Growing evidence that the air we breathe in our homes, schools and offices is an overlooked but potentially huge health threat has prompted calls for new standards.
A major report published by the Government last week found our greatest exposure to outdoor air might occur indoors, as it infiltrated buildings where Kiwis who live in cities spend around 90 per cent of their time.
New Zealand's air quality is generally measured by the level of particulate matter (PM) that we send into the atmosphere, mostly through warming our homes in winter with wood and coal, or pumping nitrogen dioxide from our car exhausts.
The report highlighted how closeness to roadways had been linked with high indoor levels of traffic-related pollutants.
Further, it found the proportion of smaller-sized PM indoors could be even higher, especially in communities with a high number of wood burners, because fine particles were more capable of infiltrating cracks and gaps.
That was on top of pollution created from within buildings through cooking, household dust, too much moisture, cleaning products, tobacco, pets and even carpet and furniture.
Pollutants included volatile organic compounds (VOCs) like benzene or formaldehyde, biological contaminants like bacteria or dust mites, PM that varied from to ultrafine in size, and gases like nitrogen dioxide and carbon monoxide from exhausts.
Dr Bill Trompetter, an atmospheric scientist at GNS Science, said our exposure to PMs might even be higher than outdoor air monitoring suggests, "with a consequent greater impact on our health outcomes".
That impact wasn't something to be sneezed at.
In New Zealand, the health impacts and costs for poor indoor air quality were likely to be comparable, if not worse, than those already demonstrated for outdoor air quality.
And while New Zealand generally had good outdoor air quality, it was still estimated to cost $8.4 billion each year, through around 2300 premature deaths, increased hospital admissions, and days where activity was restricted.
Elsewhere, the US Environmental Protection Agency had singled out indoor air quality as one of the top five environmental hazards for the Western world.
That was backed up by a 2012 World Health Organisation report that drew links with cancer, heart disease, acute respiratory infections and chronic obstructive pulmonary diseases.
In fact, Trompetter said, more deaths were related to indoor than outdoor air pollution.
"Therefore, exposure and health risk from poor indoor air quality needs to be addressed similar to that of outdoor air quality," he said.
"The public awareness and concern around