PM(10) IN CANADA

Annual mean PM(10) concentrations in Canadian cities are between five and eight times estimated background levels. Federal and Provincial ag encies in Canada are currently reviewing particulate standards, and co nsidering replacing current total suspended particulate (TSP) standard s with standards to regulate PM(10) (thoracic particles) because epide miological research suggests that this size fraction is active in the production of adverse health impacts. This paper documents the spatial and temporal variability of current particulate levels in Canada, and compares them with TSP standards presently implemented in Canada and PM(10) standards as applied by the US EPA, state of California and the World Health Organization (WHO). Twenty-four-hour averaged PM(10) dat a from the 52 sites described here exceed the standard as applied in C alifornia on up to 35% of monitoring days. The threshold suggested by the WHO for 24-h averaged concentrations is passed at the majority of the sites on approximately 5% of monitoring days.