Death toll from dirty air rising, study finds

An estimated 1,700 people die prematurely each year, city's health department warns

By MARTIN MITTELSTAEDT
ENVIRONMENT REPORTER; With a report from Joe Friesen
The Globe and Mail - Friday, July 9, 2004 - Page A11

Air pollution leads to an estimated 1,700 premature deaths each year in Toronto and causes 6,000 additional hospital admissions, says a new study by the city's public health department.

Health officials say Toronto's air, easily the most polluted in the country, is so dirty it is killing many residents and needs to be cleaned up. "These premature deaths and hospital admissions are preventable and they likely wouldn't have occurred when they did without the exposure to air pollution," said Barbara Yaffe, the city's acting medical officer of health.

Although the study was unable to pinpoint any specific individuals who were killed by pollution, Dr. Yaffe said the likely victims were people who were already suffering from chronic health conditions. This includes those with heart problems, people with asthma, the elderly and young children.

The study was based on death and hospitalization data for 1999, the most recent year for which complete information is available, and took into account pollution levels for each day of the year.

There is little mystery about the source of air pollution in Toronto. It is caused by the burning of fossil fuels by the hundreds of thousands of cars, trucks and buses that stream into the city daily, along with emissions from power plants, industries and space heating.

City and public health officials who released the study yesterday used it to argue for more provincial funding for the Toronto Transit Commission to encourage reduced automobile use, along with tighter land-use controls to curb sprawl.

The new study is a more refined version of one the city released four years ago that estimated about 1,000 people died annually from exposure to Toronto's air.

Since that previous study, new research has found that the extremely small particles of soot in air pollution are far more deadly than had been thought. The particles, so small that dozens would be needed to make up the width of a human hair, can become embedded deep in lung tissues.

Researchers have advanced several theories on why the airborne particles are dangerous. They may reduce lung function and harm health that way. They may also make lungs more vulnerable to bacterial attack. Although scientists do not know exactly how the particles kill people, population studies have found death rates rise in areas with high levels of this pollutant.

These small particles have been killing people for years, and health authorities believe their earlier work underestimated the likely death toll from pollution. They believe the actual tally has probably stayed around 1,700 in recent years.

The study attributed the adverse health affects to five compounds commonly found in dirty air. Besides small particles, these are ozone, nitrogen dioxide, carbon monoxide and sulphur dioxide.

There have been dozens of studies that have found that deaths and illness in cities rise and fall as concentrations of these pollutants wax and wane. In one noteworthy study, epidemiologists found that severe asthma attacks in Atlanta unexpectedly plunged during the 1996 Olympic Games because reductions in car use cleaned the air.

Although air pollution levels in Ontario have generally been declining because of better car-emission controls, the study found concentrations of some dangerous pollutants, such as nitrogen oxides, have actually been rising in Toronto because of increased car use.

Comparing 27 major international cities, the study concluded that Toronto had air quality in the middle of the pack, about as dirty as Cleveland, Boston and Chicago, but not as clean as Miami and Singapore. Cities such as Los Angeles and Hong Kong were worse.

Ross McKitrick, an environmental economist at the University of Guelph, says there's no question that studies linking air pollution and deaths have scientific merit, but some of the assumptions they make should be looked at more closely. "You could get a sense of the diceyness of these results if you were to ask them for a list of the names of those 1,700 people, because they're not actual people, they're just extrapolations from a statistical model. I think they're going too far when they take these correlations and then plug them into the population numbers and say, 'Therefore 1,700 people dropped dead last year from air pollution.' "

One of the other criticisms that has been levelled against these type of air pollution health studies is that the extra deaths may be of extremely old people or ill people who would die soon anyway.

Despite these criticisms, the World Health Organization has taken approaches to air pollution similar to that in Toronto. The WHO released a report in June on air pollution in Europe that contained an estimated annual mortality level of 100,000 people due to small- particle pollution.

Environmentalists say the scientific case for the harm from air pollution is overwhelming and has been subjected to intense academic scrutiny. Keith Stewart, a spokesman for the Toronto Environmental Alliance, says studies such as the recent one done by WHO are unassailable because they've been "peer reviewed to the ying yang."

<< Back to Air Purifiers