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

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 (PM₂.₅). Wood stove use is associated with adverse health outcomes, which can be a particular risk in vulnerable populations including older adults. We assessed the impact of portable air filtration units and educational approaches that incorporated elements of traditional knowledge on indoor and personal PM₂.₅ concentrations among rural, Native American elder households with wood stoves. 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 PM₂.₅ 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. Geometric mean indoor PM₂.₅ concentrations were 50.5 % lower (95 % confidence interval: −66.1, −27.8) in the air filtration arm versus placebo, with similar results for personal PM₂.₅. Indoor PM₂.₅ concentrations among education arm households were similar to placebo, although personal PM₂.₅ concentrations were 33.3 % lower for the education arm versus placebo (95 % confidence interval: −63.2, 21.1). 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 PM₂.₅ 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 PM₂.₅ relative to placebo. However, there is evidence that the educational interventions reduced indoor PM₂.₅ in some subsets of the study households. More study is required to determine ways to optimize educational interventions within Native American communities.