Poor air quality has long been known to have a significant impact on people living with respiratory conditions. Gases and particles in the air from polluting sources like cars, coal and wood fires can get into the lungs and worsen existing conditions like asthma and COPD.

A recent New Zealand study found that many Kiwis are being exposed to air pollution, and that is causing serious health impacts especially for children with asthma. We spoke to Guy Coulson, an air quality scientist at the National Institute of Water and Air (NIWA) to find out more about air quality in New Zealand.

Do New Zealanders need to be worried about air quality?

By international standards the air quality in New Zealand is pretty good. But there are pockets of poor air quality, so if you live or work or travel around those pockets you are more likely to be affected. Those pockets include areas with a lot of wood-burning fires in winter and city centres where there is a lot of pollution, usually from traffic. In big cities, you can find pollution canyons, where pollutants gather in corridors between multi-storey buildings.

How does NZ compare to the World Health Organisation air quality standards?

We are not in line with those standards, but nowhere is currently. The new standards came out a year ago and these basically state there is no safe limit for air pollution. This is a change from the past when we had ‘acceptable levels’ of air pollution. The problem with that past approach was that countries weren’t motivated to reduce air pollution any further than ‘the acceptable level’. For that reason, air quality in New Zealand hasn’t improved in a decade.

Should we be concerned about indoor air quality also?

There’s been a belief that indoor air was cleaner than outdoor air, but that’s not always true. Outdoor pollutants can come inside – things like traffic fumes, smoke etc – but there are also indoor pollutants. Mould is by far the biggest threat to indoor air quality, but there are also pollutants that come from some cleaning products and some materials or furnishings. But the problem is we don’t really know how much of a problem indoor air pollution is, because there is very little research on it.

Is that why the Indoor Air Quality Research Centre NZ was set up?

Yes, the Centre is a collection of half a dozen or more groups from around the country that all have an interest in air quality from a health or building perspective. There is growing interest in research on this topic, particularly as a result of COVID-19, and we want to coordinate our work.

What does the Centre do?

We advised the Ministry of Education after the last lockdown on how to best ventilate classrooms to minimise the spread of COVID in schools. We have recently received funding to look at how to best ventilate other environments with vulnerable populations like aged care facilities to reduce the spread of disease.

What is the best way to improve indoor air quality?

Opening windows is remarkably effective, unless you live in an area with a lot of wood burning in the middle of winter. In that case, you might want to consider using a ventilation system or an air cleaner with a HEPA filter. Even during winter, opening all the windows and doors for a 10-minute blast to flush out all of the dust mites and stale air will make a big difference to air quality. Also, improve your source of heating by changing from wood burning to electric heating. It’s important to note that heat pumps do not ventilate rooms, but heat or cool existing air within a room.

How do we improve outdoor air quality?

It would be great if New Zealand could set a target for zero air pollution to go along with a zero carbon emissions target. It makes sense to tie those two goals together, as the sources responsible for carbon emissions are also responsible for a lot of our air pollution.

Air Pollution in NZ

The HAPINZ 3.0 (Health and Air Pollution in NZ)study estimated that human-made air pollution was responsible for 13,229 cases of childhood asthma and 845 hospitalisations of children with asthma. It also estimated that air pollution causes 1.75 million restricted activity days for Kiwis, when people were prevented from regular activities due to air quality.

The main causes of air pollution are nitrogen dioxide from motor vehicles and fine particulate matter (PM2.5), tiny particles of pollution that come from domestic wood and coal fires, cars and windblown dust. The study showed that the areas worst affected were Auckland and Christchurch, followed by Dunedin, Tauranga and Hamilton.

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