National Ambient Air Quality Objectives For Particulate Matter

Canadian air quality objectives for particulate matter (PM) were first developed in the 1970s and were revised in the 1980s. At that time, the understanding was that episodes of severe pollution could result in adverse health and environmental impacts but that lower concentrations of PM, such as those generally experienced across Canada, were not particularly detrimental. Beginning about 1990, serious doubt was cast on this assumption, because of an avalanche of scientific studies emerging from the U.S., Canada, Britain and Europe. These studies demonstrated adverse effects of PM on cardio-respiratory health, including both increased hospitalizations and increased premature mortality at pollutant levels that were often far below the current air quality objectives. These findings have prompted re-examination of PM air quality objectives not only in Canada, but also in the U.S., Britain, the European Community and the World Health Organization.

National Ambient Air Quality Objectives For Particulate Matter - Summary