A US study has found a 70% drop in hospital admissions and days off from work or school when people with poorly controlled asthma had their gas stove and hob replaced with electric.
Ohio’s publicly owned MetroHealth began the study in December 2024 but funding was terminated early by the incoming Trump administration. It had been designed to investigate if replacing gas cooking improved asthma for 1,200 people living near Cleveland, Ohio.
Prof Ash Sehgal of Case Western Reserve University, the project’s leader, said: “We had completed the project at fewer than 100 households. As a result, over 1,100 households were unable to benefit. We also had to lay off about 20 project staff.”
The team finished the stove replacements that were under way and closed the project, but to the researchers’ surprise, the benefits could be clearly detected even in the scaled-down study of 72 homes.
Sehgal said: “We were surprised when we analysed the results and found a very large effect size. The improvements in asthma symptoms following stove change were similar to – or even greater than – those reported in clinical trials of commonly used asthma medications.”
Each person was assessed for four weeks before the gas cooking replacement, and for four weeks afterwards, including scoring their asthma using an internationally recognised scale of zero to six.
The average asthma score improved from 2.6 to 1.5, on a scale where a change of 0.5 is considered to be clinically significant. This included fewer hospital visits and fewer days off school or work for asthma flare-ups. They also found less wheezing, less use of reliver inhalers and fewer people saying that their asthma had woken them during the night.
Air pollution was measured in 44 of the homes. On average, nitrogen dioxide dropped 70%.
Angela Bland, a 38-year-old resident of Akron, Ohio, said: “I didn’t realise my gas stove was the issue until I used the electric stove. I now need my inhaler way less often.”
Sehgal said: “The improvement in asthma control after changing stoves was much larger than improvements seen with placebo drugs, so the placebo effect is unlikely to explain our findings.” He added that there would be benefits in repeating the study with more people and with a control group.
Dr Tiffany Yang from NHS Born in Bradford, who was not involved in the US research, said: “The Ohio study adds to the growing evidence that reducing indoor air pollution can have meaningful health benefits, particularly for people with asthma. As governments and housing providers invest in improving the housing stock, indoor air quality should be considered alongside energy efficiency and decarbonisation measures to maximise health benefits.”
In the Ohio study, over 97% of the participants were satisfied or very satisfied with their new stove. High levels of satisfaction have also been found in a pilot stove and induction-hob replacement project in Greater Manchester.
An evidence review more than 10 years ago considered 41 studies and concluded that gas cooking increased the risk of asthma in children. With around an estimated 40,000 early deaths each year from gas cooking across the EU and UK, improved health could be an important co-benefit of net zero actions to replace gas cooking at home.
