to continuously monitor personal exposure to particulate matter of aerodynamic diameter < 2.5 µm (PM2.5), relative humidity and temperature, geolocation (GPS), and asthma outcomes including lung function, medication use, and symptoms for 14 days. Hourly ambient (PM2.5, nitrogen dioxide (NO2), ozone (O3)) and traffic-related (nitrogen oxides (NOx) and PM2.5) air pollution exposures were modeled based on location. We used mixed-effects models to examine the association of same day and lagged (up to 2 days) exposures with daily changes in % predicted forced expiratory volume in 1 s (FEV1) and % predicted peak expiratory flow (PEF), count of rescue inhaler puffs, and symptoms. Results: Participants were on average 12.0 years old (range: 8.4−16.8) with mean (SD) morning %predicted FEV1 of 67.9% (17.3%) and PEF of 69.1% (18.4%) and 1.4 (3.5) puffs per day of rescue inhaler use. Participants reported chest tightness, wheeze, trouble breathing, and cough symptoms on 36.4%, 17.5%, 32.3%, and 42.9%, respectively (n = 217 person-days). One SD increase in previous day O3 exposure was associated with reduced morning (beta [95% CI]: −4.11 [−6.86, −1.36]), evening (−2.65 [−5.19, −0.10]) and daily average %predicted FEV1 (−3.45 [−6.42, −0.47]). Daily (lag 0) exposure to traffic-related PM2.5 exposure was associated with reduced morning %predicted PEF (−3.97 [−7.69, −0.26]) and greater odds of “feeling scared of trouble breathing” symptom (odds ratio [95% CI]: 1.83 [1.03, 3.24]). Exposure to ambient O3, NOx, and NO was significantly associated with increased rescue inhaler use (rate ratio [95% CI]: O3 1.52 [1.02, 2.27], NOx 1.61 [1.23, 2.11], NO 1.80 [1.37, 2.35]). Conclusions: We found significant associations of air pollution exposure with lung function, rescue inhaler use, and “feeling scared of trouble breathing.” Our study demonstrates the potential of informatics and wearable sensor technologies at collecting highly resolved, contextual, and personal exposure data for understanding acute pediatric asthma triggers.

Long-Term PM2.5 Exposure Is Associated with Symptoms of Acute Respiratory Infections among Children under Five Years of Age in Kenya, 2014

Introduction: Short-term exposures to air pollutants such as particulate matter (PM) have been associated with increased risk for symptoms of acute respiratory infections (ARIs). Less well understood is how long-term exposures to fine PM (PM2.5) might increase risk of ARIs and their symptoms. This research uses georeferenced Demographic Health Survey (DHS) data from Kenya (2014) along with a remote sensing based raster of PM2.5 concentrations to test associations between PM2.5 exposure and ARI symptoms in children for up to 12 monthly lags. Methods: Predicted PM2.5 concentrations were extracted from raster of monthly averages for latitude/longitude locations of survey clusters. These data and other environmental and demographic data were used in a logistic regression model of ARI symptoms within a distributed lag nonlinear modeling framework (DLNM) to test lag associations of PM2.5 exposure with binary presence/absence of ARI symptoms in the previous two weeks. Results: Out of 7036 children under five for whom data were available, 46.8% reported ARI symptoms in the previous two weeks. Exposure to PM2.5 within the same month and as an average for the previous 12 months was 18.31 and 22.1 µg/m3, respectively, far in excess of guidelines set by the World Health Organization. One-year average PM2.5 exposure was higher for children who experienced ARI symptoms compared with children who did not (22.4 vs. 21.8 µg/m3, p < 0.0001.) Logistic regression models using the DLNM framework indicated that while PM exposure was not significantly associated with ARI symptoms for early lags, exposure to high concentrations of PM2.5 (90th percentile) was associated with elevated odds for ARI symptoms along a gradient of lag exposure time even when controlling for age, sex, types of cooking fuels, and precipitation. Conclusions: Long-term exposure to high concentrations of PM2.5 may increase risk for acute respiratory problems in small children. However, more work should be carried out to increase capacity to accurately measure air pollutants in emerging economies such as Kenya.

Particulate emissions of real-world light-duty gasoline vehicle fleet in Iran

Fine particulate matter cause profound adverse health effects in Iran. Road traffic is one of the main sources of particulate matter (PM) in urban areas, and has a large contribution in PM_2.5 and organic carbon concentration, in Tehran, Iran. The composition of fine PM vehicle emission is poorly known, so this paper aims to determine the mixed fleet source profile by using the analysed data from the two internal stations and the emission factor for PM light-duty vehicles emission. Tunnels are ideal media for extraction vehicle source profile and emission factor, due to vehicles are the only source of pollutant in the urban tunnels. In this study, PM samples were collected simultaneously in two road tunnel stations and at a background site in Niyayesh tunnel in Tehran, Iran. The tunnel samples show a large contribution for some elements and ions, such as Fe (0.23 μg μg^-1 OC), Al (0.02 μg μg^-1 OC), Ca (0.055 μg μg^-1 OC), SO₄ (0.047 μg μg^-1 OC), Docosane (0.0017 μg μg^-1 OC), Triacontane (0.016 μg μg^-1 OC), Anthracenedione (0.0003 μg μg^-1 OC) and Benzo-perylene (0.0002 μg μg^-1 OC). In overall, on-road gasoline vehicle fleets source profile extracted in this study is similar to composite profiles derived from roadside tunnel measurment performed in other countries during the last decades. The PM_2.5 emission factor for Tehran's light-duty vehicle fleet has been extracted 16.23 mg km^-1. vehicle^-1and 0.09 g kg^-1. The profile would be used for Chemical Mass Balance Model studies for Iran and other countries with a similar road traffic fleet mix. Also, it would be very suitable for use in emission inventories improvement. The results of this study can be used for choosing the best management strategies and provide comperhensive insight to fine PM traffic emission in Tehran.

Djulis (Chenopodium formosanum) and Its Bioactive Compounds Protect Human Lung Epithelial A549 Cells from Oxidative Injury Induced by Particulate Matter via Nrf2 Signaling Pathway

The protective effects of water extracts of djulis (Chenopodium formosanum) (WECF) and their bioactive compounds on particulate matter (PM)-induced oxidative injury in A549 cells via the nuclear factor-erythroid 2-related factor 2 (Nrf2) signaling were investigated. WECF at 50-300 µg/mL protected A549 cells from PM-induced cytotoxicity. The cytoprotection of WECF was associated with decreases in reactive oxygen species (ROS) generation, thiobarbituric acid reactive substances (TBARS) formation, and increases in superoxide dismutase (SOD) activity and glutathione (GSH) contents. WECF increased Nrf2 and heme oxygenase-1 (HO-1) expression in A549 cells exposed to PM. SP600125 (a JNK inhibitor) and U0126 (an ERK inhibitor) attenuated the WECF-induced Nrf2 and HO-1 expression. According to the HPLC-MS/MS analysis, rutin (2219.7 µg/g) and quercetin derivatives (2648.2 µg/g) were the most abundant bioactive compounds present in WECF. Rutin and quercetin ameliorated PM-induced oxidative stress in the cells. Collectively, the bioactive compounds present in WECF can protect A549 cells from PM-induced oxidative injury by upregulating Nrf2 and HO-1 via activation of the ERK and JUN signaling pathways.

Effects of Exposure to Indoor Fine Particulate Matter on Atopic Dermatitis in Children

This study aimed to investigate the short-term effect of exposure to indoor fine particulate matter (PM_2.5) on atopic dermatitis (AD) symptoms in children. Sixty-four children (40 boys and 24 girls) with moderate-to-severe AD, aged under 18 years were enrolled in the study. They were followed up from February 2019 through November 2020. Exposure to indoor PM_2.5 in each household of the enrolled children and their AD symptoms were measured daily. The generalized linear mixed model was utilized for statistical analysis. Subdivision analysis was performed by stratifying the patients by age, sex, season, severity, the presence of family allergic diseases, sensitization, and indoor environment conditions including temperature and relative humidity. A total of 9,321 person-days of AD symptom data were collected. The average PM_2.5 concentration was 28.7 ± 24.3 µg/m³, with the highest value in winter (47.1 ± 29.6 µg/m³). The overall effect of PM_2.5 on AD symptoms was not statistically significant. However, an increase of 10 µg/m³ in indoor PM_2.5 concentration increased AD symptom scores by 16.5% (95% CI: 6.5, 27.5) in spring and12.6% (95% CI: 4.3, 21.5) in winter, 6.7% (95% CI: 2.3, 11.3) at indoor temperatures of <25.5 °C, and by 15.0% (95% CI: 3.5, 27.7) with no use of an air purifier. The harmful effect of PM_2.5 in boys, in children aged ≥6 years, and in children with inhalant allergen sensitization was significant, showing an increase in AD symptoms of 4.9% (95% CI: 1.4, 8.6), 12.0% (95% CI: 5.3, 19.1), and 7.0% (95% CI: 1.9, 12.3) per 10 µg/m³ of PM_2.5, respectively. Furthermore, children with inhalant allergen sensitization plus severe symptoms (SCORing Atopic Dermatitis, SCORAD ≥ 30.7, median value) showed more harmful effects from exposure to PM_2.5 (15.7% (95% CI: 4.5, 28.1) increase in AD symptom scores per 10 µg/m³ of PM_2.5 increase). Indoor exposure to PM_2.5 exacerbated AD symptoms in children in spring, winter, and at indoor temperatures of < 25.5 °C. In particular, this harmful effect was prominent in children with inhalant allergen sensitization and severe symptoms. Minimizing exposure to indoor PM_2.5 is needed for the proper management of AD.

Respiratory function declines in children with asthma associated with chemical species of fine particulate matter (PM2.5) in Nagasaki, Japan

BACKGROUND

The differential effects of PM_2.5 fractions on children's lung function remain inconclusive. This study aimed to examine whether lung function in asthmatic children was associated with increased PM_2.5 fractions in urban areas in Nagasaki prefecture, Japan, where the air pollution level is relatively low but influenced by transboundary air pollution.

METHODS

We conducted a multiyear panel study of 73 asthmatic children (boys, 60.3%; mean age, 8.2 years) spanning spring 2014-2016 in two cities. We collected self-measured peak expiratory flow (PEF) twice a day and daily time-series data for PM_2.5 total mass and its chemical species. We fitted a linear mixed effects model to examine short-term associations between PEF and PM_2.5, adjusting for individual and time-varying confounders. A generalized linear mixed effects model was also used to estimate the association for worsening asthma defined by severe PEF decline. Back-trajectory and cluster analyses were used to investigate the long-range transboundary PM_2.5 in the study areas.

RESULTS

We found that morning PEFs were adversely associated with higher levels of sulfate (- 1.61 L/min; 95% CI: - 3.07, - 0.15) in Nagasaki city and organic carbon (OC) (- 1.02 L/min; 95% CI: - 1.94, - 0.09) in Isahaya city, per interquartile range (IQR) increase at lag1. In addition, we observed consistent findings for worsening asthma, with higher odds of severe PEF decline in the morning for sulfate (odds ratio (OR) = 2.31; 95% CI: 1.12, 4.77) and ammonium (OR = 1.73; 95% CI: 1.06, 2.84) in Nagasaki city and OC (OR = 1.51; 95% CI: 1.06, 2.15) in Isahaya city, per IQR increase at lag1. The significant chemical species were higher on days that could be largely attributed to the path of Northeast China origin (for sulfate and ammonium) or both the same path and local sources (for OC) than by other clusters.

CONCLUSIONS

This study provides evidence of the differential effects of PM_2.5 fractions on lung function among asthmatic children in urban areas, where the Japanese national standards of air quality have been nearly met. Continuous efforts to promote mitigation actions and public awareness of hazardous transboundary air pollution are needed to protect susceptible children with asthma.

Fine particulate matter constituents associated with emergency room visits for pediatric asthma: a time-stratified case-crossover study in an urban area

BACKGROUND

Global asthma-related mortality tallies at around 2.5 million annually. Although asthma may be triggered or exacerbated by particulate matter (PM) exposure, studies investigating the relationship of PM and its components with emergency department (ED) visits for pediatric asthma are limited. This study aimed to estimate the impact of short-term exposure to PM constituents on ED visits for pediatric asthma.

METHODS

We retrospectively evaluated non-trauma patients aged younger than 17 years who visited the ED with a primary diagnosis of asthma. Further, measurements of PM with aerodynamic diameter of < 10 μm (PM₁₀), PM with aerodynamic diameter of < 10 μm (PM_2.5), and four PM_2.5 components (i.e., nitrate (NO^3-), sulfate (SO₄^2-), organic carbon (OC), and elemental carbon (EC)) were collected between 2007 and 2010 from southern particulate matter supersites. These included one core station and two satellite stations in Kaohsiung City, Taiwan. A time-stratified case-crossover study was conducted to analyze the hazard effect of PM.

RESULTS

Overall, 1597 patients were enrolled in our study. In the single-pollutant model, the estimated risk increase for pediatric asthma incidence on lag 3 were 14.7% [95% confidence interval (CI), 3.2-27.4%], 13.5% (95% CI, 3.3-24.6%), 14.8% (95% CI, 2.5-28.6%), and 19.8% (95% CI, 7.6-33.3%) per interquartile range increments in PM_2.5, PM₁₀, nitrate, and OC, respectively. In the two-pollutant models, OC remained significant after adjusting for PM_2.5, PM₁₀, and nitrate. During subgroup analysis, children were more vulnerable to PM_2.5 and OC during cold days (< 26 °C, interaction p = 0.008 and 0.012, respectively).

CONCLUSIONS

Both PM_2.5 concentrations and its chemical constituents OC and nitrate are associated with ED visits for pediatric asthma. Among PM_2.5 constituents, OC was most closely related to ED visits for pediatric asthma, and children are more vulnerable to PM_2.5 and OC during cold days.

The association between asthma emergency department visits and satellite-derived PM2.5 in Lima, Peru

BACKGROUND

Asthma affects millions of people worldwide. Lima, Peru is one of the most polluted cities in the Americas but has insufficient ground PM2.5 (particulate matter that are 2.5 μm or less in diameter) measurements to conduct epidemiologic studies regarding air pollution. PM2.5 estimates from a satellite-driven model have recently been made, enabling a study between asthma and PM2.5.

OBJECTIVE

We conducted a daily time-series analysis to determine the association between asthma emergency department (ED) visits and estimated ambient PM2.5 levels in Lima, Peru from 2010 to 2016.

METHODS

We used Poisson generalized linear models to regress aggregated counts of asthma on district-level population weighted PM2.5. Indicator variables for hospitals, districts, and day of week were included to account for spatial and temporal autocorrelation while assessing same day, previous day, day before previous and average across all 3-day exposures. We also included temperature and humidity to account for meteorology and used dichotomous percent poverty and gender variables to assess effect modification.

RESULTS

There were 103,974 cases of asthma ED visits during the study period across 39 districts in Lima. We found a 3.7% (95% CI: 1.7%-5.8%) increase in ED visits for every interquartile range (IQR, 6.02 μg/m3) increase in PM2.5 same day exposure with no age stratification. For the 0-18 years age group, we found a 4.5% (95% CI: 2.2%-6.8%) increase in ED visits for every IQR increase in PM2.5 same day exposure. For the 19-64 years age group, we found a 6.0% (95% CI: 1.0%-11.0%) increase in ED visits for every IQR in average 3-day exposure. For the 65 years and up age group, we found a 16.0% (95% CI: 7.0%-24.0%) decrease in ED visits for every IQR increase in PM2.5 average 3-day exposure, although the number of visits in this age group was low (4,488). We found no effect modification by SES or gender.

DISCUSSION

Results from this study provide additional literature on use of satellite-driven exposure estimates in time-series analyses and evidence for the association between PM2.5 and asthma in a low- and middle-income (LMIC) country.

The Efficacy of the Dyson Air Purifier in Improving Asthma Control: Protocol for a Single-Center, Investigator-Led, Randomized, Double-Blind, Placebo-Controlled Trial

Background

Indoor air quality has been shown to influence asthma control and outcomes. Air purifiers and high-efficiency particulate air filtration devices can improve indoor air quality by reducing the indoor levels of air pollution and allergens. However, the influence of this improved indoor air quality on asthma control remains unclear; hence, randomized controlled trials are needed to further elucidate this phenomenon.

Objective

This study aims to investigate the effect of reducing the levels of allergens and pollutants in the bedroom and living room through the use of Dyson air purifiers (Dyson Pure Cool) on asthma control.

Methods

This is an 18-month long, investigator-led, randomized, double-blinded, placebo-controlled, single-center trial. Subjects will be randomized in a 1:1 ratio to active or placebo Dyson filters. The primary outcome is the change in the scores of Asthma Control Questionnaire 6 and Asthma-specific Quality of Life Questionnaire from baseline. Secondary outcomes include changes in lung function (forced expiratory volume in one second, forced expiratory volume in one second/forced vital capacity ratio, and midexpiratory flows), peak expiratory flow measurements, airway hyperresponsiveness (assessed by methacholine bronchial challenge), fractional exhaled nitric oxide, and indoor air pollutant levels. The sample size will be 50 subjects, and all subjects will have a confirmed diagnosis of mild persistent to moderate persistent asthma along with an Asthma Control Questionnaire 6 score of >1.5.

Results

This study was approved by the West Midlands Research Ethics Committee (18/WM/0277). The study results will be published in peer-reviewed scientific journals; presented at relevant scientific conferences; and shared in plain English with participants in our newsletters, in our clinics, and via the David Hide Asthma and Allergy Research Centre website. Our trial began in September 2019 and is expected to end in August 2021.

Conclusions

This is a double-blinded, placebo-controlled, randomized, investigator-led study to investigate the efficacy of a novel air purifier in improving asthma control in adults. The trial period of 18 months will facilitate the collection of robust data and will therefore generate clear signals. However, this extended trial duration may lead to patient withdrawal. Furthermore, this trial is conducted at a single center and in a location with a homogenous cohort of people, which may affect translatability. Nonetheless, it is hoped that the findings of this trial may help further inform clinicians regarding the utility of this novel device as an adjunct in asthma care.

Trial Registration

ClinicalTrials.gov NCT04729530; https://clinicaltrials.gov/ct2/show/NCT04729530

International Registered Report Identifier (IRRID)

DERR1-10.2196/28624

Indoor air quality of 5,000 households and its determinants. Part A: Particulate matter (PM2.5 and PM10-2.5) concentrations in the Japan Environment and Children's Study

Exposure to particulate matter (PM) is one of the important risk factors for morbidity and mortality. Although PM concentrations have been assessed using air quality monitoring stations or modelling, few studies have measured indoor PM in large-scale birth cohorts. The Japan Environment and Children's Study (JECS) measured indoor and outdoor air quality in approximately 5000 households when the participating children were aged 1.5 and 3 years. PM was collected using portable pumps for 7 days (total of 24 h), inside and outside each home. Prediction models for indoor PM concentrations were built using data collected at age 1.5 years and post-validated against data collected at age 3 years. Median indoor/outdoor PM_2.5 and PM_10-2.5 concentrations at age 1.5 years [3 years] were 12.9/12.7 [12.5/11.3] μg/m³ and 5.0/6.3 [5.1/6.1] μg/m³, respectively. Random forest regression analysis found that the major predictors of indoor PM_2.5 were indoor PM_10-2.5, outdoor PM_2.5, indoor smoking, observable smoke and indoor/outdoor temperature. Indoor PM_2.5, outdoor PM_10-2.5, indoor humidity and opening room windows were important predictors of indoor PM_10-2.5 concentrations. Indoor benzene, acetaldehyde, ozone and nitrogen dioxide concentrations were also found to predict indoor PM_2.5 and PM_10-2.5 concentrations, possibly due to the formation of secondary organic aerosols. These findings demonstrate the importance of reducing outdoor PM concentrations, avoiding indoor smoking, using air cleaner in applicable and diminishing sources of VOCs that could form secondary organic aerosols, and the resulting models can be used to predict indoor PM concentrations for the rest of the JECS cohort.

Air quality, Environment and Respiratory Outcomes in Bronchopulmonary Dysplasia, the AERO-BPD cohort study: design and adaptation during the SARS-CoV-2 pandemic

INTRODUCTION

Almost half of all school-age children with bronchopulmonary dysplasia (BPD) have asthma-like symptoms and more suffer from lung function deficits. While air pollution and indoor respiratory irritants are known to affect high-risk populations of children, few studies have objectively evaluated environmental contributions to long-term respiratory morbidity in this population. This study aimed to examine the role of indoor environmental exposures on respiratory morbidity in children with BPD.

METHODS AND ANALYSIS

The Air quality, Environment and Respiratory Ouctomes in BPD (AERO-BPD) study is a prospective, single-centre observational study that will enrol a unique cohort of 240 children with BPD and carefully characterise participants and their indoor home environmental exposures. Measures of indoor air quality constituents will assess the relationship of nitrogen dioxide (NO2), particulate matter (PM2.5), nitric oxide (NO), temperature and humidity, as well as dust concentrations of allergens, with concurrently measured respiratory symptoms and lung function.Adaptations to the research protocol due to the SARS-CoV-2 pandemic included remote home environment and participant assessments.

ETHICS AND DISSEMINATION

Study protocol was approved by the Boston Children's Hospital Committee on Clinical Investigation. Dissemination will be in the form of peer-reviewed publications and participant information products.

TRIAL REGISTRATION NUMBER

NCT04107701.

Current pet ownership modifies the adverse association between long-term ambient air pollution exposure and childhood asthma

BACKGROUND

Recent studies suggest that household endotoxin and allergens can modify the impact of air pollutants on development of asthma; however, epidemiological evidence is limited and conflicting.

OBJECTIVES

To investigate whether pet ownership modified the association between ambient air pollution and asthma in children.

METHODS

We conducted a population-based cross-sectional study, the Seven Northeast Cities Study in China and recruited a total of 59,754 children from 94 schools during 2012-2013. Long-term air pollutant concentrations, including airborne particulate matter with a diameter of 1 μm or less (PM₁ ), PM_2.5 , PM₁₀ , and nitrogen dioxide (NO₂ ) from 2009 to 2012 were estimated using a random forest model. We collected information of respiratory health in children using the Epidemiologic Standardization Project Questionnaire of the American Thoracic Society (ATS-DLD-78-A). Regression models were used to evaluate associations between pet ownership and air pollution on asthma after adjusting for potential covariates.

RESULTS

Exposure to increasing levels of air pollutants was associated with higher prevalence of asthma, but associations were significantly attenuated in children who owned pets. For example, compared to children without pets, those who owned pets did not have an increased risk of symptoms of asthma (odds ratio, 1.01, 95% confidence interval: 0.78, 1.30), wheeze (0.96, 95% confidence interval [CI]: 0.76, 1.21), and cough (1.01, 95% CI: 0.87, 1.18) for each 10 µg/m³ increase in PM₁ (P_-int  < 0.05). Similar trends were observed for other air pollutants. Dog and bird ownership decreased the associations of asthma and cough with air pollutant exposure. The main findings were consistent with a series of sensitivity analyses.

CONCLUSION

Current pet ownership may reduce the adverse impact of long-term air pollution on childhood asthma. Longitudinal studies are needed to confirm this finding which could have important implications for public health.

Impact assessment of clean cookstove intervention in Gujarat, India: a potential case for corporate social responsibility (CSR) funding

Exposure to indoor air pollutants released from traditional cookstoves in rural Indian households is a matter of great concern. While there are various studies over several decades focused towards intervention strategies for reducing air pollutants, limited literature exists towards the identification of appropriate methodology for feasible intervention, adoption and usage of improved cookstoves (ICS). In the present study, PM_2.5 and CO microenvironment concentrations are estimated in households using traditional and improved cookstove (NEERDHUR). The reduction in PM_2.5 and CO microenvironment concentrations after the introduction of ICS was found to be 89-94% and 35-57%, respectively. Information-education-communication (IEC) activity was used as a tool to increase the adoption and usage rate in the ICS using households. The cost-benefit analysis was also performed to check the benefits of ICS use, and the benefit-cost ratio was found to be 3 to 4 times. Findings of the study suggest that, although the ICS intervention could significantly improve the indoor air quality, however, it fails to comply with the permissible safe limits; further focus on greener fuels and ventilation characteristics is suggested. The outcomes from the study can help decision-makers, corporate social responsibility fund mobilizers and policymakers for effective policy advocacy to design efforts by promoting clean cooking interventions and linking and mapping these with national missions and flagship programs.

Effectiveness of portable HEPA air cleaners on reducing indoor PM2.5 and NH3 in an agricultural cohort of children with asthma: A randomized intervention trial

We conducted a randomized trial of portable HEPA air cleaners with pre-filters designed to also reduce NH₃ in non-smoking homes of children age 6-12 with asthma in Yakima Valley (Washington, USA). Participants were recruited through the Yakima Valley Farm Workers Clinic asthma education program. All participants received education on home triggers while intervention families additionally received two HEPA cleaners (child's sleeping area, main living area). Fourteen-day integrated samples of PM_2.5 and NH₃ were measured at baseline and one-year follow-up. We fit ANCOVA models to compare follow-up concentrations in HEPA vs control homes, adjusting for baseline concentrations. Seventy-one households (36 HEPA, 35 control) completed the study. Most were single-family homes, with electric heat and stove, A/C, dogs/cats, and mean (SD) 5.3 (1.8) occupants. In the sleeping area, baseline geometric mean (GSD) PM_2.5 was 10.7 (2.3) μg/m³ (HEPA) vs 11.2 (1.9) μg/m³ (control); in the living area, it was 12.5 (2.3) μg/m³ (HEPA) vs 13.6 (1.9) μg/m³ (control). Baseline sleeping area NH₃ was 62.4 (1.6) μg/m³ (HEPA) vs 65.2 (1.8) μg/m³ (control). At follow-up, HEPA families had 60% (95% CI, 41%-72%; p < .0001) and 42% (19%-58%; p = .002) lower sleeping and living area PM_2.5 , respectively, consistent with prior studies. NH₃ reductions were not observed.

Fine and coarse particulate matter, trace element content, and associated health risks considering respiratory deposition for Ergene Basin, Thrace

Ergene Basin is located in Thrace, Turkey, where industries are densely populated. This study aimed to determine exposure of people living in Ergene Basin (Çorlu and Çerkezköy) to fine and coarse PM, and its potentially toxic element (PTE) content by considering variation in respiratory airway deposition rates with daily activities and PM particle size by employing deposition models of International Commission on Radiological Protection and Multiple Path Particle Dosimetry. Fine and coarse PM samples were collected daily for a year at points in Çorlu and Çerkezköy representing urban and industrial settings, respectively. A questionnaire survey was conducted in the study area to obtain time-activity budgets, and associated variation was included in the health risk assessment by considering time-activity-dependent inhalation rates. The studied PTEs were Al, As, Ba, Cd, Cr, Co, Mn, Ni, Pb, and Se. The mean fine and coarse PM concentrations were measured as 23 and 14 μg/m³ in Çorlu, and 22 and 12 μg/m³ in Çerkezköy, respectively. The only PTE that exceeded acceptable risk in terms of total carcinogenic risk was Cr. Non-carcinogenic risks of all the PTEs including Cr were below the threshold. The use of deposition fractions in the health risk assessment (HRA) calculations was found to prevent overestimation of health risks by at least 91% and 87% for fine and coarse PM, respectively, compared to the regular HRA. Minor differences in risk between Çorlu and Çerkezköy suggest that urban pollution sources could be at least as influential on human health as industrial sources.

Fine Particulate Matter Exposure Alters Pulmonary Microbiota Composition and Aggravates Pneumococcus-Induced Lung Pathogenesis

Exposure to fine particulate matter (PM) with aerodynamic diameter ≤2.5 μm (PM2. 5) is closely correlated with respiratory diseases. Microbiota plays a key role in maintaining body homeostasis including regulation of host immune status and metabolism. As reported recently, PM2. 5 exposure causes microbiota dysbiosis and thus promotes disease progression. However, whether PM2. 5 alters pulmonary microbiota distribution and aggravates bacteria-induced pathogenesis remains unknown. In this study, we used mouse experimental models of PM2. 5 exposure combined with Streptococcus pneumonia infection. We characterized the airway microbiota of bronchoalveolar lavage fluid (BALF) by sequencing the 16S rRNA V3-V4 amplicon on the Illumina MiSeq platform, followed by a combination of bioinformatics and statistical analyses. Shannon-diversity index, observed ASVs, and Fisher's diversity index indicated that microbiota richness was significantly decreased in the mice treated with either PM2. 5 or pneumococcus when compared with the control group. The genera Streptococcus, Prevotella, Leptotrichia, and Granulicatella were remarkably increased in mice exposed to PM2. 5 combined with pneumococcal infection as compared to mice with pneumococcal infection alone. Histopathological examination exhibited that a more pronounced inflammation was present in lungs of mice treated with PM2. 5 and pneumococcus than that in mouse groups exposed to either PM2. 5 or pneumococcal infection alone. Our results demonstrate that PM2. 5 alters the microbiota composition, thereby enhancing susceptibility to pneumococcal infection and exacerbating lung pathogenesis.

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.

PM2.5 impairs macrophage functions to exacerbate pneumococcus-induced pulmonary pathogenesis

Background

Pneumococcus is one of the most common human airway pathogens that causes life-threatening infections. Ambient fine particulate matter (PM) with aerodynamic diameter ≤ 2.5 μm (PM_2.5) is known to significantly contribute to respiratory diseases. PM_2.5-induced airway inflammation may decrease innate immune defenses against bacterial infection. However, there is currently limited information available regarding the effect of PM_2.5 exposure on molecular interactions between pneumococcus and macrophages.

Results

PM_2.5 exposure hampered macrophage functions, including phagocytosis and proinflammatory cytokine production, in response to pneumococcal infection. In a PM_2.5-exposed pneumococcus-infected mouse model, PM_2.5 subverted the pulmonary immune response and caused leukocyte infiltration. Further, PM_2.5 exposure suppressed the levels of CXCL10 and its receptor, CXCR3, by inhibiting the PI3K/Akt and MAPK pathways.

Conclusions

The effect of PM_2.5 exposure on macrophage activity enhances pneumococcal infectivity and aggravates pulmonary pathogenesis.

Relationship between biometeorological factors and the number of hospitalizations due to asthma

The incidence of asthma exacerbation depends on atmospheric conditions, including such meteorological factors as the ambient temperature, relative air humidity or concentration of atmospheric aerosols. An assessment of relations between the frequency of asthma exacerbation and environmental conditions was made according to the meteorological components, the biometeorological index UTCI (Universal Thermal Climate Index), as well as selected air quality parameters, including concentrations of PM₁₀ and PM_2.5. The study was conducted on the basis of a retrospective analysis of medical data collected at the Independent Public Hospital of Tuberculosis and Pulmonary Diseases in Olsztyn (Poland). Our analysis of patient data (from 1 January 2013 until 31 December 2017) showed a significant correlation between the number of asthma exacerbation and the UTCI value. More frequent asthma exacerbations are observed in patients aged over 65 years when air humidity increases. The UTCI values contained within class 5, describing thermoneutral conditions, correspond to an average frequency of asthma exacerbation. A decline in the UTCI value leads to a reduced number of asthma exacerbation, while a rise makes the cases of asthma exacerbations increase.

The Impact of PM2.5 on the Host Defense of Respiratory System

The harm of fine particulate matter (PM_2.5) to public health is the focus of attention around the world. The Global Burden of Disease (GBD) Study 2015 (GBD 2015 Risk Factors Collaborators, 2016) ranked PM_2.5 as the fifth leading risk factor for death, which caused 4.2 million deaths and 103.1 million disability-adjusted life-years (DALYs) loss, representing 7.6% of total global deaths and 4.2% of global DALYs. Epidemiological studies have confirmed that exposure to PM_2.5 increases the incidence and mortality of respiratory infections. The host defense dysfunction caused by PM_2.5 exposure may be the key to the susceptibility of respiratory system infection. Thus, this review aims to assess the impact of PM_2.5 on the host defense of respiratory system. Firstly, we elaborated the epidemiological evidence that exposure to PM_2.5 increases the risk of respiratory infections. Secondly, we summarized the experimental evidence that PM_2.5 exposure increases the susceptibility of different pathogens (including bacteria and viruses) in respiratory system. Furthermore, here we discussed the underlying host defense mechanisms by which PM_2.5 exposure increases the risk of respiratory infections as well as future perspectives.

Source apportionment of fine particulate matter in a Middle Eastern Metropolis, Tehran-Iran, using PMF with organic and inorganic markers

With over 8 million inhabitants and 4 million motor vehicles on the streets, Tehran is one of the most crowded and polluted cities in the Middle East. Frequent exceedances of national daily PM_2.5 limit have been reported in this city during the last decade, yet, the chemical composition and sources of fine particles are poorly determined. In the present study, 24-hour PM_2.5 samples were collected at two urban sites during two separate campaigns, a one-year period from 2014 to 2015 and another three-month period at the beginning of 2017. Concentrations of organic carbon (OC), elemental carbon (EC), inorganic ions, trace metals and specific organic molecular markers were measured by chemical analysis of filter samples. The dominant mass components were organic matter (OM), sulfate and EC. With a 20% water-soluble organic carbon (WSOC) fraction, the predominance of primary anthropogenic sources (i.e. fossil fuel combustion) was anticipated. A positive matrix factorization (PMF) analysis using the ME-2 (Multilinear Engine-2) solver was then applied to this dataset. 5 factors were identified by Marker-PMF, named as traffic exhaust (TE), biomass burning (BB), industries (Ind.), nitrate-rich and sulfate-rich. Another 4 factors were identified by Metal-PMF, including, dust, vehicles (traffic non-exhaust, TNE), industries (Ind.) and heavy fuel combustion (HFC). Traffic exhaust was the dominant source with 44.5% contribution to total quantified PM_2.5 mass. Sulfate-rich (24.2%) and nitrate-rich (18.4%) factors were the next major contributing sources. Dust (4.4%) and biomass burning (6.7%) also had small contributions while the total share of all other factors was < 2%. Investigating the correlations of different factors between the two sampling sites showed that traffic emissions and biomass burning were local, whereas dust, heavy fuel combustion and industrial sources were regional. Results of this study indicate that gas- and particle-phase pollutants emitted from fossil fuel combustion (mobile and stationary) are the principal origin of both primary and secondary fine aerosols in Tehran.

Indoor PM2.5, tobacco smoking and chronic lung diseases: A narrative review

The lung is one of the most important organs exposed to environmental agents. People spend approximately 90% of their time indoors, and risks to health may thus be greater from exposure to poor air quality indoors than outdoors. Multiple indoor pollutants have been linked to chronic respiratory diseases. Environmental tobacco smoke (ETS) is known as an important source of multiple pollutants, especially in indoor environments. Indoor PM_2.5 (particulate matter with aerodynamic diameter < 2.5 μm) was reported to be the most reliable marker of the presence of tobacco smoke. Recent studies have demonstrated that PM_2.5 is closely correlated with chronic lung diseases. In this paper, we reviewed the relationship of tobacco smoking and indoor PM_2.5 and the mechanism that underpin the link of tobacco smoke, indoor PM_2.5 and chronic lung diseases.

Children's acute respiratory symptoms associated with PM2.5 estimates in two sequential representative surveys from the Mexico City Metropolitan Area

BACKGROUND

Respiratory diseases are a major component of morbidity in children and their symptoms may be spatially and temporally exacerbated by exposure gradients of fine particulate matter (PM_2.5) in large polluted urban areas, like the Mexico City Metropolitan Area (MCMA).

OBJECTIVES

To analyze the association between satellite-derived and interpolated PM_2.5 estimates with children's (≤9 years old) acute respiratory symptoms (ARS) in two probabilistic samples representing the MCMA.

METHODS

We obtained ARS data from the 2006 and 2012 National Surveys for Health and Nutrition (ENSaNut). Two week average exposure to PM_2.5 was assessed for each household with spatial estimates from a hybrid model with satellite measurements of aerosol optical depth (AOD-PM_2.5) and also with interpolated PM_2.5 measurements from ground stations, from the Mexico City monitoring network (MNW-PM_2.5). We used survey-adjusted logistic regressions to analyze the association between PM_2.5 estimates and ARS reported on children.

RESULTS

A total of 1,005 and 1,233 children were surveyed in 2006 and 2012 representing 3.1 and 3.5 million children, respectively. For the same years and over the periods of study, the estimated prevalence of ARS decreased from 49.4% (95% CI: 44.9,53.9%) to 37.8% (95% CI: 34,41.7%). AOD-PM_2.5 and MNW-PM_2.5 estimates were associated with significantly higher reports of ARS in children 0-4 years old [OR₂₀₀₆ = 1.29 (95% (CI): 0.99,1.68) and OR₂₀₀₆ = 1.24 (95% CI: 1.08,1.42), respectively]. We observed positive non-significant associations in 2012 in both age groups and in 2006 for children 5-9 years old. No statistically significant differences in health effect estimates of PM_2.5 were found comparing AOD-PM_2.5 or MNW-PM_2.5 for exposure assessment.

CONCLUSIONS

Our findings suggest that PM_2.5 is a risk factor for the prevalence of ARS in children and expand the growing evidence of the utility of new satellite AOD-based methods for estimating health effects from acute exposure to PM_2.5.

Viruses and non-allergen environmental triggers in asthma

Asthma is a complex inflammatory disease with many triggers. The best understood asthma inflammatory pathways involve signals characterized by peripheral eosinophilia and elevated immunoglobulin E levels (called T2-high or allergic asthma), though other asthma phenotypes exist (eg, T2-low or non-allergic asthma, eosinophilic or neutrophilic-predominant). Common triggers that lead to poor asthma control and exacerbations include respiratory viruses, aeroallergens, house dust, molds, and other organic and inorganic substances. Increasingly recognized non-allergen triggers include tobacco smoke, small particulate matter (eg, PM2.5), and volatile organic compounds. The interaction between respiratory viruses and non-allergen asthma triggers is not well understood, though it is likely a connection exists which may lead to asthma development and/or exacerbations. In this paper we describe common respiratory viruses and non-allergen triggers associated with asthma. In addition, we aim to show the possible interactions, and potential synergy, between viruses and non-allergen triggers. Finally, we introduce a new clinical approach that collects exhaled breath condensates to identify metabolomics associated with viruses and non-allergen triggers that may promote the early management of asthma symptoms.

Indoor particulate matter and lung function in children

People generally spend more time indoors than outdoors resulting in a higher proportion of exposure to particulate matter (PM) occurring indoors. Consequently, indoor PM levels, in contrast to outdoor PM levels, may have a stronger relationship with lung function. To test this hypothesis, indoor and outdoor PM_2.5 and fungal spore data were simultaneously collected from the homes of forty-four asthmatic children aged 10-16 years. An optical absorption technique was utilized on the collected PM_2.5 mass to obtain concentrations of black carbon (BC) and ultraviolet light absorbing particulate matter, (UVPM; a marker of light absorbing PM_2.5 emitted from smoldering organics). Enrolled children completed spirometry after environmental measurements were made. Given the high correlation between PM_2.5, BC, and UVPM, principal component analysis was used to obtain uncorrelated summaries of the measured PM. Separate linear mixed-effect models were developed to estimate the association between principal components of the PM variables and spirometry values, as well as the uncorrelated original PM variables and spirometry values. A one-unit increase in the first principal component variable representing indoor PM (predominantly composed of UVPM and PM_2.5) was associated with 4.1% decrease (99% CI = -6.9, -1.4) in FEV₁/FVC ratio. 11.3 μg/m³ increase in indoor UVPM was associated with 6.4% and 14.7% decrease (99% CI = -10.4, -2.4 and 99% CI = -26.3, -2.9, respectively) in percent predicted FEV₁/FVC ratio and FEF_25-75 respectively. Additionally, 17.7 μg/m³ increase in indoor PM_2.5 was associated with 6.1% and 12.9% decrease (99% CI = -10.2, -1.9 and 99% CI = -24.9, -1.0, respectively) in percent predicted FEV₁/FVC ratio and FEF_25-75, respectively. Outdoor PM, indoor BC, and indoor fungal spores were not significantly associated with lung function. The results indicate that indoor PM is more strongly associated with lung function in children with asthma as compared with outdoor PM.

Different health effects of indoor- and outdoor-originated PM2.5 on cardiopulmonary function in COPD patients and healthy elderly adults

Numerous research has explored the associations of outdoor or indoor fine particulate matter (PM_2.5 ) and health effects; however, few studies compared the effects of indoor PM_2.5 originated from outdoor (PM_2.5,os ) and indoor sources (PM_2.5,is ). To assess the associations of PM_2.5,os and PM_2.5,is with cardiopulmonary function in patients with chronic obstructive pulmonary disease (COPD) and healthy elderly adults, blood pressure (BP) and pulmonary function were repeatedly examined in 43 COPD patients and their 32 healthy spouses in Beijing, China. Iron was used as tracer element to separate PM_2.5,os and PM_2.5,is . Mixed-effects models were applied to assess the associations of PM_2.5,os or PM_2.5,is and health effects after controlling for potential confounders. There was a reduction in forced expiratory volume in first second (FEV₁ ) in COPD patients associated with PM_2.5,is during the heating season. PM_2.5,os was positively associated with diastolic BP (DBP) in healthy elderly adults during the heating season. There was a reduction in peak expiratory flow (PEF) in healthy elderly adults associated with PM_2.5,os during the non-heating season. Exposure to indoor- and outdoor-originated PM_2.5 had different health effects on cardiopulmonary function in different populations. The results provide supporting evidence for improving indoor air quality to promote public health among susceptible population.

Removal of PM2.5 and secondary inorganic aerosols in the North China Plain by dry deposition

The North China Plain (NCP) has experienced heavy air pollution in the past several decades featured by high levels of fine particulate matter (PM_2.5). PM_2.5 removal from the atmosphere in the NCP by dry deposition was estimated from 1999 through 2013 using the inferential method, which combined PM_2.5 air concentrations retrieved from satellite remote sensing and dry deposition velocities (V_d) calculated using a bulk particle dry deposition model. Dry deposition of the three major inorganic ions in PM_2.5, namely NH₄⁺ (ammonium), NO₃^- (nitrate), and SO₄^2- (sulfate), with their concentrations in 2000 and 2010 obtained from WRF-Chem model simulations, were also investigated considering their important roles in PM_2.5 formation and ecosystem health. High levels of modeled and satellite-retrieved PM_2.5 air concentrations, the secondary inorganic aerosols (the sum of NH₄⁺, NO₃^-, and SO₄^2-), and their respective deposition fluxes were identified from the southern NCP to Beijing-Tianjin metropolitans. The deposition fluxes derived from the inferential method and WRF-Chem increased considerably in the 2000s due to rising PM_2.5 atmospheric levels across the NCP. The enhancement of dry deposition velocities of PM_2.5 and three aerosol species in the NCP were associated nicely with increasing vegetation coverage and wind speed. We show that both air concentrations of PM_2.5 and secondary inorganic aerosols and rising dry deposition velocities related to extensive afforestation activities contributed to their deposition fluxes and an inclining trend of PM_2.5 removal from the atmosphere.

Pediatric Asthma: A Global Epidemic

The global prevalence, morbidity and mortality related to childhood asthma among children has increased significantly over the last 40 years. Although asthma is recognized as the most common chronic disease in children, issues of underdiagnosis and undertreatment persist. There are substantial global variations in the prevalence of asthma symptoms in children, with up to 13-fold differences between countries. The rising number of hospital admissions for asthma may reflect an increase in asthma severity, poor disease management and/or the effect of poverty. The financial burden of asthma is relatively high within developed countries (those for which data is available) spending 1 to 2% of their healthcare budget on this condition. Established in 1989, the Global Initiative for Asthma (GINA) attempts to raise awareness about the increasing prevalence of asthma, improve management and reduce the burden of asthma worldwide. Despite global efforts, GINA has not achieved its goal, even among developed nations. There are multiple barriers to reducing the global burden of asthma, including limited access to care and/or medications, and lack of prioritization as a public healthcare priority. In addition, the diversity of healthcare systems worldwide and large differences in access to care require that asthma management guidelines be tailored to local needs.

Indoor Particulate Matters, Microbial Count Assessments, and Wheezing Symptoms among Toddlers in Urban Day Care Centers in the District of Seremban, Malaysia

Introduction:

Indoor air quality in day care centers (DCCs) is an emerging research topic nowadays. Indoor air pollutants such as particulate matter (PM) and microbes have been linked to respiratory health effects in children, particularly asthma-related symptoms such as night coughs and wheezing due to early exposure to indoor air contaminants.

Objective:

The aim of this study was to determine the association between wheezing symptoms among toddlers attending DCCs and indoor particulate matter, PM10, PM2.5, and microbial count level in urban DCCs in the District of Seremban, Malaysia.

Methods:

Data collection was carried out at 10 DCCs located in the urban area of Seremban. Modified validated questionnaires were distributed to parents to obtain their children’s health symptoms. The parameters measured were indoor PM2.5, PM10, carbon monoxide, total bacteria count, total fungus count, temperature, air velocity, and relative humidity using the National Institute for Occupational Safety and Health analytical method.

Results:

All 10 DCCs investigated had at least one indoor air quality parameter exceeding the acceptable level of standard guidelines. The prevalence of toddlers having wheezing symptoms was 18.9%. There was a significant different in mean concentration of PM2.5 and total bacteria count between those with and those without wheezing symptoms (P = 0.02, P = 0.006).

Conclusions:

Urban DCCs are exposed to many air pollutants that may enter their buildings from various adjacent sources. The particle concentrations and presence of microbes in DCCs might increase the risk of exposed children for respiratory diseases, particularly asthma, in their later life.

Indoor ozone levels, houseplants and peak expiratory flow rates among healthy adults in Taipei, Taiwan

The association between houseplants and indoor air quality improvement has been reported in previous studies. However, the effect of houseplant-emitted isoprene on the association between ozone (O₃) formation and respiratory health remains unclear. We recruited 60 adult subjects from 60 houses with or without houseplants (1:1) in Taipei; twelve house visits were conducted in each home throughout 2014. The indoor air pollutants that were measured consisted of particulate matter less than or equal to 2.5 μm in diameter (PM_2.5), O₃ and isoprene. Peak expiratory flow rate (PEFR) was measured in each study subject during each house visit. Household information was collected by a questionnaire. Mixed-effects models were used to explore the association between indoor air pollution levels and PEFR. We found that the concentrations of O₃ and isoprene in houses with houseplants were higher than those in houses without houseplants. In contrast, PM_2.5 levels and % predicted PEFR were higher in houses without houseplants than in those with houseplants. Moreover, increased levels of O₃ and PM_2.5 in houses with houseplants were associated with a decreased % predicted PEFR, especially in the summer. We concluded that increased levels of indoor O₃ and PM_2.5 were associated with decreased PEFR. The presence of houseplants was associated with indoor O₃, isoprene and PEFR variations in the summer.