Why is air quality important for health?
Good air quality is fundamental to our health and wellbeing. We each breathe about 14,000 litres of air each day. Contaminants in outdoor air can adversely affect our health.
Particulate matter in the air can contribute to heart (cardiovascular) and lung (respiratory) diseases, leading to hospital admissions and premature death . Outdoor air pollution can also cause cancer .
People more at risk from poor air quality include:
- young children
- older adults
- people with chronic health conditions, particularly cardiovascular or respiratory disease.
What is air pollution?
Air pollution is a complex mix of tiny particles and gases, including:
- particulate matter (such as PM10 and PM2.5)
- carbon monoxide
- nitrogen oxides
- sulphur oxides
- volatile organic compounds.
What is particulate matter (PM)?
Particulate matter (PM) consists of small airborne particles, including solid matter and liquid droplets. These particles can’t always be seen by the human eye.
PM10(particles with a diameter less than 10 micrometres) is the major air pollutant monitored in New Zealand. The small particles can be breathed into the human lung, and are associated with health problems, particularly affecting the lungs and heart.
Fine particulate matter (PM2.5) refers to particles with a diameter of less than 2.5 micrometres. Finer particles can reach further into the lungs than larger particles, and can cause more serious health problems.
Figure 1: Relative size of particulate matter
Source: Ministry for the Environment 
Health effects of air pollution
Air pollution can affect people’s health, especially their heart and lungs – and can even lead to early death. Most of the health impacts from air pollution are associated with particulate matter .
Particulate matter (PM10 and PM₂.₅) can reach far into people’s lungs. Health effects include heart (cardiovascular) and lung (respiratory) disease, and early death . Outdoor air pollution (PM10 and PM2.5) can cause lung cancer, and is also linked to bladder cancer .
Sulphur dioxide (SO₂) and nitrogen dioxide (NO₂) can cause health problems at certain concentrations, particularly respiratory symptoms.
Carbon monoxide (CO) can cause a range of health symptoms. Lower levels of carbon monoxide can cause respiratory problems, headaches and poor concentration; higher levels can result in unconsciousness and death.
Some people are more at risk of poor health due to air pollution. Population groups most affected by air pollution include: children, especially those with asthma; older adults; people with pre-existing health conditions, particularly respiratory and heart conditions, and diabetes.
Natural and human sources of air pollution
Air pollution can be produced from human activity or naturally. The main sources of air pollution in New Zealand are:
- wood and coal fires (for home heating)
- motor vehicles
- open burning
- natural sources.
Wood and coal fires produce particulate matter, carbon monoxide, nitrogen dioxide and other organic compounds. Read the latest statistics about wood and coal fires on the wood and coal fires webpage.
Motor vehicles produce a range of gases and particles, including particulate matter, carbon monoxide, nitrogen dioxide and sulphur dioxide. Air pollution from vehicles comes from vehicle exhaust and brake and tyre wear. Diesel vehicles, older cars and cars not well maintained tend to produce more emissions. Read the latest statistics on the motor vehicles webpage.
Industrial sources of air pollution include major facilities like steel mills, chemical plants and coal-fired power plants. The most common pollutants from manufacturing, construction and electricity production activities are sulphur dioxide, PM₁₀ and nitrogen oxides .
Open burning (or outdoor burning) refers to burning combustible material outdoors. These materials can include household rubbish, garden clippings and agricultural waste.
Natural sources of air pollution include windblown dust, pollen, volcanic ash and sea spray.
Another impact of fires, vehicle emissions and industrial sources is the release of greenhouse gases (mainly carbon dioxide). Greenhouse gases contribute to climate change. Read more on the climate change webpage.
Weather conditions and topography affect air quality
Weather and topography can influence air pollution. Air pollution levels tend to be worse during winter, particularly on cold calm days. Weather conditions can affect the quantity, patterns and dispersal trends of air pollutants .
- On cold days, households may burn more wood and coal for home heating. Vehicles may also release more emissions due to ‘cold starts’.
- Low wind speeds can prevent pollutants from dispersing.
- Low wind speeds and cold temperatures can cause temperature inversions. These are where a cold layer of air is trapped by a warmer layer of air above, trapping air pollution near to the ground. Temperature inversions are more likely to occur in valley locations.
- Most urban air pollution occurs in winter and is worst during cold calm conditions.
- In some cases (usually in warmer months), strong winds can lead to higher PM₁₀ levels by raising dust – particularly during droughts.
Guidelines and standards for air quality in New Zealand
Guidelines for annual average PM10 levels are set by the World Health Organization (WHO). The guidelines set a maximum annual average PM10 concentration of 20 μg/m3. This guideline provides a minimum level of protection against long-term health risks. However, there is no evidence of a safe threshold for PM10 below which there are no adverse health effects.
New Zealand has guidelines (Ambient Air Quality Guidelines 2002), which are mostly drawn from the WHO. See the guideline values on the Ministry for the Environment’s website.
The New Zealand National Environmental Standards (NES) for Air Quality set standards for short-term levels of the following air pollutants:
- particulate matter (PM₁₀)
- carbon monoxide (CO)
- nitrogen dioxide (NO₂)
- sulphur dioxide (SO₂)
- ground level ozone (O₃).
For more information, visit the Ministry for the Environment’s National Environmental Standards for Air quality webpage.
Monitoring air quality in New Zealand
Air quality is measured at monitoring stations throughout New Zealand. Air quality data is collected by regional councils and unitary authorities, and reported to the Ministry for the Environment.
In 2012, there were 54 monitoring sites for PM₁₀, covering about 75 percent of the population. Some of these monitoring sites also monitored other air pollutants.
Air quality may vary from year to year, depending on weather conditions. Colder winters may lead to households burning more wood and coal for home heating, and higher levels of air pollution. Statistical analysis of several years of data is needed to determine long-term trends in air quality in an airshed.
What are airsheds?
An airshed is a legally designated (‘gazetted’) area where air quality is monitored. These areas are likely, or known, to have unacceptable levels of pollutants, or may require air-quality management.
1. World Health Organization. 2013. Review of evidence on health aspects of air pollution - REVIHAAP Project: Final technical report. Copenhagen: World Health Organization Regional Office for Europe.
2. Loomis D, Grosse Y, Lauby-Secretan B, El Ghissassi F, Bouvard V, Benbrahim-Tallaa L, et al. 2013. The carcinogenicity of outdoor air pollution. The Lancet Oncology 14(13): 1262-1263. doi: 10.1016/S1470-2045(13)70487-X
3. Ministry for the Environment and Statistics New Zealand. 2014. New Zealand's Environmental Reporting Series: 2014 Air domain report. Wellington: Ministry for the Environment.
4. Kuschel G, Metcalfe J, Wilton E, Guria J, Hales S, Rolfe K, et al. 2012. Updated Health and Air Pollution in New Zealand Study. Volume 1: Summary report. Prepared by Emission Impossible and others for Health Research Council of New Zealand, Ministry of Transport, Ministry for the Environment, and NZ Transport Agency. Available online: http://www.hapinz.org.nz/