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How to Get — Or Make — a Free Or Low-Cost Air Purifier For Your Home

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Smoke from the Camp Fire blankets the Bay Bridge and the city of San Francisco on November 13, 2018. (Samantha Shanahan/KQED)

Bay Area residents have navigated hazardous smoke each year since 2017. At this point, “smoke days” are expected.

This year is no exception. Wildfires are burning across Northern California, producing noxious air that covers large swaths of the state, forcing people to evacuate or spend weeks inside to spare their lungs.

To keep that indoor air clean, it’s crucial to limit additional contaminants, like gas from stoves, fumes from scented candles, and outdoor air that may sneak in through leaky windows or exhaust fans. It’s also important to clean that indoor air. The best way to do this is with an air purifier or, if you have in-home air filtration, upgrading the filters you use in your system.

But preparation — including acquiring air purifiers — is expensive and largely left up to individuals, says Amee Raval, policy and research director at the environmental justice organization Asian Pacific Environmental Network.


There are very few programs run by state and local governments to help people secure air purifiers.

“We’re told every year, that preparedness means going out and spending hundreds of dollars on air purifiers,” Raval said.

“These individual approaches are based on how much money you have and worsen the divide between people who have the means to spend hundreds of dollars on equipment and people who don’t,” Raval said.

“Right now the government and county run approaches are largely failing us,” she said.

Until we address the root causes of these extreme fires (a century of fire suppression and warming temperatures driven by burning fossil fuels to start), individuals, community groups and governments must adapt.

We asked counties, government agencies, and community-based organizations about programs that provide free or discounted assistance to help people attain cleaner indoor air when the smoke hits. Here’s what we found.

Where are the programs?

Counties and state agencies point to the Bay Area Air Quality Management District’s new Clean Air Filtration Program. The district will spend $350,000 to provide 3,000 portable air purifiers to mostly people with respiratory illnesses. The program will prioritize low-income areas and residents, and install larger air purifiers at homeless shelters and cooling centers. The regulator’s goal is to distribute all air purifiers before the end of this fire season, and to expand the program.

The California Air Resources Board doesn’t offer free air filters but intends to spend $5 million to help communities upgrade ventilation systems and purchase portable air cleaners for cooling centers this year.

While this is a start, the scope of these programs are limited.

A Roots Community Health Program flyer advertises a program in which it partners with the Bay Area Air Quality Management District. One aspect of this program involves receiving a free air purifier for your home.
A Roots Community Health Program flyer advertises an air filter partner program with the Bay Area Air Quality Management District.

Julia Hatton, CEO at Rising Sun Center for Opportunity, a workforce development organization that helps people make their homes more climate resilient, says there are a lot of programs that will measure air quality in local communities. “But they don’t necessarily offer any solutions for the residents of those communities,” Hatton said.

She says many conversations around air quality are focused on installing air quality monitors in homes, “which is great. But if someone finds out their indoor air quality is really bad and they don’t have the ability to address that issue or leave the house, you’re not really contributing to a solution.”

Hatton says distributing air purifiers could be straightforward for programs like hers, which regularly provide other energy upgrades and could include air purifiers in their services. Funding, she says, is another story.  She’d like to see financial support come from the entities responsible for sparking some of the state’s wildfires, like PG&E, or local or state air districts.

The nonprofit organization, Association for Energy Affordability, also focuses on energy efficiency and healthy housing, centering their work in low-income communities. Andy Brooks is senior director of the West Coast office and agrees more programs are needed to secure air purifiers for communities around the Bay Area, “everyone in my space talks about it all the time,” he said.

A reason there are not more programs providing air purifiers or other filtration, he says, is that a lot of funding for housing improvements comes from utilities and must be tied to energy efficiency. Air purifiers do not fall into that category.

Brooks says collaboration between the Bay Area’s air district and organizations like his could address both energy and carbon use in residences, as well as health.

Counties reported few resources for people seeking free or discounted air purifiers, apart from the air district’s program. Several suggested people seek a respite from poor indoor air quality by going to public centers with strong air systems. But during a pandemic, community centers can be a hard sell, and put people at more risk of exposure to COVID-19.

“Clean air respite centers, or cooling centers, are largely being underutilized,” Raval said. “And that’s because the solutions aren’t being designed with the leadership and partnership of community residents and advocates in mind.”

Raval says working with community groups will help better get the word out and build trust in centers like these, which are a good way to serve the community as a whole.

State and local counties do have some initiatives addressing cleaning up air in people’s homes, such as weatherization programs for people with low or fixed incomes.

While “weatherizing” a home includes things like installing carbon monoxide filters and water-saving devices, it also involves improvements that will keep dangerous particulates out of your house, says Michael Kent, hazardous materials ombudsman at Contra Costa Health Services. Improvements like sealing cracks, replacing damaged windows, and putting weatherstripping around drafty windows or doors.

California’s Department of Community Services and Development also has weatherization programs, including the federally funded Low Income Home Energy Assistance Program (LIHEAP) and Weatherization Assistance Program (WAP), and the state cap-and-trade funded Low-Income Weatherization Program (LIWP). All three programs are available for low-income households at no cost.

Resources run by local government

The Clean Air Filtration Program

Supply: 3,000 air purifiers for Bay Area counties, plus larger purifiers for shelters and emergency centers.

Who’s it for: Medi-Cal patients and undocumented people without Medi-Cal. Most people who will qualify must have “moderate to severe” or “poorly controlled” asthma and be enrolled in the state’s Asthma Mitigation Project.

How to access: Email the air district: airfilters@baaqmd.gov. Note: the process could take several weeks, according to partner organizations.

Resources run by community organizations

Several community-based organizations are building or providing materials and training for people to make their own air purifiers out of a box fan and filter.

One of them is the East Oakland-based community organization Homies Empowerment. The nonprofit already provides free food, toiletries, diapers and other basics at their FREEdom Store. In September of last year, customers said they were struggling to breathe. So the Homies Empowerment team added air purifiers to their offerings.

“We took matters into our own hands and we did it do-it-yourself, DIY, style,” one of the group’s founders, César Cruz, said. The organization raised money to purchase a hundred fans and air filters. “They went like hotcakes,” he said.

This year, the group is partnering with Ace Makerspace, to bring the community 500 DIY air purifier kits.

Community-based organizations providing air purifiers:

Homies Empowerment

Supply: 500 DIY air purifier kits, with instructions in various languages.

Who’s it for: “You can be from anywhere,” Cruz said.

How to access: Air purifier kits will be at the FREEdom Store, 7631 MacArthur Blvd., Oakland, CA 94605. The store is open on Tuesdays from 10 a.m. – 3 p.m.

North Fair Oaks Community Alliance

Supply: 40 DIY air purifier kits.

Who’s it for: Priority for residents of North Fair Oaks in San Mateo County, a community of roughly 4,200 households.

North Fair Oaks Community Alliance President Ever Rodriguez said “ideally, we would like to open it up to the surrounding communities. If more resources are available, we will be happy to continue giving those out to our surrounding neighbors.”

How to access: Contact North Fair Oaks Community Alliance directly. Purifier kits available in September.

Brightline Defense

Supply: 20 DIY air purifiers, and workshops on assemblage and use.

Who’s it for: SRO tenants anywhere in San Francisco, with a focus on SRO tenant leaders from Central City SRO Collaborative. The DIY purifiers are intended to be shared between tenants, as SRO rooms are small, and air can be cleaned relatively quickly.

How to access: Contact Brightline Defense directly.

How to make your own air purifier

Not able to access an air purifier through any of the narrow means above? No problem. You can make your own:


      1. A new, 20″ box fan (the cord should come out of the bottom, not the center)
      2. A 20″ x 20″ MERV 12 or 13 furnace/HVAC filter
      3. Heavy-duty tape (clear plastic or duct tape)


      1. Place the MERV filter on the back of the fan (the filter can be put on the front too, but can stress the motor).
      2. Make sure the filter is facing the correct direction for air to flow through.
      3. Tape around the edges, making a seal between the box fan and the filter.

Cost: roughly $40

The makeshift devices are “not rocket science,” but are effective, said Jose-Luis Jimenez, a chemistry professor at the University of Colorado Boulder. He’s been looking into how Do-It-Yourself purifiers can help filter air from both COVID-19 and wildfire smoke.

He points to a peer-reviewed study out of Singapore, which found similar DIY air filters removing around 75% of particulate matter.

The purifiers in that study pulled air from outside, something doctors and scientists recommend avoiding when thick wildfire smoke infiltrates indoors. Instead, they say, it’s better to keep the windows closed and to focus on cleaning the air that’s already in your home.

It’s also more effective to clean the air in a limited area, says Theresa Pistochini, engineering manager at the UC Davis Western Cooling Efficiency Center.

“You want a smaller, enclosed space,” she said. “Like a bedroom that you’re trying to drop the smoke levels in. When [the smoke] was really bad, a couple of us were sleeping in one room, so we could manage to filter better,” she said, referring to her experience during the 2018 Camp Fire.

Tips for your DIY filter

  1. Use a MERV 12 or 13 filter. HEPA filters are stronger but their thickness could cause the box fan to overheat or fail. Placing the filter on the back of the fan reduces the filtration a little, but is recommended over placing the filter on the front, which can tax the motor more.
  2.  Purchase box fans at a local hardware store or larger retailer. If filters are harder to find, try Filter Buy, Target, or Home Depot.
  3. Don’t leave the DIY purifier unattended, it could become a fire hazard.
  4. Place the DIY purifier in the middle of the room at a height midway between the floor and the ceiling.
  5. DIY air purifiers are a short-term solution, for a few months or “until it’s visibly obstructed with smoke or dirt” Pistochini said.


Joe Fitzgerald Rodriguez contributed reporting to this post.

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