THE RELATIONSHIP AMONG TSP, PM(10), PM(2.5), AND INORGANIC CONSTITUENTS OF ATMOSPHERIC PARTICULATE MATTER AT MULTIPLE CANADIAN LOCATIONS

The Canadian NAPS (National Air Pollution Surveillance) network has pr oduced one of the largest and more geographically diverse databases of high quality atmospheric particle measurements in the world. A maximu m of ten and a minimum of two years of data are available for 19 Canad ian locations. These data were used to investigate relationships betwe en collocated measurements of TSP, PM(10), PM(2.5), SO42-, and other i norganic ions and elements at a variety of urban and rural locations. Amongst all locations and all 24-hour measurements, the 10th and 90th percentile TSP concentrations were 22 and 98 mu g m(-3), respectively. A majority of the PM(10) concentrations were below 47 mu g m(-3) and most of the PM(2.5) concentrations across Canada were below 26 mu g m( -3) (90th percentiles). On average across all sites, PM(10) accounted for 49% of the PM(10), and PM(10) accounted for 44% of the TSP. Howeve r, there was considerable variability among sites, with the mean PM(2. 5) to PM(10) ratio ranging from 0.36 to 0.65. This ratio also varied s ubstantially from measurement to measurement, but at most sites a majo rity (>50%) of the ratios were within +/-10% of the median value. PM,, concentrations tended to increase from summer to winter except at som e of the eastern sites, particularly the rural locations, where sulfat e was an important constituent. Coarse particles (2.5 mu m < diameter < 10 mu m) were found to exhibit the opposite seasonal pattern. Partic le levels were highest at a high-density traffic site in Montreal, Que bec Excluding this site, which was influenced by local sources, the pa rticle levels tended to be highest in southwestern Ontario. Depending upon site, only about 37% to 61% of the PM,, could be explained given the measured concentrations of several inorganic ions and elements. Mu ch of the unexplained portions are assumed to be carbonaceous and pred ominantly organic in nature. Due to the predominance of crustal materi al, a greater portion of the coarse particle mass (similar to 70%) was explained by the inorganic constituents.