Mixing and Sink Effects of Air Purifiers on Indoor PM2.5 Concentrations: A Pilot Study of 8 Residential Homes in Fresno, California

In each home, we used a real-time monitor to log PM2.5 levels every 5 min over 12 weeks during which air purifiers were operating, except for a designed 3-day shutdown period for baseline measurements.

We assessed how the operation of air purifiers changed the patterns of the frequency distributions for short-term (5-min) concentrations, which included spikes produced by sporadic indoor activities or emissions. This allowed us to examine the reduction effectiveness of air purifiers on concentrations of both recently-emitted and well-mixed background aerosols. We observed a systematic change in the 5-min PM2.5 distributions in different homes - while air purifiers reduced 96% of the 5-min concentrations, they increased the magnitudes of the top 4%, representing transient concentration peaks.