Diabetes enhances vulnerability to particulate air pollution-associated impairment in vascular reactivity and endothelial function

Brachial artery responses to ambient pollution, temperature, and humidity in people with type 2 diabetes: a repeated-measures study

BACKGROUND

Extreme weather and air pollution are associated with increased cardiovascular risk in people with diabetes.

OBJECTIVES

In a population with diabetes, we conducted a novel assessment of vascular brachial artery responses both to ambient pollution and to weather (temperature and water vapor pressure, a measure of humidity).

METHODS

Sixty-four 49- to 85-year-old Boston residents with type 2 diabetes completed up to five study visits (279 repeated measures). Brachial artery diameter (BAD) was measured by ultrasound before and after brachial artery occlusion [i.e., flow-mediated dilation (FMD)] and before and after nitroglycerin-mediated dilation (NMD). Ambient concentrations of fine particulate mass (PM2.5), black carbon (BC), organic carbon (OC), elemental carbon, particle number, and sulfate were measured at our monitoring site; ambient concentrations of carbon monoxide, nitrogen dioxide, and ozone were obtained from state monitors. Particle exposure in the home and during each trip to the clinic (home/trip exposure) was measured continuously and as a 5-day integrated sample. We used linear models with fixed effects for participants, adjusting for date, season, temperature, and water vapor pressure on the day of each visit, to estimate associations between our outcomes and interquartile range increases in exposure.

RESULTS

Baseline BAD was negatively associated with particle pollution, including home/trip-integrated BC (-0.02 mm; 95% CI: -0.04, -0.003, for a 0.28 μg/m3 increase in BC), OC (-0.08 mm; 95% CI: -0.14, -0.03, for a 1.61 μg/m3 increase) as well as PM2.5, 5-day average ambient PM2.5, and BC. BAD was positively associated with ambient temperature and water vapor pressure. However, exposures were not consistently associated with FMD or NMD.

CONCLUSION

Brachial artery diameter, a predictor of cardiovascular risk, decreased in association with particle pollution and increased in association with ambient temperature in our study population of adults with type 2 diabetes.

CITATION

Zanobetti A, Luttmann-Gibson H, Horton ES, Cohen A, Coull BA, Hoffmann B, Schwartz JD, Mittleman MA, Li Y, Stone PH, de Souza C, Lamparello B, Koutrakis P, Gold DR. 2014. Brachial artery responses to ambient pollution, temperature, and humidity in people with type 2 diabetes: a repeated-measures study. Environ Health Perspect 122:242-248; http://dx.doi.org/10.1289/ehp.1206136.

Associations between short-term changes in air pollution and correlates of arterial stiffness: The Veterans Affairs Normative Aging Study, 2007-2011

We investigated associations between short-term exposure to air pollution and central augmentation index and augmentation pressure, correlates of arterial stiffness, in a cohort of elderly men in the Boston, Massachusetts, metropolitan area. This longitudinal analysis included 370 participants from the Veterans Affairs Normative Aging Study with up to 2 visits between 2007 and 2011 (n = 445). Augmentation index (as %) and augmentation pressure (in mmHg) were measured at each visit by using radial artery applanation tonometry for pulse wave analysis and modeled in a mixed effects regression model as continuous functions of moving averages of air pollution exposures (over 4 hours and 1, 3, 7, and 14 days). The results suggest that short-term changes in air pollution were associated with augmentation index and augmentation pressure at several moving averages. Interquartile range (IQR) increases in 3-day average exposure to particles with aerodynamic diameter less than 2.5 μm (3.6-μg/m(3) IQR increase) and sulfate (1.4-μg/m(3) IQR increase) and 1-day average exposure to particle number counts (8,741-counts/cm(3) IQR increase) were associated with augmentation index values that were 0.8% (95% confidence interval (CI): 0.2, 1.4), 0.6% (95% CI: 0.1, 1.2), and 1.7% (95% CI: 0.4, 2.9) higher, respectively. Overall, the findings were similar for augmentation pressure. The findings support the hypothesis that exposure to air pollution may affect vascular function.

Effects of exposure to particles and ozone on hospital admissions for cardiorespiratory diseases in SetúBal, Portugal

In recent years, the adverse health effects attributed to air pollution have been a focus of intense study. Exposure to pollutants such as airborne particulate matter (PM) and ozone (O3) has been associated with increases in morbidity and mortality due to respiratory and cardiovascular diseases. The aim of this study was to determine a correlation between particles (PM10, PM2.5) and O3 with hospital admissions in Setúbal, a densely populated Portuguese urban region that coexists with a heavy industrial area. A database with daily air quality and hospital admission data over 5 years (2005-2009) was assembled and associations were investigated by ordinary least squares linear regression. Results showed positive significant associations between PM10 and respiratory diseases for ages below 14 yr and above 64 yr, and between PM2.5 and respiratory diseases for ages above 64 yr.

Cardiovascular depression in rats exposed to inhaled particulate matter and ozone: effects of diet-induced metabolic syndrome

BACKGROUND

High ambient levels of ozone (O3) and fine particulate matter (PM2.5) are associated with cardiovascular morbidity and mortality, especially in people with preexisting cardiopulmonary diseases. Enhanced susceptibility to the toxicity of air pollutants may include individuals with metabolic syndrome (MetS).

OBJECTIVE

We tested the hypothesis that cardiovascular responses to O3 and PM2.5 will be enhanced in rats with diet-induced MetS.

METHODS

Male Sprague-Dawley rats were fed a high-fructose diet (HFrD) to induce MetS and then exposed to O3, concentrated ambient PM2.5, or the combination of O3 plus PM2.5 for 9 days. Data related to heart rate (HR), HR variability (HRV), and blood pressure (BP) were collected.

RESULTS

Consistent with MetS, HFrD rats were hypertensive and insulin resistant, and had elevated fasting levels of blood glucose and triglycerides. Decreases in HR and BP, which were found in all exposure groups, were greater and more persistent in HFrD rats compared with those fed a normal diet (ND). Coexposure to O3 plus PM2.5 induced acute drops in HR and BP in all rats, but only ND rats adapted after 2 days. HFrD rats had little exposure-related changes in HRV, whereas ND rats had increased HRV during O3 exposure, modest decreases with PM2.5, and dramatic decreases during O3 plus PM2.5 coexposures.

CONCLUSIONS

Cardiovascular depression in O3- and PM2.5-exposed rats was enhanced and prolonged in rats with HFrD-induced MetS. These results in rodents suggest that people with MetS may be prone to similar exaggerated BP and HR responses to inhaled air pollutants.

Long-term exposure to high particulate matter pollution and cardiovascular mortality: a 12-year cohort study in four cities in northern China

Epidemiologic studies have demonstrated that long-term exposure to relatively low levels of particulate air pollution is associated with adverse cardiovascular outcomes in Europe and North America. However, few studies have assessed the association with high level air pollutants. We aimed to assess the cardiovascular effects of long-term exposure to high level concentrations of inhalable particulate and to identify the characteristics of the Chinese population that are susceptible to the health effects. A retrospective cohort, containing 39,054 subjects from four cities in northern China, was followed for mortality of all cause and specific cardiovascular diseases from 1998 to 2009. Information on concentrations of PM10 (particulate matter<10 μm in aerodynamic diameter) was collected from the local Environmental Monitoring Centers. The estimated exposure for the study participants was the mean concentration of PM10 over their surviving years during the cohort period. Relative risk values were obtained using Cox proportional hazards regression models after adjusting for potential confounding factors. For each 10 μg/m(3) increase in PM10, the relative risk ratios (RRs) of all-cause mortality, cardiovascular disease mortality, ischemic heart disease mortality, heart failure disease mortality, and cerebrovascular disease mortality were 1.24 (95% CI, 1.22-1.27), 1.23 (95% CI, 1.19-1.26), 1.37 (95% CI, 1.28-1.47), 1.11(95% CI, 1.05-1.17), and 1.23(95% CI:1.18-1.28), respectively. Results from stratified analyses suggest that the effects of PM10 on cardiovascular mortality were more pronounced in males, smokers and people with a higher socioeconomic status. Long-term exposure to PM10 increases mortality from cardiovascular disease, especially from ischemic heart disease and this association seemed to be modified by other factors. Further research that focuses on exploring dose-response relationship and inter-population comparisons is warranted.

Ozone air pollution and ischaemic stroke occurrence: a case-crossover study in Nice, France

OBJECTIVES

Relationship between low-level air pollution and stroke is conflicting. This study was conducted to document the relationship between outdoor air pollution and ischaemic stroke occurrence.

DESIGN

Time-stratified case-crossover analysis.

SETTING

University Hospital of Nice, France.

PARTICIPANTS

All consecutive patients with ischaemic stroke living in Nice admitted in the University Hospital of Nice (France) between January 2007 and December 2011.

MAIN OUTCOME MEASURE

Association (adjusted OR) between daily levels of outdoor pollutants (ozone (O3), nitrogen dioxide (NO2), particulate matter (PM10) and sulfur dioxide (SO2)) and ischaemic stroke occurrence.

RESULTS

1729 patients with ischaemic stroke (mean age: 76.1±14.0 years; men: 46.7%) were enrolled. No significant association was found between stroke occurrence and short-term effects of all pollutants tested. In stratified analysis, we observed significant associations only between recurrent (n=280) and large artery ischaemic stroke (n=578) onset and short-term effect of O3 exposure. For an increase of 10 µg/m(3) of O3 level, recurrent stroke risk (mean D-1, D-2 and D-3 lag) was increased by 12.1% (95% CI 1.5% to 23.9%) and large artery stroke risk (mean D-3 and D-4 lag) was increased by 8% (95% CI 2.0% to 16.6%). Linear dose-response relationship for both subgroups was found.

CONCLUSIONS

Our results confirm the relationship between low-level O3 exposure and ischaemic stroke in high vascular risk subgroup with linear exposure-response relation, independently of other pollutants and meteorological parameters. The physiopathological processes underlying this association between ischaemic stroke and O3 exposure remain to be investigated.

Associations between ambient air pollution and daily mortality among elderly persons in Montreal, Quebec

BACKGROUND

Persons with underlying health conditions may be at higher risk for the short-term effects of air pollution. We have extended our original mortality time series study in Montreal, Quebec, among persons 65 years of age and older, for an additional 10 years (1990-2003) to assess whether these associations persisted and to investigate new health conditions.

METHODS AND RESULTS

We created subgroups of subjects diagnosed with major health conditions one year before death using billing and prescription data from the Quebec Health Insurance Plan. We used parametric log-linear Poisson models within the distributed lag non-linear models framework, that were adjusted for long-term temporal trends and daily maximum temperature, for which we assessed associations with NO2, O3, CO, SO2, and particles with aerodynamic diameters 2.5 μm in diameter or less (PM2.5). We found positive associations between daily non-accidental mortality and all air pollutants but O3 (e.g., for a cumulative effect over a 3-day lag, with a mean percent change (MPC) in daily mortality of 1.90% [95% confidence interval: 0.73, 3.08%] for an increase of the interquartile range (17.56 μg m(-3)) of NO2). Positive associations were found amongst persons having cardiovascular disease (cumulative MPC for an increase equal to the interquartile range of NO2=2.67%), congestive heart failure (MPC=3.46%), atrial fibrillation (MPC=4.21%), diabetes (MPC=3.45%), and diabetes and cardiovascular disease (MPC=3.50%). Associations in the warm season were also found for acute and chronic coronary artery disease, hypertension, and cancer. There was no persuasive evidence to conclude that there were seasonal associations for cerebrovascular disease, acute lower respiratory disease (defined within 2 months of death), airways disease, and diabetes and airways disease.

CONCLUSIONS

These data indicate that individuals with certain health conditions, especially those with diabetes and cardiovascular disease, hypertension, atrial fibrillation, and cancer, may be susceptible to the short-term effects of air pollution.

Exposure to airborne particulate matter is associated with methylation pattern in the asthma pathway

BACKGROUND

Asthma exacerbation and other respiratory symptoms are associated with exposure to air pollution. Since environment affects gene methylation, it is hypothesized that asthmatic responses to pollution are mediated through methylation.

MATERIALS & METHODS

We study the possibility that airborne particulate matter affects gene methylation in the asthma pathway. We measured methylation array data in clinic visits of 141 subjects from the Normative Aging Study. Black carbon and sulfate measures from a central monitoring site were recorded and 30-day averages were calculated for each clinic visit. Gene-specific methylation scores were calculated for the genes in the asthma pathway, and the association between the methylation in the asthma pathway and the pollution measures was analyzed using sparse Canonical Correlation Analysis.

RESULTS

The analysis found that exposures to black carbon and sulfate were significantly associated with the methylation pattern in the asthma pathway (p-values 0.05 and 0.02, accordingly). Specific genes that contributed to this association were identified.

CONCLUSION

These results suggest that the effect of air pollution on asthmatic and respiratory responses may be mediated through gene methylation.

Ambient fine particulate matter alters cerebral hemodynamics in the elderly

BACKGROUND AND PURPOSE

Short-term elevations in fine particulate matter air pollution (PM2.5) are associated with increased risk of acute cerebrovascular events. Evidence from the peripheral circulation suggests that vascular dysfunction may be a central mechanism. However, the effects of PM2.5 on cerebrovascular function and hemodynamics are unknown.

METHODS

We used transcranial Doppler ultrasound to measure beat-to-beat blood flow velocity in the middle cerebral artery at rest and in response to changes in end-tidal CO2 (cerebral vasoreactivity) and arterial blood pressure (cerebral autoregulation) in 482 participants from the Maintenance of Balance, Independent Living, Intellect, and Zest in the Elderly (MOBILIZE) of Boston study. We used linear mixed effects models with random subject intercepts to evaluate the association between cerebrovascular hemodynamic parameters and mean PM2.5 levels 1 to 28 days earlier adjusting for age, race, medical history, meteorologic covariates, day of week, temporal trends, and season.

RESULTS

An interquartile range increase (3.0 µg/m(3)) in mean PM2.5 levels during the previous 28 days was associated with an 8.6% (95% confidence interval, 3.7%-13.8%; P<0.001) higher cerebral vascular resistance and a 7.5% (95% confidence interval, 4.2%-10.6%; P<0.001) lower blood flow velocity at rest. Measures of cerebral vasoreactivity and autoregulation were not associated with PM2.5 levels.

CONCLUSIONS

In this cohort of community-dwelling seniors, exposure to PM2.5 was associated with higher resting cerebrovascular resistance and lower cerebral blood flow velocity. If replicated, these findings suggest that alterations in cerebrovascular hemodynamics may underlie the increased risk of particle-related acute cerebrovascular events.

Long-term exposure to black carbon and carotid intima-media thickness: the normative aging study

BACKGROUND

Evidence suggests that air pollution is associated with atherosclerosis and that traffic-related particles are a particularly important contributor to the association.

OBJECTIVES

We investigated the association between long-term exposure to black carbon, a correlate of traffic particles, and intima-media thickness of the common carotid artery (CIMT) in elderly men residing in the greater Boston, Massachusetts, area.

METHODS

We estimated 1-year average exposures to black carbon at the home addresses of Normative Aging Study participants before their first CIMT measurement. The association between estimated black carbon levels and CIMT was estimated using mixed effects models to account for repeated outcome measures. In secondary analyses, we examined whether living close to a major road or average daily traffic within 100 m of residence was associated with CIMT.

RESULTS

There were 380 participants (97% self-reported white race) with an initial visit between 2004 and 2008. Two or three follow-up CIMT measurements 1.5 years apart were available for 340 (89%) and 260 (68%) men, respectively. At first examination, the average ± SD age was 76 ± 6.4 years and the mean ± SD CIMT was 0.99 ± 0.18 mm. A one-interquartile range increase in 1-year average black carbon (0.26 µg/m3) was associated with a 1.1% higher CIMT (95% CI: 0.4, 1.7%) based on a fully adjusted model.

CONCLUSIONS

Annual mean black carbon concentration based on spatially resolved exposure estimates was associated with CIMT in a population of elderly men. These findings support an association between long-term air pollution exposure and atherosclerosis.

A framework to spatially cluster air pollution monitoring sites in US based on the PM2.5 composition

BACKGROUND

Heterogeneity in the response to PM2.5 is hypothesized to be related to differences in particle composition across monitoring sites which reflect differences in source types as well as climatic and topographic conditions impacting different geographic locations. Identifying spatial patterns in particle composition is a multivariate problem that requires novel methodologies.

OBJECTIVES

Use cluster analysis methods to identify spatial patterns in PM2.5 composition. Verify that the resulting clusters are distinct and informative.

METHODS

109 monitoring sites with 75% reported speciation data during the period 2003-2008 were selected. These sites were categorized based on their average PM2.5 composition over the study period using k-means cluster analysis. The obtained clusters were validated and characterized based on their physico-chemical characteristics, geographic locations, emissions profiles, population density and proximity to major emission sources.

RESULTS

Overall 31 clusters were identified. These include 21 clusters with 2 or more sites which were further grouped into 4 main types using hierarchical clustering. The resulting groupings are chemically meaningful and represent broad differences in emissions. The remaining clusters, encompassing single sites, were characterized based on their particle composition and geographic location.

CONCLUSIONS

The framework presented here provides a novel tool which can be used to identify and further classify sites based on their PM2.5 composition. The solution presented is fairly robust and yielded groupings that were meaningful in the context of air-pollution research.

Systematic review of the effects of black carbon on cardiovascular disease among individuals with pre-existing disease

OBJECTIVES

Recent interest has developed in understanding the health effects attributable to different components of particulate matter. This review evaluates the effects of black carbon (BC) on cardiovascular disease in individuals with pre-existing disease using evidence from epidemiologic and experimental studies.

METHODS

A systematic literature search was conducted to identify epidemiologic and experimental studies examining the relationship between BC and cardiovascular health effects in humans with pre-existing diseases. Nineteen epidemiologic and six experimental studies were included. Risk of bias was evaluated for each study.

RESULTS

Evidence across studies suggested ambient BC is associated with changes in subclinical cardiovascular health effects in individuals with diabetes and coronary artery disease (CAD). Limited evidence demonstrated that chronic respiratory disease does not modify the effect of BC on cardiovascular health.

CONCLUSIONS

Results in these studies consistently demonstrated that diabetes is a risk factor for BC-related cardiovascular effects, including increased interleukin-6 and ECG parameters. Cardiovascular effects were associated with BC in individuals with CAD, but few comparisons to individuals without CAD were provided in the literature.

Exposure to ambient air particulate matter and non-alcoholic fatty liver disease

The present study was designed to alert the public opinion and policy makers on the supposed enhancing effects of exposure to ambient air particulate matter with aerodynamic diameters < 2.5 mm (PM_2.5) on non-alcoholic fatty liver disease (NAFLD), the most common chronic liver disease in Western countries. For far too long literature data have been fixated on pulmonary diseases and/or cardiovascular disease, as consequence of particulate exposure, ignoring the link between the explosion of obesity with related syndromes such as NAFLD and air pollution, the worst characteristics of nowadays civilization. In order to delineate a clear picture of this major health problem, further studies should investigate whether and at what extent cigarette smoking and exposure to ambient air PM_2.5 impact the natural history of patients with obesity-related NAFLD, i.e., development of non alcoholic steatohepatitis, disease characterized by a worse prognosis due its progression towards fibrosis and hepatocarcinoma.

Exposure to air pollution near a steel plant and effects on cardiovascular physiology: a randomized crossover study

BACKGROUND

Iron and steel industry is an important source of air pollution emissions. Few studies have investigated cardiovascular effects of air pollutants emitted from steel plants.

OBJECTIVE

We examined the influence of outdoor air pollution in the vicinity of a steel plant on cardiovascular physiology in Sault Ste. Marie, Canada.

METHODS

Sixty-one healthy, non-smoking subjects (females/males=33/28, median age 22 years) spent 5 consecutive 8-hour days outdoors in a residential area neighbouring a steel plant, or on a college campus approximately 5 kilometres away from the plant, and then crossed over to the other site with a 9-day washout. Mid day, subjects underwent daily 30-minute moderate intensity exercise. Blood pressure (BP) and pulse rate were determined daily and post exercise at both sites. Flow-mediated vasodilation (FMD) was determined at the site near the plant. Air pollution was monitored at both sites. Mixed-effects regressions were run for statistical associations, adjusting for weather variables.

RESULTS

Concentrations of ultrafine particles, sulphur dioxide (SO2), nitrogen dioxide (NO2) and carbon monoxide (CO) were 50-100% higher at the site near the plant than at the college site, with minor differences in temperature, humidity, and concentrations of particulate matter ≤2.5 μm in size (PM2.5) and ozone (O3). Resting pulse rate [mean (95% confidence interval)] was moderately higher near the steel plant [+1.53 bpm (0.31, 2.78)] than at the college site, male subjects having the highest pulse rate elevation [+2.77 bpm (0.78, 4.76)]. Resting systolic and diastolic BP and pulse pressure, and post-exercise BP and pulse rate were not significantly different between two sites. Interquartile range concentrations of SO2 (2.9 ppb), NO2 (5.0 ppb) and CO (0.2 ppm) were associated with increased pulse rate [0.19 bpm (-0.00, 0.38), 0.86 bpm (0.03, 1.68), and 0.11 bpm (0.00, 0.22), respectively], ultrafine particles (10,256 count/cm(3)) associated with increased pulse pressure [0.85 mmHg (0.23, 1.48)], and NO2 and CO inversely associated with FMD [-0.14% (-0.31, 0.02), -0.02% (-0.03, -0.00), respectively]. SO2 during exercise was associated with increased pulse rate [0.26 bpm (0.01, 0.51)].

CONCLUSION

Air quality in residential areas near steel plants may influence cardiovascular physiology.

Risk of incident diabetes in relation to long-term exposure to fine particulate matter in Ontario, Canada

BACKGROUND

Laboratory studies suggest that fine particulate matter (≤ 2.5 µm in diameter; PM(2.5)) can activate pathophysiological responses that may induce insulin resistance and type 2 diabetes. However, epidemiological evidence relating PM2.5 and diabetes is sparse, particularly for incident diabetes.

OBJECTIVES

We conducted a population-based cohort study to determine whether long-term exposure to ambient PM(2.5) is associated with incident diabetes.

METHODS

We assembled a cohort of 62,012 nondiabetic adults who lived in Ontario, Canada, and completed one of five population-based health surveys between 1996 and 2005. Follow-up extended until 31 December 2010. Incident diabetes diagnosed between 1996 and 2010 was ascertained using the Ontario Diabetes Database, a validated registry of persons diagnosed with diabetes (sensitivity = 86%, specificity = 97%). Six-year average concentrations of PM2.5 at the postal codes of baseline residences were derived from satellite observations. We used Cox proportional hazards models to estimate the associations, adjusting for various individual-level risk factors and contextual covariates such as smoking, body mass index, physical activity, and neighborhood-level household income. We also conducted multiple sensitivity analyses. In addition, we examined effect modification for selected comorbidities and sociodemographic characteristics.

RESULTS

There were 6,310 incident cases of diabetes over 484,644 total person-years of follow-up. The adjusted hazard ratio for a 10-µg/m(3) increase in PM(2.5) was 1.11 (95% CI: 1.02, 1.21). Estimated associations were comparable among all sensitivity analyses. We did not find strong evidence of effect modification by comorbidities or sociodemographic covariates.

CONCLUSIONS

This study suggests that long-term exposure to PM2.5 may contribute to the development of diabetes.

Impact of experimental type 1 diabetes mellitus on systemic and coagulation vulnerability in mice acutely exposed to diesel exhaust particles

Background

Epidemiological evidence indicates that diabetic patients have increased susceptibility to adverse cardiovascular outcomes related to acute increases in exposures to particulate air pollution. However, mechanisms underlying these effects remain unclear.

Methods

To evaluate the possible mechanisms underlying these actions, we assessed the systemic effects of diesel exhaust particles (DEP) in control mice, and mice with streptozotocin–induced type 1 diabetes. Four weeks following induction of diabetes, the animals were intratracheally instilled (i.t.) with DEP (0.4 mg/kg) or saline, and several cardiovascular endpoints were measured 24 h thereafter.

Results

DEP caused leukocytosis and a significant increase in plasma C-reactive protein and 8-isoprostane concentrations in diabetic mice compared to diabetic mice exposed to saline or non-diabetic mice exposed to DEP. The arterial PO₂ as well as the number of platelets and the thrombotic occlusion time in pial arterioles assessed in vivo were significantly decreased following the i.t. instillation of DEP in diabetic mice compared to diabetic mice exposed to saline or non-diabetic mice exposed to DEP. Both alanine aminotransferase and aspartate transaminase activities, as well as the plasma concentrations of plasminogen activator inhibitor and von Willebrand factor were significantly increased in DEP-exposed diabetic mice compared to diabetic mice exposed to saline or DEP-exposed non-diabetic mice. The in vitro addition of DEP (0.25-1 μg/ml) to untreated mouse blood significantly and dose-dependently induced in vitro platelet aggregation, and these effects were exacerbated in blood of diabetic mice.

Conclusion

This study has shown that systemic and coagulation events are aggravated by type 1 diabetes in mice, acutely exposed to DEP and has described the possible mechanisms for these actions that may also be relevant to the exacerbation of cardiovascular morbidity accompanying particulate air pollution in diabetic patients.

Combining a road pollution dispersion model with GIS to determine carbon monoxide concentration in Tennessee

The purpose of this paper is to develop an air pollution model that is independent from pollution monitoring sites and highly accurate through space and time. Total carbon monoxide concentration is computed with the use of traffic flow data, vehicle speed and dimensions, emission rates, wind speed, and temperature. The data are interpolated using a geographic information system universal kriging technique, and the end results produce state level air pollution maps with high local accuracy. The model is validated against Environment Protection Agency (EPA) pollution data. Overall, the model has 71 % agreement with EPA, overestimating values of carbon monoxide for less than 1 ppm. The model has three advantages over already assessed air pollution models. First, it is completely independent of any air pollution monitoring stations; thus, possible temporary or permanent unreliability or lack of the data is avoided. Second, being based on a 5,710 traffic count network, the problem of remote places coverage is avoided. Third, it is based on a straightforward equation, where minimal preprocessing of traffic and climatic data is required.

Long-term exposure to air pollution is associated with survival following acute coronary syndrome

Aims

The aim of this study was to determine (i) whether long-term exposure to air pollution was associated with all-cause mortality using the Myocardial Ischaemia National Audit Project (MINAP) data for England and Wales, and (ii) the extent to which exposure to air pollution contributed to socioeconomic inequalities in prognosis.

Methods and results

Records of patients admitted to hospital with acute coronary syndrome (ACS) in MINAP collected under the National Institute for Cardiovascular Outcomes Research were linked to modelled annual average air pollution concentrations for 2004–10. Hazard ratios for mortality starting 28 days after admission were estimated using Cox proportional hazards models. Among the 154 204 patients included in the cohort, the average follow-up was 3.7 years and there were 39 863 deaths. Mortality rates were higher for individuals exposed to higher levels of particles with a diameter of ≤2.5 µm (PM_2.5; PM, particulate matter): the fully adjusted hazard ratio for a 10 µg/m³ increase in PM_2.5 was 1.20 (95% CI 1.04–1.38). No associations were observed for larger particles or oxides of nitrogen. Air pollution explained socioeconomic inequalities in survival to only a small extent.

Conclusion

Mortality from all causes was higher among individuals with greater exposure to PM_2.5 in survivors of hospital admission for ACS in England and Wales. Despite higher exposure to PM_2.5 among those from more deprived areas, such exposure was a minor contribution to the socioeconomic inequalities in prognosis following ACS. Our findings add to the evidence of mortality associated with long-term exposure to fine particles.

Vascular responses to long- and short-term exposure to fine particulate matter: MESA Air (Multi-Ethnic Study of Atherosclerosis and Air Pollution)

OBJECTIVES

This study evaluated the association of long- and short-term air pollutant exposures with flow-mediated dilation (FMD) and baseline arterial diameter (BAD) of the brachial artery using ultrasound in a large multicity cohort.

BACKGROUND

Exposures to ambient air pollution, especially long-term exposure to particulate matter <2.5 μm in aerodynamic diameter (PM(2.5)), are linked with cardiovascular mortality. Short-term exposure to PM(2.5) has been associated with decreased FMD and vasoconstriction, suggesting that adverse effects of PM(2.5) may involve endothelial dysfunction. However, long-term effects of PM(2.5) on endothelial dysfunction have not been investigated.

METHODS

FMD and BAD were measured by brachial artery ultrasound at the initial examination of the Multi-Ethnic Study of Atherosclerosis. Long-term PM(2.5) concentrations were estimated for the year 2000 at each participant's residence (n = 3,040) using a spatio-temporal model informed by cohort-specific monitoring. Short-term PM(2.5) concentrations were based on daily central-site monitoring in each of the 6 cities.

RESULTS

An interquartile increase in long-term PM(2.5) concentration (3 μg/m(3)) was associated with a 0.3% decrease in FMD (95% confidence interval [CI] of difference: -0.6 to -0.03; p = 0.03), adjusting for demographic characteristics, traditional risk factors, sonographers, and 1/BAD. Women, nonsmokers, younger participants, and those with hypertension seemed to show a greater association of PM(2.5) with FMD. FMD was not significantly associated with short-term variation in PM(2.5) (-0.1% per 12 μg/m(3) daily increase [95% CI: -0.2 to 0.04] on the day before examination).

CONCLUSIONS

Long-term PM(2.5) exposure was significantly associated with decreased endothelial function according to brachial ultrasound results. These findings may elucidate an important pathway linking air pollution and cardiovascular mortality.

Air pollution and hospitalization for acute complications of diabetes in Chile

Exposure to air pollution has been shown to cause insulin resistance in mice. To determine the relevance to humans, we tested the association between daily air pollution concentrations and daily hospitalization for acute serious complications of diabetes, coma and ketoacidosis, in Santiago between 2001 and 2008, using generalized linear models with natural splines to control for long term trends. For an interquartile range (IQR) increase in air pollutant, the relative risks (95% CI) of hospitalization for diabetes were: 1.15 (1.10, 1.20) for carbon monoxide (IQR=1.00); 1.07 (0.98, 1.16) for ozone (IQR=63.50); 1.14 (1.06, 1.22) for sulfur dioxide (IQR=5.88); 1.12(1.05, 1.20) for nitrogen dioxide (IQR=27.94); 1.11 (1.07, 1.15) for particulate matter≤10 μm diameter(IQR=34.00); and 1.11 (1.06, 1.16) for fine particulate matter ≤2.5 μm diameter (IQR=18.50). Results were similar when stratified by age, sex and season. Air pollution appears to increase the risk of acute complications of diabetes requiring hospitalization, suggesting that improvements in air quality may reduce morbidity from diabetes.

GSTM1, GSTT1, and GSTP1 polymorphisms and associations between air pollutants and markers of insulin resistance in elderly Koreans

BACKGROUND

Previous studies have suggested that diabetes mellitus (DM) is an outcome of exposure to air pollution, and metabolic detoxification genes affect air pollution-related outcomes.

OBJECTIVES

We evaluated associations between air pollutants and markers of insulin resistance (IR), an underlying mechanism of type 2 DM, and effect modification by GSTM1, GSTT1, and GSTP1 genotypes among elderly participants in the Korean Elderly Environmental Panel (KEEP) study.

METHODS

We recruited 560 people ≥ 60 years of age and obtained blood samples from them up to three times between 2008 and 2010. For air pollution exposure, we used ambient air pollutant [i.e., particulate matter ≤ 10 µm in diameter (PM10), sulfur dioxide (SO2), ozone (O3), and nitrogen dioxide (NO2)] monitoring data. We measured levels of fasting glucose and insulin and derived the homeostatic model assessment (HOMA) index to assess IR. Mixed-effect models were used to estimate associations between air pollutants and IR indices on the same day or lagged up to 10 days prior, and effect modification by GSTM1, GSTT1, and GSTP1 genotypes.

RESULTS

Interquartile range increases in PM10, O3, and NO2 were significantly associated with IR indices, depending on the lag period. Associations were stronger among participants with a history of DM and among those with GSTM1-null, GSTT1-null, and GSTP1 AG or GG genotypes.

CONCLUSIONS

Our results suggest that PM10, O3, and NO2 may increase IR in the elderly, and that GSTM1-null, GSTT1-null, and GSTP1 AG or GG genotypes may increase susceptibility to potential effects of ambient air pollutants on IR.

Cardio-respiratory outcomes associated with exposure to wildfire smoke are modified by measures of community health

BACKGROUND

Characterizing factors which determine susceptibility to air pollution is an important step in understanding the distribution of risk in a population and is critical for setting appropriate policies. We evaluate general and specific measures of community health as modifiers of risk for asthma and congestive heart failure following an episode of acute exposure to wildfire smoke.

METHODS

A population-based study of emergency department visits and daily concentrations of fine particulate matter during a wildfire in North Carolina was performed. Determinants of community health defined by County Health Rankings were evaluated as modifiers of the relative risk. A total of 40 mostly rural counties were included in the study. These rankings measure factors influencing health: health behaviors, access and quality of clinical care, social and economic factors, and physical environment, as well as, the outcomes of health: premature mortality and morbidity. Pollutant concentrations were obtained from a mathematically modeled smoke forecasting system. Estimates of relative risk for emergency department visits were based on Poisson mixed effects regression models applied to daily visit counts.

RESULTS

For asthma, the strongest association was observed at lag day 0 with excess relative risk of 66% (28,117). For congestive heart failure the excess relative risk was 42% (5,93). The largest difference in risk was observed after stratifying on the basis of Socio-Economic Factors. Difference in risk between bottom and top ranked counties by Socio-Economic Factors was 85% and 124% for asthma and congestive heart failure respectively.

CONCLUSIONS

The results indicate that Socio-Economic Factors should be considered as modifying risk factors in air pollution studies and be evaluated in the assessment of air pollution impacts.

Residential proximity to major roadway and 10-year all-cause mortality after myocardial infarction

BACKGROUND

The relationship between residential proximity to roadway and long-term survival after acute myocardial infarction (AMI) is unknown. We investigated the association between distance from residence and major roadway and 10-year all-cause mortality after AMI in the Determinants of Myocardial Infarction Onset Study (Onset Study), hypothesizing that living closer to a major roadway at the time of AMI would be associated with increased risk of mortality.

METHODS AND RESULTS

The Onset Study enrolled 3886 individuals hospitalized for AMI in 64 centers across the United States from 1989 to 1996. Institutionalized patients, those providing only post office boxes, and those whose addresses could not be geocoded were excluded, leaving 3547 patients eligible for analysis. Addresses were geocoded, and distance to the nearest major roadway was assigned. Cox regression was used to calculate hazard ratios, with adjustment for personal characteristics (age, sex, race, education, marital status, distance to nearest acute care hospital), clinical characteristics (smoking, body mass index, comorbidities, medications), and neighborhood-level characteristics derived from US Census block group data (household income, education, urbanicity). There were 1071 deaths after 10 years of follow-up. In the fully adjusted model, compared with living >1000 m, hazard ratios (95% confidence interval) for living ≤100 m were 1.27 (1.01-1.60), for 100 to ≤200 m were 1.19 (0.93-1.60), and for 200 to ≤1000 m were 1.13 (0.99-1.30) (P(trend)=0.016).

CONCLUSIONS

In this multicenter study, living close to a major roadway at the time of AMI was associated with increased risk of all-cause 10-year mortality; this relationship persisted after adjustment for individual and neighborhood-level covariates.

Vasoactive alteration and inflammation induced by polycyclic aromatic hydrocarbons and trace metals of vehicle exhaust particles

Exposure to particulate matter (PM) increases the incidence of cardiovascular disease, but the underlying mechanisms remain unclear. To characterise ambient PM collected from a coach station in an urban area, particulate polycyclic aromatic hydrocarbons (PAHs) and trace metals were evaluated, and diagnostic ratios were then used to determine the sources based on the PAHs identified in PM. To elucidate the mechanism of PM-induced vascular toxicology, human coronary artery endothelial cells (HCAECs) were exposed to PM, PM-free supernatant and residual PM, and the associations between PAHs and trace metals, nitric oxide (NO), endothelin-1 (ET-1) and interleukin-6 (IL-6) were investigated. Petrogenic-related particulate emissions, such as vehicle exhaust, accounted for 68.75% and 75.00% of mass in the 0.1-1-μm PM (PM(0.1-1)) and <0.1-μm PM (PM(0.1)) size fractions, respectively. Vehicle exhaust particles (VEPs) caused significant NO suppression and increase in ET-1 and IL-6, whereas residual PM caused an increase in NO, ET-1 and IL-6 compared with the effects of the corresponding supernatants. PAHs in PM, particularly those with 4-6 rings, were associated with NO suppression, and ET-1 and IL-6 were positively correlated with the amount of trace metal compounds. These findings suggest that chemical components affect the regulation of vasoactive function and inflammation.

Using new satellite based exposure methods to study the association between pregnancy PM₂.₅ exposure, premature birth and birth weight in Massachusetts

BACKGROUND

Adverse birth outcomes such as low birth weight and premature birth have been previously linked with exposure to ambient air pollution. Most studies relied on a limited number of monitors in the region of interest, which can introduce exposure error or restrict the analysis to persons living near a monitor, which reduces sample size and generalizability and may create selection bias.

METHODS

We evaluated the relationship between premature birth and birth weight with exposure to ambient particulate matter (PM₂.₅) levels during pregnancy in Massachusetts for a 9-year period (2000-2008). Building on a novel method we developed for predicting daily PM₂.₅ at the spatial resolution of a 10x10 km grid across New-England, we estimated the average exposure during 30 and 90 days prior to birth as well as the full pregnancy period for each mother. We used linear and logistic mixed models to estimate the association between PM₂.₅ exposure and birth weight (among full term births) and PM₂.₅ exposure and preterm birth adjusting for infant sex, maternal age, maternal race, mean income, maternal education level, prenatal care, gestational age, maternal smoking, percent of open space near mothers residence, average traffic density and mothers health.

RESULTS

Birth weight was negatively associated with PM₂.₅ across all tested periods. For example, a 10 μg/m³ increase of PM₂.₅ exposure during the entire pregnancy was significantly associated with a decrease of 13.80 g [95% confidence interval (CI) = -21.10, -6.05] in birth weight after controlling for other factors, including traffic exposure. The odds ratio for a premature birth was 1.06 (95% confidence interval (CI) = 1.01-1.13) for each 10 μg/m3 increase of PM₂.₅ exposure during the entire pregnancy period.

CONCLUSIONS

The presented study suggests that exposure to PM₂.₅ during the last month of pregnancy contributes to risks for lower birth weight and preterm birth in infants.

A meta-analysis and multisite time-series analysis of the differential toxicity of major fine particulate matter constituents

Health risk assessments of particulate matter less than 2.5 μm in diameter (PM(2.5)) often assume that all constituents of PM(2.5) are equally toxic. While investigators in previous epidemiologic studies have evaluated health risks from various PM(2.5) constituents, few have conducted the analyses needed to directly inform risk assessments. In this study, the authors performed a literature review and conducted a multisite time-series analysis of hospital admissions and exposure to PM(2.5) constituents (elemental carbon, organic carbon matter, sulfate, and nitrate) in a population of 12 million US Medicare enrollees for the period 2000-2008. The literature review illustrated a general lack of multiconstituent models or insight about probabilities of differential impacts per unit of concentration change. Consistent with previous results, the multisite time-series analysis found statistically significant associations between short-term changes in elemental carbon and cardiovascular hospital admissions. Posterior probabilities from multiconstituent models provided evidence that some individual constituents were more toxic than others, and posterior parameter estimates coupled with correlations among these estimates provided necessary information for risk assessment. Ratios of constituent toxicities, commonly used in risk assessment to describe differential toxicity, were extremely uncertain for all comparisons. These analyses emphasize the subtlety of the statistical techniques and epidemiologic studies necessary to inform risk assessments of particle constituents.

Air pollution and health: emerging information on susceptible populations

Outdoor air pollution poses risks to human health in communities around the world, and research on populations who are most susceptible continues to reveal new insights. Human susceptibility to adverse health effects from exposure to air pollution can be related to underlying disease; demographic or anthropometric characteristics; genetic profile; race and ethnicity; lifestyle, behaviors, and socioeconomic position; and location of residence or daily activities. In health research, an individual or group may have an enhanced responsiveness to a given, identical level of pollution exposure compared to those who are less susceptible. Or, people in these different groups may experience varying levels of exposure (for example, a theoretically homogeneous population whose members differ only by proximity to a road). Often the information available for health research may relate to both exposure and enhanced response to a given dose of pollution. This paper discusses the general direction of research on susceptibility to air pollution, with a general though not an exclusive focus on particulate matter, with specific examples of research on susceptibility related to cardiovascular disease, diabetes, asthma, and genetic and epigenetic features. We conclude by commenting how emerging knowledge of susceptibility can inform policy for controlling pollution sources and exposures to yield maximal health benefit and discuss two areas of emerging interest: studying air pollution and its connection to perinatal health, as well as land use and urban infrastructure design.

Selected physiological effects of ultrafine particles in acute cardiovascular morbidity

Ultrafine particles (UFPs) have emerged as a potentially important environmental health concern as they are produced in large numbers by vehicle emissions and may contribute to previously reported associations between traffic pollution and acute cardiovascular morbidity. This review examines recent epidemiological evidence of UFP exposures and selected physiological outcomes that may be modified as part of the underlying causal pathway(s) linking particulate air pollution and acute cardiovascular morbidity. Outcomes examined included changes in heart rate variability (HRV) (autonomic function), ST-segment depression (myocardial ischemia), QT-interval (ventricular repolarization), and endothelial vasomotor function. Twenty-two studies were reviewed in total: 10 prospective panel studies and 12 randomized cross-over studies. Sixteen studies identified a significant relationship between UFPs and at least one of the above outcomes and current evidence generally supports the biological plausibility of a relationship between UFPs and acute cardiovascular morbidity. However, discrepancies were apparent in the direction of observed associations, particularly for HRV and ventricular repolarization. Reasons for these discrepancies may include differences in particle composition, time-point of clinical evaluation, and population susceptibilities. Nevertheless, evidence to date suggests that UFPs have a measureable impact on physiological measures known to be altered in cases of acute cardiovascular morbidity. Moving forward, expanded use of personal exposure measures is recommended for prospective panel studies to minimize exposure misclassification. In addition, effort should be made to include more women in studies of the acute cardiovascular effects of UFPs as findings to date generally reflect responses in men.

Acute and chronic effects of particles on hospital admissions in New-England

Background

Many studies have reported significant associations between exposure to PM_2.5 and hospital admissions, but all have focused on the effects of short-term exposure. In addition all these studies have relied on a limited number of PM_2.5 monitors in their study regions, which introduces exposure error, and excludes rural and suburban populations from locations in which monitors are not available, reducing generalizability and potentially creating selection bias.

Methods

Using our novel prediction models for exposure combining land use regression with physical measurements (satellite aerosol optical depth) we investigated both the long and short term effects of PM_2.5 exposures on hospital admissions across New-England for all residents aged 65 and older. We performed separate Poisson regression analysis for each admission type: all respiratory, cardiovascular disease (CVD), stroke and diabetes. Daily admission counts in each zip code were regressed against long and short-term PM_2.5 exposure, temperature, socio-economic data and a spline of time to control for seasonal trends in baseline risk.

Results

We observed associations between both short-term and long-term exposure to PM_2.5 and hospitalization for all of the outcomes examined. In example, for respiratory diseases, for every10-µg/m³ increase in short-term PM_2.5 exposure there is a 0.70 percent increase in admissions (CI = 0.35 to 0.52) while concurrently for every10-µg/m³ increase in long-term PM_2.5 exposure there is a 4.22 percent increase in admissions (CI = 1.06 to 4.75).

Conclusions

As with mortality studies, chronic exposure to particles is associated with substantially larger increases in hospital admissions than acute exposure and both can be detected simultaneously using our exposure models.

Ambient air pollution and the risk of acute ischemic stroke

BACKGROUND

The link between daily changes in level of ambient fine particulate matter (PM) air pollution (PM <2.5 μm in diameter [PM(2.5)]) and cardiovascular morbidity and mortality is well established. Whether PM(2.5) levels below current US National Ambient Air Quality Standards also increase the risk of ischemic stroke remains uncertain.

METHODS

We reviewed the medical records of 1705 Boston area patients hospitalized with neurologist-confirmed ischemic stroke and abstracted data on the time of symptom onset and clinical characteristics. The PM(2.5) concentrations were measured at a central monitoring station. We used the time-stratified case-crossover study design to assess the association between the risk of ischemic stroke onset and PM(2.5) levels in the hours and days preceding each event. We examined whether the association with PM(2.5) levels differed by presumed ischemic stroke pathophysiologic mechanism and patient characteristics.

RESULTS

The estimated odds ratio (OR) of ischemic stroke onset was 1.34 (95% CI, 1.13-1.58) (P < .001) following a 24-hour period classified as moderate (PM(2.5) 15-40 μg/m(3)) by the US Environmental Protection Agency's (EPA) Air Quality Index compared with a 24-hour period classified as good (≤15 μg/m(3)). Considering PM(2.5) levels as a continuous variable, we found the estimated odds ratio of ischemic stroke onset to be 1.11 (95% CI, 1.03-1.20) (P = .006) per interquartile range increase in PM(2.5) levels (6.4 μg/m(3)). The increase in risk was greatest within 12 to 14 hours of exposure to PM(2.5) and was most strongly associated with markers of traffic-related pollution.

CONCLUSION

These results suggest that exposure to PM(2.5) levels considered generally safe by the US EPA increase the risk of ischemic stroke onset within hours of exposure.

Association of long-term air pollution with ventricular conduction and repolarization abnormalities

BACKGROUND

Short-term exposure to air pollution may affect ventricular repolarization, but there is limited information on how long-term exposures might affect the surface ventricular electrocardiographic (ECG) abnormalities associated with cardiovascular events. We carried out a study to determine whether long-term air pollution exposure is associated with abnormalities of ventricular repolarization and conduction in adults without known cardiovascular disease.

METHODS

A total of 4783 participants free of clinical cardiovascular disease in the Multi-Ethnic Study of Atherosclerosis underwent 12-lead ECG examinations, cardiac-computed tomography, and calcium scoring, as well as estimation of air pollution exposure using a finely resolved spatiotemporal model to determine long-term average individual exposure to fine particulate matter (PM(2.5)) and proximity to major roadways. We assessed ventricular electrical abnormalities including presence of QT prolongation (Rautaharju QTrr criteria) and intraventricular conduction delay (QRS duration >120 milliseconds). We used logistic regression to determine the adjusted relationship between air pollution exposures and ECG abnormalities.

RESULTS

A 10-μg/m³ increase in estimated residential PM(2.5) was associated with an increased odds of prevalent QT prolongation (adjusted odds ratio [OR] = 1.6 [95% confidence interval (CI) = 1.2-2.2]) and intraventricular conduction delay (1.7 [1.0-2.6]), independent of coronary-artery calcium score. Living near major roadways was not associated with ventricular electrical abnormalities. No evidence of effect modification by traditional risk factors or study site was observed.

CONCLUSIONS

This study demonstrates an association between long-term exposure to air pollution and ventricular repolarization and conduction abnormalities in adults without clinical cardiovascular disease, independent of subclinical coronary arterial calcification.

Association between long-term exposure to traffic particles and blood pressure in the Veterans Administration Normative Aging Study

OBJECTIVES

Particulate air pollution is associated with cardiovascular events, but the mechanisms are not fully understood. The main objective was to assess the relationship between long-term exposure to traffic-related air pollution and blood pressure (BP).

METHODS

The authors used longitudinal data from 853 elderly men participating in the Veterans Administration Normative Aging Study, followed during 1996-2008. Long-term average exposures to traffic particles were created from daily predictions of black carbon (BC) exposure at the geocoded address of each subject, using a validated spatiotemporal model based on ambient monitoring at 82 Boston-area locations. The authors examined the association of these exposures with BP using a mixed model. The authors included the following covariates: age, body mass index, smoking, alcohol, fasting glucose, creatinine clearance, use of cardiovascular medication, education, census-level poverty, day of week and season of clinical visit.

RESULTS

The authors found significant positive associations between 1-year average BC exposure and both systolic and diastolic blood pressure. An IQR increase in 1-year average BC exposure (0.32 μg/m(3)) was associated with a 2.64 mm Hg increase in systolic blood pressure (95% CI 1.47 to 3.80) and a 2.41 mm Hg increase in diastolic blood pressure (95% CI 1.77 to 3.05).

CONCLUSIONS

Long-term exposure to traffic particles is associated with increased BP, which may explain part of the association with myocardial infarctions and cardiovascular deaths reported in cohort studies.

Opposing effects of particle pollution, ozone, and ambient temperature on arterial blood pressure

BACKGROUND

Diabetes increases the risk of hypertension and orthostatic hypotension and raises the risk of cardiovascular death during heat waves and high pollution episodes.

OBJECTIVE

We examined whether short-term exposures to air pollution (fine particles, ozone) and heat resulted in perturbation of arterial blood pressure (BP) in persons with type 2 diabetes mellitus (T2DM).

METHODS

We conducted a panel study in 70 subjects with T2DM, measuring BP by automated oscillometric sphygmomanometer and pulse wave analysis every 2 weeks on up to five occasions (355 repeated measures). Hourly central site measurements of fine particles, ozone, and meteorology were conducted. We applied linear mixed models with random participant intercepts to investigate the association of fine particles, ozone, and ambient temperature with systolic, diastolic, and mean arterial BP in a multipollutant model, controlling for season, meteorological variables, and subject characteristics.

RESULTS

An interquartile increase in ambient fine particle mass [particulate matter (PM) with an aerodynamic diameter of ≤ 2.5 μm (PM2.5)] and in the traffic component black carbon in the previous 5 days (3.54 and 0.25 μg/m3, respectively) predicted increases of 1.4 mmHg [95% confidence interval (CI): 0.0, 2.9 mmHg] and 2.2 mmHg (95% CI: 0.4, 4.0 mmHg) in systolic BP (SBP) at the population geometric mean, respectively. In contrast, an interquartile increase in the 5-day mean of ozone (13.3 ppb) was associated with a 5.2 mmHg (95% CI: -8.6, -1.8 mmHg) decrease in SBP. Higher temperatures were associated with a marginal decrease in BP.

CONCLUSIONS

In subjects with T2DM, PM was associated with increased BP, and ozone was associated with decreased BP. These effects may be clinically important in patients with already compromised autoregulatory function.

Air pollution-associated procoagulant changes: the role of circulating microvesicles

BACKGROUND

Epidemiological studies suggest an association between exposure to particulate matter (PM) in air pollution and the risk of venous thromboembolism (VTE).

OBJECTIVES

To investigate the underlying pathophysiological pathways linking PM exposure and VTE.

PATIENTS AND METHODS

We assessed potential associations between PM exposure and coagulation and inflammation parameters, including circulating microvesicles, in a group of 233 patients with diabetes.

RESULTS

The numbers of circulating blood platelet-derived and annexin V-binding microvesicles were inversely associated with the current levels of PM(2.5) or PM(10), measured on the day of sampling. Recent past exposure to PM(10), up to 1 week prior to blood sampling, estimated at the patients' residential addresses, was associated with elevated high-sensitivity C-reactive protein (CRP), leukocytes and fibrinogen, as well as with tissue factor (TF)-dependent procoagulant changes in thrombin generation assays. When longer windows of past exposure were considered, up to 1 year preceding blood sampling, procoagulant changes were evident from the strongly increased numbers of red blood cell-derived circulating microvesicles and annexin V-binding microvesicles, but they no longer associated with TF. Past PM exposure was never associated with activated partial thromboplastin time (aPTT), prothrombin time (PT), or factor (F) VII, FVIII, FXII or D-dimers. Residential distance to a major road was only marginally correlated with procoagulant changes in FVIII and thrombin generation.

CONCLUSIONS

Increases in the number of microvesicles and in their procoagulant properties, rather than increases in coagulation factors per se, seem to contribute to the risk of VTE, developing during prolonged exposure to air pollutants.

Effects of temple particles on inflammation and endothelial cell response

To pray in temples is a regular activity in Buddhism and Taoism societies, yet few studies investigated the effects of particles from incense-burning in temples. The objectives of this study are to examine particle size and polycyclic aromatic hydrocarbon (PAH) effects of particles on coronary artery endothelial cell. We used two micro-orifice uniform deposit impactors to collect 11 sets of particles at a Chinese temple in Yi-Lan, Taiwan. 16 PAHs were determined by a high-resolution gas chomatograph/high-resolution mass spectrometer. Human coronary artery endothelial cells were exposed to particle extracts in three size ranges: PM(0.1) (diameters less than 0.1 μm), PM(1.0-0.1) (diameters between 1.0 and 0.1 μm), and PM(10-1.0) (diameters between 10 and 1.0 μm) at 50 μg/mL for 4h, and interleukin-6 (IL-6), endothelin-1 (ET-1), and nitric oxide (NO) concentrations in the medium were measured. We found that PM(1.0-0.1) stimulation resulted in significantly higher IL-6 and ET-1 production than PM(0.1) and PM(10-1.0). PM(1.0-0.1) also significantly reduced HCAEA cells to synthesize NO. Naphthalene, acenaphthylene, acenaphthene and anthracene of PM(1.0-0.1) were highly correlated with NO reduction. This study found that size and composition of temple particles were both important factors in inducing cytokine production and reducing NO formation in human coronary artery endothelial cell cultures.

Exploring potential sources of differential vulnerability and susceptibility in risk from environmental hazards to expand the scope of risk assessment

Genetic factors, other exposures, individual disease states and allostatic load, psychosocial stress, and socioeconomic position all have the potential to modify the response to environmental exposures. Moreover, many of these modifiers covary with the exposure, leading to much higher risks in some subgroups. These are not theoretical concerns; rather, all these patterns have already been demonstrated in studies of the effects of lead and air pollution. However, recent regulatory impact assessments for these exposures have generally not incorporated these findings. Therefore, differential risk and vulnerability is a critically important but neglected area within risk assessment, and should be incorporated in the future.

Peat bog wildfire smoke exposure in rural North Carolina is associated with cardiopulmonary emergency department visits assessed through syndromic surveillance

BACKGROUND

In June 2008, burning peat deposits produced haze and air pollution far in excess of National Ambient Air Quality Standards, encroaching on rural communities of eastern North Carolina. Although the association of mortality and morbidity with exposure to urban air pollution is well established, the health effects associated with exposure to wildfire emissions are less well understood.

OBJECTIVE

We investigated the effects of exposure on cardiorespiratory outcomes in the population affected by the fire.

METHODS

We performed a population-based study using emergency department (ED) visits reported through the syndromic surveillance program NC DETECT (North Carolina Disease Event Tracking and Epidemiologic Collection Tool). We used aerosol optical depth measured by a satellite to determine a high-exposure window and distinguish counties most impacted by the dense smoke plume from surrounding referent counties. Poisson log-linear regression with a 5-day distributed lag was used to estimate changes in the cumulative relative risk (RR).

RESULTS

In the exposed counties, significant increases in cumulative RR for asthma [1.65 (95% confidence interval, 1.25-2.1)], chronic obstructive pulmonary disease [1.73 (1.06-2.83)], and pneumonia and acute bronchitis [1.59 (1.07-2.34)] were observed. ED visits associated with cardiopulmonary symptoms [1.23 (1.06-1.43)] and heart failure [1.37 (1.01-1.85)] were also significantly increased.

CONCLUSIONS

Satellite data and syndromic surveillance were combined to assess the health impacts of wildfire smoke in rural counties with sparse air-quality monitoring. This is the first study to demonstrate both respiratory and cardiac effects after brief exposure to peat wildfire smoke.

Particle-associated organic compounds and symptoms in myocardial infarction survivors

CONTEXT

The aerosol components responsible for the adverse health effects of the exposure to particulate matter (PM) have not been conclusively identified, and there is especially little information on the role of particulate organic compounds (POC).

OBJECTIVE

This study evaluated the role of PM and POC with regard to daily symptoms.

METHODS

One hundred and fifty-three myocardial infarction survivors from Augsburg, Germany, recorded daily occurrence of different symptoms in winter 2003/2004. Ambient concentrations of PM with a diameter <2.5 μm (PM(2.5)), particle number concentration (PNC), PM(2.5)-bound hopanes, and polycyclic aromatic hydrocarbons (PAH) were quantified. Data were analyzed using generalized estimating equations adjusting for meteorological and other time-variant confounders.

RESULTS

The odds for avoidance of physically demanding activities due to heart problems increased immediately associated with most POC measures (e.g. 5% per 1.08 ng/m(3) increase in benzo[a]pyrene, 95%-confidence interval (CI):1-9%) and tended to a delayed decrease. After a 2-day delayed decrease associated with hopanes, the odds for shortness of breath increased consistently after 3 days with almost all POC measures (e.g. 4% per 0.21 ng/m(3) increase in 17α(H), 21β(H)-hopane, CI: 1-8%). The odds for heart palpitations marginally increased immediately in association with PNC (8% per 8146 cm(-3) increase in PNC, CI: 0-16%).

CONCLUSIONS

The study showed an association between PM, particle-bound POC, and daily symptoms. The organic compounds may be causally related with cardiovascular health or act rather as indicators for traffic- and combustion-related particles.

Fine particulate air pollution (PM2.5) and the risk of acute ischemic stroke

BACKGROUND

Short-term changes in levels of fine ambient particulate matter (PM2.5) may increase the risk of acute ischemic stroke; however, results from prior studies have been inconsistent. We examined this hypothesis using data from a multicenter prospective stroke registry.

METHODS

We analyzed data from 9202 patients hospitalized with acute ischemic stroke, having a documented date and time of stroke onset, and residing within 50 km of a PM2.5 monitor in 8 cities in Ontario, Canada. We evaluated the risk of ischemic stroke onset associated with PM2.5 in each city using a time-stratified case-crossover design, matching on day of week and time of day. We then combined these city-specific estimates using random-effects meta-analysis techniques. We examined whether the effects of PM2.5 differed across strata defined by patient characteristics and ischemic stroke etiology.

RESULTS

Overall, PM2.5 was associated with a -0.7% change in ischemic stroke risk per 10-μg/m increase in PM2.5 (95% confidence interval = -6.3% to 5.1%). These overall negative results were robust to a number of sensitivity analyses. Among patients with diabetes mellitus, PM2.5 was associated with an 11% increase in ischemic stroke risk (1% to 22%). The association between PM2.5 and ischemic stroke risk varied according to stroke etiology, with the strongest associations observed for strokes due to large-artery atherosclerosis and small-vessel occlusion.

CONCLUSIONS

These results do not support the hypothesis that short-term increases in PM2.5 levels are associated with ischemic stroke risk overall. However, specific patient subgroups may be at increased risk of particulate-related ischemic strokes.

Traffic exposure in a population with high prevalence type 2 diabetes--do medications influence concentrations of C-reactive protein?

Type 2 Diabetes (T2D) and particulate air pollution are associated with inflammatory dysregulation. We assessed the modifying effects of diabetes medications on the association of C-reactive protein (CRP), a marker of inflammation, and traffic exposure in adults with T2D (n = 379). CRP concentrations were significantly positively associated with residence ≤100 m of a roadway, >100 m and ≤200 m of a roadway and increased traffic density for individuals using insulin. For individuals using oral hypoglycemic medications (OHAs), CRP was significantly negatively associated with residence >100 m - ≤200 m of a roadway and multiple roadway exposure in an interaction model. Among people with diabetes, individuals on insulin appear to be most vulnerable to the effects of traffic exposure. Disease severity among insulin users may promote the pro-inflammatory response to traffic exposure, though diabetes medications may also modify the response. Possible anti-inflammatory effects of OHAs with traffic exposure merit further evaluation.

Vascular function and short-term exposure to fine particulate air pollution

Exposure to fine particulate air pollution has been implicated as a risk factor for cardiopulmonary disease and mortality. Proposed biological pathways imply that particle-induced pulmonary and systemic inflammation play a role in activating the vascular endothelium and altering vascular function. Potential effects of fine particulate pollution on vascular function are explored using controlled chamber exposure and uncontrolled ambient exposure. Research subjects included four panels with a total of 26 healthy nonsmoking young adults. On two study visits, at least 7 days apart, subjects spent 3 hr in a controlled-exposure chamber exposed to 150-200 microg/m3 of fine particles generated from coal or wood combustion and 3 hr in a clean room, with exposure and nonexposure periods alternated between visits. Baseline, postexposure, and post-clean room reactive hyperemia-peripheral arterial tonometry (RH-PAT) was conducted. A microvascular responsiveness index, defined as the log of the RH-PAT ratio, was calculated. There was no contemporaneous vascular response to the few hours of controlled exposure. Declines in vascular response were associated with elevated ambient exposures for the previous 2 days, especially for female subjects. Cumulative exposure to real-life fine particulate pollution may affect vascular function. More research is needed to determine the roles of age and gender, the effect of pollution sources, the importance of cumulative exposure over a few days versus a few hours, and the lag time between exposure and response.

Electrocardiographic and respiratory responses to coal-fired power plant emissions in a rat model of acute myocardial infarction: results from the Toxicological Evaluation of Realistic Emissions of Source Aerosols Study

BACKGROUND

Ambient particulate matter (PM) derived from coal-fired power plants may have important cardiovascular effects, but existing toxicological studies are inadequate for understanding these effects. The Toxicological Evaluation of Realistic Emissions of Source Aerosols (TERESA) study aims to evaluate the toxicity of primary and secondary PM derived from coal-fired power plants. As a part of this effort, we evaluated in susceptible animals the effect of stack emissions on cardiac electrophysiology and respiratory function under exposure conditions intended to simulate an aged plume with unneutralized acidity and secondary organic aerosols (POS exposure scenario).

METHODS

Rats with acute myocardial infarction were exposed to either stack emissions (n = 15) or filtered air (n = 14) for 5 h at a single power plant. Respiration and electrocardiograms were continuously monitored via telemetry and heart rate, heart rate variability (HRV), premature ventricular beat (PVB) frequency, electrocardiographic intervals, and respiratory intervals and volumes were evaluated. Similar experiments at another power plant were attempted but were unsuccessful.

RESULTS

POS exposure (fine particle mass = 219.1 µg/m(3); total sulfate = 172.5 µg/m(3); acidic sulfate = 132.5 µg/m(3); organic carbon = 50.9 µg/m(3)) was associated with increased PVB frequency and decreased respiratory expiratory time and end-inspiratory pause, but not with changes in heart rate, HRV, or electrocardiographic intervals. RESULTS from a second power plant were uninterpretable.

CONCLUSIONS

Short-term exposure to primary and unneutralized secondary PM formed from aged emissions from a coal-fired power plant, as simulated by the POS scenario, may be associated with increased risk of ventricular arrhythmias in susceptible animals.

Ambient air pollutants and risk of fatal coronary heart disease among kidney transplant recipients

BACKGROUND

There is increasing evidence that specific ambient air pollutants are associated with coronary heart disease (CHD) morbidity and mortality. Because kidney transplant recipients have prevalent traditional and nontraditional risk factors, they may constitute a sensitive subgroup.

STUDY DESIGN

Retrospective cohort.

SETTING & PARTICIPANTS

This study includes 32,239 nonsmoking adult kidney transplant recipients who underwent transplant in 1997-2003, identified through the US Renal Data System and living in the United States within 50 km of an air pollution monitoring station.

PREDICTOR

Long-term ambient pollutant ozone and particulate matter ≤10 μm (PM(10)), assessed from monthly concentrations of ozone and PM(10) calculated from ambient monitoring data by the US Environmental Protection Agency Air Quality System and interpolated to zip code centroids according to patients' residence.

OUTCOMES

Outcomes of interest were death from CHD and natural-cause mortality.

RESULTS

For the entire transplant cohort, average pollutant levels for ozone and PM(10) were 25.5 ± 4.4 parts per billion (ppb) and 25.3 ± 6.4 μg/m(3), respectively. Correlation between ozone and PM(10) values was low, but statistically significant (P < 0.001). There were deaths from CHD (n = 267) and natural causes (n = 2,076) during the 7-year study period. For each 10-ppb increase in ozone, the risk of fatal CHD increased by 35% (RR, 1.35; 95% CI, 1.04-1.77) in the single-pollutant model and 34% (RR, 1.34; 95% CI, 1.03-1.76) in the 2-pollutant model. No independent association was found between CHD and PM(10). No significant association was identified for PM(10) or ozone level and natural-cause mortality (RR, 1.09; 95% CI, 0.99-1.21).

LIMITATIONS

Exposure assignment based on only residential location.

CONCLUSIONS

For kidney transplant recipients, ambient ozone levels potentially are associated with higher risk of fatal CHD. These findings may have implications for regulations governing air pollution and the development of individual CHD risk-reduction strategies.

Geoenvironmental diabetology

Many reports have documented the negative health consequences that environmental stressors can have on patients with diabetes. Studies examining the interaction between the environment and a patient with diabetes can be unified under a single discipline termed "geoenvironmental diabetology." Geoenvironmental diabetology is defined more specifically as the study of how geophysical phenomena impact a patient with diabetes, to include effects on metabolic control, ancillary equipment (e.g., glucometers and insulin pumps), medications, supplies, access to care, and influences on the adaptive strategies employed by patients to care for their diabetes under extreme circumstances. Geological events such as natural disasters (e.g., earthquakes) or extreme weather (e.g., heat waves) are examples of stressors that can affect patients with diabetes and that can be included under the heading of geoenvironmental diabetology. As proposed here, geoenvironmental diabetology refers to how events in the physical world affect those with diagnosed diabetes, rather than how environmental factors might trigger development of disease. As the global prevalence of diabetes continues to increase, including in parts of the world that are especially vulnerable to disasters and climate change, further discussion is warranted on how to best prepare for management of diabetes under conditions of extreme geological and weather events and a changing climate. An overview is presented of various studies that have detailed how geoenvironmental phenomena can adversely affect patients with diabetes and concludes with a discussion of requirements for developing strategies for geoenvironmental diabetes management.