Air pollution puts stress on heart

Fine particles in air pollution can interfere with the functioning of the heart and harm people suffering from heart conditions, according to a report by researchers at Harvard University.

While previous studies have shown that pollution can trigger attacks, the mechanism for this is not well-known.

The team found that fine particles in air pollution, whether from traffic or non-traffic sources, can adversely affect the way electrical signals in the heart system are conducted.

The research team, which was led by a Harvard professor of medicine and environmental health, collected data on 48 patients with coronary artery disease. All these patients had histories of hospitalization for treatment of heart attack and deteriorating status of coronary artery disease. They all came from the Boston area.

Portable electrocardiograph machines were used to monitor the patients on a 24-hour basis, for fluctuations in the electrical conductivity around the heart system (known as ST-segment depression). Any irregularities in the rhythmic beating of the heart (called dysrhythmia) would point to an inadequacy in the flow of blood to the heart or an inflammation of the muscles in the heart.

The team also monitored the average 24-hour readings of all types of pollutants in Boston. The readings were all below, that is they were well within, the currently accepted or even the proposed limits of National Air Quality Standards.

The results showed that increased levels of black carbon and of a pollutant known as PM 2.5, ordinarily found in traffic exhaust, were directly linked with increased fluctuations of electrical conductivity (ST-segment depression). Sulfur dioxide, a byproduct of combustion from factories, was also similarly associated.

The increases in ST-segment depression were found to be significantly higher in patients who were still recovering from heart attacks in comparison to the other patients.

The researchers believe that if the ST-segment fluctuations are indications of heart muscle inflammation or ischemia risk, then these can possibly be minimized by reductions in air pollution coming from traffic and non-traffic sources. Conceivably, the risk for heart attack, heart failure and other heart conditions would then be reduced for patients with coronary artery disease.

The report gives very solid evidence of how much stress environmental pollution puts on the heart. The stress on the hearts of patients just recovering from hospitalization for heart treatment is even greater.

Safety Tips:

* Steer clear of heavy traffic. If you or somebody in the car with you is just recovering from heart attack, it is best to avoid being exposed to pollution.

* Avoid going outdoors in days when smog is heavy.

* Get closer monitoring of your condition. If you recently had a heart attack and you live in areas with high air pollution levels, make sure you get closer follow-up from your physician.