10th International Aerosol Conference September 2 - September 7, 2018 America's Center Convention Complex St. Louis, Missouri, USA
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Deployment of Low-cost Sensors to Assess the Impacts of Portable Air Filtration on Indoor PM2.5 and Associated Personal Exposure
KAROLINE JOHNSON, Christina Norris, Tongshu Zheng, Michael Bergin, James Schauer, Junfeng Zhang, Yinping Zhang, Duke University
Abstract Number: 1392 Working Group: Low-Cost and Portable Sensors
Abstract In highly polluted Chinese cities, air purifiers are used in an attempt to reduce exposure to air pollution. The impacts of air purifiers on indoor air quality, personal exposure, and the resulting health impacts can differ greatly depending on a number of factors including the purifier selected, participant behavior patterns, home design, and indoor sources of pollutants. During this study, forty-three asthmatic children were recruited from around suburban Shanghai. Portable air filtration devices were installed in the children’s bedrooms and operated as true purifiers for 2 weeks and as sham purifiers (without the filter media installed) for 2 weeks. During the project, participants were instructed to keep the windows and doors in the room closed. Air quality sensor packages were installed in each child’s bedroom, and outside ~50% of the homes. Sensor packages contained Plantower sensors for fine particulate matter (PM2.5) and Alphasense sensors for ozone (O3). About 80% of the child participants carried a personal monitoring bag for a 48-hour period during both true and sham filtration. Air quality and health monitoring occurred from February until April of 2017. Ambient PM2.5 and O3 concentrations from a nearby monitoring site varied over this 3-month time period with concentrations averaging 56 µg m-3 for PM2.5 and 81 ppb for O3. Since ambient pollutant concentrations varied over the project and indoor concentration and personal exposure are typically a function of outdoor concentration, purifier performance has been evaluated by comparing indoor to outdoor (I/O) ratios and personal to outdoor ratios during true and sham filtration. Preliminary results show average PM2.5 indoor to outdoor ratios below 1 during sham filtration (I/O = 0.6) and lower ratios during true filtration (I/O = 0.2). Purifiers appear to have lowered indoor to outdoor PM2.5 ratios by roughly 70%. Forty homes had successful indoor monitoring and all but two homes saw reductions of indoor to outdoor ratios of >30%. Reductions in PM2.5 personal exposure to outdoor ratios decreased by roughly 30% on average. Further analyses highlight the microenvironments that were the highest contributors to personal exposure. The purifiers do not appear to reduce indoor O3. The results of this project provide important information on the impacts of portable air filtration on children’s exposure in China.