The California Heat Wave 2006 with Impacts on Statewide Medical Emergency: A space-time analysis

  • Alexander Gershunov University of California
  • Zane Johnston University of California
  • Helene G. Margolis University of California
  • Kristen Guirguis University of California
Keywords: Heat Waves, Public Health, Canonical Correlation Analysis, Temperature, Humidity, Morbidity, Climate Change


The unprecedented July 2006 California heat wave was associated with an accelerating trend in regional humid heat wave activity that is related to global warming. In this work, we identify and summarize effects of that meteorological extreme event on California morbidity as quantified by daily emergency department (ED) visits data aggregated at the county level. Besides local county-level daily correlation analysis, we use canonical correlation analysis (CCA) to summarize space-time relationships between ED visits and temperature as well as humidity. We find intriguing spatial patterns of public health impacts of heat and humidity that potentially suggest modulation by various factors including demographics, adaptation and acclimatization that may be related to local climatology and social factors determining access to air conditioning. Health outcomes as measured by ED visits are found to be generally more sensitive to extreme heat and humidity in coastal counties and the north-central part of the Central Valley, which are known to be more affected by coastal influences, than in inland counties.


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