Evaluating portable air cleaner effectiveness in residential settings to reduce exposures to biomass smoke resulting from prescribed burns.

Aim: Prescribed burning is the most common method employed to reduce fuel loads in flammable landscapes. This practice is designed to reduce the hazard associated with uncontrolled bushfires. Prescribed burns are frequently conducted close to residential areas, and the associated smoke impacts can adversely affect community health. Particulate matter is the predominant pollutant within the smoke and is strongly and consistently linked with adverse health effects. Outdoor smoke readily infiltrates buildings and reduces the quality of indoor air. Portable air cleaners containing high-efficiency particulate air (HEPA) filters are a promising indoor air quality intervention for reducing outdoor smoke exposure.

Methods: We provided 10 homes from semirural regions of Victoria, Australia, with HEPA cleaners and conducted continuous monitoring of indoor and outdoor fine particulate matter (PM2.5) for 2-4 weeks during prescribed burning periods. We calculated the potential improvements to indoor air quality when operating a HEPA cleaner during a smoke episode. Ventilation measures were conducted to identify points of smoke ingress and housing characteristics that could lead to higher infiltration rates.

Results: Depending on the house, the use of HEPA cleaners resulted in a reduction in indoor PM2.5 concentrations of 30-74%.

Conclusions: HEPA cleaners have the potential to substantially improve indoor air quality during episodic smoke episodes.