A new study has revealed the significant health and economic toll of using gas stoves, unflued gas heaters, open fires and wood burners in New Zealand homes.
The study, which was commissioned to inform future government policy and cost-benefit analyses, estimated that indoor air pollution from combustion appliances carries a total social cost of around $5 billion per year, alongside $102 million in annual fiscal costs to the health system and lost productivity.
These figures reflect the combined impacts of premature deaths, hospitalisations, restricted activity days, and childhood asthma linked to exposure to pollutants such as nitrogen dioxide (NO2) and PM2.5.
In terms of severity, open fires and unflued gas heaters were identified as the most harmful, followed by gas stoves and older wood burners. Modern wood burners, while cleaner, were still found to generate appreciable costs.
The study linked gas stove use alone to more than 208 premature deaths, 3,320 asthma cases in children, and over 1,000 cardiovascular and respiratory hospitalisations each year, with a social cost of $3.3 billion annually.
This research has been published just days after we reported that a number of manufacturers of gas stoves were taking legal action over a decision to mark their appliances with a safety warning.
The researchers drew on both New Zealand and international evidence to estimate typical annual indoor pollution increments for each appliance. These were paired with locally relevant exposure – response functions to model health outcomes. The impacts were then converted into monetary terms using Treasury’s value of a statistical life for social costs and health system data for fiscal costs.
The study distinguished indoor exposure from outdoor air pollution, which is already well documented in New Zealand and primarily linked to traffic emissions and wood smoke. The researchers found no correlation between indoor and outdoor pollutant levels, meaning the effects of indoor air pollution are additional rather than overlapping.
The report also highlighted gaps in current data, noting that while ventilation and extractor fan use were accounted for, uncertainties remain high – particularly for gas stoves, where exposure estimates vary widely. Even so, the central finding was clear: all indoor combustion appliances studied impose meaningful health and economic costs, even under conservative assumptions.
The panel discussion at our National Air Quality Conference in November will look at the issues of both domestic wood burning and gas stoves.
The full research can be read here.
Photo: Jason Briscoe
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