| Summary: | Does ambient air pollution in Canada pose a threat to respiratory health? For a
study initiated by Health Canada, we combined analyses of micro-level data from both
the 1990 Ontario Health Survey with an environmental air monitoring system to obtain a
quantitative answer to the question.
In contrast to studies designed to collect special purpose data, the Ontario Health
Survey was not designed to address respiratory health issues. In spite of this, this cross
sectional database was rich enough for modelling. We used asthma and emphysema as the
response variables in assessing the impact of four pollutants estimated for summer and
winter.
Two analyses were conducted for each response variable, one incorporating survey de
sign information the other ignoring it. Age, income, smoker type and sex were significantly
related to asthma at a a = 5% level of confidence in both analyses. None of the pollutant
covariates figured in the model.
Using the classical x2 test for nested models as the criterion, the emphysema model
achieved a better fit than the asthma model. Smoker type and age, in particular, were
strongly related to emphysema; income and number of cigarettes smoked were significantly
but less strongly related; summer N2O was marginally significant, depending on which of
the two analyses was considered.
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