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Ambient Temperature and Cardiorespiratory Morbidity: A Systematic Review and Meta-analysis

Turner, Lyle R.a; Barnett, Adrian G.a; Connell, Desb; Tong, Shilua,c

doi: 10.1097/EDE.0b013e3182572795
Global Warming

Background: The effect of extreme temperature has become an increasing public health concern. Evaluating the impact of ambient temperature on morbidity has received less attention than its impact on mortality.

Methods: We performed a systematic literature review and extracted quantitative estimates of the effects of hot temperatures on cardiorespiratory morbidity. There were too few studies on effects of cold temperatures to warrant a summary. Pooled estimates of effects of heat were calculated using a Bayesian hierarchical approach that allowed multiple results to be included from the same study, particularly results at different latitudes and with varying lagged effects.

Results: Twenty-one studies were included in the final meta-analysis. The pooled results suggest an increase of 3.2% (95% posterior interval = −3.2% to 10.1%) in respiratory morbidity with 1°C increase on hot days. No apparent association was observed for cardiovascular morbidity (−0.5% [−3.0% to 2.1%]). The length of lags had inconsistent effects on the risk of respiratory and cardiovascular morbidity, whereas latitude had little effect on either.

Conclusions: The effects of temperature on cardiorespiratory morbidity seemed to be smaller and more variable than previous findings related to mortality.

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From the aSchool of Public Health and Social Work, Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Australia; bSchool of Environment, Griffith University, Brisbane, Australia; and cSchool of Public Health, Anhui Medical University, Hefei, Anhui, China.

Submitted 29 June 2011; accepted 7 February 2012; posted 23 April 2012.

Supported partly by funds from the Australian Research Council (DP1095752) (to S.T. and D.C.); and by NHMRC Research Fellowship (#553043) (to S.T.). The authors reported no other financial interests related to this research.

Supplemental digital content is available through direct URL citations in the HTML and PDF versions of this article ( This content is not peer-reviewed or copy-edited; it is the sole responsibility of the author.

Correspondence: Shilu Tong, School of Public Health and Social Work, Institute of Health and Biomedical Innovation, Queensland University of Technology, Victoria Park Road, Kelvin Grove, QLD 4059, Australia. E-mail:

© 2012 Lippincott Williams & Wilkins, Inc.