Heart disease is the leading cause of death and hospitalization among the elderly population, which makes the identification of preventable causes for heart disease morbidity and mortality a major goal of epidemiologic research. Numerous studies have shown associations of outdoor particulate matter (PM) air pollution with cardiovascular hospital admissions and mortality. The causal pollutant components and physiologic mechanisms for these associations are not fully understood. There is evidence that airway inflammation resulting from airway deposition of ultrafine particles (< 0.1 mu/m in diameter) could lead to an increase in thrombogenic and inflammatory activity in the blood, and to a disturbance in cardiovascular function, resulting from oxidant stress responses at extra-pulmonary sites, including the vascular endothelium of the heart. This is expected to increase the risk of adverse cardiovascular outcomes, particularly in people with underlying coronary heart disease (CHD). We propose to conduct a panel study with repeated measurements to evaluate acute cardiovascular and respiratory health effects of ultrafine PM personal, indoor and outdoor exposures. Over seven month periods, we will follow 72 nonsmoking elderly individuals with CHD living in areas with high air pollution levels in the Los Angeles Air Basin of California. The design will maximize the utility of intensive exposure assessments by measuring multiple interrelated clinical, physiological and biochemical outcomes.
The specific aims will address the following hypotheses: 1) Exposure to ultrafine particles will be associated with increased circulating biomarkers of inflammation and thrombosis, increased blood pressure, adverse cardiac clinical outcomes, and increases in a biomarker of airway inflammation, exhaled nitric oxide; and 2) These associations will be stronger for measurements of particle components and certain ambient sources thought to influence inflammatory processes through oxidant damage. We will also evaluate relationships of outcomes with accumulation mode PM (0.18-2.5 mu/m) and coarse mode PM (2.5-10 fm). We will assess whether estimates of association for predicted (adjusted) personal or indoor exposure to ultrafine or accumulation mode PM of outdoor origin are stronger than estimates of association for unadjusted (raw) personal or indoor exposures. Results of this study will advance knowledge on the cardiovascular and respiratory effects of ultrafine particles. Our results are expected to clarify findings in the literature of associations between ambient particulate air pollution (PM10 and PM2.5) and severe cardiovascular outcomes, including mortality and hospital admissions.
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