Chapter 7: Air

At a glance

Air quality in New Zealand

New Zealand has good air quality in most locations for most of the time. However, coal and wood used for home heating and exhaust emissions from transport can affect air quality in about 30 locations, particularly during winter. About 53 per cent of New Zealanders live in these affected locations.

Pollutants in the air can affect our health, because we inhale them into our lungs. Vulnerable groups such as the very young, the very old, and people with underlying respiratory or cardiac disease are particularly at risk. About 1,100 New Zealanders die prematurely each year from exposure to air pollution. The number of New Zealanders who die prematurely from traffic-related air pollution is similar to the number killed in road accidents each year.

Levels of air pollution in New Zealand

PM₁₀ particulates

In most of the areas in New Zealand where air quality can be poor, the cause is high winter levels of PM₁₀ particulates from coal and wood used for home heating. Auckland, where about a third of New Zealand’s population lives, also experiences high levels of PM₁₀ particulates from road transport. Levels of PM₁₀ particulates appear to be falling in some of the main centres of population, although the influence of weather on air pollution makes it difficult to assess trends. Levels of PM₁₀ particulates at roadside locations in Auckland appear to have fallen over the past 10 years.

Nitrogen dioxide

Levels of nitrogen dioxide are at an acceptable level around New Zealand, with the exception of some locations in Auckland affected by traffic emissions. Emissions of nitrogen dioxide in Auckland appear to be increasing.

Carbon monoxide

Levels of carbon monoxide, mostly from traffic emissions, were of concern 10 years ago. Since then, levels appear to have fallen at locations that have historically experienced high concentrations. The improvement is most likely due to improved vehicle technology.

Sulphur dioxide

Sulphur dioxide levels declined in the 1980s and are considered to be low in most parts of the country. However, the areas around the Marsden Point Oil Refinery and other individual locations have higher levels than the rest of the country.

Ozone

Based on traffic emissions data, areas around Auckland, Hamilton, and Christchurch were identified in the mid-1990s as having the greatest potential for elevated levels of ground-level ozone. However, the results from monitoring indicate that ozone levels are satisfactory in these locations.

PM_2.5 particulates, benzene, and airborne lead

Monitoring for PM_2.5 particulates is not widespread in New Zealand. However, where PM_2.5 particulates are monitored, a strong relationship exists between high levels of PM₁₀ particulates and high levels of PM_2.5 particulates.

Benzene levels at monitored locations are at an acceptable level. Levels are higher near busy roads than in residential areas, but appear to be improving. This improvement is probably due to changes in vehicle fuel composition.

Lead was eliminated from New Zealand petrol in 1996, so airborne lead levels are now very low.

Present and future management

Today, the main focus for improving air quality in New Zealand is to reduce PM₁₀ particulate emissions from home heating and traffic. Having put in place regular monitoring of air quality in managed airsheds, future effort will continue to focus on tracking PM₁₀ particulate levels against the 2013 target set under the national environmental standards for air quality.

Future work on improving air quality may also focus on developing a better understanding of PM_2.5 levels around New Zealand.