The authors discuss that recent epidemiology studies have reported associations between acute ozone exposure and mortality. However, in contrastto airborne particulate matter pollution (PM), there are few controlled human exposure studies for ozone,which have tested whether exposure can modulate the cardiovascular system.

In the study, 23 young healthy individuals were exposed in a randomized crossover fashion to clean air and 0.3 ppm ozone for two hours while undergoing intermittent exercise. Blood was obtained immediately prior to exposure, immediately afterward, and the next morning. Continuous Holter monitoring began immediately prior to exposure and continued for 24 hours. Lung function was performed immediately prior to and immediately after post exposure and bronchoalveolar lavage was performed 24 hours after exposure. Immediately following ozone exposure the authors observed a 98.9% increase in IL-8, a 21.4% decrease in plasminogen activator inhibitor 1 (PAI-1), a 51.3% decrease in the high frequency component of HRV, and a 1.2 % increase in QT duration. Changes in IL-1B, and PAI-1 were apparent 24 hours after exposure. The authors also observed ozone-induced drops in lung function and an increase in pulmonary inflammation.

The authors conclude that this controlled human exposure study shows that ozone can cause an increase in vascular markers of inflammation, changes in markers of fibrinolysis, as well markers that affect autonomic control of heart rate and repolarization. The authors state that these findings provide biologic plausibility for the epidemiology studies that associate ozone exposure with mortality.

Reference:
Devlin RB,Duncan KE,Jardim M, Schmitt MT,Rappold AG,Diaz-Sanchez D. Controlled Exposure of Healthy Young Volunteers to Ozone Causes Cardiovascular Effects. Controlled exposure of healthy young volunteers to ozone causes cardiovascular effects. Circulation. 2012;126:104-11.