A state-of-the-air review of Do-It-Yourself (DIY) air cleaner performance

Evidence linking exposures to air pollutants and a range of acute and chronic adverse health effects has been well-established. Vulnerable populations are particularly susceptible to the adverse health effects of indoor air pollution as they spend more time in the home environment, where levels of air pollutants can be 2 to 5 times higher than those outdoors, depending on specific indoor sources and environmental conditions. A substantial body of literature has reported that portable air cleaners equipped with high-efficiency particulate air (HEPA) filters can indeed reduce particulate matter (PM) concentrations and improve health outcomes or biomarkers. In recent years, do-it-yourself (DIY) air cleaners have emerged as low-cost alternatives to commercially available PACs, especially during the COVID-19 pandemic and wildfire events. These DIY air cleaners can be typically made from a box fan and furnace filter(s). Although DIY air cleaners have been proven effective in reducing PM in several experimental studies, research has not yet examined the interactions among design parameters such as configuration, filter and fan selection, shroud, and more. We reviewed the literature to date on the performance of DIY air cleaners across different design parameters and found out that more filters, higher ratings generally improved clean air delivery rate (CADR). Additionally, among the various designs, the 5×1 configuration demonstrated the highest CADR and cost-effectiveness, although the available data remain limited.