Efficacy of air filtration and education interventions on fine particulate matter among rural Native American homes heated with wood stoves: Results from the EldersAIR randomized trial

Background: Native Americans living in rural areas often rely upon wood stoves for home heating that can lead to elevated indoor concentrations of fine particulate matter (PM_2.5). Wood stove use is associated with adverse health outcomes, which can be a particular risk in vulnerable populations including older adults. Objectives: We assessed the impact of portable air filtration units and educational approaches that incorporated elements of traditional knowledge on indoor and personal PM_2.5 concentrations among rural, Native American elder households with wood stoves. Methods: EldersAIR was a three-arm, pre-post randomized trial among rural households from the Navajo Nation and Nez Perce Tribe in the United States. We measured personal and indoor PM_2.5 concentrations over 2-day sampling periods on up to four occasions across two consecutive winter seasons in elder participant homes. We assessed education and air filtration intervention efficacy using linear mixed models. Results: Geometric mean indoor PM_2.5 concentrations were 50.5 % lower (95 % confidence interval: −66.1, −27.8) in the air filtration arm versus placebo, with similar results for personal PM_2.5. Indoor PM_2.5 concentrations among education arm households were similar to placebo, although personal PM_2.5 concentrations were 33.3 % lower for the education arm versus placebo (95 % confidence interval: −63.2, 21.1). Significance: The strong partnership between academic and community partners helped facilitate a culturally acceptable approach to a clinical trial intervention within the study communities. Portable air filtration units can reduce indoor PM_2.5 that originates from indoor wood stoves, and this finding was supported in this study. The educational intervention component was meaningful to the communities, but did not substantially impact indoor PM_2.5 relative to placebo. However, there is evidence that the educational interventions reduced indoor PM_2.5 in some subsets of the study households. More study is required to determine ways to optimize educational interventions within Native American communities.