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Poor ventilation in buildings in Aotearoa NZ means the air we are breathing indoors may potentially be contaminated with harmful pollutants and pathogens, both of which can make us sick. On World Ventil8 Day (8 Nov), experts are calling for improvements to our Building Code to put health front and centre, and the adoption of indoor air quality guidelines to ensure we are all breathing air that enhances our health and productivity.

In the latest Briefing from the Public Health Communication Centre, World Ventilation Day – How do our buildings measure up, public health experts look at how NZ lags behind comparable countries on indoor ventilation standards and what should be done.

Dr Julie Bennett of the University of Otago says there is little air quality monitoring done in NZ buildings which is a problem. “However data our group has collected recently indicates that NZ homes may be reaching well beyond the Centres for Disease Control and Prevention (CDC) recommended maximum level of CO2, particularly overnight in our bedrooms. And newer homes may be even more at risk, as buildings are becoming increasingly airtight.”

“We know good indoor ventilation is good for our health. It not only reduces our exposure to air pollutants and infectious diseases, but it also enables us to think more clearly, sleep better and be more productive,” says Dr Bennett. “Yet the NZ Building Code has minimum requirements for ventilation compared to international standards, and those only apply to new builds or buildings undergoing upgrades.”

New Zealand standards recommend ventilation be sufficient to keep CO2 levels below 1,000 parts per million (ppm). However the US Centres for Disease Control recommends a lower threshold of 800 ppm. In other countries, such as Belgium, legislation requires CO2 levels to be displayed on monitors in public spaces, such as bars, cafes or gyms.

“Remembering to regularly open windows, that’s if you are in buildings that allows that, is important. But research shows that installing mechanical ventilation systems which can self-ventilate when levels of CO2 or other pollutants get too high is also needed.”

Although a review of the Building Code was conducted during the Covid-19 pandemic, there appears to be minimal change to ventilation requirements. “It’s frustrating, that the quality of the air we breathe, which is as fundamental to life as access to clean water, is so often overlooked.” says Dr Bennett.


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