According to the study long-term exposure to ozone in Toronto may be responsible for approx. 20% of all lung-related deaths in the city. The massive new American study on health risks of the common air pollutant compares smog levels in major North American cities and deaths caused by smog.
People who live in cities with smoggy ozone pollution are 25% to 30% more likely to die from lung disease than those living in areas with the cleanest air, researchers reported.
The study, which looked at data tracking 450,000 people over 18 years, suggests the current emphasis on peak ozone days (also known as smog days) as the smog component's major health danger ignores the serious, cumulative perils that breathing it over a lifetime impose."It's not just the peaks you should worry about, it's the cumulative, entire ozone season that's important, too," says George Thurston, a professor of environmental medicine at New York University.
"So we can't just sort of hide in our homes on the peak days and avoid the adverse effects of ozone," says Thurston, who directed the air pollution portion of the study.
The report, released today in the New England Journal of Medicine, does not look at Canadian cities, but York University air pollution expert Geoff Harris says Toronto's ozone levels are almost identical with those found in many large cities in the northeast United States.
About 20% of respiratory deaths in these cities can be directly attributable to long-term exposure to the pollutant. Ozone and fine airborne particles are two of the major components of smog. In New York and Washington ozone smog increased the risk of dying of any respiratory ailment, from cancers to a severe asthma attack, by approx. 25%.
In very smoggy Los Angeles ozone increased the risk of dying of any respiratory ailment by about 50%.
Ozone in the upper reaches of the atmosphere helps protect the Earth from the sun's punishing ultraviolet rays. But at ground level, ozone is corrosive is a key player in respiratory fatalities.
Ground level ozone is created by sunlight reacting with nitrogen dioxide and fine particle pollutants emitted by cars, factories and coal-fired generating plants. The resulting triple oxygen molecule (O3) is volatile, and can react with the vulnerable surface of the lung, breaking down the tissue and causing a host of pulmonary conditions.
Doctors have long known that ozone is hazardous. Short-term exposure aggravates asthma symptoms and causes breathing problems. It is especially dangerous for those people who suffer from pre-existing pulmonary conditions such as emphysema.
The study is the first to tease out the relative percentage that ozone exposure contributes to deaths due to smog. The study will give more ammunition to groups like his to argue for tougher pollution standards.
Toronto Public Health says air pollution in general accounts for about 1,700 premature deaths in the GTA and 6,000 hospital admissions each year.
See Also: Pollution in Canada getting worse, statistics show
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