Real‐time measurements of PM_2.5and ozone to assess the effectiveness of residential indoor air filtration in Shanghai homes

Abstract

Portable air cleaners are increasingly used in polluted areas in an attempt to reduce human exposure; however, there has been limited work characterizing their effectiveness at reducing exposure. With this in mind, we recruited forty‐three children with asthma from suburban Shanghai and deployed air cleaners (with HEPA and activated carbon filters) in their bedrooms. During both 2‐week filtration and non‐filtration periods, low‐cost PM2.5 and O3 air monitors were used to measure pollutants indoors, outdoors, and for personal exposure. Indoor PM2.5 concentrations were reduced substantially with the use of air cleaners, from 34 ± 17 to 10 ± 8 µg/m3, with roughly 80% of indoor PM2.5 estimated to come from outdoor sources. Personal exposure to PM2.5 was reduced from 40 ± 17 to 25 ± 14 µg/m3. The more modest reductions in personal exposure and high contribution of outdoor PM2.5 to indoor concentrations highlight the need to reduce outdoor PM2.5 and/or to clean indoor air in multiple locations. Indoor O3 concentrations were generally low (mean = 8±4 ppb), and no significant difference was seen by filtration status. The concentrations of pollutants and the air cleaner effectiveness were highly variable over time and across homes, highlighting the usefulness of real‐time air monitors for understanding individual exposure reduction strategies.

Impact of Wildfire Smoke Events on Indoor Air Quality and Evaluation of a Low-cost Filtration Method

“…Selected responding locations, which included five residential, one school, and two commercial buildings, served as case studies. In comparison to previous surveys of wildfire impacts on IAQ (Barkjohn et al, 2021;Barn et al, 2008;Kirk et al, 2018;Reisen et 103 al., 2019), we examine a larger sample and more building types, but with less information on building characteristics and occupant behavior, and no examination of chemical composition of pollutants.…”

Development and Application of a United States wide correction for PM<sub>2.5</sub> data collected with the PurpleAir sensor

“…for Plantower sensors and other light scattering measurements (Tryner et al, 2020a;Malings et al, 2019;Chakrabarti et al, 2004;Zheng et al, 2018;Zhang et al, 1994;Day and Malm, 2001;Soneja et al, 2014;Lal et al, 2020;Barkjohn et al, 2020b).…”

Wildfire Smoke Impacts on Indoor Air Quality Assessed Using Crowdsourced Data in California

“…To accurately characterize and reduce population exposures to wildfire PM2.5, it is necessary to understand then optimize how buildings are used by their occupants to mitigate exposure. Previous estimations of indoor particles of outdoor origin typically relied on measurements from a limited number of buildings, and extrapolation of these measurements to other buildings based on the empirical infiltration and removal parameters (12,13). However, such extrapolation is not applicable to wildfire events because it does not take into account the distribution of protection provided by buildings (including natural and mechanical ventilation) due to lack of data measuring infiltration under representative conditions.…”