NAMClimate Health Hazard SummarySummary: Health Impacts of Climate Change

Health Impacts of Climate Change

This summary is part of the NAM’s “Communicating About Climate Change and Health” project. The project aims to support health providers and other communicators in sharing actionable information with patients and the public.

Summary

Since 1900, the average temperature on Earth has risen by about 2 degrees Fahrenheit. Most of the increase has occurred over the past 50 years, and temperatures are continuing to rise sharply. Without intervention to slow the pace of climate change, temperatures are on track to increase by an additional 7 degrees F by the year 2100 (NASEM, 2025).

This warming trend is driven in large part by the combustion of fossil fuels—coal, oil, and natural gas—which account for over 75% of all greenhouse gas (GHG) emissions. These emissions form a heat-trapping “blanket” in the Earth’s atmosphere, causing global temperatures to rise at unprecedented rates (UN, 2025). This is rapidly changing the environment in ways that affect human health.

Major climate change hazards currently affecting people’s health in the United States include air pollution, vector-borne and fungal diseases; extreme weather; wildfires; and extreme heat. These threats affect different populations differently depending on exposure and vulnerability.

Several of these hazards may be experienced at once, increasing the severity of outcomes. Hazards affect people differently but can exacerbate underlying medical conditions for many. Some health impacts may be acute, such as heat illness from extreme temperatures or asthma events from nearby wildfire smoke. Other impacts may be more chronic, such as mental health conditions. Extreme weather events, including floods, droughts, and storms, can cause injury, death, or displacement; impact employment; disrupt access to health care; and result in long-term physical and mental impacts. Health hazards are expected to increase in coming years in frequency, intensity, and extent.

The tables below contain key facts about the health impacts of five major climate change hazards affecting health in the United States today.

Air Pollution

Climate change and the combustion of fossil fuels each contribute to reduction in air quality and reinforce one another’s effects. Combustion releases pollutants that directly degrade air quality, while climate change amplifies pollution by increasing ozone formation, intensifying wildfires, and altering weather patterns that trap pollutants near the ground (EPA, 2025a; 2025b).

Selected Health Impacts

Exposure to fossil fuel pollution is associated with an increased risk of heart disease, lung cancer, chronic obstructive pulmonary disease (COPD), lower respiratory infections, stroke, type 2 diabetes, autism, Parkinson's disease, and adverse birth outcomes, including neurodevelopmental harms (Lelieveld et al., 2023; Lin et al., 2021; Mitku et al., 2023; Murata et al., 2022).
Every year, more than 8 million worldwide people die prematurely as a result of fossil fuel air pollution (Lilieveld et al., 2023).
Deaths related to fossil fuel combustion cost the U.S. economy an estimated $151 billion in 2020 (Lancet Countdown, 2023).
Prenatal and early childhood exposure to pollutants is associated with cognitive challenges, attention deficit hyperactivity disorder, and autistic traits in children (Perera and Nadeau, 2022).
Pollution disproportionately affects low-income communities and people of color due to historic redlining and the prevalence of oil and gas infrastructure in their neighborhoods (Morello-Frosch and Obasogie, 2023).
High ozone levels worsen asthma symptoms, particularly for children (EPA, 2025). Almost 9% of Americans have asthma (CDC, 2023).

Vector-Borne and Fungal Diseases

Vector-borne diseases are spread by insects like mosquitoes and ticks. Climate change is expanding the habitats and activity periods of these organisms, putting more people at risk for infection. Fungal diseases, caused by fungi that grow in or on the body, are fueled by changing weather patterns.

Selected Health Impacts

Between 1998 and 2016, the range of the blacklegged tick, which carries Lyme disease, increased from 30% to about 45% of U.S. counties--more than doubling in less than two decades (Eisen et al., 2016).
The mosquito that spreads dengue fever, which previously limited to tropical environments, has been found as far north as San Francisco and Washington, DC. Locally transmitted cases have been recorded in California, Arizona, Florida, and Texas (Sullivan et al., 2024).
An increase in dust storms in the Southwest United States corresponded with an 800% increase in cases of Valley fever, a fungal disease that affects the lungs (Tong et al, 2017).

Extreme Weather

Climate change is increasing the frequency and intensity of extreme weather events such as storms, droughts, and floods, often referred to as “natural disasters.”

Selected Health Impacts

Natural disasters are linked to a range of human health impacts, including death, injury, illness, exacerbation of underlying medical conditions, and adverse effects on mental health (Bell et al., 2016).
Globally, from 1970 to 2021, extreme weather, climate, and water-related events caused 2 million deaths, 12,000 disasters, and $4.3 trillion in reported economic losses (World Meteorological Association, 2023).
Up to half of people exposed to an extreme weather event experience a mental health impact such as anxiety, depression, or PTSD (Clayton and Brown, 2024).
Children are especially vulnerable to natural disasters, with negative outcomes ranging from missed school, emotional distress, and ongoing behavioral problems.

Wildfires

Environmental conditions fueled by climate change, such as extended drought, low humidity, rising temperatures, and lack of moisture in forest debris can increase the risk of wildfires.

Selected Health Impacts

Exposure to wildfire smoke is associated with a range of respiratory conditions, reduced lung function, heart failure, heart attack, stroke, and premature death (EPA, 2025). For pregnant women, exposure may increase the risk of preterm birth (EPA, 2024). Long-term exposure may increase the risk of lung and brain cancer (Korsiak et al., 2022)
Even thousands of miles away, wildfire smoke can cause breathing difficulties and exacerbate underlying conditions (American Lung Association, 2016).
People exposed to traumatic wildfire disasters such as the 2018 "Camp Fire" in California experience chronic posttraumatic stress disorder, anxiety, and depression and display lasting cognitive deficits (Grennan et al., 2023).

Extreme Heat

Today, heat waves are more than four times as frequent in the United States as they were in the 1960s (U.S. Global Change Research Program, n.d.).

Selected Health Impacts from Extreme Heat in the United States

Extreme heat can be fatal, especially for children, people over age 65, people with cardiovascular or respiratory conditions, people with lower incomes, and non-Hispanic Black people (EPA, 2024).
People with mental health conditions, including depression and schizophrenia, are more likely to die during extreme heat events. Certain psychiatric medications interfere with temperature regulation and make people more vulnerable to heat (Lee et al., 2023).
Black people are over 5 times more likely to die from heat than White people, with much of the difference explained by disparities in access to air conditioning (Morello-Frosch and Obasogie, 2023).
Farmworkers, 78% of whom are Hispanic or Latino, are 35 times more likely to die from heat than other workers (American Lung Association, 2023).
By the middle of this century, heat-related cardiovascular deaths are projected to increase by 233% in the United States (Khatana et al., 2023).
For pregnant women, heat exposure is associated with a higher risk of preterm birth (Yuzen et al., 2023).
Higher temperatures are associated with an increase in suicides and psychiatric hospitalizations (Thompson et al., 2023).
Higher temperatures are associated with a greater likelihood of missing essential primary care, prenatal, and cancer care visits (Fitzpatrick et al., 2024).

Options to Protect Yourself, Your Family, and Your Community

Increasing your awareness about the health impacts of climate change can help you feel more empowered and able to make informed decisions to protect your health. The following are key takeaways from published research on actions that can protect personal and community health.

Reducing exposure to extreme heat. Stay informed about heat risks and available cooling centers, reduce outdoor activities during peak heat hours, and ensure access to cooling when needed. Websites such as HEAT.gov provide heat alerts.
Reducing exposure to poor air quality. Stay informed about air quality, use air-filtration systems at home, and avoid outdoor activities during high pollution periods. Air quality apps can help to track daily pollution levels.
Preventing vector-borne diseases. Take preventive strategies such as reducing skin exposure to ticks and mosquitoes, checking for ticks after outdoor activities, and limiting outdoor activity after dusk. Stay up to date on current diseases in your area.
Fostering your own resilience. Utilize mental health services and stress reduction techniques and offer support and empathy to people experiencing climate anxiety or distress. Participating in community support groups or therapy sessions for climate-related distress can also help people find like-minded allies and create opportunities for action instead of feeling stuck.
Building community resilience. Promote community support systems and check on individuals at risk during climate-related events. Community members can help others by supporting local organizations, such as mental health services, soup kitchens, homeless shelters, and more.
Reducing your climate impact. While individual actions to reduce the impacts of climate change will be inadequate without broad societal change supported by policies, there are still ways for every person to reduce greenhouse gas emissions. These include walking and cycling where possible in lieu of driving and reducing meat intake. Individuals can also conserve energy at home, support renewable energy initiatives and energy-efficient buildings in their communities, and use clean energy options when possible.

Options for Health Professionals to Support Patients and Their Communities

Health professionals are trusted messengers that can play an important role in supporting patients and their families in responding to the health impacts of climate change. The following are key takeaways from published research on actions health professionals can take to share information and help patients navigate concerns.

Informing patients about the signs and symptoms of heat-related illness and when to seek medical attention and providing guidance to reduce risks (e.g., seeking cooling environments and fluids).
Identifying heat-vulnerable patients based on their occupation, living condition, or medication use and alerting them to potential risks.
Informing patients about air quality and pollen monitoring resources.
Engaging in conversations about the health benefits of strategies to reduce fossil fuel pollution and address climate change.
Providing guidance on nutrition programs and safe eating habits during power outages and extreme heat events.
Asking patients about their coping and resilience strategies and connecting them to resources for climate-change-related mental health support.

Apr 15, 2025Key Facts

Summary: Health Impacts of Wildfires

Exposure to wildfire smoke is linked to a range of respiratory conditions, reduced lung function, heart failure, heart attack, stroke, and premature death.