Improved heating reduced children's visits to a doctor for their asthma and also reduced reports of poor health, sleep disturbed by wheezing and lower respiratory tract infections.
It did not, however, lead to a significant improvement in children's lung function, assessed as the primary outcome in the trial.
Researchers installed replacement heaters in the households of 200 children with asthma before the study and examined changes in lung function and asthma symptoms. A group of 209 children whose homes had new heaters installed after the study acted as a control group.
The replacement heaters reduced nitrogen dioxide levels and increased living room temperatures by around 1 degsC, to 17.1 degsC, and bedroom temperatures by around 0.6 degsC, to 14.8 degsC.
The researchers suggest that such changes could be used as an addition to drug treatment.
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