Can Public Spaces Effectively Be Used as Cleaner Indoor Air Shelters during Extreme Smoke Events?

Amanda J Wheeler; Ryan W Allen; Kerryn Lawrence; Christopher T Roulston; Jennifer Powell; Grant J Williamson; Penelope J Jones; Fabienne Reisen; Geoffrey G Morgan; Fay H Johnston

doi:10.3390/ijerph18084085

Can Public Spaces Effectively Be Used as Cleaner Indoor Air Shelters during Extreme Smoke Events?

Int J Environ Res Public Health. 2021 Apr 13;18(8):4085. doi: 10.3390/ijerph18084085.

Authors

Affiliations

¹ Mary MacKillop Institute for Health Research, Australian Catholic University, Melbourne 3000, Australia.
² Menzies Institute for Medical Research, University of Tasmania, Hobart 7000, Australia.
³ Faculty of Health Sciences, Simon Fraser University, Burnaby, BC V5A 1S6, Canada.
⁴ Mid North Coast Local Health District, Port Macquarie 2444, Australia.
⁵ Climate Science Centre, CSIRO Oceans and Atmosphere, Aspendale 3195, Australia.
⁶ School of Natural Sciences, University of Tasmania, NSW Bushfire Risk Management Research Hub, Hobart 7000, Australia.
⁷ Sydney School of Public Health, and University Centre for Rural Health, University of Sydney, Sydney 2006, Australia.

Abstract

During extreme air pollution events, such as bushfires, public health agencies often recommend that vulnerable individuals visit a nearby public building with central air conditioning to reduce their exposure to smoke. However, there is limited evidence that these "cleaner indoor air shelters" reduce exposure or health risks. We quantified the impact of a "cleaner indoor air shelter" in a public library in Port Macquarie, NSW, Australia when concentrations of fine particulate matter (PM_2.5) were elevated during a local peat fire and nearby bushfires. Specifically, we evaluated the air quality improvements with central air conditioning only and with the use of portable high efficiency particulate air (HEPA) filter air cleaners. We measured PM_2.5 from August 2019 until February 2020 by deploying pairs of low-cost PM_2.5 sensors (i) inside the main library, (ii) in a smaller media room inside the library, (iii) outside the library, and (iv) co-located with regulatory monitors located in the town. We operated two HEPA cleaners in the media room from August until October 2019. We quantified the infiltration efficiency of outdoor PM_2.5 concentrations, defined as the fraction of the outdoor PM_2.5 concentration that penetrates indoors and remains suspended, as well as the additional effect of HEPA cleaners on PM_2.5 concentrations. The infiltration efficiency of outdoor PM_2.5 into the air-conditioned main library was 30%, meaning that compared to the PM_2.5 concentration outdoors, the concentrations of outdoor-generated PM_2.5 indoors were reduced by 70%. In the media room, when the HEPA cleaners were operating, PM_2.5 concentrations were reduced further with a PM_2.5 infiltration efficiency of 17%. A carefully selected air-conditioned public building could be used as a cleaner indoor air shelter during episodes of elevated smoke emissions. Further improvements in indoor air quality within the building can be achieved by operating appropriately sized HEPA cleaners.

Keywords: HEPA; PM2.5; cleaner indoor air shelter; disaster; indoor air quality; interventions; smoke.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Air Pollutants* / analysis
Air Pollution, Indoor* / analysis
Australia
Environmental Monitoring
Humans
Particle Size
Particulate Matter / analysis
Smoke / analysis

Substances

Air Pollutants
Particulate Matter
Smoke