Associations between ambient particulate sulfate and admissions to Ontario hospitals for cardiac and respiratory diseases.

The association of daily cardiac and respiratory admissions to 168 acute care hospitals in Ontario, Canada, with daily levels of particulate sulfates was examined over the 6-year period 1983-1988. Sulfate levels were recorded at nine monitoring stations in regions of southern and central Ontario spanned by three monitoring networks. A 13-micrograms/m3 increase in sulfates recorded on the day prior to admission (the 95th percentile) was associated with a 3.7% (p < 0.0001) increase in respiratory admissions and a 2.8% (p < 0.0001) increase in cardiac admissions. Increases were observed for all age groups examined. Admissions for cardiac diseases increased 2.5% for those under 65 years and 3.5% for those 65 years and older. After adjusting for ambient temperature and ozone, similar increases in respiratory admissions were observed in the period from April to September (3.2%) and in the period from October to March (2.8%). A 3.2% increase was observed for cardiac admissions in the period from April to September, and a 3.4% increase was observed in the period from October to March after adjusting for ambient temperature and ozone.