State of the Environment Report 2007
Carbon monoxide was identified as an issue in the 1998 State of the Environment Report (Government of Western Australia, 1998), but is not identified as a major environmental issue for this report.
Carbon monoxide is an air pollutant produced by incomplete combustion of carbon-based fuels (e.g. petrol, diesel, oil, gas, wood or coal). Carbon monoxide (CO) is a colourless and odourless gas and is a common urban air pollutant. Carbon monoxide can have significant health effects. It is absorbed into the body via the lungs and enters the blood stream, where it reduces the blood's ability to deliver oxygen to organs and tissues. Exposure to carbon monoxide at high levels is poisonous to humans, and may result in increased incidence and duration of angina pectoris (chest pain sometimes leading to heart attack), visual impairment, reduced motor skills, poor learning ability, difficulty in performing complex tasks and low birth weight (Department of Environmental Protection, 2000a).
In Perth, 80% of all carbon monoxide emissions are from motor vehicle exhausts (Department of Environmental Protection, 2002a). The highest recorded levels of carbon monoxide are in areas of dense vehicle traffic (Government of Western Australia, 1998). Other significant sources of carbon monoxide include power generation, domestic solid fuel heaters and burning vegetation. It is also formed in the atmosphere by the oxidation of methane.
Two network monitoring stations have been selected to show concentrations of carbon monoxide monitored in the Perth airshed over time. The Duncraig monitoring station displays a strongly seasonal trend with high emissions during winter from wood heaters, but no trend from year-to-year is obvious (Figure A6.1). The Queens Building station in Perth's central business district primarily detects motor vehicle emissions (Figure A6.2), and shows that ambient CO concentration is declining. Overall, ambient carbon monoxide concentrations in the Perth airshed have been decreasing since 1992 and no exceedences of the NEPM standard has been recorded (A Grieco, Department of Environment, pers. comm.).
Carbon monoxide is a good example of positive progress arising after implementation of progressively better technologies to reduce emissions from motor vehicles. Efficiency gains from better engine technologies have resulted in a significant reduction in emissions of both carbon monoxide and oxides of nitrogen from vehicles. The decline in carbon monoxide concentration has occurred despite increases in total vehicle kilometres travelled and number of vehicles registered (see 'Transport').
![Figure A10.1: Ambient yearly range of carbon monoxide levels at Duncraig air quality monitoring station, compared with the Australian standard.[Data source: Department of Environment and Conservation.]](/site/files/images/Figure-A10.1_Large.jpg)
![Figure A10.2: Ambient yearly range of carbon monoxide levels at Queens Building (Perth central business district) air quality monitoring station, compared with the Australian standard for exposure.[Data source: Department of Environment and Conservation.]](/site/files/images/Figure-A10.2_Large.jpg)
