Wheeler, A.J., Longley, I., Reisen, F., Allen, R., Borchers Arriagada, N., Olivares, G., Williamson, G., Dennekamp, M., Garvey, K., Johnston, F.H.
The use of portable HEPA air cleaners to improve residential indoor air quality during biomass burning events.
Bushfires, prescribed burns and residential wood burning are a significant source of fine particles (PM2.5) affecting the health and well-being of many communities. Studies conducted internationally have demonstrated that much of the outdoor particulate matter generated through biomass burning is able to infiltrate indoors resulting in elevated residential indoor PM2.5 concentrations. There is some international evidence of the value of using portable indoor air cleaners to reduce PM2.5 exposure. These have yet to be successfully evaluated in the Australian context where building codes and housing designs differ significantly from Europe, Canada and the US, where much of this research has been previously conducted.
Between 2017 – 2020 three residential indoor air quality studies were undertaken to assess the efficacy of portable High Efficiency Particulate Air (HEPA) cleaners at reducing indoor PM2.5 concentrations. Homes participated in the studies that included emissions from winter woodsmoke, planned burns and a Tasmanian bushfire emergency. Residential indoor and outdoor PM2.5 concentrations were measured continuously using Plantower 3003 sensors. Baseline and intervention periods using a portable HEPA air cleaner were conducted in all homes. Housing characteristic surveys and daily diaries of household activities were tracked to interpret the findings. A subset of homes included air exchange rate measurements using the carbon dioxide decay method.
Preliminary data from regulatory monitoring stations indicate that ambient PM2.5 concentrations reached hourly averages of approximately 1,200µg/m3 during the bushfire and approximately 80µg/m3 during winter woodsmoke events. Woodsmoke impacted homes demonstrated an average change in PM2.5 indoor to outdoor ratios from baseline to HEPA interventions between 0.89–0.76. Preliminary results suggest that on average the HEPA cleaners reduce PM2.5 concentrations by approximately 50% (range 27-84%). Data from all biomass events will be presented including results from the bushfire emergency. This will provide intervention data for regulatory agencies facing extreme smoke events in populated areas where evacuations are challenging or there are populations vulnerable to health effects of smoke exposure.