Cardiovascular Effects of Exposure to Ozone

This multicenter study will investigate whether short-term exposure of elderly volunteers to ambient levels of O3 in a controlled exposure setting while intermittently exercising causes acute cardiovascular responses. The study is based on the suppositions that: 1) elderly people are a susceptible group for cardiovascular effects; and 2) effects are more likely with exercise. The study will involve approximately 90 healthy volunteers aged ≥55 and ≤70 who meet strict criteria for inclusion. They will be exposed for 3 hours to clean air, 0.07 ppm O3 (near the current NAAQS), and 0.12 ppm O3 (a level measured in several locations in the US). A suite of cardiovascular and pulmonary endpoints will be measured on the day before the exposure and up to 22 hours after the exposures. The study is being conducted at three centers using a common protocol and common SOPs. Most the endpoints will be analyzed by core laboratories to reduce the variability in the results. A Data Coordination and Analysis Center will assemble all the data generated by the three centers and conduct the statistical analyses on the combined data sets. The study has 3 main objectives: 1. To determine the relationship of altered autonomic balance (measured as changes in heart rate and heart rate variability (HRV)), cardiac arrhythmia, and repolarization and ozone exposure. 2. To identify instances of altered systemic vascular function \[measured as brachial artery flow-mediated dilation (FMD)without and with nitroglycerin (NTG) when exposed to ozone. 3. To identify pro-thrombotic vascular state (measured as increase in von Willebrand factor antigen in blood - primary endpoints) when exposed to ozone. Additional objectives include: 1. To identify any increase in micro particle-associated tissues factor (measured as number of particles and tissue factor activity) and platelet activation) in ozone exposure. 2. To identify if markers of systemic oxidative stress and inflammation and any correlation with the cardiovascular effects and degree of airway injury (measured as CC16) and airway inflammatory effects (neutrophils and cytokines in induced sputum) in ozone exposure. 3. To determine if cardiovascular effects in ozone exposure are correlated with airway inflammatory effects, but not lung function effects.