Furnace Air Filter Replacement Practices and Implications for Indoor Air Quality: A Pilot Study

Utah typically experiences 18 days with high fine particulate matter (PM_2.5) levels exceeding the National Ambient Air Quality Standards per year. In August of 2022, Salt Lake City Mayor Erin Mendenhall convened an Indoor Air Quality Summit, during which experts in healthcare, industrial hygiene, and atmospheric science, among others, expressed the need to prioritize indoor air quality interventions more within the state. We conducted a furnace filter exchange pilot project that involved 11 families in Salt Lake City’s Westside. These families completed a survey regarding air quality-related concerns while researchers took air quality measurements—both inside and outside the residence. The goals of this pilot study were to gather data about the participants’ indoor and outdoor air quality perceptions, how frequently they changed their home air filters, and any barriers they experienced. In addition, this study developed a proof of concept demonstrating collecting preliminary indoor and outdoor air quality data and furnace filter deposition information alongside the survey. The survey results were limited by a small sample size (11 participants); however, among those sampled we found that residents are acutely concerned about outdoor air quality but are less worried about indoor air quality. We measured substantially lower indoor PM_2.5 levels compared to ambient air and found a wide range of filter replacement times from those less than a month to over two years. Our research team learned not only about indoor air quality conditions and resident perceptions, but also about the needs of community members including access to filters, health education, and the need to allow more time to build trust between researchers and residents.