Effectiveness of Air Filtration in Reducing PM_2.5 Exposures at a School in a Community Heavily Impacted by Air Pollution

Abstract

Reducing children’s exposure to air pollution is a priority among California communities heavily impacted by air pollution exposures. We conducted an observational air quality study at a school to investigate the effectiveness of improved Heating, Ventilation, and Cooling (HVAC) system filters and portable air cleaners (PACs) in reducing children’s exposure to fine particulate matter (PM2.5) under real-world classroom conditions. This study included five classrooms, three of which had PACs. Halfway through the study period, high-efficiency HVAC filters were installed in all five classrooms. Continuous measurements of outdoor and in-classroom PM2.5 concentrations were used to evaluate filtration effectiveness. The air filtration strategies, alone and in combination, demonstrated 14–56% reductions in indoor PM2.5 concentrations compared to outdoor levels. There were significant improvements in filtration resulting from HVAC filter upgrades in the two classrooms without PACs (11% and 22% improvement, p 2 data, as a proxy for ventilation, helped demonstrate that the observed filtration effectiveness was likely impacted by the variable HVAC system use and open doors.

Keywords

• indoor air quality
• schools
• particulate matter
• air filtration