Public buildings, like schools, libraries, and community centers, can serve as vital cleaner air and cooling spaces during wildfire smoke and extreme heat events. This page outlines simple, effective strategies, such as using portable air cleaners and improving HVAC systems, to reduce indoor air pollution and protect public health. It also highlights key outreach tips and equity considerations to ensure these spaces are accessible to all. Explore the resources below to help prepare and maintain safe indoor environments for your community. Be sure to visit the city planning page for more information on how public buildings can be used as community resilience hubs in times of immediate crisis.
Much like in homes, portable air cleaners can be utilized in other buildings that do not have sufficient built-in HVAC air filtration systems. Furthermore, they can also be an alternative for those who cannot or will not go to a cleaner air center during a wildfire smoke event. However, portable air cleaners tend to be inaccessible to many people due to economic constraints. In that case, a portable air cleaner can be made by attaching a MERV 13 filter to the intake side of a box fan.
In buildings where many people are congregated, portable air cleaners are also effective in reducing infectious disease transmission when masking and/or vaccinations may not be consistent. Coupled with an updated HVAC air filtration system, a building can address smoke intrusion and risk of virus transmission simultaneously to keep community members safe during smoke events.
Many of the resources on the “Keeping Your Household Safe” page are also applicable to public buildings. The following are some of the most helpful resources from that page and includes extra information/considerations specific to public buildings.
Best Practices Guide for Improving Indoor Air Quality in Commercial/Public Buildings: An EPA guide to provide a concise and complete source of information on the steps that can be taken to reduce the impacts of wildfire smoke indoors in commercial or public buildings. These include improving HVAC systems, weatherizing buildings, installing portable air cleaners, establishing cleaner air rooms, and installing indoor air sensors.
Air Quality in Schools and Commercial Buildings : Provides several resources for building owners and managers, school facility managers, public health officials, and emergency managers to reduce smoke concentration in buildings during wildfires.
Choosing an Air Purifier DOH: Provides a simple breakdown about the considerations when choosing an air purifier, other tips for improving your indoor air quality, and additional wildfire smoke resources.
How to Make a DIY Box Fan Air Cleaner: A one-minute instructional video from the Washington Department of Ecology demonstrating how to make your own simple air purifier using a box fan and a MERV filter. This DIY option is a low-cost and effective way to reduce harmful smoke particles in the air.
Evidence review: Home and community clean air shelters to protect public health during wildfire smoke events: Published paper from BC Centre for Disease Control that includes a detailed section with tables about types of air filters, how they work, and pros and cons for each.
Can Public Spaces Effectively Be Used as Cleaner Indoor Air Shelters during Extreme Smoke Events?: This study provides helpful insight into the efficiency of HEPA filters at reducing PM2.5 and their infiltration rate into cleaner air shelters. It provides a concrete example of the effectiveness of cleaner air shelters during a smoke event.
Figure 1. Sources of smoke infiltration during a smoke event (EPA) 1.
Advertising cleaner air spaces across multiple platforms is essential. These can be, but are not limited to:
Each of these modes of communication can reach different demographics across ages, socioeconomic backgrounds, access to technology, and neighborhoods. These advertisements should highlight the location, benefit of use, and resources available at each cleaner air space. Communication methods should also be translated into languages other than English spoken in the area surrounding the cleaner air shelter network. In Spokane, this could include Spanish, Russian, Vietnamese, Marshallese, and others. Advertising the cleaner air centers correctly is crucial to persuading people to go during a smoke event. Emphasize that the space is for everyone, describe what activities or resources are available, and promote if pets are allowed. It should also be noted that the space is equally open to housed and unhoused individuals - having a home does not necessarily mean having adequate air filtration/cooling resources. Some additional amenities that may convince people to use cleaner air or cooling spaces include free Wi-Fi, food, educational opportunities, and the ability to bring a pet with them. A sufficient number of charging stations for electronics or medical devices, movie screenings, and activities for children would also encourage use of a public cooling or cleaner air space.
The buildings being used as cooling or cleaner air spaces will have previously set capacity limits, meaning that not everyone will be able to enter the space if the capacity has already been reached. In this case, the area could benefit from a network of cooling and cleaner air spaces that are in communication with each other. Taking the time to find new arrangements for visitors in need can be lifesaving.
In addition, transportation access to cooling and cleaner air spaces is essential to ensuring the safety and health of those who need them most. Some may have personal vehicles and be able to drive to the space, some may rely on buses, and others may not be able to access either due to age, medical conditions, or other mobility issues. Partnering with a public transportation system to provide free bus fare and paratransit is one strategy to lower barriers to accessing cooling and cleaner air spaces. Some people may not want to leave their homes for a variety of reasons such as distrust, not wanting to leave possessions or a pet, or uncertainty of what the center will be like. Policy can also be used to encourage the use of these spaces or to get cleaner air and cooling to those who cannot relocate. Government programs can be used to subsidize the purchasing of portable air cleaners to supply residences who cannot or will not go to a cooling or cleaner air space.
To ensure all considerations are met, building managers can learn more about how to protect building occupants from smoke during wildfires and follow these 10 key steps for creating building-specific readiness plans:
Purchase smoke preparation supplies
Upgrade HVAC system recirculation filters
Maintain the HVAC system
Optimize system airflows
Prepare to add supplemental filtration
Assess filter conditions
Limit smoke intrusion
Prepare to monitor indoor PM2.5
Determine how to create temporary cleaner air spaces
Anticipate sources of indoor PM2.5
Note: Readiness plans should be tested before heat and smoke season to ensure efficiency and standards can be met. Steps can be adapted to better suit the building's needs, but this general framework is most recommended for cleaner air spaces.
There are also numerous resources for guidance for cleaner air spaces during wildfire smoke events, which generally recommend the following target conditions:
PM2.5 should be kept as low as possible. Indoor levels should be lower than outdoor levels.
Carbon monoxide (CO) should be kept below 10 ppm.
Carbon dioxide (CO2) should be kept below 1000 ppm.
Temperature should be kept below 78°F (28°C).
Relative humidity should be kept between 35 and 50%.
Other pollutants such as nitrogen oxides (NOx), polycyclic aromatic hydrocarbons (PAHs), and volatile organic compounds (VOCs), should also be kept as low as possible.
For more information, the following resources give more insight into creating cleaner air spaces and preparing for these types of extreme events:
Creating Clean Air Spaces During Wildland Fire Smoke Episodes: Web Summit Summary : This article summarizes a recent virtual meeting held by the EPA to share research, experiences, and other information that can inform best practices for creating cleaner air spaces during wildland fire smoke events. The meeting included presentations on the public health impacts of wildland fire smoke; public health agencies' experiences and resilience efforts; and methods to improve indoor air quality.
Preparing for Wildland Fire Smoke Webinar Archive: This webinar covers preparing for wildland fire smoke that can infiltrate indoors, highlighting the ASHRAE Planning Framework for protecting commercial building occupants from smoke during wildfires. The Planning Framework is a publicly available resource developed by government and industry experts that provides building managers for public and commercial buildings, including schools, with advice on steps to reduce smoke exposures that can occur indoors during wildfires and prescribed burning.
Figure 2. The Clean First Framework for Buildings 2.
EPA, Environmental Protection Agency, "Wildfires and Indoor Air Quality in Schools and Commercial Buildings," Last updated on May 29, 2025, www.epa.gov/emergencies-iaq/wildfires-and-indoor-air-quality-schools-and-commercial-buildings#best.
Enverid, "How to Achieve Sustainable Indoor Air Quality: A Roadmap to Simultaneously Improving Indoor Air Quality & Meeting Building Decarbonization and Climate Resiliency Goals," Accessed 23 June 2025, enverid.com/resources/learning/how-to-achieve-sustainable-indoor-air-quality-a-roadmap-to-simultaneously-improving-indoor-air-quality-meeting-building-decarbonization-and-climate-resiliency-goals/.