Impacts of using auto-mode portable air cleaner on indoor PM2.5 levels: An intervention study

Ching Hsuan Huang, Jianbang Xiang, Elena Austin, Jeff Shirai, Yisi Liu, Christopher Simpson, Catherine J. Karr, Amber L. Fyfe-Johnson, Thomas Kronborg Larsen, Edmund Seto

Research output: Contribution to journalArticlepeer-review

25 Scopus citations


“Auto-mode” portable air cleaners (PACs) designed to turn on automatically in response to elevated indoor PM2.5 concentrations are widely used in residences. This study assesses the impacts of using such PACs equipped with high-efficiency particulate air filters on residential PM2.5 levels in six households recruited in Seattle, Washington, for a randomized crossover study, in which participants used a PAC in their homes under three intervention scenarios: (1) sham-mode filtration in which all filters in the PAC were removed, (2) auto-mode filtration in which the PAC was set to auto mode, and (3) adjustable-mode filtration in which the participants were allowed to manually adjusted the PACs. Each filtration session was one-week long. PM2.5 levels were measured at 1-min intervals in the kitchen and living room of each household. Also, an hourly time-activity log was collected from each participant. The empirical concentrations and I/O ratios of PM2.5 were compared among the three filtration modes. Additionally, linear mixed-effects regression models (LMER) were developed to reveal the impacts of different filtration modes on indoor PM2.5, while controlling for outdoor PM2.5, indoor cooking events, and indoor relative humidity, and temperature. Based on the LMER models, when indoor cooking events were present and absent, auto-mode filtration significantly reduced the indoor PM2.5 levels by 31% [95% CI: 19%, 42%] and 28% [95% CI: 22%, 34%], respectively, compared with sham-mode filtration, and reduced the indoor PM2.5 levels by 19% [95% CI: 6%, 31%] and 4% [95% CI: 4%, 11%], respectively, compared with adjustable-mode filtration. These findings suggest that using such PACs running in auto mode is a practical and effective way to reduce indoor PM2.5 levels.

Original languageEnglish
Article number107444
JournalBuilding and Environment
StatePublished - Jan 15 2021

Bibliographical note

Publisher Copyright:
© 2020 Elsevier Ltd


  • Auto mode
  • Cooking
  • Indoor air quality (IAQ)
  • Linear mixed-effects regression (LMER)
  • PM
  • Portable air cleaner (PAC)

ASJC Scopus subject areas

  • Environmental Engineering
  • Civil and Structural Engineering
  • Geography, Planning and Development
  • Building and Construction


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