Carbon monoxide
Chemical
formula and description
The chemical formula for carbon monoxide is CO.
Carbon monoxide is a colourless, odourless and tasteless gas.
Sources
Carbon monoxide is produced both by natural processes (for example, from volcanoes, fires and metabolism of organisms) and by human activities (for example, the incomplete combustion of carbon-containing fuels and industrial processes). The most common sources of carbon monoxide are human activities. These include large amounts of carbon monoxide produced from the incomplete combustion of fossil fuels such as petrol used by cars, and from wood and coal, which is commonly burnt in fires for home heating. Tobacco smoke and indoor gas fires are also common sources of carbon monoxide.
Effects on health
When you breathe in carbon monoxide, it attaches to the haemoglobin molecules in your bloodstream, which carry oxygen around your body to your tissues. Carbon monoxide reduces the amount of oxygen that your body tissues receive, which is particularly bad for your brain and heart and your general health. Low exposure to carbon monoxide can make you feel dizzy, weak, nauseous, confused and disoriented, and can also reduce your performance while doing exercise. The higher the level of carbon monoxide in your blood stream, the worse the effects. So at very high levels, coma, collapse, loss of consciousness and death can occur.
Groups most sensitive to carbon monoxide
Middle-aged and elderly people with heart disease, and foetuses of pregnant mothers.
Standards and Guideline values to protect health
The national environmental standard for carbon monoxide is 10 µg/m3 as an 8-hour average. The national ambient air quality guideline for carbon monoxide is 10 µg/m3 as a 1-hour average.
Usual levels in New Zealand
Carbon monoxide levels are generally highest in urban areas along or close to busy roads. However, levels of carbon monoxide have significantly reduced over the past 10 years so that levels are generally below the ambient standard. Further information can be found in monitoring of CO, NO,2, SO2, ozone, benzene and benzo(a)pyrene in New Zealand and the state of the environment report 2007.
Areas where carbon monoxide may affect health
Carbon monoxide can be both a local problem around congested roads and an urban-wide problem where winter smog traps carbon monoxide discharged from domestic fires and vehicles causing high concentrations during temperature inversion conditions.
Last updated: 17 July 2009
