Portable HEPA air filtration effects on particulate matter, radioactivity, and chemical constituents in occupied homes

Although in-home air cleaners are known to reduce particulate matter (PM) concentrations, their effects on PM chemical constituents and particle-bound radioactivity (PR) under real-world residential conditions remain poorly characterized. We evaluated the effects of a portable high-efficiency particulate air (HEPA) cleaner on particle mass, chemical composition, and particle-bound radioactivity in occupied homes. We collected 86 indoor samples from 19 homes in the Boston metropolitan area between June 2017 and March 2018. Measurements included size-resolved PM fractions (PM 2.5 , PM 10–2.5 , and > PM 10 ), short-lived α activity (SLA) and long-lived α activity (LLA) associated with PM 2.5 , elemental composition, black carbon (BC), and a biomass-burning/cooking surrogate (DC). HEPA operation substantially reduced indoor particle concentrations, with mean decreases of 3.7, 1.0, and 0.5 µg/m 3 for PM 2.5 , PM 10–2.5 , and >PM 10 , corresponding to removal efficiencies of approximately 60, 37, and 32%, respectively. LLA decreased by 0.68 mBq/m 3 , corresponding to a 63% removal efficiency ( p