An Australian national panel study of diurnal temperature range and children's respiratory health.
BACKGROUND
It is still uncertain whether diurnal temperature range (DTR) affects children's respiratory function.


OBJECTIVE
To examine the effects of DTR on lung function and respiratory symptoms for school children with asthma in Australia.


METHODS
A panel of 270 children (ages 7-12 years) with asthma living in 6 Australian cities was recruited. They were asked to perform 3 successive forced expiratory maneuvers using a portable electronic peak flow meter twice daily for 4 weeks. The highest values for peak expiratory flow (PEF) were stored for each session. At the same time, they were asked to record their respiratory symptoms (eg, cough and/or phlegm and wheeze and/or chest tightness) every day in the morning (for nighttime symptoms) and evening (for daytime symptoms). Daily data on different metrics of ambient temperature and air pollution were obtained from fixed monitors nearby. Relative humidity data were downloaded from the Weather Underground website. Mixed models, adjusting for children's individual characteristics and air pollution, were used to examine the effects of DTR on PEF and respiratory symptoms.


RESULTS
DTR had linear effects on PEF and respiratory symptoms. An increase in DTR induced a reduction in PEF and increased the occurrence of respiratory symptoms. In general, the effects lasted for 3 days (lag, 0-2 days). The effects occurred for both boys and girls.


CONCLUSIONS
Our findings provide evidence that DTR had significant effects on lung function and respiratory symptoms for children with asthma. These results indicate that it is important and necessary to protect children with asthma from the effect of unstable weather.
School of Population Health, University of Queensland, Queensland, Australia. Electronic address: uqshandy0601@gmail.com.
Shanshan
S
Li
School of Population Health, University of Queensland, Queensland, Australia.
Peter J
PJ
Baker
Centre for Research, Evidence Management and Surveillance, Sydney and South Western Sydney Local Health Districts, New South Wales, Australia; School of Public Health and Community Medicine, University of New South Wales, New South Wales, Australia.
Bin B
BB
Jalaludin
School of Population Health, University of Queensland, Queensland, Australia.
Yuming
Y
Guo
Department of Respiratory Medicine, Liverpool Hospital, New South Wales, Australia; Woolcock Institute of Medical Research, University of Sydney, Sydney, New South Wales, Australia.
Guy B
GB
Marks
Pacific Environment-Toxikos, Victoria, Australia.
Lyn S
LS
Denison
School of Population Health, University of Queensland, Queensland, Australia.
Gail M
GM
Williams
D000397:Air Pollution / Q000009:adverse effects / Q000706:statistics & numerical data*; D001249:Asthma / Q000175:diagnosis / Q000453:epidemiology*; D001315:Australia / Q000453:epidemiology; D002648:Child; D005260:Female; D006801:Humans; D006813:Humidity / Q000009:adverse effects; D008297:Male; D015233:Models, Statistical; D010507:Periodicity; D011153:Population; D012016:Reference Values; D012129:Respiratory Function Tests; D013696:Temperature; D014887:Weather