CO is a colourless, odourless and tasteless but poisonous gas produced primarily by incomplete burning of fossil fuels.
Carbon monoxide is produced primarily by the incomplete combustion of fossil fuels. The transportation sector is the main source of CO emissions.
CO enters the blood stream and reduces oxygen delivery to the organs and tissues. People with heart disease are particularly sensitive. Exposure to high levels is linked with impairment of vision, work capacity, learning ability and performance of difficult tasks.
The Ontario Ambient Air Quality Criteria (AAQC) for 1-hour average CO concentrations is 30 parts per million (ppm).