A new report from the World Health Organisation (WHO) shows air quality in some of New Zealand's small towns is worse than in the largest city.
The WHO estimates air pollution caused $3.7 million premature deaths worldwide in 2012, mainly from heart and lung disease.
The organisation's report shows Timaru had the worst air quality in New Zealand, followed by Christchurch and Rotorua.
Rotorua's poor score is partly due to natural geothermal gasses.
All other towns and cities met the organisation's air quality guidelines.
However, National Institute of Water and Atmospheric Research air quality research leader Ian Longley said New Zealand had higher than normal levels of pollution in its smaller towns.
"This is something you generally don't see internationally and is related to the features of New Zealand where a lot of our poor quality air comes form burning wood for domestic heating."
Mr Longley said air quality could be improved by burning less wood, driving less and using more fuel-efficient engines.
Blenheim and Dunedin also scored poorly, while the Wellington region has the cleanest air.
New Zealand Climate and Health Council co-convener Alex MacMillan said a 2012 study found 1100 people a year died prematurely from air pollution in New Zealand.
"More than half of that man-made air pollution gas came from domestic fires," Dr McMillan said.
"About a quarter came from motor vehicles. We've got all the things we need to put policies immediately. All that's needed, really, is political will."
The following numbers refer to the annual average amount of micrograms of PM10 (particulate matter 10 microns or smaller) per cubic meter of air. Data is from 2011 and 2012.
WHO guidelines recommend PM10 should not exceed an average of 20 ug/m3 per year.
- Whangarei 15
- Auckland 15
- Hamilton 13
- Rotorua 20
- Napier 14
- Hastings 15
- Taupo 13
- Masterton 14
- Porirua 12
- Upper Hutt 10
- Lower Hutt 10
- Wainuiomata 10
- Wellington 13
- Blenheim 19
- Christchurch 23
- Timaru 28
- Dunedin 18