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Center for American Progress

The Health Care Consequences of Extreme Heat Are Just the Tip of the Iceberg

The Health Care Consequences of Extreme Heat Are Just the Tip of the Iceberg

Costly, heat-related emergency department visits and hospitalizations are rising as the climate warms, reflecting only a small portion of extreme heat-related consequences.

A child sips water from a bottle under a scorching sun in Los Angeles on August 30, 2022. (Getty/Frederic J. Brown)

Across the United States and globally, human-caused climate change is producing more severe weather, and there is no escaping the increase in extreme heat and its devastating impact. The health implications of extreme heat—brought on by increasing concentrations of greenhouse gases that raise both average and extreme temperatures—include heat stroke, heart disease, and respiratory disorders such as asthma. These conditions can result in disability and death. As a result, extreme heat is killing more people in the United States than any other type of severe weather or climate disaster and disproportionately affecting low-income areas and communities of color.

These deaths are preventable. Policy choices—such as improving coordination across federal departments, ensuring infrastructure investments are equitable, supporting decarbonization and climate resilience within the health care sector, enhancing forecasting and modeling of heat events and mitigation measures, and protecting workers from extreme heat—can drastically reduce the number of people who suffer from extreme heat. Indeed, more must be done, for the costs of excess hospitalizations and emergency department (ED) visits, while substantial, reflect only a small portion of extreme heat-related consequences.

Heat-related ED visits, hospitalizations, and deaths are on the rise

During the 2021 heat wave in the Western United States, heat-related deaths increased from two to 145 in Washington, zero to 119 in Oregon, and 12 to 25 in California, compared with the same two-week period of the previous year. And yet, this crisis is worsening: Heat-related deaths increased nearly 70 percent from 2008 to 2018, and by mid-July 2022, 200 million people were expected to experience temperatures in the 90s or higher for three consecutive days, prompting National Weather Service alerts in 28 states.

Extreme heat: By the numbers


Percentage increase in heat-related deaths from 2008 to 2018


Number of states with extreme heat weather alerts in July 2022


Estimate of heat-related premature deaths annually by the end of the century

Higher temperatures are associated with higher mortality; researchers have found that each additional day of heat above 90 degrees Fahrenheit increases the mortality rate by 1 percent compared with a 60- to 69-degree day. Unsurprisingly, the U.S. Centers for Disease Control and Prevention’s (CDC’s) National Syndromic Surveillance Program found that the rate of heat-related illness per ED visit increased in most regions of the United States when comparing May 1–June 30, 2019, to the same 61-day time period in 2022.

The inequitable impacts of extreme heat

The health risks of extreme heat—from dehydration and heat exhaustion to heat stroke—are greatest for populations that are disproportionately exposed and have limited resources to prepare and recover. These include low-income people, Black populations and other communities of color, people who are 65 years old or older, those with certain health conditions, and people who are exposed by working outdoors and living in places with inadequate protection, such as in urban heat islands or prisons and jails.

Studies of ED visits, hospital admissions, and ambulance trips show significant numbers of deaths and health care costs resulting from extreme heat exposure. According to the CDC, in the average year from 2004 to 2018, 9,235 people were hospitalized, there were 67,512 ED visits due to heat-related illness, and 702 heat-related deaths occurred.

See also

Yet these estimates likely undercount the true number of cases, given a variety of factors that complicate attempts to estimate and generalize. Cardiovascular or respiratory disease, for instance, may not be recognized as heat-related. Similarly, conditions such as hyponatremia may not be coded as heat-related. The CDC’s estimate of deaths reflects only those identified with specific diagnostic codes included in the National Vital Statistics System’s multiple-cause-of-death mortality data. Nevertheless, modeling studies support the case for climate policies and the urgent need for action.

Such studies found that:

  • Heat-related premature deaths in the United States were estimated at 12,000 annually from 2010 to 2020, with potentially 50,000 to 110,000 premature deaths annually by the end of the century.
  • From 2001 to 2010, the average cost per hospitalization due to heat-related illness was $5,359, according to a study that examined national hospital data.
  • UCLA Heat Maps estimates an average of 8,222 excess ED visits in California on an average heat event day.
  • The estimated costs of ED visits and hospitalizations due to heat-related illnesses in metro Phoenix is $7.3 million per year. In that 2021 study, AECOM and the Nature Conservancy estimated patient out-of-pocket costs and insurance payments of $1,066 for an ED visit and $11,343 for hospitalization.

The far-ranging consequences of extreme heat

In addition to the most recognizable heat-related illnesses and deaths, many additional consequences lie just under the surface. Heat waves have been associated with increases in ED visits related to mood and behavioral disorders and increased risk of aggression, which can result in crime and violence, including both homicide and suicide. Exposure to heat waves is also associated with increased risk of low birth weight and pre-term birth, which can have long-term consequences for physical and mental health and well-being.

Beyond health care outcomes are the economic and environmental costs associated with lost productivity and environmental destruction, including but not limited to worker injury; decreased student learning and performance; diminished output of the agricultural industry; drier vegetation, which can act as fuel for wildfires; water shortages; and damaging impacts for the ocean economy, wildlife, and ecosystems. In the United States, the estimated costs of heat-related worker productivity losses alone amount to $100 billion per year.


Fortunately, there are several tools policymakers can use to address this crisis. The following recommendations to address the health impacts of extreme heat can complement expanded access to health care and paid family and medical leave to ensure that those who are affected by extreme heat can seek care and recover from its effects. Moreover, these policy solutions can build on greenhouse gas reduction efforts to slow climate change and prevent its associated harms as well as efforts to build resilience to climate threats the country can no longer avoid.

Provide resources for the federal Office of Climate Change and Health Equity

States and cities are establishing heat officers to coordinate across departments to identify communities at greatest risk; increase public awareness of heat danger; make sure that cooling is accessible, especially for those at highest risk; and mitigate heat. For example, among the approaches of Phoenix’s Office of Heat Response and Mitigation is a tree donation program to help cool the city. California Assembly Bill 2076 would likewise establish a state chief heat officer position and create an interagency task force, heat-related illness reporting system, and incentives for community planning.

The United States would benefit from a similar approach at the federal level. In September 2021, President Joe Biden launched a coordinated, interagency, whole-of-government approach to respond to extreme heat, which included establishing the Office of Climate Change and Health Equity within the U.S. Department of Health and Human Services (HHS) to address the health impacts of climate change and coordinate efforts across departments. The office provides a climate and health outlook with resources to keep the public and workers safe and outline best practices for clinicians and emergency managers.

However, Congress has not funded the office, leaving it without any full-time staff or support. Congress should approve President Biden’s budget request of $3 million to enable the office to hire staff and advance its goals of protecting health, addressing health disparities that lead to disproportionate impact of extreme heat, and improving the sustainability and resilience of the health system.

Center equity and justice in reducing greenhouse gas emissions and building resilience to threats

The Inflation Reduction Act provides historic investments in efforts to address global warming and build community resilience to extreme weather and is expected to reduce U.S. emissions by about 40 percent below 2005 levels by 2030.

For instance, the legislation will invest $3 billion in environmental and climate justice block grants to cut pollution and improve public health in low-income and communities of color that suffer the most from environmental and health hazards, and is part of a package of programs that together will deliver $60 billion for environmental justice priorities. However, observers have raised environmental justice concerns about some of the Inflation Reduction Act’s provisions that risk adding health burdens in some disadvantaged communities, particularly from drilling and continued production of dirty fossil fuels. Rollout of these provisions must advance the Justice40 Initiative so that solutions—such as climate-resilient affordable housing, expansion of green spaces and tree canopies, cooling centers, and access to care—reach disadvantaged communities.

Use payment levers to bolster the health care sector’s response to extreme heat

The health care industry is a significant source of pollution that contributes an estimated 8.5 percent of national carbon emissions. In 2021, the National Academy of Medicine also launched the public/private Action Collaborative on Decarbonizing the U.S. Health Sector. And on April 22, 2022—Earth Day—HHS, in partnership with the White House, issued a call for health care organizations to sign a pledge to reduce greenhouse gas emissions. Some experts have suggested that HHS can use its regulatory and payment levers to go further—for instance, by requiring health systems to publicly report carbon emissions through conditions of participation in the Medicaid and Medicare programs and to comply with the U.S. Department of Energy’s ASHRAE 90.1 standards, which outline minimum requirements for energy-efficient design.

Others have called on the federal government to incentivize health care providers to prepare for extreme heat events and to tie Medicare reimbursement to carbon footprint reduction plans. The U.S. Centers for Medicare and Medicaid Services can likewise encourage and support states to use program flexibility to creatively address heat-related illness.

For instance, under Oregon’s Section 1115 Demonstration, coordinated care organizations (CCOs)—community networks of health care providers who serve people covered by the state Medicaid program—can offer flexible services that are not typically covered by Medicaid but that support beneficiary health. In particular, CCOs can purchase air conditioning units and assist beneficiaries with increased electricity costs as part of these services.

Ensure health care systems are heat-resilient and prepared to respond to more frequent extreme heat events

Extreme heat strains power grids and can lead to power outages, which in turn can hamper health care responders. Power outages impede cooling methods such as air conditioning, potentially resulting in greater heat exposure. They also hinder the use of electrically powered medical devices and equipment, such as feeding equipment and motorized vehicles. Finally, hospitals and other providers may lose power, disrupting care.

Federal agencies can encourage and support health care systems by using a framework adapted from the U.S. Climate Resilience Toolkit to conduct assessments, train providers to identify and support patients at risk, and engage in community planning.

Expand research capacity to enhance forecasting and modeling to better understand extreme heat and interventions

Communities need tools and resources to identify the most effective and efficient solutions for their needs. The National Oceanic and Atmospheric Administration’s Climate Program Office is funding programs to address research gaps and evaluate interventions. Other recent developments have filled some gaps. UCLA Heat Maps, for example, provides daily numbers and rates of excess ED visits in California due to extreme heat provided at the county and zip code levels, along with the costs and benefits of policy solutions. Similarly, Heat.gov, introduced by the National Integrated Heat Health Information System, provides information to help reduce the health and economic impacts of extreme heat. And the CDC’s Heat and Health Tracker provides heat and health data, including a forecast of the expected number of days at or above a dangerous level of heat based on climatological norms.

Yet more precise data and modeling are still needed to inform actions that can protect the public and prevent additional deaths, similar to systems used for tornadoes and other extreme weather. For example, the Preventing HEAT Illness and Deaths Act of 2021 would require recording the “number of schools, prisons, and other public facilities that lack air conditioning and the demographic breakdown of people affected by heat events, including by race, age, gender, occupation, and income.” And the Climate Change Health Protection and Promotion Act would enhance forecasting and modeling and develop a coordinated research agenda.

Establish hazardous heat standards for working and other conditions

A study using the nation’s largest workers’ compensation system estimated that hotter temperatures caused about 20,000 additional worker injuries per year in California from 2001 to 2018. To protect workers from hazardous heat, the U.S. Department of Labor’s Occupational Safety and Health Administration (OSHA) administers a Heat Illness Prevention campaign. In October 2021, OSHA published an advance notice of proposed rulemaking for heat injury and illness prevention in outdoor and indoor work settings to establish a standard for hazardous heat conditions. This standard should include training on signs of heat-related illness; requirements to provide water, rest breaks, and cool rest areas; and a protocol for acclimatizing workers to hot environments. The agency has prioritized inspections when daily temperatures rise above 80 degrees, but increased funding for inspectors is critical for effective enforcement.

States can also do more to establish safer conditions in prisons and jails, where extreme heat and lack of air conditioning cause deaths among incarcerated persons and more frequent incidents of violence. The Texas Commission on Jail Standards, for instance, requires that temperatures in county jails remain between 65 degrees and 85 degrees to prevent heat-related illness.

Read more recommendations from the Center for American Progress on extreme heat


With temperatures rising, it is too costly and dangerous not to act to identify, prevent, and mitigate the increasingly deadly consequences of extreme heat. A federal response to the substantial impact of heat-related ED visits and hospitalizations would be a significant step forward, but it must be coupled with efforts to address the additional consequences that lie just below the surface.

The author would like to thank Emily Gee, Marquisha Johns, Nicole Rapfogel, Sarah Millender, Steve Woolf, Christian Weller, Stephanie Bailey, Shannon Baker-Branstetter, Karla Walter, Rachael Eisenberg, Cathleen Kelly, and Max Hoffman for their review and helpful feedback.

The positions of American Progress, and our policy experts, are independent, and the findings and conclusions presented are those of American Progress alone. A full list of supporters is available here. American Progress would like to acknowledge the many generous supporters who make our work possible.


Jill Rosenthal

Director, Public Health


Health Policy

The Health Policy team advances health coverage, health care access and affordability, public health and equity, social determinants of health, and quality and efficiency in health care payment and delivery.

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