Air contaminants in the Waikato

Clearing the air •
When air is polluted •
Open fire place bans •
Polluted air sheds •
Polluted air causes problems •
Air quality in the Waikato region •
Air contaminants in the Waikato region •
What can we do to protect air quality?

Clearing the air

The Waikato region generally enjoys good air quality, but in some areas air pollution can build up. This happens mostly in our inland city and towns.

Visibility monitoring in the Hamilton Basin shows that visibility varies a lot from day to day. On some days Mount Ruapehu (170 km away from Hamilton) is visible from some of the higher buildings in Hamilton. On other days, Mount Pirongia (30 km away) is not.

The Waikato region is pretty big, so different areas have different populations, weather patterns, landscapes and activities that affect air quality. Most air pollution comes from localised point sources such as from large industries and non-point sources such as domestic heating and vehicles.

However air pollution is also affected by natural sources such as weather, landscapes, seaspray, windblown dust, plant pollen and geothermal emissions.

Air is made up of two main gases - nitrogen and oxygen - with small amounts of carbon dioxide and other gases.

Air can be contaminated by:

solids - such as dust and soot particles
liquids - such as herbicide sprays
gases - such as carbon monoxide and nitrogen oxides.

Some air contaminants can damage human health. These often have guidelines stating the highest average amount that can be present in air over a period of time, for example 24 hours.

Other contaminants are a nuisance because they reduce our enjoyment of the environment, affecting visibility or creating odours. Usually there are no guidelines for these contaminants.

When air is polluted

Air is polluted when contaminants are in air for long enough, and at concentrations high enough, to affect humans, plants, animals, property, or amenity values (visibility and odour).

Contaminants come from many sources. Some are natural, such as geothermal emissions, but many are human-made. In the Waikato region, human-made emissions are mostly from:

Home fires Agrichemicals Motor vehicles Industry Outdoor burning Livestock farming

Air pollution can happen on a:

local scale - typically odour, dust and smoke
regional scale - emissions from transport and large industries
global scale - climate change and ozone depletion.

In the Waikato region the main contaminants of our air are fine particles (PM₁₀), contained in contaminants such as smoke. We measure local PM₁₀levels in selected airshed and compare it against the national environmental standards for air quality set by the Ministry for the Environment. For PM₁₀ the standard is 50 micrograms of PM₁₀ per cubic metre of air (50 µg/m³) as a 24-hour average. It allows one day per 12 month period when concentrations can be greater than 50 µg/m³.

When this standard is exceeded in an airshed two or more times in a 12-month period, we are required to follow the Ministry’s regulations and publicly notify the breach and put in place restrictions on fireplace use. Industrial discharges may also be affected.

Open fire place bans

Triggered by Regulation 24A of the Resource Management (National Environmental Standards for Air Quality) Regulations 2004, the following open fire place bans are now in place in the Waikato region.

The discharge of particles from domestic solid-fuel burning open fires installed in the Putaruru airshed on or after 9 April 2015 is prohibited.
The discharge of particles from domestic solid-fuel burning open fires installed in the Taupō airshed on or after 27 June 2014 is prohibited.
The discharge of particles from domestic solid-fuel burning open fires installed in the Te Kuiti airshed on or after 3 July 2013 is prohibited.
The discharge of particles from domestic solid-fuel burning open fires installed in the Tokoroa airshed on or after 21 May 2013 is prohibited.

Advisory notes

A domestic solid-fuel burning open fire –

(a) means an appliance or a structure inside a domestic building that can burn solid-fuel but cannot effectively control the rate of air supply to the combustion zone; and

(b) to avoid doubt, includes a fireplace to which paragraph (a) applies that has a cover or doors that cannot effectively control the rate of air supply to the combustion zone i.e. any fire where the combustion chamber is not totally enclosed e.g. brick or masonary fireplaces, visors, open hearths, Jetmaster fireplaces.

Polluted airsheds

Over a 5-year period (2008 to 2013) Putaruru, Taupō, Te Kūiti and Tokoroa regularly exceeded the national environmental standards for PM₁₀ and were classified as polluted airsheds under Regulation 16D and 17(4) of the Resource Management (National Environmental Standards for Air Quality) Regulations 2004.

While Tokoroa remains classified as polluted, Te Kūiti, Taupō and Putaruru were found to meet the criteria under Regulation 17(4) of the standards for being re-classified as non-polluted as of 10 December 2016, 27 June 2018 and 14 March 2019 respectively. The classification for the Taupō airshed has reverted back to polluted since 27 May 2021. The classification for the Te Kuiti airshed has reverted back to polluted since 23 June 2021.

Under Regulation 17, the standards require us to assess all resource consent applications for substantial discharges of PM₁₀ into polluted airsheds to determine whether offsets will be necessary.

Polluted air causes problems

Air pollution can damage our health and reduce our enjoyment of life. It can affect our health by causing:

burning eyes and nose
irritated and scratchy throat
respiratory symptoms - especially in sensitive people like asthmatics, children and the elderly
cancer, birth defects, brain and nerve damage and long-term injury to the lungs and breathing passages.
reduced life expectancy
restricted activity days (days on which people cannot do the things they might otherwise have done if air pollution was not present)

Air pollution can also cause:

haze - which reduces visibility
dust - which deposits in our homes and on our cars
odours - which are a nuisance, especially for people living close to the source.

Air contaminants that cause health effects in humans can also affect other living things. A few air contaminants are so dangerous that accidental releases can cause serious injury or death.

Air quality in the Waikato region

Many tourists visiting the Waikato region are attracted by our clean, green image. Poor visibility, odours, dust and other air pollution problems may damage our tourism industry.

Air quality in the Waikato region is generally good, but some areas are more prone to air pollution because of:

localised point-source pollution from industry
pollution from motor vehicle exhausts and domestic heating.

In most inland towns air pollution is a problem in the winter because the local climate is cold and calm with frequent inversion layers that trap air contaminants close to the ground.

We all contribute to air pollution and we are all affected by it.

Some air contaminants have thinned the ozone layer above earth, and others are believed to be causing climate change. Find out more about how climate change and ozone depletion affect us.