Skip to main content

Home heating - a hot issue

Photograph of smoke from home heating in HamiltonHome fires are a major source of air pollution in some areas of the Waikato region. You can help reduce air pollution from home fires. 

On this page: Contaminants from home heating, using your wood burner efficiently, more information

Contaminants from home heating

Wood is a popular fuel for home heating in the Waikato. But wood fires can produce large amounts of contaminants that affect our air quality. These include:

  • smoke - made up of fine particles (PM10)
  • combustion gases - such as carbon dioxide, carbon monoxide, nitrogen dioxide
  • other contaminants - such as benzene.

Contaminants from home heating are generally more of a problem in winter when wood burners and open fires tend to be used. This happens especially in inland towns, such as Tokoroa and Te Kuiti where frequent calm conditions and inversion layers mean the smoke stays around.

View the video clip below for more information about home fires and how they affect you and the region's air quality:



Smoke consists of very small particles (PM10) that are less than 10 microns across - a fifth of the size of a human hair. These particles can get into our lungs causing health problems, especially for people with asthma, small children and the elderly.

Smoke can also reduce visibility and make it unpleasant to be outside at certain times of the day.

The particles in smoke are unburnt and partially burnt fuel so the key to reducing smoke is to burn the fuel more completely.

Carbon dioxide and carbon monoxide

Burning fuel normally gives off carbon dioxide (CO2) when there is plenty of oxygen present. The carbon (C) comes from the fuel and the oxygen (O2) comes from the air. But, when there’s not enough oxygen present only one oxygen molecule binds with a carbon – forming carbon monoxide (CO).

Carbon dioxide is a greenhouse gas. Increases in carbon dioxide in the atmosphere are likely to be responsible for global warming which may cause climate change.

Carbon monoxide is a poisonous gas. It attaches to our red blood cells better than oxygen - reducing the blood’s ability to carry oxygen around the body. Low exposure to carbon monoxide causes in headaches, dizziness and nausea.

Nitrogen dioxide

Solid-fuel burners (for example, wood burners) are a source of nitrogen oxide (NO). Nitrogen oxide oxidises (oxygen is added) to form nitrogen dioxide (NO2). Nitrogen dioxide affects people’s health by aggravating asthma and decreasing their lung’s ability to fight infection.

Using burners

Not all burners are the same

Enclosed burners minimise heat loss. In contrast, up to 80 per cent of the heat from open fires can disappear up the chimney. As well, open fires and early (pre-1989) wood burners produce more smoke than modern burners.

Burners must be properly installed, operated and maintained. If you’re buying a burner make sure it meets the Australia/New Zealand standard for emissions (Aus/NZ 4013), buy the cleanest burning model you can afford, and have it professionally installed. Ensure your chimney is the right size and height to create enough draft for the fire.

Photograph of a hot fire burning.Using your wood burner efficiently

Reduce the amount you use your wood burner by making your home more energy efficient:

  • insulate your ceilings and walls
  • cover your windows at night - for example, curtains, blinds
  • use floor coverings and ‘draught sausages’ to reduce cold draughts.

You could also try putting on an extra layer of clothing.

When you do use your wood burner you can reduce the amount of pollution given off by:

  • choosing the right fuel
  • operating your burner properly
  • maintaining your burner.

Choosing the right fuel

When lighting a cold wood burner:

  • use enough kindling to get a hot fire going as quickly as possible
  • scrunch up two or three sheets of newspaper and place on top of the kindling – they will burn quickly, heat the flue and get a draught going to oxygenate the fire.

Once you have got the fire going:

  • use the right fuel for your burner
  • burn dry wood only (not green) - store your wood in a dry area for 6-12 months before use.


  • treated, painted, green or wet wood
  • plywood or particle board rubbish
  • plastic and cardboard.

Find out more about how to get the most heat from your firewood.

Operating your burner

There are several things you can do while operating your burner that will reduce the amount of contaminants given off:

  • light small, hot fires
  • place two or three smaller logs in your burner, rather than one big one – they give off more heat
  • place logs about 2 cm apart and 5-10 cm back from the door – allowing air to flow down to the base of the fire
  • add only a little fuel at a time – a half-full burner is about right.

Give your fire more air:

  • if you can see smoke coming out of your chimney
  • when putting more fuel on the fire – keep the air controls fully open for 15-20 minutes after adding fuel.

The longer you run a hot fire before turning it down, the less smoke and combustion gases will be produced.

Maintaining your burner

  • Clean out your firebox regularly and keep it in good working order.
  • Clean your flue regularly and check its condition each year.

View the video clip below for more information on how to operate your woodburner efficiently, to stay warm and save money. Please note that this video is American and the certification schemes mentioned do not apply to New Zealand.

More information

Image of factsheet.


Clean heat

This factsheet  tells you a bit about how smoke affects your health, and gives you some other heating options that are cleaner and more efficient. 

>>> Read or download the factsheet here. [PDF, 411 KB]