Wildland Fire Research: Reducing Exposures

Wildland fire smoke is a major public health issue. EPA’s 2020 National Emissions Inventory estimated 52% of the total PM_2.5 emitted in the U.S. was from wildland fires. As wildfire smoke continues to impact the health of people across the United States, state agencies and community leaders want to know how best to educate and prepare residents on ways to reduce their smoke exposure and protect their health.

On this page:

• Wildfire Advancing Science Partnerships for Indoor Reductions of Smoke Exposures (ASPIRE) Study
  • Field Studies: Indoor and Outdoor Concentrations
  • Lab Studies: Low-Cost Indoor Air Cleaners
  • Field Studies: Low-Cost Indoor Air Cleaners
  • Challenge: Cleaner Indoor Air During Wildfires
  • Wildfire Smoke Guidance for Building Managers
• Smoke Sense
• Smoke Ready Communities
• Research Grants: Interventions and Communications Strategies to Reduce Health Risk
• Future Directions​

Wildfire Advancing Science Partnerships for Indoor Reductions of Smoke Exposures (ASPIRE) Study

Communities can be exposed to smoke from wildland fires for days, weeks, or even months each year. This smoke exposure can lead to increased health risks. To reduce exposure, a common recommendation is to stay indoors and close all windows and doors, but wildland fire smoke can infiltrate indoors. What actions can be most effective for building owners and the public to reduce health risks during smoke events?

EPA researchers applied the principles of solutions-driven research, an approach that emphasizes working directly with stakeholders to develop solutions. Find out more about the Wildfire ASPIRE Study.

Lessons learned and recommendations in conducting solutions-driven environmental and public health research (2024)

Field Studies: Indoor and Outdoor Concentrations

Are do-it-yourself (DIY) air cleaners safe and effective in a laboratory setting?

EPA researchers tested of the effectiveness and safety of low-cost, accessible, DIY air cleaners in improving indoor air quality during wildfire smoke events. Find out more about EPA Research on DIY Air Cleaners to Reduce Wildfire Smoke Indoors.

Lab Studies: Low-Cost Indoor Air Cleaners

Are do-it-yourself (DIY) and commercial portable air cleaners effective in a real-world setting?

Researchers measured indoor and outdoor PM_2.5, indoor CO₂, and main door activity in homes on the Hoopa Valley Indian Reservation during 8 wildfire and 11 woodstove pilot studies. Low-cost DIY portable air cleaners can reduce infiltrated and indoor-generated smoke (as quantified by PM2.5) in residences at least as effectively as a commercial PAC with a similar Clean Air Delivery Rate.

For public health and local air quality agencies, an important takeaway is that PAC efficacy and usage depend on support for filter replacement (frequent filter changes may be needed during smoke events) and that quiet, unobtrusive designs are more likely to be used.

Find out more about EPA Research on DIY Air Cleaners to Reduce Wildfire Smoke Indoors.

EPA Science Matters: Multi-faceted EPA Research Addressing Threats to Public Health from Wildfire Smoke

Field Studies: Low-Cost Indoor Air Cleaners

How do building characteristics and heating, cooling, ventilation and air conditioning (HVAC) systems influence indoor PM_2.5 concentrations during smoke events?

EPA researchers, in partnership with Missoula Public Health, measured indoor and outdoor PM_2.5 in public/commercial buildings in and around Missoula, MT. Indoor air quality was only minimally impacted in 2019, but 2020 – with a week of heavy smoke from western wildfires - had much higher outdoor smoke concentrations. The study found large PM_2.5 reduction variability among study buildings and identified HVAC operation and maintenance characteristics that likely influenced indoor PM_2.5 concentrations.

To prevent unhealthy smoke concentrations indoors, particularly in areas where wildfire smoke is more common, HVAC maintenance (e.g., replacing dirty filters, repairing dampers) is crucial. Also important is modifying the HVAC system (e.g., increasing the filter MERV rating), improving building weatherization, and managing door and window use.

Influence of Building Characteristics on Wildfire Smoke Impacts on Indoor Air Quality (2025)

EPA Science Matters: In the Field with EPA: Monitoring the Impact of Wildfires and Woodsmoke on Indoor Air Quality

Challenge: Cleaner Indoor Air During Wildfires

How to encourage the development of new, effective, low-cost technologies that can clean indoor air during wildland fire smoke events?

EPA researchers launched a public prize challenge to spur innovation in developing lower cost approaches to provide clean air during smoke events. Find out more about the Cleaner Indoor Air During Wildfires Challenge.

Wildfire Smoke Guidance for Building Managers

Can we provide plain language strategies that can help communities reduce indoor smoke exposures in commercial, public, and multi-unit residential buildings during wildland fire smoke events?

EPA researchers built upon the knowledge they gained during the field studies in Missoula, MT and Hoopa, CA (including building inspections) and worked with HVAC professionals and ASHRAE (formerly the American Society of Heating, Refrigerating and Air Conditioning Engineers) to develop best practices for reducing smoke exposures in buildings.

EPA’s Best Practices Guide for Improving Indoor Air Quality in Commercial/Public Buildings During Wildland Fire Smoke Events is a concise and complete source of information on reducing the impacts of wildfire smoke indoors in commercial or public buildings. It is for 1) individuals and groups who make decisions regarding public, commercial, and multi-unit residential buildings including building owners and managers, school administrators, and facility managers, and 2) federal, state, local, and Tribal environmental and public health organizations that provide information to communities to reduce exposure to wildland fire smoke in public or commercial spaces.

Wildfires and Indoor Air Quality in Schools and Commercial Buildings

Smoke Sense

During smoke events, what communication is most effective in helping people understand the health risks of smoke exposures and what they can do to protect themselves? Can we improve communication strategies using input from citizen scientists?

EPA’s Smoke Sense was a crowdsourced, citizen science research initiative. The goal was to better understand the health effects of wildland fire smoke and identify effective risk communications strategies. A central component was the Smoke Sense smartphone app, which encouraged public participation. Through the app, users could access current and forecasted air quality information, a map with current fire locations and smoke plumes, and educational information. Users could report personal health symptoms and smoke observations.

Smoke Sense pioneered innovative engagement strategies leveraging smartphone app technologies, interactive data visualization tools, and gamification elements to enhance user participation and comprehension. By making complex scientific information accessible and engaging, we can engage diverse audiences, reach more people, and empower them to make informed decisions on proactive measures that could protect their health during wildfire smoke exposure.

Smoke Ready Communities

How can we improve the ability of communities to plan for and respond to smoke from wildland fires? Does a collaborative approach to planning for future wildfire smoke events influence community public health readiness?

EPA researchers partnered with the U.S. Forest Service on a multidisciplinary project built around a series of interactive workshops with local community public health partners in Butte-Silver Bow, Montana and Garfield County, Colorado. Local teams collectively developed their community smoke response plans. Researchers examined the process of collaboration, specifically the role of community-level influencing factors and early outcomes.

The Smoke Ready Communities research demonstrated the effectiveness of using a collaborative governance approach to strength community resilience to wildfire smoke and to inform the development of a Smoke Ready Communities program. This approach can be used by public health professionals, emergency response organizations, air quality managers and others to assist communities in preparing for wildfire smoke events.

Smoke-Ready Toolbox for Wildfires

EPA Science Matters: Partners Collaborate in Smoke-Ready Communities Research to Enhance Local Readiness for Wildfires

Webinar Recording: Smoke Ready Communities Research Study

Research Grants: Interventions and Communications Strategies to Reduce Health Risk​

How can we engage experts in institutions outside EPA to help understand what actions might be effective for reducing exposures to wildland fire smoke and how best to communicate these actions to various groups?

In 2021, as part of its Science to Achieve Results (STAR) program, EPA funded 12 external research grants to 1) assess the effectiveness of interventions to reduce individual and community exposures and associated health risks from wildland fire smoke and 2) develop and assess the effectiveness of health risk communication strategies in supporting actions to reduce wildland fire smoke exposure. Publications with the research results are available for the 12 projects.

The research findings have helped us understand practical actions that can reduce exposures to wildland fire smoke and better ways to communicate these actions to different groups.

Interventions and Communication Strategies to Reduce Health Risks of Wildland Fire Smoke Exposure

Future Directions

With larger and more intense wildfires, there is a greater potential for smoke production and chronic exposures in the U.S. Effects of smoke from wildfires can range from eye and respiratory tract irritation to more serious disorders, and smoke exposures are known to cause increased visits to hospitals and clinics. Children, pregnant women, and the elderly are especially vulnerable to smoke exposure.

Reducing smoke exposures is critical to mitigating widespread health and environmental consequences. EPA researchers have worked on strategies to communicate, educate, and prepare people who may be at risk to smoke exposure. Smoke Sense, a citizen science mobile phone app, was developed to share real-time fire, smoke, and air quality data, and more than 60,000 users downloaded it to share their experiences with smoke and its impacts on their health.

The ASPIRE study evaluated Do-It-Yourself (DIY) air cleaners to answer questions from EPA partners and the public about their effectiveness and safety. Researchers showed that DIY air cleaners, made with a box fan and MERV 13 air filter(s), were a cost-effective method for reducing indoor smoke concentrations.

• Future research is needed to continue identifying how to best communicate, educate, and prepare people who may be at risk to smoke exposure.
• Future research is needed to continue work in developing and evaluating methods to reduce individual and community air pollution exposures in the coming years.