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Motor vehicle emissions are of concern because many of the pollutants that are released are known to cause adverse health effects. Although there are a wide range of pollutants in the emissions, most of the health effects result from the following key indicator pollutants listed below. These pollutants are assessed against national standards, targets and guidelines.

Carbon monoxide (CO)

Carbon monoxide (CO) is a colourless, odourless gas formed by both natural processes (such as volcanoes) and incomplete combustion of fuels (motor vehicles and home heating). Carbon monoxide can interfere with the body’s ability to carry oxygen; at low levels affect people with heart conditions; at high levels can cause dizziness, nausea and drowsiness and at extremely high levels can even cause death.

Nitrogen dioxide (NO2)

Nitrogen dioxide (NO2) is a brown acidic gas formed by the combustion of fossil fuels (coal, oil and gas). Motor vehicles are a large source of NO2 in urban areas. Nitrogen dioxide increases susceptibility and severity of asthma; lowers lungs’ resistance to infections such as the flu; reduces lung development and function in children; can affect growth in and cause damage to some plants and at high levels, and contributes to the formation of hazes and smog.

Particulate matter

Particulate matter (PM) is a collective term used to describe very small solid or liquid particles in the air, such as PM10, dust, smoke or fog. PM10 is extremely small (as seen in the image). Each particle is a fraction of the size of a human hair (1/25th), with a diameter of less than 10 micrometres (1 micrometre = 1 millionth of a metre).

Fine particles (PM10) are linked strongly to adverse health effects, especially in asthmatics or those with heart or lung disease, and can lead to premature deaths, hospitalisation, increased medication and days off work or school, whilst larger particles (dust) cause amenity effects such as affecting visibility by creating
a haze over large areas and can contribute to soiling and corrosion of buildings.

For further information contact environment@nzta.govt.nz.

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