Indoor fine particulate matter and stove-use characteristics in homes heated by wood stoves: results from control homes in the KidsAIR randomized trial

Abstract

Background/Aim: Household heating using wood stoves is common practice in many rural areas of the United States (US) and can lead to high concentrations of indoor fine particulate matter (PM2.5); yet there is limited research on household and behavioral factors that contribute to PM2.5 levels in such homes. Our aims were to characterize PM2.5 concentrations, evaluate household and stove-use characteristics that impact PM2.5, and assess the feasibility of interventions to lower PM2.5 in rural US homes that used wood stoves for heating.Methods: KidsAIR was a three-arm post-only randomized trial in wood stove households from three study areas. We measured indoor concentrations of PM2.5 over a 6-day sampling period during the winter and assessed household and stove-use characteristics. As the two intervention arms (education and air-filtration) were designed to impact PM2.5 concentrations, we focused these analyses on homes in the control arm (no intervention, n=93).Results: In preliminary analyses, the mean indoor PM2.5 concentration across all control homes was 28 µg/m3 (standard deviation [sd]=68), with higher concentrations in Alaska sites (47 µg/m3, sd=95, n=10) than Navajo Nation (NN) or Montana sites (29 µg/m3, sd=76, n=23; 25 µg/m3, sd=59, n=60). Stoves were often over 5 years old (54%) and of poor quality. More participants in NN (35%) reported heavy burning during PM2.5 measurement than Alaska (10%) or Montana (12%), and more participants in Alaska (70%) and NN (83%) burned wood <3 months after collection than in Montana (25%). Mean wood moisture content was lower in NN (6%) than Alaska (14%) and Montana (13%).Conclusions: We observed poor stove quality, inconsistent burn practices, and moderately high PM2.5 concentrations inside rural US homes that heated with wood stoves. Our findings highlight the need for, and the complex nature of, culturally- and regionally-appropriate interventions to reduce indoor air pollution in rural wood-burning homes.