Extreme Heat and Wildfire Smoke: Consequences for Communities
More Extreme Weather Leads to More Public Health Emergencies
Extreme heat and wildfire smoke both pose significant and worsening public health threats in the United States. Extreme heat causes the premature deaths of an estimated 10,000 people in the U.S. each year, while more frequent and widespread wildfire smoke exposure has set back decades of progress on air quality in many states. Importantly, these two hazards are related: extreme heat can worsen and prolong wildfire risk, which can increase smoke exposure.
Extreme heat and wildfire smoke events are independently becoming more frequent and severe, but what is overlooked is that they are often occurring in the same place at the same time. Emerging research suggests that the combined impact of these hazards may be worse than the sum of their individual impacts. These combined impacts have the potential to put additional pressure on already overburdened healthcare systems, public budgets, and vulnerable communities. Failing to account for these combined impacts could leave communities unprepared for these extreme weather events in 2025 and beyond.
To ensure resilience and improve public health outcomes for all, policymakers should consider the intersection of wildfire smoke and extreme heat at all levels of government. Our understanding of how extreme heat and wildfire smoke compound is still nascent, which limits national and local capacity to plan ahead. Researchers and policymakers should invest in understanding how extreme heat and wildfire smoke compound and use this knowledge to design synergistic solutions that enhance infrastructure resilience and ultimately save lives.
Intersecting Health Impacts of Extremely Hot, Smoky Days
Wildfire smoke and extreme heat can each be deadly. As mentioned, exposure to extreme heat causes the premature deaths of an estimated 10,000 people in the U.S. a year. Long-term exposure to extreme heat can also worsen chronic conditions like kidney disease, diabetes, hypertension, and asthma. Exposure to the primary component of wildfire smoke, known as fine particulate matter (PM2.5), contributes to an additional estimated 16,000 American deaths annually. Wildfire smoke exacerbates and causes various respiratory and cardiovascular effects along with other health issues, such as asthma attacks and heart failure, increasing risk of early death.
New research suggests that the compounding health impacts of heat and smoke co-exposure could be even worse. For example, a recent analysis found that the co-occurrence of extreme heat and wildfire smoke in California leads to more hospitalizations for cardiopulmonary problems than on heat days or smoke days alone.
Extreme heat also contributes to the formation of ground-level ozone. Like wildfire smoke, ground-level ozone can cause respiratory problems and exacerbate pre-existing conditions. This has already happened at scale: during the 2020 wildfire season, more than 68% of the western U.S. – about 43 million people – were affected in a single day by both ground-level ozone extremes and fine particulate matter from wildfire smoke.
Impacts on Populations Most Vulnerable to Combined Heat and Smoke
While extreme heat and wildfire smoke can pose health risks to everyone, there are some groups that are more vulnerable either because they are more likely to be exposed, they are more likely to suffer more severe health consequences when they are exposed, or both. Below, we highlight groups that are most vulnerable to extreme heat and smoke and therefore may be vulnerable to the compound impacts of these hazards. More research is needed to understand how the compound impacts will affect the health of these populations.
Housing-Vulnerable and Housing-Insecure People
Access to air conditioning at home and work, tree canopy cover, buildings with efficient wildfire smoke filtration and heat insulation and cooling capacities, and access to smoke centers are all important protective factors against the effects of extreme heat and/or wildfire smoke. People lacking these types of infrastructure are at higher risk for the health effects of these two hazards as a result of increased exposure. In California, for example, communities with lower incomes and higher population density experience a greater likelihood of negative health impacts from hazards like wildfire smoke and extreme heat.
Outdoor Workers
Representing about 33% of the national workforce, outdoor workers — farmworkers, firefighters, and construction workers — experience much higher rates of exposure to environmental hazards, including wildfire smoke and extreme heat, than other workers. Farmworkers are particularly vulnerable even among outdoor workers; in fact, they face a 35 times greater risk of heat exposure death than other outdoor workers. Additionally, outdoor workers are often lower-income, making it harder to afford protections and seek necessary medical care. Twenty percent of agricultural worker families live below the national poverty line.
Wildfire smoke exposure is estimated to have caused $125 billion in lost wages annually from 2007 to 2019 and extreme heat exposure is estimated to cause $100 billion in wage losses each year. Without any changes to policies and practice, these numbers are only expected to rise. These income losses may exacerbate inequities in poverty rates and economic mobility, which determine overall health outcomes.
Pregnant Mothers and Infants
Extreme heat and wildfire smoke also pose a significant threat to the health of pregnant mothers and their babies. For instance, preterm birth is more likely during periods of higher temperatures and during wildfire smoke events. This correlation is significantly stronger among people who were simultaneously exposed to extreme heat and wildfire smoke PM2.5.
Preterm birth comes with an array of risks for both the pregnant mothers and baby and is the leading cause of infant mortality. Babies born prematurely are more likely to have a range of serious health complications in addition to long-term developmental challenges. For the parent, having a preterm baby can have significant mental health impacts and financial challenges.
Children
Wildfire smoke and extreme heat both have significant impacts on children’s health, development, and learning. Children are uniquely vulnerable to heat because their bodies do not regulate temperatures as efficiently as adults, making it harder to cool down and putting their bodies under stress. Children are also more vulnerable to air pollution from wildfire smoke as they inhale more air relative to their weight than adults and because their bodies and brains are still developing. PM2.5 exposure from wildfires has been attributed to neuropsychological effects, such as ADHD, autism, impaired school performance, and decreased memory.
When schools remain open during extreme weather events like heat and smoke, student learning is impacted. Research has found that each 1℉ increase in temperature leads to 1% decrease in annual academic achievement. However, when schools close due to wildfire smoke or heat events, children lose crucial learning time and families must secure alternative childcare.
Low-income students are more likely to be in schools without adequate air conditioning because their districts have fewer funds available for school improvement projects. This barrier has only been partially remedied in recent years through federal investments.
Older Adults
Older adults are more likely to have multiple chronic conditions, many of which increase vulnerability to extreme heat, wildfire smoke, and their combined effects. Older adults are also more likely to take regular medication, such as beta blockers for heart conditions, which increase predisposition to heat-related illness.
The most medically vulnerable older adults are in long-term care facilities. There is currently a national standard for operating temperatures for long-term care facilities, requiring them to operate at or below 81℉. There is no correlatory standard for wildfire smoke. Preliminary studies have found that long-term care facilities are unprepared for smoke events; in some facilities the indoor air quality is no better than the outdoor air quality.
Challenges and Opportunities for the Healthcare Sector
The impacts of extreme heat and smoke have profound implications for public health and therefore for healthcare systems and costs. Extreme heat alone is expected to lead to $1 billion in U.S. healthcare costs every summer, while wildfire smoke is estimated to cost the healthcare system $16 billion every year from respiratory hospital visits and PM2.5 related deaths.
Despite these high stakes, healthcare providers and systems are not adequately prepared to address wildfire smoke, extreme heat, and their combined effects. Healthcare preparedness and response is limited by a lack of real-time information about morbidity and mortality expected from individual extreme heat and smoke events. For example, wildfire smoke events are often reported on a one-month delay, making it difficult to anticipate smoke impacts in real time. Further, despite the risks posed by heat and smoke independently and when combined, healthcare providers are largely not receiving education about environmental health and climate change. As a result, physicians also do not routinely screen their patients for health risk and existing protective measures, such as the existence of air conditioning and air filtration in the home.
Potential solutions to improve preparedness in the healthcare sector include developing more reliable real-time information about the potential impacts of smoke, heat, and both combined; training physicians in screening patients for risk of heat and smoke exposure; and training physicians in how to help patients manage extreme weather risks.
Challenges and Opportunities for Federal, State, and Local Governments
State and local governments have a role to play in building facilities that are resilient to extreme heat and wildfire smoke as well as educating people about how to protect themselves. However, funding for extreme heat and wildfire smoke is scarce and difficult for local jurisdictions in need to obtain. While some federal funding is available specifically to support smoke preparedness (e.g., EPA’s Wildfire Smoke Preparedness in Community Buildings Grant Program) and heat preparedness (e.g. NOAA NIHHIS’ Centers of Excellence), experts note that the funding landscape for both hazards is “limited and fragmented.” To date, communities have not been able to secure federal disaster funding for smoke or heat events through the Public Health Emergency Declaration or the Stafford Act. FEMA currently excludes the impacts on human health from economic valuations of losses from a disaster. As a result, many of these impacted communities never see investments from post-disaster hazard mitigation, which could potentially build community resilience to future events. Even if a declaration was made, it would likely be for one “event”, e.g. wildfire smoke or extreme heat, with recovery dollars targeted towards mitigating the impacts of that event. Without careful consideration, rebuilding and resilience investments might be maladaptive for addressing the combined impacts.
Next Steps
The Wildland Fire Mitigation and Management Commission report offers a number of recommendations to improve how the federal government can better support communities in preparing for the impacts of wildfire smoke and acknowledges the need for more research on how heat and wildfire smoke compound. FAS has also developed a whole-government strategy towards extreme heat response, resilience, and preparedness that includes nearly 200 recommendations and notes the need for more data inputs on compounding hazards like wildfire smoke. Policymakers at the federal level should support research at the intersection of these topics and explore opportunities for providing technical assistance and funding that builds resilience to both hazards.
Understanding and planning for the compound impacts of extreme heat and wildfire smoke will improve public health preparedness, mitigate public exposure to extreme heat and wildfire smoke, and minimize economic losses. As the overarching research at this intersection is still emerging, there is a need for more data to inform policy actions that effectively allocate resources and reduce harm to the most vulnerable populations. The federal government must prioritize protection from both extreme heat and wildfire smoke, along with their combined effects, to fulfill its obligation to keep the public safe.
Understanding and planning for the compound impacts of extreme heat and wildfire smoke will improve public health preparedness, mitigate public exposure to extreme heat and wildfire smoke, and minimize economic losses.
This strategy provides specific, actionable policy ideas to tackle the growing threat of extreme heat in the United States and was co-signed by more than 60 labor, industry, health, housing, environmental, academic and community associations and organizations.
Extreme heat has become a national economic crisis: lowering productivity, shrinking business revenue, destroying crops, and pushing power grids to the brink. The impacts of extreme heat cost our Nation an estimated $162 billion in 2024 – equivalent to nearly 1% of the U.S. GDP.
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