Heat Stress Illness

Man wiping his brow suffering from heat stress illness

As a result of the changing climate, serious weather events, like heat waves, happen more often. These changes have the potential to affect human health in several direct and indirect ways, some of them severe.

We Track That

The Tracking Network collects data on heat-related illnesses throughout the United States and provides information so people can protect themselves. Knowing how to prepare for and respond to extreme heat events will help protect our communities, especially the most vulnerable populations.

Types of Data

The Tracking Network provides data about the health effects of a heat wave by collecting and reviewing the number of health conditions reported from local hospitals and the number of deaths reported from state health departments. The following data can be used to identify patterns in health effects related to extreme heat and conditions that make people vulnerable to heat.

Heat Stress Emergency Department Visits * ¶
This indicator estimates the number and rate of emergency department visits for heat stress. It includes all cases where heat stress is listed as a primary or other diagnosis.

Heat Stress Hospitalizations * ¶
This indicator estimates the number and rate of hospitalizations for heat stress. It includes all cases where heat stress is listed as a primary or other diagnosis.

Heat-Related Mortality
This indicator is based on data from death certificates to evaluate deaths that have identified heat as an underlying or contributing cause.

Heat Vulnerability
This indicator includes measures that may make people at greater risk for heat-related health effects. These measures are diabetes, heart disease, poverty, race, advanced age, social isolation, disabilities, population density, forest canopy, developed land use, and cultivated crop land use.

* These data come from hospital records and may not capture the full range of heat-related illness if exposure to excess heat is not explicitly documented. These data can be used to document changes over place and time, monitor vulnerable areas, and evaluate the results of local climate-adaptation strategies.
¶ These data are supplied by health departments funded by the CDC Tracking Program.

Data Highlight
CDC's Climate & Health Heat Tracker tool screenshot

CDC’s Heat and Health Tracker:
Explore how extreme heat affects your county, populations that are at risk, and resources for response.

Data in Action

Reviewing these national data helps scientists make comparisons between environmental conditions and health problems. Other examples of how extreme heat data can be used include:

  • Identifying populations and areas with high risk for heat-related deaths
  • Gaining a better understanding of trends in heat-related deaths over time
  • Comparing states and counties to plan interventions
  • Identifying communities at risk and the groups of people that may be at risk

Read these success stories to learn about the heat stress illness related work happening in our funded Tracking Programs.

California | Minnesota | Missouri | New Hampshire | New York City

Learn More

Tracking Resources

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Page last reviewed: October 21, 2020