Do-It-Yourself Air Filters Improve Air Quality in Area Homes

As the saying goes, “If you want to go fast, go alone. If you want to go far, go together.” The greater Pittsburgh region is blessed with a large number of nonprofit organizations and grassroots initiatives in a variety of communities, which proves to be a fantastic testing ground for collaborative approaches to addressing inequality. One such collaboration sought to improve indoor air quality on a budget, particularly for families living in low-income Pittsburgh neighborhoods. It is a sad truth that poor air quality, a common feature of life in Pittsburgh, disproportionately impacts low-income and minority communities, many of whom cannot afford expensive air sealing or air filtration systems to keep their homes healthy.

Photo by Matt Niemi via Flickr

The “Grassroots Green Homes” program, managed by EHP executive director Alison Steele when she worked for Pittsburgh-area nonprofit Conservation Consultants Inc. (CCI), was designed to work through existing community networks to educate residents about basic building science principles that sit at the intersection of energy efficiency, air quality, and health. The program also provided low-cost, do-it-yourself tools and guidance to help these residents improve the comfort and health of their homes. Grassroots Green Homes called on the expertise of Reducing Outdoor Contaminants in Indoor Spaces (ROCIS), another local initiative and longstanding partner of EHP, to provide guidance and evaluate data collection related to indoor air quality.

What Can You Do About Your Air Quality?

Indoor air quality matters because long-term exposure to particulate levels in the air has been linked to a host of health problems, including asthma, COPD, heart disease, lung cancer, and increased symptom severity from infectious lung diseases, like COVID-19. Houses (even newer ones) tend to be draftier than most residents realize, meaning that if there are pollutants in the air outside, some of them will be coming inside. Ultimately, poor outdoor air quality results in poor indoor air quality, and for areas like Allegheny County, which consistently tops the list as having some of the worst air quality in America, the outcome is a greater health burden for our residents.

For several years, EHP has promoted the do-it-yourself air filter designed and distributed by ROCIS. This device combines a 20”x20” box fan and a 4” MERV13 furnace filter to reduce particles in the air, making a much more affordable option than high-end air filtration systems that can cost in the hundreds of dollars. Grassroots Green Homes used these DIY filters and air quality monitors from ROCIS to measure the impacts of various healthy homes interventions on particulate levels (PM2.5) in participants’ homes.

In one round of the program, three monitors were placed at participants’ homes for two-week periods. One monitor was placed on the first floor (typically the living room), one was placed on the second floor (typically a bedroom), and one was placed in a covered location outside. Because Pittsburgh’s housing stock is typically very old and drafty, it is common to see similar spikes in particle counts when pollutants in outside air come inside. Placing a monitor outside helps to reveal if particle spikes on indoor monitors were related to outside conditions (such as a poor air quality day) or occupant activities (such as cooking, cleaning, or smoking).

During the monitoring period, the first week served as a baseline of activity and particle counts without the DIY air filter. During the second week, the DIY air filter was added to one of the rooms where a monitor was located. Participants were asked to run it constantly during the week, though there was no way to confirm how often it was used. After the two weeks, the team collected the monitors, examined the data, and summarized the results for the participants.

The Proof Is In the Particulates

A visual readout provided in the reports showed the percentage of time each monitor recorded PM2.5 values across six different levels, ranging from excellent to very poor. Two graphs, presented side by side, compared air quality conditions during Weeks 1 and 2, respective, demonstrating how air quality changed with the addition of the DIY air filter. In the example below, even though the outdoor air quality was worse in Week 2 for a larger percentage of the time, the indoor air was better for a larger percent of the time, and by a significant amount. The amount of time in the “good,” “very good,” and “excellent” range was about 20-30% during Week 1 and about 80-90% during Week 2. There were several examples like this one across the cohort of participants, reinforcing the apparent benefit of using the device to improve air quality. Some homes chose not to use the DIY filter, and the resulting graphs for Weeks 1 and 2 looked more similar in their reports, as indoor particle levels tracked more closely with outside levels.

EHP values the work that ROCIS has done in this area to bring useful, low-cost tools to communities that need them. To that end, EHP has also promoted the use of these devices for years on our website and with our own video tutorial. While Grassroots Green Homes only examined these conditions in city neighborhoods, people anywhere can benefit from cleaning the air in their homes, particularly if they live close to a pollution source.

COVID-19 Disclaimer: Air filtration alone will not stop the spread of COVID-19 and must be used in conjunction with all other CDC guidance on mitigating the spread of COVID-19, including wearing masks, avoiding large groups, maintaining social distance, practicing proper hygiene, disinfecting surfaces, isolating when symptomatic, and immunization. Fans should be avoided in the presence of people not a part of your household to prevent spread from person to person. As knowledge around the COVID-19 pandemic is constantly evolving, be sure to follow up-to-date guidance from your local, state, and federal health officials.