This randomised community trial involving 409 children from households in five communities in New Zealand investigated whether non-polluting, more effective home heating alleviates children’s winter asthma symptoms and improves lung function. In the intervention group, a more effective non-polluting replacement heater was installed before winter in June 2006. Compared with the control group, indoor temperatures for the intervention group were higher by 1.09°C in the living room and by 0.57°C in the child’s bedroom. The intervention group was exposed to low temperatures (number of hours per day by the number of degrees <10°C) in the living room for 1.13 degree hours, whereas the control group was exposed for 2.34 degree hours. Children in the intervention group had less poor health (adjusted odds ratio 0.44) and lower levels of lower respiratory symptoms (0.76) versus the control group. In addition, significantly fewer school days were missed in the intervention group versus the control group. Lung function did not differ between the groups, but after controlling for nitrogen dioxide levels in the home, the improvement in FEV1 was significant for the intervention group.
