Exposure estimates in assessing helath effects of air pollution.

Air pollution has been associated with adverse health effects. Difficulties in interpreting studies of health effects of exposure to air pollution arise in estimating exposure. Until recently, studies of effects of air pollution have relied on pollution exposure measurements obtained from fixed location air pollution stations monitoring outside air (to evaluate compliance with air quality standards, rather than to examine population exposure). However, recent evidence suggests that there are substantial differences between air pollution levels measured at such sites and levels to which people are actually exposed, i.e. 'personal exposure'. The present study examines effects of ambient urban air pollution on persons suffering from asthma, healthy non-asthmatic subjects and school children (in 2 Canadian cities, Toronto and Hamilton). Air pollution exposure is being assessed by data obtained from: (1) conventional 'abatement' oriented fixed location air pollution monitoring stations, (2) an extensive 'population' oriented network, (3) inside and (4) outside structures (homes and schools) as well as (5) 'personal' air pollution samplers. The data indicate variability in these different estimates of exposure which have implications on health effects assessment.