Carbon Monoxide (CO)
What is carbon monoxide?
CO is a colourless, odourless and tasteless but poisonous gas produced primarily by incomplete burning of fossil fuels.
What are the sources of CO?
The transportation sector accounts for 65 per cent of all CO emissions from human activity in Ontario as seen in the table and diagram below. A large part of the remainder comes from primary metal producers (24 per cent) and from fuel combustion in space heating and industrial processes (6 per cent).
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Ontario Carbon Monoxide Emissions by Sector (Emissions From Human Activity, 2000 Estimates) |
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| Pie Chart | Category | Percent |
|---|---|---|
 |
Vehicles | 45% |
| Primary Metals | 24% | |
| Other Transportation | 20% | |
| Area Fuel Combustion | 6% | |
| Other Processes | 3% | |
| Miscellaneous Area Sources | 2% | |
What are the effects of CO?
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 following table shows the health effects of different Air Quality Index levels caused by carbon monoxide.
Health effects of different Air Quality Index (AQI) levels caused by carbon monoxide
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| Category | AQI | Carbon Monoxide (CO) |
|---|---|---|
 Very Good |
0 - 15 | No health effects are expected in healthy people. |
 Good |
16 - 31 | No health effects are expected in healthy people. |
 Moderate |
32 - 49 | Blood chemistry changes but no noticeable impairment. |
 Poor |
50 - 99 | Increased symptoms in smokers with heart disease. |
 Very Poor |
100 or over | Increasing symptoms in non-smokers with heart disease; blurred vision; some clumsiness. |
