PM 10 (24 hr avg) SO4 (24 hr avg) CO (1 hr max)
CO (24 hr avg) NO2 (24 hr avg) SO2 (24 hr avg) 03 (1 hr max)
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Air Pollution Burden of Illness in Toronto
Toronto Public Health
We also summarized recent quality-controlled air pollution data for several sites within Toronto, and obtained baseline health outcome information in a form which can be linked to the air quality monitoring sites. Using this information, we estimated the air pollution burden of illness in Toronto for the year 1995, the most recent year for which there was adequate information for the key criteria pollutants of health concern. We quantified the air pollution risk in Toronto using two different methods and found that there were between 730 and 1,400 premature deaths, and between 3,300 and 7,600 hospital admissions each year associated with air pollution breathed by the public at large. We view the results of these two methods as providing a lower and upper bound estimate, respectively. For the purpose of communicating these results in a more public, policy-making forum, it is reasonable to express the air pollution burden of illness in Toronto as resulting in about 1,000 premature deaths and about 5,500 hospitalizations each year. Although the calculations were based on 1995 data, air quality in Toronto has not shown any significant improvement since then, so it is reasonable to expect these illness rates to reflect the current situation as well. These premature mortality and hospitalization estimates, while significant, greatly underestimate illness associated with poor air quality in Toronto. For the last 15 years, it has been well recognized that air pollution produces a "pyramid" of health effects, with the relatively rare but more serious health outcomes (such as premature deaths and hospitalizations) at the peak of the pyramid, and the less but more numerous health outcomes such as asthma symptom days and respiratory infections (such as pneumonia) appearing in progressive layers below that peak. The premature deaths and hospitalizations documented in this study represent only the peak of the pyramid of health effects related to poor air in Toronto. In addition to estimating the total air pollution burden of illness due to premature mortality and hospitalizations, this study sought to assess the relative importance of each of Toronto's critical air pollutants in contributing to ill health. It is recognized that there is some uncertainty in attributing illness rates to each pollutant, and that consequently, the reader should consider such outcomes as estimates, rather than precise accounts of exactly how many people are affected by a given pollutant. However, given that the purpose of doing so is to better identify reasonable policy responses to reduce air-related illness, the approach is justified. For example, if one finds that a large amount of illness is associated with a pollutant known to come from a specific source, then it makes sense in terms of risk management to strategically direct control measures towards that source. It is for this reason that we calculated and documented the illness outcomes for each key pollutant. The following table summarizes these results.

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