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?

Approximately 85 per cent of the CO emitted in Ontario in 2006 came from the transportation sector. The remainder came from residential/miscellaneous (7 per cent), other industrial processes (5 per cent) and smelters/primary metals (3 per cent).

Ontario Carbon Monoxide Emissions by Sector (Emissions from Point/Area/Transportation Sources, 2006 Estimates)
Category	Percent
Road Vehicles	45%
Other Transportation	40%
Residential/Miscellaneous	7%
Other Industrial Processes	5%
Smelters/Primary Metals	3%

Note: 2006 is the latest complete inventory. Emissions may be revised with updated source/sector information or emission estimation methodologies as they become available.

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
Category	AQI	Pollutant Concentration Breakpoints (ppm)	Carbon Monoxide (CO)
Very Good	0 - 15	0 - 12	No health effects are expected in healthy people.
Good	16 - 31	13 - 22	No health effects are expected in healthy people.
Moderate	32 - 49	23 - 30*	Blood chemistry changes but no noticeable impairment.
Poor	50 - 99	31 - 49	Increased symptoms in smokers with heart disease.
Very Poor	100 or over	50 or over	Increasing symptoms in non-smokers with heart disease; blurred vision; some clumsiness.

* Ontario 1-hour AAQC for CO = 30 ppm

Note: ppm = parts per million.