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The overlooked health hazard lurking in many homes
Indoor air pollution from gas cooking stoves is bad, particularly for children. Dr Ben Ewald discusses how GPs can help patients reduce the risks.
Gas flames release both nitrogen dioxide and formaldehyde, which are respiratory irritants and can increase the risk of asthma.
Recent publicity for the group Global Cooksafe Coalition has drawn attention to the problem of indoor air pollution from gas cooking stoves and its link to asthma – especially in children.
Since gas stoves are in widespread use and asthma is common, there may be many parents of children with asthma bringing their concerns to their GP.
So, what is the evidence behind the story linking gas stoves and asthma?
A systematic review published in 2013 found 41 studies looking at the association between gas cooking, indoor nitrogen dioxide levels and respiratory health effects in children.
Four of the studies were Australian. Meta-analysis showed an odds ratio of 1.42 for current asthma in those children living in houses with gas stoves, a result that was statistically significant. The four Australian studies showed risks ranging from 1.08–1.79 consistent with the overall result.
We can interpret this to mean that for a child with asthma who lives in a home with a gas stove, 30% of their risk of asthma is from stove exposure.
Gas flames release both nitrogen dioxide and formaldehyde which are respiratory irritants. Nitrogen dioxide has also been shown to promote the development of allergy to other triggers, such as dust mites, and these effects occur at low concentration levels measured in parts per million or even parts per billion.
The evidence supports wanting to minimise exposure to these gases, so does every family have to remove their gas stove or are there some less disruptive and expensive steps that doctors can advise?
Possible responses
- The first thing is to improve ventilation. This could mean opening a door or window if the weather allows it
- Turning on a rangehood or extraction fan can help, although ask whether the rangehood is ducted to outside the building. The ones that blow air back into the kitchen do nothing to reduce nitrogen dioxide, and even many of the ducted ones are fairly ineffective. Rangehoods work better for back burners than front burners, and should be turned on every time the stove is lit
- Some families can reduce gas stove use by getting a single-pot induction hob. These bench-top appliances plug into a normal power point, cost about $100, and can manage all those one-pot meals
- Those ready to get rid of their gas stove generally go to an induction cooktop. These used to be more expensive than gas stoves but prices have come down, and the feature everybody likes is that the smooth glass surface is so easy to clean. The stove heats only the pot rather than the air in the kitchen, which is a welcome improvement in summer
- Gas space heating needs to be considered also. If heaters are unflued they contribute to indoor nitrogen dioxide
As doctors, we strive to deliver health advice supported by good science, and just as 30 years ago we recognised the benefits of protecting children from cigarette smoke, there is now a strong rationale to protect them from indoor gas combustion. This will be a slow process of cultural change that we can support through conversations with our patients.
All the old domestic uses of gas now have better electric alternatives and there will be a respiratory health dividend as families disconnect from the gas network.
The Global Cooksafe Coalition includes property developers who have committed to removing gas from their new buildings. The same idea has been implemented in Canberra where whole suburbs have been built without gas, and gas connections to new houses will not be permitted from 2023.
Leaving out the pipes and meters brings down the cost of a new dwelling by thousands of dollars, and as household energy costs are reduced by going all-electric the choice to avoid gas seems obvious. Archaic planning laws, however, still support gas connections in some other states.
Doubtless, the gas industry will soon ramp up its promotional activities telling us how wonderful it is to cook with gas. Readers with long memories will probably recognise tactics borrowed from the tobacco industry, sowing doubt about the health effects.
Standby for some pseudo health experts rolled out to reassure the public that the harms are exaggerated and there is nothing to fear.
There is a range of useful resources about the risks of indoor gas exposure to help GPs:
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