A Narrative Review on the Impact of Air Pollution on Heart Failure Risk and Exacerbation

Air pollution is a risk factor for many cardiovascular diseases, including heart failure (HF). Although the links between air pollution and HF have been explored, the results are scattered and difficult to piece together into a cohesive story. Therefore, we undertook a narrative review of all aspects of the relationship between HF and air pollution exposure, including risks of developing HF when exposed to air pollution, the exacerbation of HF symptoms by air pollution exposure, and the increased susceptibility that individuals with HF have for air pollution-related health risks. We also examined the literature on environmental justice as well as air pollution interventions for HF. We found substantial evidence linking air pollution exposure to HF incidence. There were a limited number of studies that examined air pollution exposure in clearly defined populations with HF to explore exacerbation of HF or the susceptibility of individuals with HF to air pollution health risks. However, there is substantial evidence that HF-related hospitalisations are increased under air pollution exposure and that the air pollution associated increase in HF-related hospitalisations is greater than hospitalisations for other chronic diseases, supporting links between air pollution and both exacerbation of HF and susceptibility of individuals with HF. There is emerging evidence for interventions that can decrease air pollution health risks for individuals with HF, and more studies are needed, particularly randomised controlled trials. Thus, although the air pollution-related health risks for HF incidence and hospitalisations are clear, further studies specifically targeted at identified data gaps will greatly improve our knowledge of the susceptibility of individuals with HF and interventions to reduce risks.

Exposures to low-levels of fine particulate matter are associated with acute changes in heart rate variability, cardiac repolarization, and circulating blood lipids in coronary artery disease patients

Exposure to air pollution is a major risk factor for cardiovascular disease, disease risk factors, and mortality. Specifically, particulate matter (PM), and to some extent ozone, are contributors to these effects. In addition, exposures to these pollutants may be especially dangerous for susceptible populations. In this repeated-visit panel study, cardiovascular markers were collected from thirteen male participants with stable coronary artery disease. For 0-4 days prior to the health measurement collections, daily concentrations of fine PM (PM_2.5) and ozone were obtained from local central monitoring stations located near the participant's homes. Then, single (PM_2.5) and two-pollutant (PM_2.5 and ozone) models were used to assess whether there were short-term changes in cardiovascular health markers. Per interquartile range increase in PM_2.5, there were decrements in several heart rate variability metrics, including the standard deviation of the normal-to-normal intervals (lag 3, -5.8%, 95% confidence interval (CI) = -11.5, 0.3) and root-mean squared of successive differences (five day moving average, -8.1%, 95% CI = -15.0, -0.7). In addition, increases in PM_2.5 were also associated with changes in P complexity (lag 1, 4.4%, 95% CI = 0.5, 8.5), QRS complexity (lag 1, 4.9%, 95% CI = 1.4, 8.5), total cholesterol (five day moving average, -2.1%, 95% CI = -4.1, -0.1), and high-density lipoprotein cholesterol (lag 2, -1.6%, 95% CI = -3.1, -0.1). Comparisons to our previously published work on ozone were conducted. We found that ozone affected inflammation and endothelial function, whereas PM_2.5 influenced heart rate variability, repolarization, and lipids. All the health changes from these two studies were found at concentrations below the United States Environmental Protection Agency's National Ambient Air Quality Standards. Our results imply clear differences in the cardiovascular outcomes observed with exposure to the two ubiquitous air pollutants PM_2.5 and ozone; this observation suggests different mechanisms of toxicity for these exposures.

Short-term PM2.5 exposure and early-readmission risk: a retrospective cohort study in North Carolina heart failure patients

BACKGROUND

Short-term changes in ambient fine particulate matter (PM_2.5) increase the risk for unplanned hospital readmissions. However, this association has not been fully evaluated for high-risk patients or examined to determine if the readmission risk differs based on time since discharge. Here we investigate the relation between ambient PM_2.5 and 30-day readmission risk in heart failure (HF) patients using daily time windows and examine how this risk varies with respect to time following discharge.

METHODS

We performed a retrospective cohort study of 17,674 patients with a recorded HF diagnosis between 2004 and 2016. The cohort was identified using the EPA CARES electronic health record resource. The association between ambient daily PM_2.5 (μg/m³) concentration and 30-day readmissions was evaluated using time-dependent Cox proportional hazard models. PM_2.5 associated readmission risk was examined throughout the 30-day readmission period and for early readmissions (1-3 days post-discharge). Models for 30-day readmissions included a parametric continuous function to estimate the daily PM_2.5 associated readmission hazard. Fine-resolution ambient PM_2.5 data were assigned to patient residential address and hazard ratios are expressed per 10 μg/m³ of PM_2.5. Secondary analyses examined potential effect modification based on the time after a HF diagnosis, urbanicity, medication prescription, comorbidities, and type of HF.

RESULTS

The hazard of a PM_2.5-related readmission within 3 days of discharge was 1.33 (95% CI 1.18-1.51). This PM_2.5 readmission hazard was slightly elevated in patients residing in non-urban areas (1.43, 95%CI 1.22-1.67) and for HF patients without a beta-blocker prescription prior to the readmission (1.35; 95% CI 1.19-1.53).

CONCLUSION

Our findings add to the evidence indicating substantial air quality-related health risks in individuals with underlying cardiovascular disease. Hospital readmissions are key metrics for patients and providers alike. As a potentially modifiable risk factor, air pollution-related interventions may be enacted that might assist in reducing costly and burdensome unplanned readmissions.

Associations between short-term exposure to PM2.5 and cardiomyocyte injury in myocardial infarction survivors in North Carolina

Objective

Short-term ambient fine particulate matter (PM_2.5) is associated with adverse cardiovascular events including myocardial infarction (MI). However, few studies have examined associations between PM_2.5 and subclinical cardiomyocyte damage outside of overt cardiovascular events. Here we evaluate the impact of daily PM_2.5 on cardiac troponin I, a cardiomyocyte specific biomarker of cellular damage.

Methods

We conducted a retrospective cohort study of 2924 patients identified using electronic health records from the University of North Carolina Healthcare System who had a recorded MI between 2004 and 2016. Troponin I measurements were available from 2014 to 2016, and were required to be at least 1 week away from a clinically diagnosed MI. Daily ambient PM_2.5 concentrations were estimated at 1 km resolution and assigned to patient residence. Associations between log-transformed troponin I and daily PM_2.5 were evaluated using distributed lag linear mixed effects models adjusted for patient demographics, socioeconomic status and meteorology.

Results

A 10 µg/m³ elevation in PM_2.5 3 days before troponin I measurement was associated with 0.06 ng/mL higher troponin I (95% CI=0.004 to 0.12). In stratified models, this association was strongest in patients that were men, white and living in less urban areas. Similar associations were observed when using 2-day rolling averages and were consistently strongest when using the average exposure over the 5 days prior to troponin I measurement.

Conclusions

Daily elevations in PM_2.5 were associated with damage to cardiomyocytes, outside of the occurrence of an MI. Poor air quality may cause persistent damage to the cardiovascular system leading to increased risk of cardiovascular disease and adverse cardiovascular events.

Associations between neighborhood socioeconomic cluster and hypertension, diabetes, myocardial infarction, and coronary artery disease within a cohort of cardiac catheterization patients

Background

Neighborhood-level socioeconomic status (SES) is associated with health outcomes, including cardiovascular disease and diabetes, but these associations are rarely studied across large, diverse populations.

Methods

We used Ward’s Hierarchical clustering to define eight neighborhood clusters across North Carolina using 11 census-based indicators of SES, race, housing, and urbanicity and assigned 6992 cardiac catheterization patients at Duke University Hospital from 2001 to 2010 to clusters. We examined associations between clusters and coronary artery disease index > 23 (CAD), history of myocardial infarction, hypertension, and diabetes using logistic regression adjusted for age, race, sex, body mass index, region of North Carolina, distance to Duke University Hospital, and smoking status.

Results

Four clusters were urban, three rural, and one suburban higher-middle-SES (referent). We observed greater odds of myocardial infarction in all six clusters with lower or middle-SES. Odds of CAD were elevated in the rural cluster that was low-SES and plurality Black (OR 1.16, 95% CI 0.94-1.43) and in the rural cluster that was majority American Indian (OR 1.31, 95% CI 0.91-1.90). Odds of diabetes and hypertension were elevated in two urban and one rural low- and lower-middle SES clusters with large Black populations.

Conclusions

We observed higher prevalence of cardiovascular disease and diabetes in neighborhoods that were predominantly rural, low-SES, and non-White, highlighting the importance of public health and healthcare system outreach into these communities to promote cardiometabolic health and prevent and manage hypertension, diabetes and coronary artery disease.

Evaluation of PM2.5 air pollution sources and cardiovascular health

Long-term air pollution exposure, notably fine particulate matter, is a global contributor to morbidity and mortality and a known risk factor for coronary artery disease (CAD) and myocardial infarctions (MI). Knowledge of impacts related to source-apportioned PM2.5 is limited. New modeling methods allow researchers to estimate source-specific long-term impacts on the prevalence of CAD and MI. The Catheterization Genetics (CATHGEN) cohort consists of patients who underwent a cardiac catheterization at Duke University Medical Center between 2002 and 2010. Severity of coronary blockage was determined by coronary angiography and converted into a binary indicator of clinical CAD. History of MI was extracted from medical records. Annual averages of source specific PM2.5 were estimated using an improved gas-constrained source apportionment model for North Carolina from 2002 to 2010. We tested six sources of PM2.5 mass for associations with CAD and MI using mixed effects multivariable logistic regression with a random intercept for county and multiple adjustments. PM2.5 fractions of ammonium bisulfate and ammonium nitrate were associated with increased prevalence of CAD (odds ratio [OR] 1.20; 95% CI = 1.11, 1.22 and OR 1.18; 95% CI = 1.05, 1.32, respectively). PM2.5 from ammonium bisulfate and ammonium nitrate were also associated with increased prevalence of MI (OR 1.20; 95% CI = 1.10, 1.29 and OR 1.35; 95% CI = 1.20, 1.53, respectively). Greater PM2.5 concentrations of ammonium bisulfate and ammonium nitrate are associated with greater MI and CAD prevalence. The association with bisulfate suggests aerosol acidity may play a role. Our findings suggest analyses of source specific PM2.5 mass can reveal novel associations.

Long-Term Exposure to Particulate Air Pollution Is Associated With 30-Day Readmissions and Hospital Visits Among Patients With Heart Failure

Background

Long‐term air pollution exposure is a significant risk factor for inpatient hospital admissions in the general population. However, we lack information on whether long‐term air pollution exposure is a risk factor for hospital readmissions, particularly in individuals with elevated readmission rates.

Methods and Results

We determined the number of readmissions and total hospital visits (outpatient visits+emergency room visits+inpatient admissions) for 20 920 individuals with heart failure. We used quasi‐Poisson regression models to associate annual average fine particulate matter at the date of heart failure diagnosis with the number of hospital visits and 30‐day readmissions. We used inverse probability weights to balance the distribution of confounders and adjust for the competing risk of death. Models were adjusted for age, race, sex, smoking status, urbanicity, year of diagnosis, short‐term fine particulate matter exposure, comorbid disease, and socioeconomic status. A 1‐µg/m³ increase in fine particulate matter was associated with a 9.31% increase (95% CI, 7.85%–10.8%) in total hospital visits, a 4.35% increase (95% CI, 1.12%–7.68%) in inpatient admissions, and a 14.2% increase (95% CI, 8.41%–20.2%) in 30‐day readmissions. Associations were robust to different modeling approaches.

Conclusions

These results highlight the potential for air pollution to play a role in hospital use, particularly hospital visits and readmissions. Given the elevated frequency of hospitalizations and readmissions among patients with heart failure, these results also represent an important insight into modifiable environmental risk factors that may improve outcomes and reduce hospital use among patients with heart failure.

Association between short-term exposure to ambient fine particulate matter and myocardial injury in the CATHGEN cohort

Exposure to fine particulate matter (PM_2.5) has been associated with a higher risk for coronary events. Elevated circulating cardiac troponins (cTn) are suggestive of myocardial injury in both ischemic and non-ischemic conditions. However, little is known about the association between PM_2.5 and cTn. In this study, we investigated short-term PM_2.5 effects on cardiac troponin T (cTnT), as well as N-terminal-pro brain natriuretic peptide (NT-pro BNP) and inflammatory biomarkers among cardiac catheterized participants. We analyzed 7444 plasma cTnT measurements in 2732 participants who presented to Duke University Hospital with myocardial infarction symptoms between 2001 and 2012, partly along with measurements of NT-pro BNP and inflammatory biomarkers. Daily PM_2.5 concentrations were predicted by a neural network-based hybrid model and were assigned to participants' residential addresses. We applied generalized estimating equations to assess associations of PM_2.5 with biomarker levels and the risk of a positive cTnT test (cTnT > 0.1 ng/mL). The median plasma cTnT concentration at presentation was 0.05 ng/mL and the prevalence of a positive cTnT test was 35.4%. For an interquartile range (7.6 μg/m³) increase in PM_2.5 on the previous day, cTnT concentrations increased by 7.7% (95% CI: 3.4-12.3) and the odds ratio of a positive cTnT test was 1.08 (1.01-1.16). Participants under 60 years (effect estimate: 15.2%; 95% CI: 7.4-23.5) or living in rural areas (12.3%; 95% CI: 4.8-20.3) were more susceptible. There was evidence for increases in fibrinogen and NT-pro BNP associated with elevated PM_2.5 on the concurrent and previous two days. Our study suggests that acute PM_2.5 exposure may elevate indicators of myocardial tissue damage. This finding substantiates the association of air pollution exposure with adverse cardiovascular events.

Association of short-term exposure to ambient PM2.5 with hospital admissions and 30-day readmissions in end-stage renal disease patients: population-based retrospective cohort study

OBJECTIVES

To examine the effect of short-term exposure to ambient fine particulate matter (PM_2.5) on all-cause, cardiovascular and respiratory-related hospital admissions and readmissions among patients receiving outpatient haemodialysis.

DESIGN

Retrospective cohort study.

SETTING

Inpatient hospitalisation claims identified from the US Renal Data System in 530 US counties.

PARTICIPANTS

All patients receiving in-centre haemodialysis between 2008 and 2014.

PRIMARY AND SECONDARY OUTCOME MEASURES

Risk of all-cause, cardiovascular and respiratory-related hospital admissions and 30-day all-cause and cause-specific readmission following an all-cause, cardiovascular, and respiratory-related discharges. Readmission risk was evaluated for early (1-7 days postdischarge) and late (8-30 days postdischarge) readmission time periods. Relative risk is expressed per 10 μg/m³ of PM_2.5.

RESULTS

Same-day ambient PM_2.5 was associated with increased hospital admission risk for cardiovascular causes (0.9%, 95% CI 0.2 to 1.7). Greater PM_2.5-related associations were observed with 30-day readmission risk. Early-readmission risk was increased by 1.6%-1.8% following all-cause (1.6%, 95% CI 0.6% to 2.6%), cardiovascular (1.8%, 95% CI 0.4% to 3.2%) and respiratory (1.8%, 95% CI 0.4% to 3.2%) discharges; while late-readmission risk increased by 1.2%-1.3% following all-cause and cardiovascular discharges. PM_2.5-related associations with readmission risk were greatest for certain cause-specific readmissions ranging 4.0%-6.5% for dysrhythmia and conduction disorder, heart failure, chronic obstructive pulmonary disease, other non-cardiac chest pain or respiratory syndrome and pneumonia. Following all-cause discharges, the cause-specific early-readmission risk was increased by 6.5% (95% CI 3.5% to 9.6%) for pneumonia, 4.8% (95% CI 2.3% to 7.4%) for dysrhythmia and conduction disorder, 3.7% (95% CI 1.4% to 6.0%) for heart failure and 2.7% (95% CI 1.2% to 4.2%) for other non-cardiac chest pain or respiratory syndrome-related causes.

CONCLUSIONS

Daily ambient PM_2.5 was associated with an increased risk of cardiovascular admissions and 30-day readmissions following cardiopulmonary-related discharges in a vulnerable end-stage renal disease population. In the first week following discharge, greater PM_2.5-related risk of rehospitalisation was identified for some diagnoses.

Cardiopulmonary Impact of Particulate Air Pollution in High-Risk Populations: JACC State-of-the-Art Review

Fine particulate air pollution <2.5 μm in diameter (PM2.5) is a major environmental threat to global public health. Multiple national and international medical and governmental organizations have recognized PM2.5 as a risk factor for cardiopulmonary diseases. A growing body of evidence indicates that several personal-level approaches that reduce exposures to PM2.5 can lead to improvements in health endpoints. Novel and forward-thinking strategies including randomized clinical trials are important to validate key aspects (e.g., feasibility, efficacy, health benefits, risks, burden, costs) of the various protective interventions, in particular among real-world susceptible and vulnerable populations. This paper summarizes the discussions and conclusions from an expert workshop, Reducing the Cardiopulmonary Impact of Particulate Matter Air Pollution in High Risk Populations, held on May 29 to 30, 2019, and convened by the National Institutes of Health, the U.S. Environmental Protection Agency, and the U.S. Centers for Disease Control and Prevention.

Wildfire Smoke: Opportunities for Cooperation Among Health Care, Public Health, and Land Management to Protect Patient Health

Preventing the adverse health impacts of wildfire smoke involves helping people understand if they are at risk, and the actions they can take to limit exposure. Cooperation between land managers, public health officials, and the health care system could alert the public to take actions that reduce wildfire smoke-related health risks.

Out-of-Hospital Cardiac Arrests and Wildfire-Related Particulate Matter During 2015-2017 California Wildfires

Background

The natural cycle of large‐scale wildfires is accelerating, increasingly exposing both rural and populous urban areas to wildfire emissions. While respiratory health effects associated with wildfire smoke are well established, cardiovascular effects have been less clear.

Methods and Results

We examined the association between out‐of‐hospital cardiac arrest and wildfire smoke density (light, medium, heavy smoke) from the National Oceanic Atmospheric Association's Hazard Mapping System. Out‐of‐hospital cardiac arrest data were provided by the Cardiac Arrest Registry to Enhance Survival for 14 California counties, 2015–2017 (N=5336). We applied conditional logistic regression in a case‐crossover design using control days from 1, 2, 3, and 4 weeks before case date, at lag days 0 to 3. We stratified by pathogenesis, sex, age (19–34, 35–64, and ≥65 years), and socioeconomic status (census tract percent below poverty). Out‐of‐hospital cardiac arrest risk increased in association with heavy smoke across multiple lag days, strongest on lag day 2 (odds ratio, 1.70; 95% CI, 1.18–2.13). Risk in the lower socioeconomic status strata was elevated on medium and heavy days, although not statistically significant. Higher socioeconomic status strata had elevated odds ratios with heavy smoke but null results with light and medium smoke. Both sexes and age groups 35 years and older were impacted on days with heavy smoke.

Conclusions

Out‐of‐hospital cardiac arrests increased with wildfire smoke exposure, and lower socioeconomic status appeared to increase the risk. The future trajectory of wildfire, along with increasing vulnerability of the aging population, underscores the importance of formulating public health and clinical strategies to protect those most vulnerable.

Associations Between Long-Term Fine Particulate Matter Exposure and Mortality in Heart Failure Patients

Background Environmental health risks for individuals with heart failure (HF) have been inadequately studied, as these individuals are not well represented in traditional cohort studies. To address this we studied associations between long-term air pollution exposure and mortality in HF patients. Methods and Results The study population was a hospital-based cohort of individuals diagnosed with HF between July 1, 2004 and December 31, 2016 compiled using electronic health records. Individuals were followed from 1 year after initial diagnosis until death or the end of the observation period (December 31, 2016). We used Cox proportional hazards models to evaluate the association of annual average fine particulate matter (PM_2.5) exposure at the time of initial HF diagnosis with all-cause mortality, adjusted for age, race, sex, distance to the nearest air pollution monitor, and socioeconomic status indicators. Among 23 302 HF patients, a 1 μg/m³ increase in annual average PM_2.5 was associated with an elevated risk of all-cause mortality (hazard ratio 1.13; 95% CI, 1.10-1.15). As compared with people with exposures below the current national PM_2.5 exposure standard (12 μg/m³), those with elevated exposures experienced 0.84 (95% CI, 0.73-0.95) years of life lost over a 5-year period, an observation that persisted even for those residing in areas with PM_2.5 concentrations below current standards. Conclusions Residential exposure to elevated concentrations of PM_2.5 is a significant mortality risk factor for HF patients. Elevated PM_2.5 exposures result in substantial years of life lost even at concentrations below current national standards.

Ambient Particulate Matter and Acrolein Co-Exposure Increases Myocardial Dyssynchrony in Mice via TRPA1

Air pollution is a complex mixture of particulate matter and gases linked to adverse clinical outcomes. As such, studying responses to individual pollutants does not account for the potential biological responses resulting from the interaction of various constituents within an ambient air shed. We previously reported that exposure to high levels of the gaseous pollutant acrolein perturbs myocardial synchrony. Here, we examined the effects of repeated, intermittent co-exposure to low levels of concentrated ambient particulates (CAPs) and acrolein on myocardial synchrony and the role of transient receptor potential cation channel A1 (TRPA1), which we previously linked to air pollution-induced sensitization to triggered cardiac arrhythmia. Female B6129 and Trpa1-/- mice (n = 6/group) were exposed to filtered air (FA), CAPs (46 µg/m3 of PM2.5), Acrolein (0.42 ppm), or CAPs+Acrolein for 3 h/day, 2 days/week for 4 weeks. Cardiac ultrasound was conducted to assess cardiac synchronicity and function before and after the first exposure and after the final exposure. Heart rate variability (HRV), an indicator of autonomic tone, was assessed after the final exposure. Strain delay (time between peak strain in adjacent cardiac wall segments), an index of myocardial dyssynchrony, increased by 5-fold after the final CAPs+Acrolein exposure in B6129 mice compared with FA, CAPs, or Acrolein-exposed B6129 mice, and CAPs+Acrolein-exposed Trpa1-/- mice. Only exposure to acrolein alone increased the HRV high frequency domain (5-fold) in B6129 mice, but not in Trpa1-/- mice. Thus, repeated inhalation of pollutant mixtures may increase risk for cardiac responses compared with single or multiple exposures to individual pollutants through TRPA1 activation.

A case-crossover analysis of the relationship of air pollution with out-of-hospital sudden unexpected death in Wake County, North Carolina (2013-2015)

Out-of-hospital sudden unexpected deaths are non-accidental deaths that occur without obvious underlying causes and may account for 10% of natural deaths before age 65. Short-term exposure to ambient air pollution is associated with all-cause (non-accidental) and cause-specific (e.g., cardiovascular) mortality, and with immediate exposures often yielding the highest magnitude risk estimates. Few studies have focused on short-term exposure to air pollution and sudden unexpected deaths. Using the University of North Carolina Sudden Unexpected Death in North Carolina population, we examine associations between short-term criteria air pollutant exposures with sudden unexpected deaths using a time-stratified case-crossover design, with data on criteria air pollutants from the Environmental Protection Agency's Air Quality System. Odds ratios (OR) and 95% confidence intervals (CI) were estimated using conditional logistic regression with air pollutant exposures scaled to roughly inter-quartile ranges; models were adjusted for average temperature and relative humidity on event day and preceding 3 days. Potential for confounding by co-pollutants were examined in two pollutant models. ORs for PM_2.5 at lag day 1 were elevated (adjusted OR for 5 μg/m³ increase: 1.17 (0.98, 1.40)), and were robust to co-pollutant adjustment. Elevated odds were observed for SO₂ at lag day 0, and reduced odds for O₃ at lag day 0; however, these associations were somewhat attenuated toward the null (SO₂) or were not robust (O₃) to co-pollutant adjustment. This analysis in a racially and socioeconomically diverse cohort, with a more inclusive definition of sudden unexpected death than is typically employed offers evidence that PM_2.5 may be a clinically relevant trigger of sudden unexpected deaths in susceptible individuals.

High-Throughput Video Processing of Heart Rate Responses in Multiple Wild-type Embryonic Zebrafish per Imaging Field

Heart rate assays in wild-type zebrafish embryos have been limited to analysis of one embryo per video/imaging field. Here we present for the first time a platform for high-throughput derivation of heart rate from multiple zebrafish (Danio rerio) embryos per imaging field, which is capable of quickly processing thousands of videos and ideal for multi-well platforms with multiple fish/well. This approach relies on use of 2-day post fertilization wild-type embryos, and uses only bright-field imaging, circumventing requirement for anesthesia or restraint, costly software/hardware, or fluorescently-labeled animals. Our original scripts (1) locate the heart and record pixel intensity fluctuations generated by each cardiac cycle using a robust image processing routine, and (2) process intensity data to derive heart rate. To demonstrate assay utility, we exposed embryos to the drugs epinephrine and clonidine, which increased or decreased heart rate, respectively. Exposure to organic extracts of air pollution-derived particulate matter, including diesel or biodiesel exhausts, or wood smoke, all complex environmental mixtures, decreased heart rate to varying degrees. Comparison against an established lower-throughput method indicated robust assay fidelity. As all code and executable files are publicly available, this approach may expedite cardiotoxicity screening of compounds as diverse as small molecule drugs and complex chemical mixtures.

Association of long-term PM2.5 exposure with traditional and novel lipid measures related to cardiovascular disease risk

BACKGROUND

Fine particulate matter (PM_2.5) exposure is associated with increased morbidity and mortality, particularly for cardiovascular disease. The association between long-term exposure to PM_2.5 and measures of lipoprotein subfractions remains unclear. Therefore, we examined associations between long-term PM_2.5 exposure and traditional and novel lipoprotein measures in a cardiac catheterization cohort in North Carolina.

METHODS

This cross-sectional study included 6587 patients who had visited Duke University for a cardiac catheterization between 2001 and 2010 and resided in North Carolina. We used estimates of daily PM_2.5 concentrations on a 1 km-grid based on satellite measurements. PM_2.5 predictions were matched to the address of each patient and averaged for the year prior to catheterization date. Serum lipids included HDL, LDL, and triglyceride-rich particle, and apolipoprotein B concentrations (HDL-P, LDL-P, TRL-P, and apoB, respectively). Linear and quantile regression models were used to estimate change in lipoprotein levels with each μg/m³ increase in annual average PM_2.5. Models were adjusted for age, sex, race/ethnicity, history of smoking, area-level education, urban/rural status, body mass index, and diabetes.

RESULTS

For a 1-μg/m³ increment in PM_2.5 exposure, we observed increases in total and small LDL-P, LDL-C, TRL-P, apoB, total cholesterol, and triglycerides. The percent change from the mean outcome level was 2.00% (95% CI: 1.38%, 2.64%) for total LDL-P and 2.25% (95% CI: 1.43%, 3.06%) for small LDL-P.

CONCLUSION

Among this sample of cardiac catheterization patients residing in North Carolina, long-term PM_2.5 exposure was associated with increases in several lipoprotein concentrations. This abstract does not necessarily reflect U.S. EPA policy.

Short-term effects of fine particulate matter and ozone on the cardiac conduction system in patients undergoing cardiac catheterization

BACKGROUND

Air pollution-induced changes in cardiac electrophysiological properties could be a pathway linking air pollution and cardiovascular events. The evidence of air pollution effects on the cardiac conduction system is incomplete yet. We investigated short-term effects of particulate matter ≤ 2.5 μm in aerodynamic diameter (PM_2.5) and ozone (O₃) on cardiac electrical impulse propagation and repolarization as recorded in surface electrocardiograms (ECG).

METHODS

We analyzed repeated 12-lead ECG measurements performed on 5,332 patients between 2001 and 2012. The participants came from the Duke CATHGEN Study who underwent cardiac catheterization and resided in North Carolina, United States (NC, U.S.). Daily concentrations of PM_2.5 and O₃ at each participant's home address were predicted with a hybrid air quality exposure model. We used generalized additive mixed models to investigate the associations of PM_2.5 and O₃ with the PR interval, QRS interval, heart rate-corrected QT interval (QTc), and heart rate (HR). The temporal lag structures of the associations were examined using distributed-lag models.

RESULTS

Elevated PM_2.5 and O₃ were associated with four-day lagged lengthening of the PR and QRS intervals, and with one-day lagged increases in HR. We observed immediate effects on the lengthening of the QTc interval for both PM_2.5 and O₃, as well as delayed effects for PM_2.5 (lagged by 3 - 4 days). The associations of PM_2.5 and O₃ with the PR interval and the association of O₃ with the QRS interval persisted until up to seven days after exposure.

CONCLUSIONS

In patients undergoing cardiac catheterization, short-term exposure to air pollution was associated with increased HR and delays in atrioventricular conduction, ventricular depolarization and repolarization.

Ambient Air Quality and Cardiovascular Health: Translation of Environmental Research for Public Health and Clinical Care

Air pollution is intuitively associated with respiratory effects, but evidence has emerged over the past few decades that the cardiovascular effects of air pollution can be much more adverse and represent a greater public health burden. In this article, we present background on the sources, exposures, and health effects of air pollution and discuss the potential for intervention strategies in the health care system to help reduce individual and population exposure and the attendant risk from the cardiovascular effects of air pollution.

Wildland fire smoke and human health

The natural cycle of landscape fire maintains the ecological health of the land, yet adverse health effects associated with exposure to emissions from wildfire produce public health and clinical challenges. Systematic reviews conclude that a positive association exists between exposure to wildfire smoke or wildfire particulate matter (PM2.5) and all-cause mortality and respiratory morbidity. Respiratory morbidity includes asthma, chronic obstructive pulmonary disease (COPD), bronchitis and pneumonia. The epidemiological data linking wildfire smoke exposure to cardiovascular mortality and morbidity is mixed, and inconclusive. More studies are needed to define the risk for common and costly clinical cardiovascular outcomes. Susceptible populations include people with respiratory and possibly cardiovascular diseases, middle-aged and older adults, children, pregnant women and the fetus. The increasing frequency of large wildland fires, the expansion of the wildland-urban interface, the area between unoccupied land and human development; and an increasing and aging U.S. population are increasing the number of people at-risk from wildfire smoke, thus highlighting the necessity for broadening stakeholder cooperation to address the health effects of wildfire. While much is known, many questions remain and require further population-based, clinical and occupational health research. Health effects measured over much wider geographical areas and for longer periods time will better define the risk for adverse health outcomes, identify the sensitive populations and assess the influence of social factors on the relationship between exposure and health outcomes. Improving exposure models and access to large clinical databases foreshadow improved risk analysis facilitating more effective risk management. Fuel and smoke management remains an important component for protecting population health. Improved smoke forecasting and translation of environmental health science into communication of actionable information for use by public health officials, healthcare professionals and the public is needed to motivate behaviors that lower exposure and protect public health, particularly among those at high risk.

Cardiovascular and Cerebrovascular Emergency Department Visits Associated With Wildfire Smoke Exposure in California in 2015

BACKGROUND

Wildfire smoke is known to exacerbate respiratory conditions; however, evidence for cardiovascular and cerebrovascular events has been inconsistent, despite biological plausibility.

METHODS AND RESULTS

A population-based epidemiologic analysis was conducted for daily cardiovascular and cerebrovascular emergency department (ED) visits and wildfire smoke exposure in 2015 among adults in 8 California air basins. A quasi-Poisson regression model was used for zip code-level counts of ED visits, adjusting for heat index, day of week, seasonality, and population. Satellite-imaged smoke plumes were classified as light, medium, or dense based on model-estimated concentrations of fine particulate matter. Relative risk was determined for smoky days for lag days 0 to 4. Rates of ED visits by age- and sex-stratified groups were also examined. Rates of all-cause cardiovascular ED visits were elevated across all lags, with the greatest increase on dense smoke days and among those aged ≥65 years at lag 0 (relative risk 1.15, 95% confidence interval [1.09, 1.22]). All-cause cerebrovascular visits were associated with smoke, especially among those 65 years and older, (1.22 [1.00, 1.49], dense smoke, lag 1). Respiratory conditions were also increased, as anticipated (1.18 [1.08, 1.28], adults >65 years, dense smoke, lag 1). No association was found for the control condition, acute appendicitis. Elevated risks for individual diagnoses included myocardial infarction, ischemic heart disease, heart failure, dysrhythmia, pulmonary embolism, ischemic stroke, and transient ischemic attack.

CONCLUSIONS

Analysis of an extensive wildfire season found smoke exposure to be associated with cardiovascular and cerebrovascular ED visits for all adults, particularly for those over aged 65 years.

Exploring links between greenspace and sudden unexpected death: A spatial analysis

Greenspace has been increasingly recognized as having numerous health benefits. However, its effects are unknown concerning sudden unexpected death (SUD), commonly referred to as sudden cardiac death, which constitutes a large proportion of mortality in the United States. Because greenspace can promote physical activity, reduce stress and buffer air pollutants, it may have beneficial effects for people at risk of SUD, such as those with heart disease, hypertension, and diabetes mellitus. Using several spatial techniques, this study explored the relationship between SUD and greenspace. We adjudicated 396 SUD cases that occurred from March 2013 to February 2015 among reports from emergency medical services (EMS) that attended out-of-hospital deaths in Wake County (central North Carolina, USA). We measured multiple greenspace metrics in each census tract, including the percentages of forest, grassland, average tree canopy, tree canopy diversity, near-road tree canopy and greenway density. The associations between SUD incidence and these greenspace metrics were examined using Poisson regression (non-spatial) and Bayesian spatial models. The results from both models indicated that SUD incidence was inversely associated with both greenway density (adjusted risk ratio [RR] = 0.82, 95% credible/ confidence interval [CI]: 0.69-0.97) and the percentage of forest (adjusted RR = 0.90, 95% CI: 0.81-0.99). These results suggest that increases in greenway density by 1 km/km2 and in forest by 10% were associated with a decrease in SUD risk of 18% and 10%, respectively. The inverse relationship was not observed between SUD incidence and other metrics, including grassland, average tree canopy, near-road tree canopy and tree canopy diversity. This study implies that greenspace, specifically greenways and forest, may have beneficial effects for people at risk of SUD. Further studies are needed to investigate potential causal relationships between greenspace and SUD, and potential mechanisms such as promoting physical activity and reducing stress.

Fine particulate matters: The impact of air quality standards on cardiovascular mortality

BACKGROUND

In 1997 the U.S. Environmental Protection Agency set the first annual National Ambient Air Quality Standard (NAAQS) for fine particulate matter (PM2.5). Although the weight of scientific evidence has determined that a causal relationship exists between PM2.5 exposures and cardiovascular effects, few studies have concluded whether NAAQS-related reductions in PM2.5 led to improvements in public health.

METHODS

We examined the change in cardiovascular (CV) mortality rate and the association between change in PM2.5 and change in CV-mortality rate before (2000-2004) and after implementation of the 1997 annual PM2.5 NAAQS (2005-2010) among U.S. counties. We further examined how the association varied with respect to two factors related to NAAQS compliance: attainment status and design values (DV). We used difference-in-differences and linear regression models, adjusted for sociodemographic confounders.

FINDINGS

Across 619 counties, there were 1.10 (95% CI: 0.37, 1.82) fewer CV-deaths per year per 100,000 people for each 1µg/m3 decrease in PM2.5. Nonattainment counties had a twofold larger reduction in mean annual PM2.5, 2.1µg/m3, compared to attainment counties, 0.97µg/m3. CV-mortality rate decreased by 0.59 (95% CI: -0.54, 1.71) in nonattainment and 1.96 (95% CI: 0.77, 3.15) deaths per 100,000 people for each 1µg/m3 decrease in PM2.5 in attainment counties. When stratifying counties by DV, results were similar: counties with DV greater than 15µg/m3 experienced the greatest decrease in mean annual PM2.5 (2.29µg/m3) but the smallest decrease in CV-mortality rate per unit decrease in PM2.5, 0.73 (95% CI: -0.57, 2.02).

INTERPRETATION

We report a significant association between the change in PM2.5 and the change in CV-mortality rate before and after the implementation of NAAQS and note that the health benefits per 1µg/m3 decrease in PM2.5 persist at levels below the current national standard.

FUNDING

US EPA intermural research.

Ultrafine particulate matter exposure impairs vasorelaxant response in superoxide dismutase 2-deficient murine aortic rings

Studies have linked exposure to ultrafine particulate matter (PM) and adverse cardiovascular events. PM-induced oxidative stress is believed to be a key mechanism underlying observed adverse vascular effects. Advanced age is one factor known to decrease antioxidant defenses and confer susceptibility to the detrimental vascular effects seen following PM exposure. The present study was designed to investigate the vasomotor responses following ultrafine PM exposure in wild type (WT) and superoxide dismutase 2-deficient (SOD2^+/-) mice that possess decreased antioxidant defense. Thoracic aortic rings isolated from young and aged WT and SOD2^+/- mice were exposed to ultrafine PM in a tissue bath system. Aortic rings were then constricted with increasing concentrations of phenylephrine, followed by relaxation with rising amounts of nitroglycerin (NTG). Data demonstrated that ultrafine PM decreased the relaxation response in both young WT and young SOD2^+/- mouse aortas, and relaxation was significantly reduced in young SOD2^+/- compared to WT mice. Ultrafine PM significantly diminished the NTG-induced relaxation response in aged compared to young mouse aortas. After ultrafine PM exposure, the relaxation response did not differ markedly between aged WT and aged SOD2^+/- mice. Data demonstrated that the greater vascular effect in aortic rings in aged mice ex vivo after ultrafine PM exposure may be attributed to ultrafine PM-induced oxidative stress and loss of antioxidant defenses in aged vascular tissue. Consistent with this conclusion is the attenuation of NTG-induced relaxation response in young SOD2^+/- mice.

ABBREVIATIONS

H₂O₂: hydrogen peroxide; NTG: nitroglycerin; PAH: polycyclic aromatic hydrocarbons; PE: l-phenylephrine; PM: particulate matter; ROS: reactive oxygen species; SOD2: superoxide dismutase 2 deficient; WT: wild type.

Associations Between Residential Proximity to Traffic and Vascular Disease in a Cardiac Catheterization Cohort

OBJECTIVE

Exposure to mobile source emissions is nearly ubiquitous in developed nations and is associated with multiple adverse health outcomes. There is an ongoing need to understand the specificity of traffic exposure associations with vascular outcomes, particularly in individuals with cardiovascular disease.

APPROACH AND RESULTS

We performed a cross-sectional study using 2124 individuals residing in North Carolina, United States, who received a cardiac catheterization at the Duke University Medical Center. Traffic-related exposure was assessed via 2 metrics: (1) the distance between the primary residence and the nearest major roadway; and (2) location of the primary residence in regions defined based on local traffic patterns. We examined 4 cardiovascular disease outcomes: hypertension, peripheral arterial disease, the number of diseased coronary vessels, and recent myocardial infarction. Statistical models were adjusted for race, sex, smoking, type 2 diabetes mellitus, body mass index, hyperlipidemia, and home value. Results are expressed in terms of the odds ratio (OR). A 23% decrease in residential distance to major roadways was associated with higher prevalence of peripheral arterial disease (OR=1.29; 95% confidence interval, 1.08-1.55) and hypertension (OR=1.15; 95% confidence interval, 1.01-1.31). Associations with peripheral arterial disease were strongest in men (OR=1.42; 95% confidence interval, 1.17-1.74) while associations with hypertension were strongest in women (OR=1.21; 95% confidence interval, 0.99-1.49). Neither myocardial infarction nor the number of diseased coronary vessels were associated with traffic exposure.

CONCLUSIONS

Traffic-related exposure is associated with peripheral arterial disease and hypertension while no associations are observed for 2 coronary-specific vascular outcomes.

Acrolein Inhalation Alters Myocardial Synchrony and Performance at and Below Exposure Concentrations that Cause Ventilatory Responses

Acrolein is an irritating aldehyde generated during combustion of organic compounds. Altered autonomic activity has been documented following acrolein inhalation, possibly impacting myocardial synchrony and function. Given the ubiquitous nature of acrolein in the environment, we sought to better define the immediate and delayed functional cardiac effects of acrolein inhalation in vivo. We hypothesized that acrolein inhalation would increase markers of cardiac mechanical dysfunction, i.e., myocardial dyssynchrony and performance index in mice. Male C57Bl/6J mice were exposed to filtered air (FA) or acrolein (0.3 or 3.0 ppm) for 3 h in whole-body plethysmography chambers (n = 6). Echocardiographic analyses were performed 1 day before exposure and at 1 and 24 h post-exposure. Speckle tracking echocardiography revealed that circumferential strain delay (i.e., dyssynchrony) was increased at 1 and 24 h following exposure to 3.0 ppm, but not 0.3 ppm, when compared to pre-exposure and/or FA exposure. Pulsed wave Doppler of transmitral blood flow revealed that acrolein exposure at 0.3 ppm, but not 3.0 ppm, increased the Tei index of myocardial performance (i.e., decreased global heart performance) at 1 and 24 h post-exposure compared to pre-exposure and/or FA exposure. We conclude that short-term inhalation of acrolein can acutely modify cardiac function in vivo and that echocardiographic evaluation of myocardial synchrony and performance following exposure to other inhaled pollutants could provide broader insight into the health effects of air pollution.

Community Vulnerability to Health Impacts of Wildland Fire Smoke Exposure

Identifying communities vulnerable to adverse health effects from exposure to wildfire smoke may help prepare responses, increase the resilience to smoke and improve public health outcomes during smoke days. We developed a Community Health-Vulnerability Index (CHVI) based on factors known to increase the risks of health effects from air pollution and wildfire smoke exposures. These factors included county prevalence rates for asthma in children and adults, chronic obstructive pulmonary disease, hypertension, diabetes, obesity, percent of population 65 years of age and older, and indicators of socioeconomic status including poverty, education, income and unemployment. Using air quality simulated for the period between 2008 and 2012 over the continental U.S. we also characterized the population size at risk with respect to the level and duration of exposure to fire-originated fine particulate matter (fire-PM_2.5) and CHVI. We estimate that 10% of the population (30.5 million) lived in the areas where the contribution of fire-PM_2.5 to annual average ambient PM_2.5 was high (>1.5 μg/m³) and that 10.3 million individuals experienced unhealthy air quality levels for more than 10 days due to smoke. Using CHVI we identified the most vulnerable counties and determined that these communities experience more smoke exposures in comparison to less vulnerable communities.

Chemical Risk Assessment: Traditional vs Public Health Perspectives

Preventing adverse health effects of environmental chemical exposure is fundamental to protecting individual and public health. When done efficiently and properly, chemical risk assessment enables risk management actions that minimize the incidence and effects of environmentally induced diseases related to chemical exposure. However, traditional chemical risk assessment is faced with multiple challenges with respect to predicting and preventing disease in human populations, and epidemiological studies increasingly report observations of adverse health effects at exposure levels predicted from animal studies to be safe for humans. This discordance reinforces concerns about the adequacy of contemporary risk assessment practices for protecting public health. It is becoming clear that to protect public health more effectively, future risk assessments will need to use the full range of available data, draw on innovative methods to integrate diverse data streams, and consider health endpoints that also reflect the range of subtle effects and morbidities observed in human populations. Considering these factors, there is a need to reframe chemical risk assessment to be more clearly aligned with the public health goal of minimizing environmental exposures associated with disease.

Ozone Exposure Increases Circulating Stress Hormones and Lipid Metabolites in Humans

RATIONALE

Air pollution has been associated with increased prevalence of type 2 diabetes; however, the mechanisms remain unknown. We have shown that acute ozone exposure in rats induces release of stress hormones, hyperglycemia, leptinemia, and glucose intolerance that are associated with global changes in peripheral glucose, lipid, and amino acid metabolism.

OBJECTIVES

To examine ozone-induced metabolic derangement in humans using serum metabolomic assessment, establish human-to-rodent coherence, and identify novel nonprotein biomarkers.

METHODS

Serum samples were obtained from a crossover clinical study that included two clinic visits (n = 24 each) where each subject was blindly exposed in the morning to either filtered air or 0.3 parts per million ozone for 2 hours during 15-minute on-off exercise. Serum samples collected within 1 hour after exposure were assessed for changes in metabolites using a metabolomic approach.

MEASUREMENTS AND MAIN RESULTS

Metabolomic analysis revealed that ozone exposure markedly increased serum cortisol and corticosterone together with increases in monoacylglycerol, glycerol, and medium- and long-chain free fatty acids, reflective of lipid mobilization and catabolism. Additionally, ozone exposure increased serum lysolipids, potentially originating from membrane lipid breakdown. Ozone exposure also increased circulating mitochondrial β-oxidation-derived metabolites, such as acylcarnitines, together with increases in the ketone body 3-hydroxybutyrate. These changes suggested saturation of β-oxidation by ozone in exercising humans.

CONCLUSIONS

As in rodents, acute ozone exposure increased stress hormones and globally altered peripheral lipid metabolism in humans, likely through activation of a neurohormonally mediated stress response pathway. The metabolomic assessment revealed new biomarkers and allowed for establishment of rodent-to-human coherence. Clinical trial registered with www.clinicaltrials.gov (NCT 01492517).

A genome-wide trans-ethnic interaction study links the PIGR-FCAMR locus to coronary atherosclerosis via interactions between genetic variants and residential exposure to traffic

Air pollution is a worldwide contributor to cardiovascular disease mortality and morbidity. Traffic-related air pollution is a widespread environmental exposure and is associated with multiple cardiovascular outcomes such as coronary atherosclerosis, peripheral arterial disease, and myocardial infarction. Despite the recognition of the importance of both genetic and environmental exposures to the pathogenesis of cardiovascular disease, studies of how these two contributors operate jointly are rare. We performed a genome-wide interaction study (GWIS) to examine gene-traffic exposure interactions associated with coronary atherosclerosis. Using race-stratified cohorts of 538 African-Americans (AA) and 1562 European-Americans (EA) from a cardiac catheterization cohort (CATHGEN), we identify gene-by-traffic exposure interactions associated with the number of significantly diseased coronary vessels as a measure of chronic atherosclerosis. We found five suggestive (P<1x10^-5) interactions in the AA GWIS, of which two (rs1856746 and rs2791713) replicated in the EA cohort (P < 0.05). Both SNPs are in the PIGR-FCAMR locus and are eQTLs in lymphocytes. The protein products of both PIGR and FCAMR are implicated in inflammatory processes. In the EA GWIS, there were three suggestive interactions; none of these replicated in the AA GWIS. All three were intergenic; the most significant interaction was in a regulatory region associated with SAMSN1, a gene previously associated with atherosclerosis and B cell activation. In conclusion, we have uncovered several novel genes associated with coronary atherosclerosis in individuals chronically exposed to increased ambient concentrations of traffic air pollution. These genes point towards inflammatory pathways that may modify the effects of air pollution on cardiovascular disease risk.

Rethinking Environmental Protection: Meeting the Challenges of a Changing World

From climate change to hydraulic fracturing, and from drinking water safety to wildfires, environmental challenges are changing. The United States has made substantial environmental protection progress based on media-specific and single pollutant risk-based frameworks. However, today’s environmental problems are increasingly complex and new scientific approaches and tools are needed to achieve sustainable solutions to protect the environment and public health. In this article, we present examples of today’s environmental challenges and offer an integrated systems approach to address them. We provide a strategic framework and recommendations for advancing the application of science for protecting the environment and public health. We posit that addressing 21st century challenges requires transdisciplinary and systems approaches, new data sources, and stakeholder partnerships. To address these challenges, we outline a process driven by problem formulation with the following steps: a) formulate the problem holistically, b) gather and synthesize diverse information, c) develop and assess options, and d) implement sustainable solutions. This process will require new skills and education in systems science, with an emphasis on science translation. A systems-based approach can transcend media- and receptor-specific bounds, integrate diverse information, and recognize the inextricable link between ecology and human health.

Morning NO2 exposure sensitizes hypertensive rats to the cardiovascular effects of same day O3 exposure in the afternoon

CONTEXT

Within urban air sheds, specific ambient air pollutants typically peak at predictable times throughout the day. For example, in environments dominated by mobile sources, peak nitrogen dioxide (NO2) levels coincide with morning and afternoon rush hours, while peak levels of ozone (O3), occur in the afternoon.

OBJECTIVE

Given that exposure to a single pollutant might sensitize the cardiopulmonary system to the effects of a subsequent exposure to a second pollutant, we hypothesized that a morning exposure to NO2 will exaggerate the cardiovascular effects of an afternoon O3 exposure in rats.

MATERIALS AND METHODS

Rats were divided into four groups that were each exposed for 3 h in the morning (m) and 3 h in the afternoon (a) on the same day: (1) m-Air/a-Air, (2) m-Air/a-O3 (0.3 ppm), (3) m-NO2 (0.5 ppm)/a-Air and (4) m-NO2/a-O3. Implanted telemetry devices recorded blood pressure and electrocardiographic data. Sensitivity to the arrhythmogenic agent aconitine was measured in a separate cohort.

RESULTS

Only m-NO2/a-O3-exposed rats had significant changes in electrophysiological, mechanical and autonomic parameters. These included decreased heart rate and increased PR and QTc intervals and increased heart rate variability, suggesting increased parasympathetic tone. In addition, only m-NO2/a-O3 exposure decreased systolic and diastolic blood pressures and increased pulse pressure and QA interval, suggesting decreased cardiac contractility.

DISCUSSION AND CONCLUSION

The findings indicate that initial exposure to NO2 sensitized rats to the cardiovascular effects of O3 and may provide insight into the epidemiological data linking adverse cardiovascular outcomes with exposures to low concentrations of O3.

Associations among plasma metabolite levels and short-term exposure to PM2.5 and ozone in a cardiac catheterization cohort

RATIONALE

Exposure to ambient particulate matter (PM) and ozone has been associated with cardiovascular disease (CVD). However, the mechanisms linking PM and ozone exposure to CVD remain poorly understood.

OBJECTIVE

This study explored associations between short-term exposures to PM with a diameter <2.5μm (PM_2.5) and ozone with plasma metabolite concentrations.

METHODS AND RESULTS

We used cross-sectional data from a cardiac catheterization cohort at Duke University, North Carolina (NC), USA, accumulated between 2001 and 2007. Amino acids, acylcarnitines, ketones and total non-esterified fatty acid plasma concentrations were determined in fasting samples. Daily concentrations of PM_2.5 and ozone were obtained from a Bayesian space-time hierarchical model, matched to each patient's residential address. Ten metabolites were selected for the analysis based on quality criteria and cluster analysis. Associations between metabolites and PM_2.5 or ozone were analyzed using linear regression models adjusting for long-term trend and seasonality, calendar effects, meteorological parameters, and participant characteristics. We found delayed associations between PM_2.5 or ozone and changes in metabolite levels of the glycine-ornithine-arginine metabolic axis and incomplete fatty acid oxidation associated with mitochondrial dysfunction. The strongest association was seen for an increase of 8.1μg/m³ in PM_2.5 with a lag of one day and decreased mean glycine concentrations (-2.5% [95% confidence interval: -3.8%; -1.2%]).

CONCLUSIONS

Short-term exposures to ambient PM_2.5 and ozone is associated with changes in plasma concentrations of metabolites in a cohort of cardiac catheterization patients. Our findings might help to understand the link between air pollution and cardiovascular disease.

The Association between Dust Storms and Daily Non-Accidental Mortality in the United States, 1993-2005

BACKGROUND

The impact of dust storms on human health has been studied in the context of Asian, Saharan, Arabian, and Australian storms, but there has been no recent population-level epidemiological research on the dust storms in North America. The relevance of dust storms to public health is likely to increase as extreme weather events are predicted to become more frequent with anticipated changes in climate through the 21st century.

OBJECTIVES

We examined the association between dust storms and county-level non-accidental mortality in the United States from 1993 through 2005.

METHODS

Dust storm incidence data, including date and approximate location, are taken from the U.S. National Weather Service storm database. County-level mortality data for the years 1993-2005 were acquired from the National Center for Health Statistics. Distributed lag conditional logistic regression models under a time-stratified case-crossover design were used to study the relationship between dust storms and daily mortality counts over the whole United States and in Arizona and California specifically. End points included total non-accidental mortality and three mortality subgroups (cardiovascular, respiratory, and other non-accidental).

RESULTS

We estimated that for the United States as a whole, total non-accidental mortality increased by 7.4% (95% CI: 1.6, 13.5; p = 0.011) and 6.7% (95% CI: 1.1, 12.6; p = 0.018) at 2- and 3-day lags, respectively, and by an average of 2.7% (95% CI: 0.4, 5.1; p = 0.023) over lags 0-5 compared with referent days. Significant associations with non-accidental mortality were estimated for California (lag 2 and 0-5 day) and Arizona (lag 3), for cardiovascular mortality in the United States (lag 2) and Arizona (lag 3), and for other non-accidental mortality in California (lags 1-3 and 0-5).

CONCLUSIONS

Dust storms are associated with increases in lagged non-accidental and cardiovascular mortality. Citation: Crooks JL, Cascio WE, Percy MS, Reyes J, Neas LM, Hilborn ED. 2016. The association between dust storms and daily non-accidental mortality in the United States, 1993-2005. Environ Health Perspect 124:1735-1743; http://dx.doi.org/10.1289/EHP216.

Proposed pathophysiologic framework to explain some excess cardiovascular death associated with ambient air particle pollution: Insights for public health translation

The paper proposes a pathophysiologic framework to explain the well-established epidemiological association between exposure to ambient air particle pollution and premature cardiovascular mortality, and offers insights into public health solutions that extend beyond regulatory environmental protections to actions that can be taken by individuals, public health officials, healthcare professionals, city and regional planners, local and state governmental officials and all those who possess the capacity to improve cardiovascular health within the population. The foundation of the framework rests on the contribution of traditional cardiovascular risk factors acting alone and in concert with long-term exposures to air pollutants to create a conditional susceptibility for clinical vascular events, such as myocardial ischemia and infarction; stroke and lethal ventricular arrhythmias. The conceptual framework focuses on the fact that short-term exposures to ambient air particulate matter (PM) are associated with vascular thrombosis (acute coronary syndrome, stroke, deep venous thrombosis, and pulmonary embolism) and electrical dysfunction (ventricular arrhythmia); and that individuals having prevalent heart disease are at greatest risk. Moreover, exposure is concomitant with changes in autonomic nervous system balance, systemic inflammation, and prothrombotic/anti-thrombotic and profibrinolytic-antifibrinolytic balance. Thus, a comprehensive solution to the problem of premature mortality triggered by air pollutant exposure will require compliance with regulations to control ambient air particle pollution levels, minimize exposures to air pollutants, as well as a concerted effort to decrease the number of people at-risk for serious clinical cardiovascular events triggered by air pollutant exposure by improving the overall state of cardiovascular health in the population. This article is part of a Special Issue entitled Air Pollution, edited by Wenjun Ding, Andrew J. Ghio and Weidong Wu.

Association between satellite-based estimates of long-term PM2.5 exposure and coronary artery disease

BACKGROUND

Epidemiological studies have identified associations between long-term PM2.5 exposure and cardiovascular events, though most have relied on concentrations from central-site air quality monitors.

METHODS

We utilized a cohort of 5679 patients who had undergone cardiac catheterization at Duke University between 2002-2009 and resided in North Carolina. We used estimates of daily PM2.5 concentrations for North Carolina during the study period based on satellite derived Aerosol Optical Depth (AOD) measurements and PM2.5 concentrations from ground monitors, which were spatially resolved with a 10×10km resolution, matched to each patient's residential address and averaged for the year prior to catheterization. The Coronary Artery Disease (CAD) index was used to measure severity of CAD; scores >23 represent a hemodynamically significant coronary artery lesion in at least one major coronary vessel. Logistic regression modeled odds of having CAD or an MI with each 1μg/m(3) increase in annual average PM2.5, adjusting for sex, race, smoking status and socioeconomic status.

RESULTS

In adjusted models, a 1μg/m(3) increase in annual average PM2.5 was associated with an 11.1% relative increase in the odds of significant CAD (95% CI: 4.0-18.6%) and a 14.2% increase in the odds of having a myocardial infarction (MI) within a year prior (95% CI: 3.7-25.8%).

CONCLUSIONS

Satellite-based estimates of long-term PM2.5 exposure were associated with both coronary artery disease (CAD) and incidence of myocardial infarction (MI) in a cohort of cardiac catheterization patients.

Repeating cardiopulmonary health effects in rural North Carolina population during a second large peat wildfire

BACKGROUND

Cardiovascular health effects of fine particulate matter (PM2.5) exposure from wildfire smoke are neither definitive nor consistent with PM2.5 from other air pollution sources. Non-comparability among wildfire health studies limits research conclusions.

METHODS

We examined cardiovascular and respiratory health outcomes related to peat wildfire smoke exposure in a population where strong associations were previously reported for the 2008 Evans Road peat wildfire. We conducted a population-based epidemiologic investigation of associations between daily county-level modeled wildfire PM2.5 and cardiopulmonary emergency department (ED) visits during the 2011 Pains Bay wildfire in eastern North Carolina. We estimated changes in the relative risk cumulative over 0-2 lagged days of wildfire PM2.5 exposure using a quasi-Poisson regression model adjusted for weather, weekends, and poverty.

RESULTS

Relative risk associated with a 10 μg/m(3) increase in 24-h PM2.5 was significantly elevated in adults for respiratory/other chest symptoms 1.06 (1.00-1.13), upper respiratory infections 1.13 (1.05-1.22), hypertension 1.05 (1.00-1.09) and 'all-cause' cardiac outcomes 1.06 (1.00-1.13) and in youth for respiratory/other chest symptoms 1.18 (1.06-1.33), upper respiratory infections 1.14 (1.04-1.24) and 'all-cause' respiratory conditions 1.09 (1.01-1.17).

CONCLUSIONS

Our results replicate evidence for increased risk of cardiovascular outcomes from wildfire PM2.5 and suggest that cardiovascular health should be considered when evaluating the public health burden of wildfire smoke.

Dietary Supplementation with Olive Oil or Fish Oil and Vascular Effects of Concentrated Ambient Particulate Matter Exposure in Human Volunteers

BACKGROUND

Exposure to ambient particulate matter (PM) induces endothelial dysfunction, a risk factor for cardiovascular disease. Olive oil (OO) and fish oil (FO) supplements have beneficial effects on endothelial function.

OBJECTIVE

In this study we evaluated the potential efficacy of OO and FO in mitigating endothelial dysfunction and disruption of hemostasis caused by exposure to particulate matter (PM).

METHODS AND RESULTS

Forty-two participants (58 ± 1 years of age) received either 3 g/day of OO or FO, or no supplements (naive) for 4 weeks prior to undergoing 2-hr exposures to filtered air and concentrated ambient particulate matter (CAP; mean, 253 ± 16 μg/m3). Endothelial function was assessed by flow-mediated dilation (FMD) of the brachial artery preexposure, immediately postexposure, and 20 hr postexposure. Levels of endothelin-1 and markers of fibrinolysis and inflammation were also measured. The FMD was significantly lower after CAP exposure in the naive (-19.4%; 95% CI: -36.4, -2.3 per 100 μg/m3 CAP relative to baseline; p = 0.03) and FO groups (-13.7%; 95% CI: -24.5, -2.9; p = 0.01), but not in the OO group (-7.6%; 95% CI: -21.5, 6.3; p = 0.27). Tissue plasminogen activator levels were significantly increased immediately after (11.6%; 95% CI: 0.8, 22.2; p = 0.04) and 20 hr after CAP exposure in the OO group. Endothelin-1 levels were significantly increased 20 hr after CAP exposure in the naive group only (17.1%; 95% CI: 2.2, 32.0; p = 0.03).

CONCLUSIONS

Short-term exposure to CAP induced vascular endothelial dysfunction. OO supplementation attenuated CAP-induced reduction of FMD and changes in blood markers associated with vasoconstriction and fibrinolysis, suggesting that OO supplementation may be an efficacious intervention to protect against vascular effects of exposure to PM.

CITATION

Tong H, Rappold AG, Caughey M, Hinderliter AL, Bassett M, Montilla T, Case MW, Berntsen J, Bromberg PA, Cascio WE, Diaz-Sanchez D, Devlin RB, Samet JM. 2015. Dietary supplementation with olive oil or fish oil and vascular effects of concentrated ambient particulate matter exposure in human volunteers. Environ Health Perspect 123:1173-1179; http://dx.doi.org/10.1289/ehp.1408988.

Association of Roadway Proximity with Fasting Plasma Glucose and Metabolic Risk Factors for Cardiovascular Disease in a Cross-Sectional Study of Cardiac Catheterization Patients

BACKGROUND

The relationship between traffic-related air pollution (TRAP) and risk factors for cardiovascular disease needs to be better understood in order to address the adverse impact of air pollution on human health.

OBJECTIVE

We examined associations between roadway proximity and traffic exposure zones, as markers of TRAP exposure, and metabolic biomarkers for cardiovascular disease risk in a cohort of patients undergoing cardiac catheterization.

METHODS

We performed a cross-sectional study of 2,124 individuals residing in North Carolina (USA). Roadway proximity was assessed via distance to primary and secondary roadways, and we used residence in traffic exposure zones (TEZs) as a proxy for TRAP. Two categories of metabolic outcomes were studied: measures associated with glucose control, and measures associated with lipid metabolism. Statistical models were adjusted for race, sex, smoking, body mass index, and socioeconomic status (SES).

RESULTS

An interquartile-range (990 m) decrease in distance to roadways was associated with higher fasting plasma glucose (β = 2.17 mg/dL; 95% CI: -0.24, 4.59), and the association appeared to be limited to women (β = 5.16 mg/dL; 95% CI: 1.48, 8.84 compared with β = 0.14 mg/dL; 95% CI: -3.04, 3.33 in men). Residence in TEZ 5 (high-speed traffic) and TEZ 6 (stop-and-go traffic), the two traffic zones assumed to have the highest levels of TRAP, was positively associated with high-density lipoprotein cholesterol (HDL-C; β = 8.36; 95% CI: -0.15, 16.9 and β = 5.98; 95% CI: -3.96, 15.9, for TEZ 5 and 6, respectively).

CONCLUSION

Proxy measures of TRAP exposure were associated with intermediate metabolic traits associated with cardiovascular disease, including fasting plasma glucose and possibly HDL-C.

Acrolein inhalation alters arterial blood gases and triggers carotid body-mediated cardiovascular responses in hypertensive rats

CONTEXT

Air pollution exposure affects autonomic function, heart rate, blood pressure and left ventricular function. While the mechanism for these effects is uncertain, several studies have reported that air pollution exposure modifies activity of the carotid body, the major organ that senses changes in arterial oxygen and carbon dioxide levels, and elicits downstream changes in autonomic control and cardiac function.

OBJECTIVE

We hypothesized that exposure to acrolein, an unsaturated aldehyde and mucosal irritant found in cigarette smoke and diesel exhaust, would activate the carotid body chemoreceptor response and lead to secondary cardiovascular responses in rats.

MATERIALS AND METHODS

Spontaneously hypertensive (SH) rats were exposed once for 3 h to 3 ppm acrolein gas or filtered air in whole body plethysmograph chambers. To determine if the carotid body mediated acrolein-induced cardiovascular responses, rats were pretreated with an inhibitor of cystathionine γ-lyase (CSE), an enzyme essential for carotid body signal transduction.

RESULTS

Acrolein exposure induced several cardiovascular effects. Systolic, diastolic and mean arterial blood pressure increased during exposure, while cardiac contractility decreased 1 day after exposure. The cardiovascular effects were associated with decreases in pO2, breathing frequency and expiratory time, and increases in sympathetic tone during exposure followed by parasympathetic dominance after exposure. The CSE inhibitor prevented the cardiovascular effects of acrolein exposure.

DISCUSSION AND CONCLUSION

Pretreatment with the CSE inhibitor prevented the cardiovascular effects of acrolein, suggesting that the cardiovascular responses with acrolein may be mediated by carotid body-triggered changes in autonomic tone. (This abstract does not reflect EPA policy.).

Cardiomyopathy confers susceptibility to particulate matter-induced oxidative stress, vagal dominance, arrhythmia and pulmonary inflammation in heart failure-prone rats

Acute exposure to ambient fine particulate matter (PM2.5) is tied to cardiovascular morbidity and mortality, especially among those with prior cardiac injury. The mechanisms and pathophysiological events precipitating these outcomes remain poorly understood but may involve inflammation, oxidative stress, arrhythmia and autonomic nervous system imbalance. Cardiomyopathy results from cardiac injury, is the leading cause of heart failure, and can be induced in heart failure-prone rats through sub-chronic infusion of isoproterenol (ISO). To test whether cardiomyopathy confers susceptibility to inhaled PM2.5 and can elucidate potential mechanisms, we investigated the cardiophysiologic, ventilatory, inflammatory and oxidative effects of a single nose-only inhalation of a metal-rich PM2.5 (580 µg/m(3), 4 h) in ISO-pretreated (35 days × 1.0 mg/kg/day sc) rats. During the 5 days post-treatment, ISO-treated rats had decreased HR and BP and increased pre-ejection period (PEP, an inverse correlate of contractility) relative to saline-treated rats. Before inhalation exposure, ISO-pretreated rats had increased PR and ventricular repolarization time (QT) and heterogeneity (Tp-Te). Relative to clean air, PM2.5 further prolonged PR-interval and decreased systolic BP during inhalation exposure; increased tidal volume, expiratory time, heart rate variability (HRV) parameters of parasympathetic tone and atrioventricular block arrhythmias over the hours post-exposure; increased pulmonary neutrophils, macrophages and total antioxidant status one day post-exposure; and decreased pulmonary glutathione peroxidase 8 weeks after exposure, with all effects occurring exclusively in ISO-pretreated rats but not saline-pretreated rats. Ultimately, our findings indicate that cardiomyopathy confers susceptibility to the oxidative, inflammatory, ventilatory, autonomic and arrhythmogenic effects of acute PM2.5 inhalation.

Cardiac effects of seasonal ambient particulate matter and ozone co-exposure in rats

Background

The potential for seasonal differences in the physicochemical characteristics of ambient particulate matter (PM) to modify interactive effects with gaseous pollutants has not been thoroughly examined. The purpose of this study was to compare cardiac responses in conscious hypertensive rats co-exposed to concentrated ambient particulates (CAPs) and ozone (O₃) in Durham, NC during the summer and winter, and to analyze responses based on particle mass and chemistry.

Methods

Rats were exposed once for 4 hrs by whole-body inhalation to fine CAPs alone (target concentration: 150 μg/m³), O₃ (0.2 ppm) alone, CAPs plus O₃, or filtered air during summer 2011 and winter 2012. Telemetered electrocardiographic (ECG) data from implanted biosensors were analyzed for heart rate (HR), ECG parameters, heart rate variability (HRV), and spontaneous arrhythmia. The sensitivity to triggering of arrhythmia was measured in a separate cohort one day after exposure using intravenously administered aconitine. PM elemental composition and organic and elemental carbon fractions were analyzed by high-resolution inductively coupled plasma–mass spectrometry and thermo-optical pyrolytic vaporization, respectively. Particulate sources were inferred from elemental analysis using a chemical mass balance model.

Results

Seasonal differences in CAPs composition were most evident in particle mass concentrations (summer, 171 μg/m³; winter, 85 μg/m³), size (summer, 324 nm; winter, 125 nm), organic:elemental carbon ratios (summer, 16.6; winter, 9.7), and sulfate levels (summer, 49.1 μg/m³; winter, 16.8 μg/m³). Enrichment of metals in winter PM resulted in equivalent summer and winter metal exposure concentrations. Source apportionment analysis showed enrichment for anthropogenic and marine salt sources during winter exposures compared to summer exposures, although only 4% of the total PM mass was attributed to marine salt sources. Single pollutant cardiovascular effects with CAPs and O₃ were present during both summer and winter exposures, with evidence for unique effects of co-exposures and associated changes in autonomic tone.

Conclusions

These findings provide evidence for a pronounced effect of season on PM mass, size, composition, and contributing sources, and exposure-induced cardiovascular responses. Although there was inconsistency in biological responses, some cardiovascular responses were evident only in the co-exposure group during both seasons despite variability in PM physicochemical composition. These findings suggest that a single ambient PM metric alone is not sufficient to predict potential for interactive health effects with other air pollutants.

Electronic supplementary material

The online version of this article (doi:10.1186/s12989-015-0087-3) contains supplementary material, which is available to authorized users.

Inhaled ozone (O3)-induces changes in serum metabolomic and liver transcriptomic profiles in rats

Air pollution has been linked to increased incidence of diabetes. Recently, we showed that ozone (O3) induces glucose intolerance, and increases serum leptin and epinephrine in Brown Norway rats. In this study, we hypothesized that O3 exposure will cause systemic changes in metabolic homeostasis and that serum metabolomic and liver transcriptomic profiling will provide mechanistic insights. In the first experiment, male Wistar Kyoto (WKY) rats were exposed to filtered air (FA) or O3 at 0.25, 0.50, or 1.0ppm, 6h/day for two days to establish concentration-related effects on glucose tolerance and lung injury. In a second experiment, rats were exposed to FA or 1.0ppm O3, 6h/day for either one or two consecutive days, and systemic metabolic responses were determined immediately after or 18h post-exposure. O3 increased serum glucose and leptin on day 1. Glucose intolerance persisted through two days of exposure but reversed 18h-post second exposure. O3 increased circulating metabolites of glycolysis, long-chain free fatty acids, branched-chain amino acids and cholesterol, while 1,5-anhydroglucitol, bile acids and metabolites of TCA cycle were decreased, indicating impaired glycemic control, proteolysis and lipolysis. Liver gene expression increased for markers of glycolysis, TCA cycle and gluconeogenesis, and decreased for markers of steroid and fat biosynthesis. Genes involved in apoptosis and mitochondrial function were also impacted by O3. In conclusion, short-term O3 exposure induces global metabolic derangement involving glucose, lipid, and amino acid metabolism, typical of a stress-response. It remains to be examined if these alterations contribute to insulin resistance upon chronic exposure.