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Climate Change

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California Environmental Health Tracking Program

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Last Edited: 4/15/2014

Heat-Related Illness and Mortality

In 2006, CEHTP initiated the formation of the Climate Change Public Health Impacts Assessment and Response Collaborative.  The collaborative produced a report on population vulnerability to heat-related illness and mortality in California.  The report identified warming trends in California and populations at risk for heat-related morbidity and mortality.  This collaborative included representatives from the CDPH Environmental Health Investigations Branch (EHIB), the CDPH Epidemiology and Prevention for Injury Control Branch, CEHTP, Lawrence Berkeley National Laboratory, and Natural Resources Defense Council.



The public health risks associated with extreme heat events vary greatly across California’s communities.  It is essential to understand which communities and individuals are most vulnerable to heat so that we can identify strategies to protect these communities.  Advanced planning will be necessary to prevent death and illness.  The primary purpose of this research is to (1) identify populations at risk during heat events and (2) inform future emergency preparedness efforts.



Data from past heat events were evaluated to identify risk factors for heat-related illness.  Environmental, health, and demographic indicators of risk, as well as data from the U.S. Census, were also evaluated.  A Geographic Information System (GIS) was used to evaluate the spatial patterns of risks related to heat illness.



California appears to be slowly warming, with temperatures increasing most rapidly in South California and major urban centers, as can be seen in maps of temperature change in California.  However, heat-related disease and mortality- a broad range of diseases- are avoidable with appropriate preventive measures. The elderly, children, the poor, outdoor workers, the chronically ill, and the medically underserved are at the greatest risk for heat-related illness (see maps of heat vulnerability).  Areas not accustomed to heat will need to measures to adapt to heat emergencies.  Strategic planning and resources will be needed to develop heat warning systems and response plans.  View complete results in the full report.



  • California Department of Public Health
  • Lawrence Berkeley National Laboratory
  • Natural Resources Defence Council
  • Zev Ross Spatial Analysis



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