Characteristics of inhalable particulate matter in Alberta cities

Inhalable particulate measurements from 1984 to 1994 at Edmonton and Calgary reveal similar physical and chemical properties which are comparable to other Canadian prairie cities. Because of geographical and emission-source differences, particulate measurements in these two Alberta cities exhibit characteristics significantly different from those obtained in eastern North American cities. While median PM10 concentration is about 25 μg m-3, which is approximately 63% of the total suspended particulates (TSP), PM2.5 concentration is about 40% of that of PM10. Over the 10 years there was a decreasing trend in both size fractions. PM2.5 shows a similar seasonal pattern in Edmonton and Calgary, with a slightly higher concentration in winter; whereas coarse particles are generally higher in spring at Edmonton and in winter at Calgary. Relationships were established from co-located measurements of Dust and Smoke index (in Coefficient of Haze, COH, units) and PM10 concentration with a correlation coefficient of 0.51, and TSP and PM10 concentrations with a correlation coefficient of 0.93. Sulphate is the highest explainable mass fraction in fine particles, while minerals contribute most to the coarse particles. About 80% of the total sulphur mass is within the fine particle fraction. Seasonal variations within individual chemical components are relatively less than that among chemical components. Particles of different sizes originate from distinct source sectors. Seasonal variations in source contribution are detected, particularly for mineral soil and road salt.