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Using Low-cost sensors to Quantify the Effects of Air Filtration on Indoor and Personal Exposure Relevant PM2.5 Concentrations in Beijing, China

Category: Urban Air Quality

Article In Press
DOI: 10.4209/aaqr.2018.11.0394

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Karoline K. Barkjohn1, Michael H. Bergin 1, Christina Norris1, James J. Schauer2, Yinping Zhang3, Marilyn Black4, Min Hu5,6, Junfeng Zhang7

  • 1 Department of Civil and Environmental Engineering, Duke University, Durham, NC 27708, USA
  • 2 Department of Civil and Environmental Engineering, University of Wisconsin at Madison, Madison, WI 53706, USA
  • 3 School of Architecture, Tsinghua University, Beijing 100084, China
  • 4 Underwriters Laboratories Inc., Marietta, GA 30067, USA
  • 5 State Key Joint Laboratory of Environmental Simulation and Pollution Control, College of Environmental Sciences and Engineering, Peking University, Beijing 100871, China
  • 6 Beijing Innovation Center for Engineering Sciences and Advanced Technology, Peking University, Beijing 100871, China
  • 7 Nicholas School of the Environment, Duke University, Durham, NC 27710, USA


  • Low-cost monitor error was reduced by calibrating against a calibrated monitor.
  • Indoor PM2.5 was primarily from outdoor sources.
  • Filtration reduced indoor PM2.5 by 72% on average and personal exposure by only 28%.
  • Personal exposure was not well correlated with outdoor PM2.5.
  • Low-cost monitors are highly valuable for intervention and exposure evaluation.


Residents of polluted cities frequently use indoor air purifiers in an attempt to improve their health by reducing their exposure to air pollutants, despite the fact that few studies have assessed these devices under relevant field conditions. Low-cost air monitors are increasingly popular for monitoring air pollution exposure; however, they must be calibrated and evaluated in their deployment location first to ensure measurement accuracy and precision. In this study, we developed a 2-step calibration method in which a low-cost monitor is calibrated against a reference analyzer and is then used to calibrate other monitors, shortening the required calibration time and reducing measurement error. The monitors in our experiment measured indoor, outdoor, and personal exposure PM2.5 concentrations during 1 week each of true and sham filtration in 7 homes in Beijing, China. On average, filtration reduced the indoor and personal exposure relevant concentrations by 72% (std. err. = 7%) and 28% (std. err. = 5%), respectively. This study indicates that minimizing personal exposure, however, also requires reducing the infiltration of outdoor air in homes or decreasing PM2.5 pollution at the city or country level.


Air filtration Low-cost sensors PM2.5 Personal Exposure Plantower

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