Factors affecting the concentration and distribution of gaseous elemental mercury in the urban atmosphere of downtown Toronto

Comparing the data set with a data set collected in 2004 from the same location revealed that the average atmospheric GEM concentration in downtown Toronto dropped from 4.5 ng/m3 to 1.78 ng/m3 (60% decrease). Decreases in GEM were also observed in the data reported by CAMNet over the same period in rural and remote areas but to a lesser extent (10.5 and 13.9% respectively). The decrease is in line with the key national and provincial policies on mercury use, emission control and management that have been enacted since 2004.