Long-term, low-level ozone exposure can be lethal, study finds

March 12, 2009 at 12:00a.m.

Los Angeles Times

Ozone pollution is a killer, increasing the yearly risk of death from respiratory diseases by 40 percent to 50 percent in heavily polluted cities in Southern California and by about 25 percent throughout the rest of the country, researchers reported today.

Environmental scientists already knew that spikes in ozone during periods of heavy pollution caused short-term effects, such as asthma attacks, increased hospitalizations and deaths from heart attacks.

But the 18-year study of nearly half a million people, reported in the New England Journal of Medicine, is the first to show that long-term, low-level exposure to the pollutant also can be lethal.

Current standards for ozone pollution cover only eight-hour averages of the colorless gas, but even with that relatively relaxed rule, 345 counties with a total population of more than 100 million people are out of compliance.