Study: Ozone Tied to the Increase in Heart Attacks During Hot Days

According to a new study, published in the journal Occupational and Environmental Medicine, ozone may be the link between the increased risk of heart attacks and high temperatures.

The study, led by Dr. C. Ren, Department of Epidemiology, School of Medicine, University of California, is part of a study know as the National Mortality and Air Pollution Study (NMMAPS), which looked at the relationship between health and weather between 1987 and 2000.

Based on a population of more than 100 million, researchers dug on 4 millions of cases of heart attacks and strokes. Then they looked at weather conditions during those days that heart attacks occurred.

Ozone (chemically written as O₃) is a triatomic molecule, consisting of three oxygen atoms. Ground-level ozone is an air pollutant with harmful effects on the respiratory systems of animals and humans. Ozone therapy is banned in the United States.

However, not all about of ozone in harmful for humans. Ozone in the stratosphere (10 km and 50 km above the surface) filters certain UV rays (shorter wavelengths -- less than 320 nm) from the sunlight. These filtered rays are known to be harmful to most forms of life in large doses.

After getting the data from the NMMAPS web site a complex statistical technique, called Response Surface Methodology, was used to analyze thousand and thousand of data sets (more than 100 locations across the US) of temperature, heart strokes and ozone levels.

What they found was starling. When they plotted daily deaths against temperatures they found that on hot days the amount of strokes increased significantly. They also found that on those hot days the amount of ozone in the air as a t the highest levels so, they concluded the higher the ozone level, the higher was the risk of cardiovascular death.

Also, the study showed that a 10-degree temperature increase is associated with an increase in heart disease or stroke deaths of almost 1% at the lowest ozone level and by more than 8% for the highest levels.