Peak Levels of Fine Particulates in Alberta

Map of monitoring stations

Maximum levels of a contaminant are important because of potential health or environmental effects of high concentrations. Scientists often find the "99th percentile" concentration more helpful in tracking trends than the maximum value. The annual 99th percentile concentration is the concentration that is higher than 99% of the concentrations recorded throughout the year. In other words, only 1% of the ambient concentrations observed during the year fall above the 99th percentile concentration.

As the figures show, 99th percentile particulate matter concentrations have been variable in Alberta from 1994 to 2007. In 2007, 99th percentile particulate matter concentrations ranged from 15 to 31 micrograms per cubic metre (µg/m³), with the maximum concentration occurring at the Fort McKay station, north of Fort McMurray. The peak concentration at Fort McKay is partly due to a forest fire in 2007.

Peak particulate matter concentrations have decreased by 6 to 70% since 1990, however peak concentrations have increased at Fort Chipewyan (57%), Fort McKay (35%) and Syncrude (23%) north of Fort McMurray since 1999.