Environmental Protection Agency: Climate Change Indicators - Heat-Related Illnesses

This indicator tracks how often people are hospitalized because of exposure to heat.

This indicator shows hospitalization rates for “heat-related” illnesses such as heat exhaustion, heat cramps, mild heat edema (swelling in the legs and hands), heat syncope (fainting), and heat stroke. It is based on hospital discharge records for patients who are admitted to the hospital for 23 hours or more. Every discharge record includes a diagnosis determined by a physician or other medical professional.

This indicator covers states across a wide range of regions and climate zones that have participated in a national hospital data tracking program since at least 2001. All of these states require hospitals to submit discharge data to a state organization, which then compiles and reports the data to the U.S. Centers for Disease Control and Prevention (CDC). Dividing the annual number of hospitalizations by the corresponding state population, then multiplying by 100,000, gives the hospitalization rates (per 100,000 people) shown in this indicator.

Figure 1 shows annual hospitalization rates, averaged over a group of 20 states. Figure 2 shows state-specific rates for 23 states, averaged over the period from 2001 to 2010. Figure 3 shows the total number of hospitalizations across the same 20 states shown in Figure 1, broken out by sex and by age group. Because excessive heat events are associated with summer months, this indicator is limited to hospitalizations occurring in May through September. Reporting of illnesses and processing of records can involve a time lag of several years, so this indicator currently only shows data through 2010.

Science Topics
Climate Change, Health & Medicine
Middle School
6th Grade, 7th Grade, 8th Grade

What are you looking for?


Environmental Protection Agency

Website URL

Type of Resource


Assigned Categories