Heat-related illness statistics span estimated global mortality, emergency-department surveillance, clinical dispositions, workplace exposure, and fatal occupational injuries. The measures below cover different populations and periods, so an estimated heat-related death, a coded emergency visit, and a work-related fatality are not interchangeable.
Key Heat-Related Illness Statistics
The most broadly useful figures are:
- 489,000 estimated heat-related deaths occurred worldwide each year during 2000–2019.
- Asia accounted for 45% of estimated global heat-related deaths during 2000–2019.
- Europe accounted for 36% of estimated global heat-related deaths during 2000–2019.
- Heat-related mortality among people over 65 increased approximately 85% globally between 2000–2004 and 2017–2021.
- Europe had an estimated 61,672 heat-related excess deaths in summer 2022.
- U.S. reporting facilities recorded 119,605 heat-related illness emergency-department visits during 2023.
- Ninety-two percent of those U.S. heat-related illness emergency visits occurred during May–September 2023.
- The average U.S. heat-related illness emergency-visit rate was 303 per 100,000 all-cause ED visits in July–August 2023.
- The average U.S. warm-season heat-related illness emergency-visit rate was 180 per 100,000 ED visits during May–September 2023.
- HHS Region 6 recorded the highest U.S. warm-season rate at 483 per 100,000 ED visits during May–September 2023.
- U.S. males had a warm-season heat-related illness ED rate of 271 per 100,000 ED visits in 2023.
- U.S. adults aged 26–54 had a warm-season heat-related illness ED rate of 222 per 100,000 ED visits in 2023.
- A U.S. study recorded 326,497 acute heat-illness ED visits during May–September 2006–2010.
- About 88% of acute heat-illness ED cases were treated and released in the 2006–2010 U.S. study.
- Heat exhaustion represented 74.7% of acute heat-illness diagnoses in the 2006–2010 U.S. study.
- Heat-stroke cases had an admission-or-ED-death outcome in 62.0% of cases in that study.
- In 2022, 32.9% of U.S. workers had occupations requiring outdoor exposure.
- Construction and extraction represented 32.3% of fatal extreme-heat work injuries during 2011–2020.
- BLS counted 436 U.S. work-related environmental-heat deaths from 2011 through 2021.
- BLS recorded 43 fatal occupational environmental-heat injuries in the United States in 2022.
Contents
- Global heat-related illness and mortality scale
- U.S. emergency-department trends
- Heat-related illness by age, sex, region, and setting
- Clinical outcomes and hospital burden
- Workplace exposure and injuries
- Fatal occupational heat exposure trends
Global Heat-Related Illness and Mortality Scale
The World Health Organization summarizes estimates rather than a single worldwide registry. For 2000–2019, the estimate was 489,000 heat-related deaths per year globally; heat attribution and reporting vary by country. WHO, “Heat and health”
The regional distribution of that estimate was concentrated in Asia and Europe:
| Geography | Period | Measure |
|---|---|---|
| Asia | 2000–2019 | 45% of estimated global heat-related deaths |
| Europe | 2000–2019 | 36% of estimated global heat-related deaths |
| Europe | Summer 2022 | 61,672 estimated heat-related excess deaths |
| Europe | June–August 2003 | About 70,000 estimated heatwave deaths |
| Russian Federation | 2010, 44-day heatwave | 56,000 estimated excess deaths |
These figures represent mortality estimates or excess mortality, not identical counts of death certificates explicitly coded as heat illness. WHO also reports that heat-related mortality among people over 65 increased approximately 85% between 2000–2004 and 2017–2021 in its cited global assessment. WHO, “Heat and health”
U.S. Heat-Related Illness Emergency-Department Trends
CDC’s National Syndromic Surveillance Program and ESSENCE recorded 119,605 heat-related illness ED visits in reporting facilities from January 1 through December 31, 2023. The system does not cover every U.S. emergency department, and its rate denominator is all-cause ED visits rather than the population. CDC, “Heat-Related Emergency Department Visits — United States, May–September 2023”
Seasonality was pronounced. Ninety-two percent of the 2023 ESSENCE visits occurred during May–September, while the average rate was 303 per 100,000 ED visits in July–August and 97 per 100,000 in May, June, and September.
| U.S. surveillance measure | Period | Rate or share |
|---|---|---|
| Annual ESSENCE ED visits | 2023 | 119,605 visits |
| Warm-season share | May–September 2023 | 92% |
| Peak-season rate | July–August 2023 | 303 per 100,000 ED visits |
| Other warm-season rate | May, June, September 2023 | 97 per 100,000 ED visits |
| Mean warm-season rate | May–September 2023 | 180 per 100,000 ED visits |
| Historical mean warm-season rate | May–September, 2018–2022 | 151 per 100,000 ED visits |
The July–August rate was 3.07 times the rate in the other warm-season months. The 2023 mean warm-season rate was measured in consistently reporting facilities, and the surveillance definition does not capture people treated elsewhere. CDC, “Heat-Related Emergency Department Visits — United States, May–September 2023”
Heat-Related Illness by Age, Sex, Region, and Setting
CDC’s May–September 2023 data show differences across sex, age, and HHS region. These are surveillance rates per 100,000 ED visits, not population incidence rates.
| Group or region | Period | HRI ED rate |
|---|---|---|
| Males | May–September 2023 | 271 per 100,000 ED visits |
| Females | May–September 2023 | 104 per 100,000 ED visits |
| Ages 18–25 | May–September 2023 | 211 per 100,000 ED visits |
| Ages 26–54 | May–September 2023 | 222 per 100,000 ED visits |
| Ages 55–64 | May–September 2023 | 207 per 100,000 ED visits |
| Ages 65–74 | May–September 2023 | 173 per 100,000 ED visits |
| HHS Region 2 | May–September 2023 | 51 per 100,000 ED visits |
| HHS Region 6 | May–September 2023 | 483 per 100,000 ED visits |
The ages 18–25 and 26–54 rates were 2.52 and 2.54 times the rate for people under 18, respectively. Region 6 included Arkansas, Louisiana, New Mexico, Oklahoma, and Texas; Region 2 included New Jersey and New York, with territories that did not report included in the report’s regional definition. CDC, “Heat-Related Emergency Department Visits — United States, May–September 2023”
Region 6 had 56 warm-season days above its 2018–2022 daily 95th-percentile HRI ED rate in 2023, representing 37% of warm-season days. This is an exceedance against a surveillance distribution, not an illness-prevalence measure. CDC, “Heat-Related Emergency Department Visits — United States, May–September 2023”
Heat-Related Illness Clinical Outcomes and Hospital Burden
A peer-reviewed national ED study examined May–September 2006–2010 using an older ICD-9 administrative case definition. It recorded 326,497 acute heat-illness ED visits and estimated 21.5 visits per 100,000 population per year in the sampled U.S. NEDS states. “Heat illness in U.S. emergency departments”
Disposition and diagnosis data show why ED volume and severity should be separated:
- 287,875 visits were treated and released, 38,392 were admissions, and 230 deaths occurred in the ED.
- About 88% of cases were treated and released, while about 12% were admitted; these are administrative dispositions, not clinical recovery rates.
- First-listed heat-illness diagnoses accounted for 221,739 visits, compared with 104,758 visits where heat illness was secondary.
- Heat exhaustion represented 74.7% of acute heat-illness diagnoses, while heat stroke represented 5.4%.
- Among heat-stroke cases, 62.0% were admitted or died in the ED.
- Heat stroke accounted for 77.0% of all ED deaths in the study.
The 2006–2010 NEDS study should not be directly pooled with CDC’s 2023 NSSP figures because the periods, coding system, coverage, and denominators differ. “Heat illness in U.S. emergency departments”
Workplace Heat Exposure and Injury Statistics
BLS occupational-requirements data describe jobs that require outdoor exposure; they do not measure observed heat illness prevalence. In 2022, 32.9% of U.S. workers had occupations requiring outdoor exposure.
| Occupation | Year | Workers requiring outdoor exposure |
|---|---|---|
| Cement masons and concrete finishers | 2022 | 100% |
| Construction laborers | 2022 | 100% |
| Firefighters | 2022 | 100% |
| Roofers | 2022 | 100% |
| Paramedics | 2022 | 98.0% |
Reported private-sector injuries requiring at least one day away from work after extreme-heat exposure included 440 in trade, transportation, and utilities; 410 in construction; 350 in professional and business services; and 290 in manufacturing during 2020. The BLS event/exposure series covers reported injuries meeting the days-away criterion. BLS, “Fire and Ice: What Do We Know About Jobs Involving Exposure to Outdoor Elements?”
Fatal Occupational Heat Exposure Trends
BLS Census of Fatal Occupational Injuries counts identified work-related deaths from environmental heat. The annual series recorded 61 deaths in 2011, 18 in 2014, 49 in 2018, 43 in 2019, 56 in 2020, and 36 in 2021; BLS reported 2021 as the lowest number since 2017. BLS, “36 work-related deaths due to environmental heat exposure in 2021”
Across 2011–2021, BLS counted 436 work-related environmental-heat deaths in the United States. Fatal occupational counts cover identified work-related deaths and may undercount cases assigned another primary classification. BLS, “36 work-related deaths due to environmental heat exposure in 2021”
During 2011–2020, the largest occupation-group shares of fatal extreme-heat work injuries were construction and extraction at 32.3%, building and grounds cleaning and maintenance at 12.0%, transportation and material moving at 9.3%, and farming, fishing, and forestry at 8.8%. BLS, “Fire and Ice: What Do We Know About Jobs Involving Exposure to Outdoor Elements?”
For 2022, BLS recorded 43 fatal occupational injuries from environmental heat in U.S. private industry, including 17 in construction and 3 in educational and health services. Industry cells are fatal-injury counts, and suppressed cells are not zero. BLS, “TABLE A-9. Fatal occupational injuries by event or exposure for all fatal injuries and major private industry sector, all United States, 2022”