Illness in the air: how pollution causes heart disease and cancer

Michele Chase, 28, has suffered from smog-related health problems for as long as she can remember. At just two years old she developed asthma and spent her early Mississauga, Ont., childhood coughing and wheezing from industrial pollutants and traffic fumes. Finally, when she was nine, her family moved to a small community near Fredericton.

"In Mississauga, it was hard to get a full breath of air on a regular summer day. I noticed a big difference when we moved to New Brunswick," says Michele. She could finally control her asthma. When she returned to Ontario to visit relatives in the summer, "I had to go to emergency a few times because of asthma attacks," she says.

While the most obvious effects of pollution are chronic lung conditions, such as asthma and chronic obstructive pulmonary disease (COPD), the complex mix of chemicals in environmental contaminants is also a significant contributor to all the major diseases that kill human beings: heart disease, stroke, lung conditions and cancer.

Today's pollution is already affecting the health of the next generation. And because they are created by fossil-fuel combustion in vehicles and power plants, pollutants are hard to avoid. 

The heart breaker
The 2008 Heart and Stroke Foundation Report Card on Canadians' Health is one of many sources showing that it's fine particles in the air -- tiny toxic compounds 30 times thinner than a human hair -- that have the most devastating impact on human health.

Each year in Canada, exposure to environmental contaminants causes up to 11,000 deaths, up to 67,000 hospitalizations and 580,000 days in hospital as a result of heart disease. This includes heart attacks, sudden death from arrhythmia (irregular heartbeat) and premature death from congestive heart failure and stroke.

In 1993, Harvard University's Six Cities study, which followed more than 13,000 people for about 15 years, found that the overall death rate was 26 per cent higher in Steubenville, Ohio, the most polluted U.S. city in the study, than in Portage, Wis., the least polluted. Of all air pollutants, fine particle levels were most closely linked to death rates. Scientists were surprised that there were many more pollution-related deaths from heart disease than from other causes, such as lung disease.

The Harvard study led the U.S. Environmental Protection Agency to establish more stringent air quality standards in 1997. An eight-year follow-up study, published in 2006, found that the death rate from heart disease plummeted after fine particle levels dropped.

Location, location, location
Another large-population health study, this time of 65,000 women, published in 2007 in the New England Journal of Medicine, found that in cities with higher levels of pollution -- or in more polluted areas within a city -- women had higher death rates from both heart attack and stroke.

In fact, the harmful effects of fine particles on arteries, blood vessels and heart rhythms can be measured almost immediately. In a University of Toronto study, healthy young people inhaled fine particles, plus ozone, for two hours. Tests showed constriction of their blood vessels. In people with heart disease, these effects can trigger a heart attack.

Click to continue for more on the effect of pollutants on our arteries...

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