Mercury (Hg) in indoor and outdoor air in the city core at various heights above ground, and in indoor and outdoor air was measured in Toronto, the largest city in Canada. For the measurements of gaseous elemental mercury (GEM), a mercury-monitoring system (Tekran Inc., Toronto, Canada) was used. In addition, mercury associated with indoor and outdoor particulate matter in the city and surrounding area was also measured. Mercury in outdoor particulate matter (as total filterable p-Hg) was determined through thermal desorption gold pre-concentration CVAFS. The analysis of mercury in indoor particulate matter (as settled dusts) followed the USEPA Method 1631E and Appendix to Method 1631. The results show:
• the higher GEM concentration values in outdoor air were more concentrated in the city core;
• GEM in indoor air was much higher than in outdoor air;
• the GEM values increased with increasing elevation;
• emissions from vehicles and ground surfaces in the city were not the major sources of GEM to the urban atmosphere;
• the concentrations of total filterable p-Hg in outdoor air ranged from 20.1 to 63.0 pg m−3 and those for indoor settled dusts ranged from 0.01 to 10.0 mg kg−1.
The findings suggest that mercury used in the indoor environment serves as a source of Hg to the urban atmosphere.
depth profiling, filterable mercury, gaseous elemental mercury, indoor settled dust, Toronto, urban atmosphere
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