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Children’s microenvironmental exposure to PM2.5 and ozone and the impact of indoor air filtration



In highly polluted urban areas, personal exposure to PM2.5 and O3 occur daily in various microenvironments. Identifying which microenvironments contribute most to exposure can pinpoint effective exposure reduction strategies and mitigate adverse health impacts.


This work uses real-time sensors to assess the exposures of children with asthma (N = 39) in Shanghai, quantifying microenvironmental exposure to PM2.5 and O3. An air cleaner was deployed in participants’ bedrooms where we hypothesized exposure could be most efficiently reduced. Monitoring occurred for two 48-h periods: one with bedroom filtration (portable air cleaner with HEPA and activated carbon filters) and the other without.


Children spent 91% of their time indoors with the majority spent in their bedroom (47%). Without filtration, the bedroom and classroom environments were the largest contributors to PM2.5 exposure. With filtration, bedroom PM2.5 exposure was reduced by 75% (45% of total exposure). Although filtration status did not impact O3, the largest contribution of O3 exposure also came from the bedroom.


Actions taken to reduce bedroom PM2.5 and O3 concentrations can most efficiently reduce total exposure. As real-time pollutant monitors become more accessible, similar analyses can be used to evaluate new interventions and optimize exposure reductions for a variety of populations.

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Fig. 1: PM2.5 concentrations across all microenvironments.
Fig. 2: Measured PM2.5 exposure contribution for each child over the 48-h periods.
Fig. 3: Ozone concentrations by microenvironment.
Fig. 4: Measured microenvironmental exposure contribution to O3.


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This work was funded by a grant from Underwriters Laboratory (UL) and supported in part by a grant from the National Natural Science Foundation of China (51420105010). The study was approved by both Duke Campus Institutional Review Board (IRB) and by First People’s Hospital IRB. We thank Amway (China) Co., Limited, for lending the air cleaners for use in this study; however, the company was not involved in study design, implementation, or data interpretation. We greatly appreciate all our participants for welcoming us into your homes and allowing us to gather data on your health and air pollution exposure. Thank you to Donghong Chen and the team at the Qingpu Environmental Monitoring station for providing access to their monitoring site and the data from our study period. We sincerely appreciate the support from the other members of the Bergin lab for their assistance in assembling and designing the air sensor packages. Thanks to Yanbo Teng at Duke Kunshan for his strong technical and administrative support throughout the project. Thanks to Jiaqi Sun from Tsinghua University, Jiang Yanyu (Jade) from Shanghai Jiaotong University as well as Dr. Zhen Li, Dr. Qian Wang and Dr. Lili Lin and the resident physicians at Shanghai General Hospital for assisting with home visits and clinical visits throughout the study.


This work was funded by a grant from Underwriters Laboratory (UL) and supported in part by a grant from the National Natural Science Foundation of China (51420105010). Amway (China) Co., Limited, lent the air cleaners for use in this study; however, the company was not involved in study design, implementation, or data interpretation.

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Correspondence to Karoline K. Barkjohn.

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Barkjohn, K.K., Norris, C., Cui, X. et al. Children’s microenvironmental exposure to PM2.5 and ozone and the impact of indoor air filtration. J Expo Sci Environ Epidemiol 30, 971–980 (2020).

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  • Air quality
  • Indoor environment
  • Children’s health
  • Exposure sensors
  • Monitoring methods
  • Exposure assessment

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