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Introduction

New Zealand has good air quality in most locations for most of the time. However, emissions from transport, industry and solid fuel (wood and coal) used for home heating can cause problems in urban areas, particularly in winter.1 Each year, about 1100 New Zealanders die prematurely from exposure to air pollution.2 Air pollutants can affect the quality of air we breathe. Carbon monoxide, nitrogen dioxide, sulphur dioxide, ozone and particulate matter are five such pollutants.

Carbon monoxide is produced mainly from the incomplete combustion of fuels such as petrol (from cars) and wood and coal (from home heating and industry). Natural sources of carbon monoxide include volcanoes and fires.

Carbon monoxide is readily absorbed by the lungs and interferes with the blood’s ability to carry oxygen. The effects of carbon monoxide increase in severity as exposure increases.

Carbon monoxide can be both a local problem, around congested roads, and an urban problem (for example, where air conditions related to cool winter temperatures can trap carbon monoxide discharged from domestic fires and vehicles).

Nitrogen dioxide is produced directly from combustion processes and indirectly as a result of the reaction of oxides of nitrogen with other chemicals in the air.

The primary source of nitrogen dioxide in New Zealand is the combustion of fossil fuels (coal, gas and oil), especially petrol used in cars. In cities, cars contribute about 80 per cent of nitrogen dioxide levels.3 Natural sources of nitrogen oxides include volcanoes and bacteria and viruses.

Nitrogen dioxide has been linked to increases in asthma symptoms and reduced lung development and function in children. Nitrogen dioxide can decrease the lungs’ defences against bacteria, making them more susceptible to infections.

Nitrogen dioxide can be both a localised problem, around congested roads, and an urban problem.

Sulphur dioxide is produced mainly from the combustion of fossil fuels that contain sulphur, such as coal and oil (for example, coal being burnt for home heating and oil- and coal-fired boilers used by industry). Sulphur dioxide is also produced from some industrial processes, such as petrol refining, fertiliser manufacturing, aluminium smelting and steel manufacturing. Natural sources of sulphur dioxide include geothermal activity and volcanoes.

Sulphur dioxide can cause respiratory problems, such as bronchitis and can aggravate symptoms of people suffering from asthma or chronic lung disease.

Sulphur dioxide is typically a localised problem caused by specific industrial discharges.

Ozone at ground level is not directly emitted, but is formed by reactions of nitrogen oxides and volatile organic compounds in sunlight. Nitrogen oxides and volatile organic compounds are produced from motor vehicle emissions, industrial combustion sources, and the industrial and domestic use of solvents and coatings.

Ozone at ground level affects the respiratory and cardiovascular system and can cause tissue damage to the lungs.

Because ozone at ground level forms over time, the highest concentrations are usually found downwind from areas, such as major cities, where most contaminants are released.

Particulate matter that is less than 10 microns in diameter (PM10) is an air pollutant that regularly occurs at high levels in urban areas, and is linked to harmful health effects. As PM10 is a pollutant of particular concern for New Zealand and is monitored at many sites, PM10 levels in New Zealand are reported separately from this report.

Carbon dioxide is not reported in this report card. For more information about carbon dioxide levels in New Zealand, please see New Zealand’s Greenhouse Gas Inventory 1990–2008: Environmental Snapshot April 2010

Text box 1: What are environmental report cards?

Environment New Zealand 2007, the country’s second national state of the environment report, provided information from around 115 national-scale environmental data sets. Its primary focus was to report on the 66 variables that constitute New Zealand’s core set of environmental indicators.

A key focus of the Ministry for the Environment’s national environmental reporting programme is to produce a series of ‘report cards’ to provide updated information on the indicators reported in Environment New Zealand 2007. This is one such report card.