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Not many Canadians realize it, but air pollution is a year-long threat to heart health, the 2008 Heart and Stroke Foundation Report Card on Canadians' Health says.

The annual report card, released Monday, says a national poll by the foundation revealed that only 13 per cent of Canadians have made the connection between air pollution and cardiovascular disease.

“Since the early 1990s, a growing body of evidence from Canada, the U.S. and Europe has documented increased rates of heart attack, and more hospitalizations for serious heart diseases such as heart failure, and stroke, after both short and long-term exposure to polluted air,” said Dr. Beth Abramson, a cardiologist who is the Heart and Stroke Foundation's spokeswoman.

The foundation said about 6,000 additional deaths occur every year in Canada because of short-term exposure to air pollution, and that research suggests that 69 per cent of these deaths come in the form of cardio and cerebrovascular disease.

According to the foundation, length of exposure is a critical factor in the impact of air pollution on cardiovascular disease. Studies in different cities and countries have produced different results, but research shows that every 10-microgram increase in long-term exposure to fine particulate matter (PM 2.5) can increase the risk of dying from heart disease and stroke – in some individuals by as much as 76 per cent.

Even short-term exposure can be dangerous. One study has reported that a day-to-day increase in a PM 2.5 level as low as 20-micrograms per cubic metre can elevate the risk of heart attack within 24 hours by 69 per cent.

Short-term exposure is only a small part of the problem, because no part of the country is free from the long-term effects of bad air. Environment Canada estimates that at least 30 per cent of Canadians are being exposed to higher than acceptable levels of fine particulates. Between 2001 and 2005, there has been no significant change in fine particulate pollution in Canada.

The Heart and Stroke Foundation surveyed a national representative sample of 1,134 Canadians for the report card, and found major discrepancies between people's knowledge of the health effects of air pollution, and how that translated to personal action. While almost two-thirds (63 per cent) believe air quality has a major effect on health, nearly the same number, six out of 10 (61 per cent), do not let smog advisories affect what they do outdoors.

"Poor air quality represents a particular challenge for our aging population and those at increased risk of heart disease," Dr. Abramson said. "It's ironic that people who are recovering from – or are trying to prevent – heart disease by being physically active may actually be exposing themselves to more risk on bad air days if they head outdoors to be active."

Although Canadians seem to make the connection between pollution and some major diseases, heart disease is under-recognized. When asked to name diseases affected by air pollution, more than eight out of 10(82 per cent) named respiratory diseases, three out of 10 (34 per cent) cancer, but only one out of 10 (13 per cent) heart disease.

The report also found that many Canadians do not think air pollution affects their communities.

Six out of ten Canadians (64 per cent) believe the quality of air in their community is generally good to excellent, with the rates being highest among those living in the Prairie provinces (84 per cent), Atlantic Canada (75 per cent) and British Columbia (71 per cent) and lowest in Quebec (59 per cent) and Ontario (53 per cent).