What are the sources of NO2?
All combustion in air produces oxides of nitrogen (NOx), of which NO2 is a major product. Approximately 63 per cent of NOx comes from the transportation sector in Ontario. A large part of the remaining 37 per cent comes from power generation, primary metal production and incineration. Natural sources of NOx include lightning and the aerobic activity of soil bacteria. These natural sources, however, are small compared to emissions caused by human activity.
