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Air Pollution Burden of Illness in Toronto
Toronto Public Health
Burden of Illness Summary for Toronto (based on HAQI approach, 1997) No. of People with Adverse Health Outcome b Pollutant Nontraumatic Mortality 226 119
a
Respiratory Hospital Admissions 555 170
Cardiac Hospital Admissions 812 169 274
Congestive Heart Failure in Elderly
PM 10 SO4 CO NO2 SO2 03
441 511 119 59 1,234 172 199
439
2,207
2,155
Total (using PM 10 1,356 2,160 5,448 but not SO4) a 405 when based on chronic exposure, rather than 24 hr exposure. b Blanks indicate no coefficients available to enable estimates to be calculated. Health outcomes for O3 and PM10 based on excess morbidity and mortality beyond that associated with 'background' levels. This study suggests that in Toronto, nitrogen dioxide (NO2 ) is the air pollutant with the greatest adverse impact on human health, being responsible for almost 40% of air-related premature mortality and 60% of cardiorespiratory admissions to hospital. These illness rates occurred despite the fact that NO 2 levels are many times lower than the existing air quality criterion. NO2 should be given high priority for regulatory review and exposure reduction measures. The transportation sector, especially cars, is a major source of NO2 . Our study indicates that carbon monoxide (CO) was responsible for approximately 30% of premature mortality due to air pollution, even though CO levels are well below Ontario's current air quality criterion of 13 ppm (8-hour). While there is little evidence that CO is linked with respiratory admission to hospital, it appears that there is an association with cardiac admission to hospital, most probably related to congestive heart failure in persons 65 and older. Within Toronto, the transportation sector is the major source of CO. For sulphur dioxide (SO 2 ), although Toronto's levels are well below Ontario's air quality criterion, there is still substantial morbidity and mortality associated with ambient levels in the city. This study estimates about 120 premature deaths and 170 respiratory hospital admissions each year in Toronto. Contrary to popular belief, poor air quality is not only a summer time health concern. The six air pollutants responsible for the illness documented in this report are present in Toronto's air all year round. Three of the six air pollutants (NO2 , CO and SO2 ) are present at higher levels in the winter months than in the summer. These three pollutants are responsible for almost 80% of air pollution-related premature deaths in Toronto.

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