Exposure to ozone, a powerful greenhouse gas and a widespread air pollutant in many major cities, may cause cardiovascular disease such as high blood pressure and lead to heart attacks and strokes, according to a new study of Chinese adults.

Ozone is a pollutant formed by a chemical reaction when sunlight interacts with nitrogen oxides and other organic compounds generated by coal-burning, vehicle exhaust and some natural sources. It has long been associated with adverse health effects in children and adults.

"We know that ozone can damage the respiratory system, reduce lung function and cause asthma attacks," said study author Junfeng Zhang, from Duke and Duke Kunshan universities. "Here, we wanted to learn whether ozone affects other aspects of human health, specifically the cardiovascular system."

Zhang and colleagues did a yearlong study of 89 healthy adults living in Changsha. They monitored indoor and outdoor ozone levels, along with other pollutants.

The team examined inflammation and oxidative stress, arterial stiffness, blood pressure, clotting factors and lung function in participants. They noted an increase in blood pressure, suggesting a possible mechanism by which ozone may affect cardiovascular health.

These effects were found with ozone exposure lower than levels that affect respiratory health.

"This study shows that standards for safe ozone exposure should take into account its effect on cardiovascular disease risk," said Zhang.

The findings were published on Monday in the US journal JAMA Internal Medicine.

Xinhua