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Practical considerations for using low-cost sensors to assess wildfire smoke exposure in school and childcare settings

Abstract

Background

More frequent and intense wildfires will increase concentrations of smoke in schools and childcare settings. Low-cost sensors can assess fine particulate matter (PM2.5) concentrations with high spatial and temporal resolution.

Objective

We sought to optimize the use of sensors for decision-making in schools and childcare settings during wildfire smoke to reduce children’s exposure to PM2.5.

Methods

We measured PM2.5 concentrations indoors and outdoors at four schools in Washington State during wildfire smoke in 2020–2021 using low-cost sensors and gravimetric samplers. We randomly sampled 5-min segments of low-cost sensor data to create simulations of brief portable handheld measurements.

Results

During wildfire smoke episodes (lasting 4–19 days), median hourly PM2.5 concentrations at different locations inside a single facility varied by up to 49.6 µg/m3 (maximum difference) during school hours. Median hourly indoor/outdoor ratios across schools ranged from 0.22 to 0.91. Within-school differences in concentrations indicated that it is important to collect measurements throughout a facility. Simulation results suggested that making handheld measurements more often and over multiple days better approximates indoor/outdoor ratios for wildfire smoke. During a period of unstable air quality, PM2.5 over the next hour indoors was more highly correlated with the last 10-min of data (mean R2 = 0.94) compared with the last 3-h (mean R2 = 0.60), indicating that higher temporal resolution data is most informative for decisions about near-term activities indoors.

Impact statement

As wildfires continue to increase in frequency and severity, staff at schools and childcare facilities are increasingly faced with decisions around youth activities, building use, and air filtration needs during wildfire smoke episodes. Staff are increasingly using low-cost sensors for localized outdoor and indoor PM2.5 measurements, but guidance in using and interpreting low-cost sensor data is lacking. This paper provides relevant information applicable for guidance in using low-cost sensors for wildfire smoke response.

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Data availability

The datasets generated during and/or analyzed during the current study are available from the corresponding author on reasonable request.

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Acknowledgements

We are grateful to the school and air quality agency personnel who hosted air quality sensors and monitors and partnered with us on this research. We thank Dr. Elena Austin, Amanda Gassett, Dr. Tim Gould, Dr. Tim Larson, Maria Tchong-French, and Jeff Shirai of University of Washington (UW) for their guidance and support in this research. We also appreciate support from Taylor Hendricksen, Kylie Milano, and Cristina Urrutia of UW. We are grateful for assistance with air sampling from Amanda Virbitsky, Megumi Matsushita (UW), and Annie Doubleday (UW).

Funding

This work was supported by the US National Institute of Environmental Health Sciences of the National Institutes of Health under Award Number #F31ES032634 and the University of Washington EDGE Center of the National Institutes of Health under award number P30ES007033. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health. This publication was supported by the American Academy of Pediatrics (AAP) and funded (in part) by the cooperative agreement award number 5 NU61TS000296-02-00 from the Agency for Toxic Substances and Disease Registry (ATSDR). The U.S. Environmental Protection Agency (EPA) supports the PEHSU by providing partial funding to ATSDR under Inter-Agency Agreement number DW-75-95877701. Neither EPA nor ATSDR endorse the purchase of any commercial products or services mentioned in PEHSU publications. This work was also supported by the University of Washington Department of Environmental & Occupational Health Sciences Castner Award. The funding sources had no involvement in the conduct of research or preparation of this article.

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CRediT author statement Orly Stampfer: Conceptualization, Data curation, Formal analysis, Funding acquisition, Investigation, Methodology, Project Administration, Software, Visualization, Writing - original draft, Writing - review & editing. Christopher Zuidema: Formal analysis, Methodology, Software, Writing - original draft, Writing - review & editing. Ryan W. Allen: Conceptualization, Methodology, Writing - original draft, Writing - review & editing, Supervision. Julie Fox: Conceptualization, Writing - review & editing Paul Sampson: Formal analysis, Methodology, Software, Writing - review & editing Edmund Seto: Conceptualization, Methodology, Funding acquisition, Writing - original draft, Writing - review & editing, Resources, Supervision. Catherine J. Karr: Conceptualization, Methodology, Funding acquisition, Writing - original draft, Writing - review & editing, Resources, Supervision.

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Stampfer, O., Zuidema, C., Allen, R.W. et al. Practical considerations for using low-cost sensors to assess wildfire smoke exposure in school and childcare settings. J Expo Sci Environ Epidemiol (2024). https://doi.org/10.1038/s41370-024-00677-8

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