The effect of temperature on hospital admissions in nine California counties

Int J Public Health. 2010 Apr;55(2):113-21. doi: 10.1007/s00038-009-0076-0. Epub 2009 Sep 22.


Objectives: This study examined the association between mean daily apparent temperature and hospital admissions for several diseases in nine California counties from May to September, 1999 to 2005.

Methods: We conducted a time-stratified case-crossover study limited to cases with residential zip codes located within 10 km of a temperature monitor. County-specific estimates were combined, using a random effects meta-analysis. The analyses also considered the effects of ozone and particulate matter (PM(2.5)).

Results: We found that a 10 degrees F increase in mean apparent temperature was associated with a 3.5% [95% confidence interval (CI) 1.5-5.6] increase in ischemic stroke and increases in several other disease-specific outcomes including all respiratory diseases (2.0%, 95% CI 0.7-3.2), pneumonia (3.7%, 95% CI 1.7-3.7), dehydration (10.8%, 95% CI 8.3-13.6), diabetes (3.1%, 95% CI 0.4-5.9), and acute renal failure (7.4%, 95% CI 4.0-10.9). There was little evidence that the temperature effects we found were due to confounding by either PM(2.5) or ozone.

Conclusion: Our results indicate that increases in ambient temperature have important public health impacts on morbidity.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • California
  • Child
  • Child, Preschool
  • Cross-Over Studies
  • Databases as Topic
  • Hot Temperature / adverse effects*
  • Humans
  • Middle Aged
  • Patient Admission / trends*
  • Young Adult