Sulfur dioxide, an Atmospheric Pollutant Much of the air pollution by sulfur dioxide in Southern Ontario comes from the combustion of coal or oil in Ontario Hydro's fossil fueled generating stations. These fuels contain some sulfur combined in organic compounds.

A major source of atmospheric SO2 in the Sudbury region is the roasting of sulfide ores during the extraction of copper and nickel at the INCO (Thompson, Manitoba) and Falconbridge (Sudbury, Ontario)smelters. Local problems have been alleviated by the construction of very high stacks which enable the SO2 to be diluted with air before it reaches the ground near the smelters.

This contributes to the problem known as acid rain. SO2 is very poisionous to both animals and plants, and can also lead to asthma attacks.