Seven reasons why using gas appliances in homes is unhealthy

A group of 20 organisations representing healthcare professionals, led by Healthy Futures and Doctors for the Environment Australia, have called on the NSW government to follow the lead of Victoria and the ACT and phase out new gas connections by 2025 because of the serious risks to human health gas appliances in the home pose.

They've written to the NSW Minister for Climate Change, Energy and Environment, Penny Sharpe, urging the Government to commit to electrifying all public and government buildings, including hospitals, and support households on low incomes to replace gas with electricity.

The group also want a ban on the sale of gas appliances by the end of 2030, and gas disconnection fees abolished by the end of 2025. Currently gas companies are charging households hundreds of dollars to disconnect from the gas network.

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The problem

Sixty-five per cent of Australian homes use gas for cooking or heating, and new gas appliances are still being connected.

For decades gas has been seen as clean and cheap, and whilst it may once have been cheap, it was never ‘clean’.

“We have known for some time that burning gas in our homes – from gas stoves and heaters – releases combustion products and pollutants that have substantial negative health impacts,” says Dr Ben Ewald, a general practitioner, spokesperson for Doctors for the Environment Australia, and Senior Lecturer in Epidemiology at the University of Newcastle.

The most significant health impacts are caused by air pollutants such as nitrogen dioxide, carbon monoxide, and benzene, which can reduce indoor air quality, especially if an appliance is faulty or poorly maintained, or there is inadequate ventilation.

These pollutants can increase the risk of asthma, exacerbate chronic illnesses and even cause death.

#1 Gas heaters linked to childhood asthma

One of the main health effects of burning gas comes from the release of nitrogen dioxide in the bright blue part of the flame.

NO₂ dissolves in the lung surface fluid and produces nitric acid, which is a respiratory irritant.

A meta-analysis on the association between indoor nitrogen dioxide and childhood respiratory illness was published back in 1992.

“As 2.7 million Australians have asthma, even a small reduction in incidence or severity will be of great value,” wrote researchers Ben Ewald, George Crisp and Marion Carey in the Australian Journal of General Practitioners in December, 2022.

The prevalence of NO₂ is particularly associated with kids who have asthma.

Back in 2004, nearly 20 years ago, a peer reviewed article published in the International Journal of Epidemiology found asthma symptoms in primary school aged children could be reduced by replacing gas heaters with either electric ones, or even flued gas heaters.

The researchers considered this should be “a public health priority.” Whilst schools around the country have been phasing out the use of unflued gas heaters, they are still easily available to buy for the home.

In 2010 a randomised controlled trial tested unflued gas heaters in primary school classrooms in the Blue Mountains and Southern Highlands of NSW. It found there was a statistically significant increase in respiratory symptoms, including asthma, during the weeks when unflued heaters were used, compared with the weeks when flued heaters were operational.

#2 Gas stoves linked to childhood asthma

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A 2013 meta-analysis concluded that children who live in homes with gas stoves had a 42% greater risk of asthma than children living in homes without gas stoves.

A 2022 analysis calculated that 12.7% of childhood asthma in the US can be attributed to the use of gas stoves.

In 2021 the Climate Council published its report Kicking the Gas Habit: How Gas is Harming our Health which found that a child living in a house with gas cooking faces the same risk of asthma as a child living with a passive smoker.

#3 Gas stoves and heaters linked to adult asthma

An increased risk of asthma has also been shown for adults. The Tasmanian Longitudinal Health Study, which studied the indoor air exposure of 3314 people for 10 years, found that those with gas heating and cooking were two and a half times more likely to experience persistent asthma symptoms compared to those that didn’t have gas appliances.

#4 Gas appliances release nitrogen dioxide that makes people more allergic

“NO2 is also a known allergic sensitiser, which means it makes people allergic to other things," said Dr Ben Ewald. "Kids who live in environments with high NO₂ are more likely to be allergic to dust mites.”

#5 Gas appliances release carbon monoxide which blocks oxygen in the blood and toxicity

Gas appliances in the home also release carbon monoxide, a problem mostly associated with faulty and poorly maintained heaters where fuel is incompletely combusted.

Carbon monoxide is tasteless, colourless and odourless but when inhaled it displaces oxygen in the blood, and blocks the delivery of oxygen to tissues, and toxicity at the cellular level.

“Mild exposure can cause headache, nausea, vomiting, dizziness, malaise and confusion, so it can be mistaken for common conditions such as influenza or gastroenteritis,” wrote Ewald, Crisp and Carey.

They also wrote that carbon monoxide poisoning is notoriously under-diagnosed and recommend that doctors should routinely ask patients with vague symptoms about their heating arrangements during winter months.

Doctors for the Environment, Australia, also wrote that between 2011 and 2016, there were fifteen confirmed fatalities from carbon monoxide poisoning in Australia. However, they believe this is an underestimation, given carbon monoxide poisoning may not be suspected in elderly people with other medical conditions who are assumed to have died of natural causes.

They also cite the case of two brothers from Victoria, aged six and eight years, who died in 2013 after going to sleep in a bedroom with an open flued gas heater.

Another report published in Toxicology in 2010 suggested that carbon monoxide poisoning may be responsible for more than half of all fatal poisonings worldwide.

#6 Gas stoves and ovens release the carcinogen benzene

A recent study from a team at Stanford University in the US found benzene, a chemical linked to a higher risk of leukemia and other blood cell cancers, is released when gas stoves are lit.

“A single gas cooktop burner on high, or a gas oven set to 350 degrees Fahrenheit [180 °Celsius] can raise indoor levels o fthe carcinogen benzene above those in second hand tobacco smoke,” wrote the report's senior researcher, Rob Jackson, the Michelle and Kevin Douglas Provostial Professor and professor of Earth system science at the Stanford Doerr School of Sustainability.

Gas and propane burners and ovens emit 10 to 50 times more benzene than electric stoves, whereas the researchers found “no detectable benzene whatsoever” was emitted by induction stoves.

The study analysed stoves and ovens in 87 homes while they were turned on, and determined, that the benzene was released by the appliances during regular operation, rather than from leaks and was emitted from the fuel used, not from the food cooked.

The study also found that benzene produced by ovens lingers for hours in the home and can migrate to other rooms where it can remain above international health benchmarks.

#7 Gas appliances in the home release other pollutants

Doctors for the Environment say that gas appliances also produce other pollutants including fine and ultra-fine particles, volatile organic compounds including formaldehyde, and polycyclic aromatic hydrocarbons.

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Minimising the health risks

The Climate Council researchers wrote that the health risks associated with gas appliances in the home can be reduced by better ventilation, including modern extraction fans over stoves, flues for gas heaters, as well as ensuring gas appliances are properly serviced, and opening windows. However, none of these strategies eliminates the risks associated with gas appliances.

The Standford researchers found that “exhaust fans were often ineffective at eliminating benzene exposure,” or other pollutants, even when range-hoods vent outdoors.

Installing a carbon monoxide alarm is a positive step for prevention, but it's not a substitute for regular servicing of heaters.

Somewhat alarmingly, attempts to make homes more energy efficient and thermally comfortable with insulation and draft sealing, can result in inadequate fresh air flow that is needed for the safe operation of gas appliances.

“The problem of poor indoor air quality is exacerbated by measures to seal air leaks to reduce heating costs, so modern housing is less leaky and retains indoor pollutants,” wrote Ewald, Crisp and Carey.

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The best solution?

Electrifying everything will help households avoid the unacceptable health risks of using gas in our homes.  

With highly efficient reverse-cycle air conditioning for heating, induction stoves for cooking, and heat pumps for hot water heating, there is no ongoing need for new houses to connect to gas, or stay connected.

Electrifying everything in our homes is good for the climate, good for our finances, and much better for our health.