Faculty Bibliography

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.

BACKGROUND: Remote sensing (RS) is increasingly used for exposure assessment in epidemiological and burden of disease studies, including those investigating whether chronic exposure to ambient fine particulate matter (PM2.5) is associated with mortality. OBJECTIVES: To compare relative risk estimates of mortality from diseases of the circulatory system for PM2.5 modeled from RS with that for PM2.5 modeled using ground-level information. METHODS: We geocoded the baseline residence of 668,629 American Cancer Society Cancer Prevention Study II (CPS-II) cohort participants followed from 1982 to 2004 and assigned PM2.5 levels to all participants using seven different exposure models. Most of the exposure models were averaged for the years 2002-2004, while one RS estimate was for a longer, contemporaneous period. We used Cox proportional hazards regression to estimate relative risks (RR) for the association of PM2.5 with circulatory mortality and ischemic heart disease. RESULTS: Estimates of mortality risk differed among exposure models. The smallest relative risk was observed for the RS estimates that excluded ground-based monitors for circulatory deaths (RR = 1.02 (95% confidence interval (CI): 1.00-1.04 per 10 microg/m3 increment in PM2.5). The largest relative risk was observed for the land use regression model that included traffic information (RR = 1.14, 95% CI: 1.11-1.17 per 10 microg/m3 increment in PM2.5). CONCLUSIONS: We found significant associations between PM2.5 and mortality in every model; however, relative risks estimated from exposure models using ground-based information were generally larger than those estimated with RS alone.

There is widespread agreement among scientists that climate change, primarily due to greenhouse gas (GHG) production from human activities, is causing significant global health impacts.The focus of this Pulmonary Perspective is to highlight emerging evidence for cardio-respiratory health impacts related to climate change, and to suggest possible strategies for individual and collective responses to this threat. Adaptation and mitigation strategies, along with co-benefits of these actions, are also discussed. The association between heat stress and cardiopulmonary mortality is well established. Hot and drier climates are associated with increased land degradation and desertification, impacting food production and particulate matter air pollution worldwide. Warmer temperatures also increase levels of ozone and combustion particles, and extend the growing season of allergenic plants and fungi. Extreme weather (e.g. hurricanes, cyclones and floods) cause acute injuries and associated mortality and morbidity, but also longer term impacts of increased gastro-intestinal illness, degraded housing, and increased levels of indoor microbial growth that can contribute to pulmonary disease. While these impacts are daunting, coping with climate change also offers opportunities for public health. Reductions in GHG emissions reduce other air pollutants. Climate-driven adaptation in our food and water distribution systems could lead to more equitable distribution of these eco-necessities. Improved urban design and transportation could improve physical activity levels and make today's urban environments more hospitable. The positive outcomes of California's multi-pronged climate change mitigation policies provide one example in which such strategies have limited GHG emissions, and shifted energy use to more sustainable sources.