Effectiveness of Do-it-Yourself Air Cleaners in Reducing Exposure to Respiratory Aerosols in Us Classrooms: A Longitudinal Study of K-12 Schools

Abstract

Poor indoor air quality (IAQ) harms student health and cognitive performance. Air filtration serves to reduce concentrations of particles in indoor environments. We have characterized the performance of Do-It-Yourself air filtration units in K-12 public schools in Arizona and Connecticut during the 2022-23 school year. We monitored indoor air quality in 53 classrooms across 5 schools in two states over a six-month period. Measurements of decay rates of aerosol particles smaller than 2.5 microns emitted into classrooms during periods with and without the air cleaners allowed for determination of the effective air changes per hour (ACHe) and apparent clean air delivery rate (CADR). Averaging across all schools and classrooms in the sample over the study duration, we observed a 43.3% reduction in PM2.5 concentrations and 30.6% reduction in PM10 concentrations. We found an average Clean Air Delivery Rate (CADR) of 239 ft3min-1 (range of 101 - 355 ft3min-1) across our sample classrooms. This study suggests that the addition of a DIY air filtration unit effectively improves indoor particle control in school classrooms across a diverse sample of geographic locations and building types, including naturally and mechanically ventilated learning environments.

Keywords: Public health, Ventilation, indoor air quality, Filtration