AAAR 35th Annual Conference October 17 - October 21, 2016 Oregon Convention Center Portland, Oregon, USA
Abstract View
Mixing and Sink Effects of Air Purifiers on Indoor PM2.5 Concentrations: A Pilot Study of 8 Residential Homes in Fresno, California
KAI-CHUNG CHENG, Hye-Kyung Park, Afua O. Tetteh, Yan Zheng, Nicholas T. Ouellette, Kari C. Nadeau, Lynn M. Hildemann, Stanford University
Abstract Number: 143 Working Group: Indoor Aerosols
Abstract We measured real-time and integrated PM2.5 inside 8 occupied single-family homes in Fresno, California to evaluate how turbulent air mixing and pollutant removal caused by a filter-based air purifier influences the levels of fine particles in everyday indoor environments. 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/emissions. This allowed us to examine the reduction effectiveness of air purifiers for different aged aerosols indoors. 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. This phenomenon is consistent with what would be theoretically expected based on passive scalar turbulence in fluid physics. We also collected gravimetric filter samples, finding significant differences in the long-term (2-5 day) concentrations of indoor PM2.5 and endotoxin between the air purifier shutdown and before/after periods. A less significant difference was seen for Pb (Lead).