U. S. researchers have said that air pollution increases stress on the heart and increases the risk of heart disease.

A body's ability to regulate the heartbeat so the heart can pump the right amount of blood into the circulation system relies on the stability of the heart's electrical activity, electrophysiology, Duanping Liao, a professor of public health sciences, at Pennsylvania State College of Medicine has said.

Liao said in a statement "Air pollution is associated with cardiopulmonary mortality and morbidity, and it is generally accepted that impaired heart electrophysiology is one of the underlying mechanisms."

The statement further said, "This impairment is exhibited through fluctuations in the heart rate from beat to beat over an established period of time, known as heart rate variability. It is also exhibited through a longer period for the electric activity to return to the baseline, known as ventricular repolarization."

Liao's team tracked 106 non-smokers age 45 and older from central Pennsylvania, who wore air-quality and heart-rate monitors for 24 hours.

It was further reported that the study found heart electrophysiology was affected up to six hours after elevated PM2.5, combustion-related small particles exposure. (With inputs from Agencies)