Ozone in Air Pollution Harms the Heart

A number of previous studies have linked adverse respiratory effects with ozone exposure, and recent epidemiologic research suggests that this environmental pollutant also may contribute to cardiovascular disease risk and death.  Robert B. Devlin, from the US Environmental Protection Agency (EPA; North Carolina, USA), and colleagues recruited 23 men and women, average age 29 years, each of whom was exposed to 2 hours of clean air while performing intermittent exercise on a stationary bicycle, and then 2 hours of ozone in a concentration of 0.3 parts per million (this concentration is higher than is recommended by the EPA, but approximates the levels seen in cities such as Beijing, China, that have heavy air pollution).  Immediately before, immediately after, and the day after the two exposures, participants underwent spirometry and had blood drawn. Ambulatory ECG monitoring was done throughout a 24-hour period. Various inflammatory markers exhibited significant changes.  Interleukin-1 (IL-1)-beta rose by 55.7%, and tumor necrosis factor-alpha rose by 10.1%.  Even 24 hours after the ozone exposure, blood levels of IL-1-beta were 103.8% higher than at baseline, and C-reactive protein (CRP) levels were 65.4% above pre-exposure levels. A decrease in the thrombotic marker PAI-1 persisted 24 hours after exposure, resulting in an overall 42.7% reduction.  After 24 hours, plasminogen levels had decreased by 41.5%.  The researchers also detected a "small but significant" lengthening of the QT interval immediately following ozone exposure, a finding which they noted can increase risk for ventricular tachyarrhythmias and even sudden death.  Additionally, spirometric measures showed changes including a 10.9% drop in forced expiratory volume in 1 second. The study authors conclude 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.”