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20-08-2013 | Respiratory | Article

Low indoor temperatures linked to pediatric asthma outcomes


Free abstract

medwireNews: Research from New Zealand shows that children with asthma experience small but significant variations in lung function in response to changes in indoor air temperature.

The data included 286 children aged between 7 and 13 years who took part in the Heating and Housing Health Study. The children measured their lung function morning and evening, while temperature recordings were taken from their bedroom and living room every hour during the winter of 2006, giving 9194 person–days of information.

Overall, severity of exposure, which accounted for both the duration and size of a fall below a selected threshold, was more strongly associated with lung function than was duration of exposure, which just accounted for the average time below a threshold; bedroom temperature exposure showed a more significant association than living room exposure.

Nevil Pierse (Wellington School of Medicine) and colleagues report that the strongest threshold for severity occurred at exposures below 9 to 11°C, depending on the specific measure. And, consistent with studies of outdoor temperature and lung function, the strongest association between lung function and bedroom temperature metrics was observed for lag periods of 7 or 12 days.

Using the model with the greatest association for each measure of lung function assessed, the team estimates that, below a threshold of 9°C, every 1°C increase in temperature would result in a 0.010 L/s improvement in peak expiratory flow rate in the morning, and a 0.008 L/s improvement in the evening.

Meanwhile, forced expiratory volume in 1 second would improve by 10.06 mL in the morning for every 1°C increase below a threshold of 12°C, and by 12.06 mL in the evening for every 1°C increase in temperature up to 10°C.

“Better metrics for measuring indoor temperature exposure will help guide estimates of health benefits that can be realized from improving the indoor environment,” the authors write, adding that the current or previous day’s temperature is suboptimal for this purpose.

“Instead, we suggest measuring indoor temperature over a longer period and subject to a local threshold similar to those used for outdoor studies,” they conclude in the Journal of Epidemiology & Community Health.

By Kirsty Oswald, medwireNews Reporter