Canadian urban air quality, 1971–1975

Abstract

Aspects of Canadian urban air quality are considered on an index basis, from both a local and national viewpoint. Seasonal trends are illustrated. National indices of suspended paniculate matter, sulphur dioxide, coefficient of haze and oxides of nitrogen show considerable decreases from 1971 to 1975. The word “national” refers to the population in areas of air quality measurement, rather than land surface. The national index of oxidants, however, shows an increase, indicating a worsening situation. A brief mathematical treatment analyzes the question of whether these are actual trends or merely statistical variations. Results are discussed in terms of the implications for public policy.