Faculty Bibliography

OBJECTIVE:Recent mechanistic and epidemiological evidence implicates air pollution as a potential risk factor for diabetes; however, mortality risks have not been evaluated in a large US cohort assessing exposures to multiple pollutants with detailed consideration of personal risk factors for diabetes. RESEARCH DESIGN AND METHODS/METHODS:. Associations between the air pollutants and the risk of diabetes mortality (N = 3598) were evaluated using multivariate Cox proportional hazards models adjusted for both individual-level and census-level contextual covariates. RESULTS:(HR = 1.09; 95% CI: 1.01-1.18 per 10 ppb). The strength of the relationship was robust to alternate exposure assessments and model specifications. We also observed significant effect modification, with elevated mortality risks observed among those with higher BMI and lower levels of fruit consumption. CONCLUSIONS:, is related to increased risk of diabetes mortality in the U.S, with attenuation of adverse effects by lower BMI and higher fruit consumption, suggesting that air pollution is involved in the etiology and/or control of diabetes.

This study provides the first comprehensive analysis of the seasonal variations and weekday/weekend differences in fine (PM2.5) and coarse (PM2.5-10) particulate matter mass concentrations, elemental constituents, and potential source origins in Jeddah, Saudi Arabia. Air quality samples were collected over one year, from June 2011 to May 2012 at a frequency of three times per week, and analyzed. The average mass concentrations of PM2.5 (21.9 mug/m3) and PM10 (107.8 mug/m3) during the sampling period exceeded the recommended annual average levels by the World Health Organization (WHO) for PM2.5 (10 mug/m3) and PM10 (20 mug/m3), respectively. Similar to other Middle Eastern locales, PM2.5-10 is the prevailing mass component of atmospheric particulate matter at Jeddah, accounting for approximately 80% of the PM10 mass. Considerations of enrichment factors, absolute principal component analysis (APCA), concentration roses, and backward trajectories identified the following source categories for both PM2.5 and PM2.5-10: 1) soil/road dust; 2) incineration; and 3) traffic; and for PM2.5 only, 4) residual oil burning. Soil/road dust accounted for a major portion of both the PM2.5 (27%) and PM2.5-10 (77%) mass, and the largest source contributor for PM2.5 was from residual oil burning (63%). Temporal variations of PM2.5-10 and PM2.5 were observed, with the elevated concentration levels observed for mass during the spring (due to increased dust storm frequency), and on weekdays (due to increased traffic). The predominant role of windblown soil and road dust in both the PM2.5 and PM2.5-10 masses in this city may have implications regarding the toxicity of these particles versus those in the western world where most PM health assessments have been made in the past. These results support the need for region-specific epidemiological investigations to be conducted and considered in future PM standard setting. Implications Temporal variation of fine and coarse PM mass, elemental constituents, and sources were examined in Jeddah, Saudi Arabia for the first time. The main source of PM2.5-10 is natural windblown soil and road dust, while the predominant source of PM2.5 is residual oil burning, generated from the port and oil refinery located west of the air sampler, suggesting that targeted emission controls could significantly improve the air quality in the city. The compositional differences point to a need for health effects studies to be conducted in this region, as to directly assess the applicability of the existing guidelines to the Middle East air pollution.

In this study, factor analysis and mass regression were used to identify four fine particulate matter sources and estimate their contributions to the ambient air pollution in Beijing. The identified sources were traffic re-suspended soil, mixed industrial sources, oil combustion, and secondary sulfate. The estimated source contributions were then introduced into two models as exposure variables to explore the relationships between cardiovascular responses in mice and PM exposures. We observed that PM2.5 has a small negative acute effect on heart rate, but the individual source factors showed much more significant effects. Traffic re-suspended soil had the most significant effect on heart rate, with a positive contribution on the day of exposure and a negative one on day lag 1. Acute heart rate variability outcomes were better explained by the total PM2.5 than by the source components. Chronic effects were observed as a decreased heart rate but an increased number of heart rate variability outcomes

Recent epidemiological evidence suggests that exposure to particulates may be a factor in the etiology of metabolic syndrome (MetS). In this novel study, we investigated the relationship between particulate levels and prevalence of MetS component abnormalities (hypertension, hyperglycemia, obesity) in a recruited cohort (N = 2025) in Jeddah, Saudi Arabia. We observed significant associations between a 10 μg/m³ increase in PM2.5 and increased risks for MetS (Risk Ratio (RR): 1.12; 95% Confidence Interval (CI): 1.06-1.19), hyperglycemia (RR: 1.08; 95% CI: 1.03-1.14), and hypertension (RR: 1.09; 95% CI: 1.04-1.14). PM2.5 from soil/road dust was found to be associated with hyperglycemia (RR: 1.12; 95% CI: 1.06-1.19) and hypertension (RR: 1.11; 95% CI: 1.05-1.18), while PM2.5 from traffic was associated with hyperglycemia (RR: 1.33; 95% CI: 1.05-1.71). We did not observe any health associations with source-specific mass exposures. Our findings suggest that exposure to specific elemental components of PM2.5, especially Ni, may contribute to the development of cardiometabolic disorders.

BACKGROUND: The statistical association between increased exposure to air pollution and increased risk of morbidity and mortality is well established. However, documentation of the health benefits of lowering air pollution levels, which would support the biological plausibility of those past statistical associations, are not as well developed. A better understanding of the aftereffects of interventions to reduce air pollution is needed in order to: 1) better document the benefits of lowered air pollution; and, 2) identify the types of reductions that most effectively provide health benefits. METHODS: This study analyzes daily health and pollution data from three major cities in Israel that have undergone pollution control interventions to reduce sulfur emissions from combustion sources. In this work, the hypothesis tested is that transitions to cleaner fuels are accompanied by a decreased risk of daily cardiovascular and respiratory mortalities. Interrupted time series regression models are applied in order to test whether the cleaner air interventions are associated with a statistically significant reduction in mortality. RESULTS: In the multi-city meta-analysis we found statistically significant reductions of 13.3% [CI -21.9%, -3.8%] in cardiovascular mortality, and a borderline significant (p=0.06) reduction of 19.0% [CI -35.1%, 1.1%] in total mortality. CONCLUSIONS: Overall, new experiential evidence is provided consistent with human health benefits being associated with interventions to reduce air pollution. The methods employed also provide an approach that may be applied elsewhere in the future to better document and optimize the health benefits of clean air interventions.