An independent report has recommended the Government toughen up air quality testing so the health effects of pollution can be accurately known.
Parliamentary Commissioner Jan Wright said air quality in New Zealand was generally good, but there is still real evidence of harm to New Zealanders' health.
Dr Wright has today released her review of the Ministry for the Environment's 2014 air quality report.
The commissioner's independent reviews of government agency reporting of air quality, atmosphere and climate, land, fresh water and marine sectors are likely to be enshrined in law, once legislation currently before a select committee is passed.
However the Ministry for the Environment and the Parliamentary Commissioner decided to begin early by looking at the ministry's report released last May.
Dr Wright's recommendations:
- Determine whether PM2.5 should be measured across the country where there is likely to be a problem
- Determine the value of setting rules for PM2.5 and long-term exposure
- Determine whether PM10 short-term rule still has value
- Determine the impact of air quality rules on other public health issues such as damp homes
- Determine how air quality policies might be designed so as to achieve progressive improvement.
Dr Wright recommends New Zealand look at whether smaller pollution particles should be measured than generally is the case at present.
At the moment, the key measure of air quality is of PM10 particles - pollution particles with a diameter of 10 microns.
But smaller PM2.5 particles cause significant health issues because they cling to the lining of the lungs and leach into the bloodstream.
These are measured continuously in Auckland, Christchurch and Masterton, but nowhere else.
Dr Wright said that needed to change and particles of that size, measured over the long term, should be the standard.
The change would bring New Zealand in line with World Health Organisation (WHO) standards and accepted best practice of air quality scientists.
Dr Wright said New Zealand performed well against WHO guidelines for PM10s but not so well in some areas for PM2.5s.
Changing the standard would also allow councils to look at air pollution more widely, rather than focusing on home heating, which causes winter spikes.
New Zealand's main source of air pollution in New Zealand is combustion, either from heating or transport.
"Air pollution may not look like an important environmental issue, but it is undoubtedly an important public health issue," Dr Wright said.
Ministry for the Environment Deputy Secretary of Sector Strategy James Palmer said it would consider the Parliamentary Commissioner's recommendations.
"It's quite important with these big regulatory instruments that we don't review them too frequently otherwise councils that are trying to review them have the goals constantly shifting on them. So we've programmed in the review for next year."
The Ministry for the Environment's 2014 air domain report was released last May, and includes samples up to 2012.
It found that from 2006 to 2012 national air quality indicators showed some improvement.
The larger sized particles measured (PM10) had fallen 8 percent between 2006 to 2012 - the 7th lowest rate in the OECD.
That is believed to have resulted in 14 percent fewer premature deaths and 15 percent fewer hospital admissions.
The smaller sized particles, PM2.5, which are linked to more severe health problems, failed WHO guidelines to a slightly greater extent.
In 2012, one of the seven monitoring sites failed the long-term guideline by 17 percent. Four of the seven sites failed the short-term guidelines.
Dr Wright said the report stated some indicators had improved during the six year period, but not in what way. For example, some were said to have improved from "very poor to poor" or "good to very good".
She said no statistical analysis was carried out to support that.
Results need to be interpreted more clearly and conclusions drawn and it was also important not to "average away" trouble hotspots.