Efficacy of Air Filtration and Education Interventions on Indoor Fine Particulate Matter and Child Lower Respiratory Tract Infections among Rural U.S. Homes Heated with Wood Stoves: Results from the KidsAIR Randomized Trial

Environ Health Perspect. 2022 Apr;130(4):47002. doi: 10.1289/EHP9932. Epub 2022 Apr 8.

ABSTRACT

BACKGROUND: Millions of rural U.S. households are heated with wood stoves. Wood stove use can lead to high indoor concentrations of fine particulate matter [airborne particles ≤2.5μm in aerodynamic diameter (PM2.5)] and is associated with lower respiratory tract infection (LRTI) in children.

OBJECTIVES: We assessed the impact of low-cost educational and air filtration interventions on childhood LRTI and indoor PM2.5 in rural U.S. homes with wood stoves.

METHODS: The Kids Air Quality Interventions for Reducing Respiratory Infections (KidsAIR) study was a parallel three-arm (education, portable air filtration unit, control), post-only randomized trial in households from Alaska, Montana, and Navajo Nation (Arizona and New Mexico) with a wood stove and one or more children <5 years of age. We tracked LRTI cases for two consecutive winter seasons and measured indoor PM2.5 over a 6-d period during the first winter. We assessed results using two analytical frameworks: a) intervention efficacy on LRTI and PM2.5 (intent-to-treat), and b) association between PM2.5 and LRTI (exposure-response).

RESULTS: There were 61 LRTI cases from 14,636 child-weeks of follow-up among 461 children. In the intent-to-treat analysis, children in the education arm [odds ratio (OR)=0.98; 95% confidence interval (CI): 0.35, 2.72] and the filtration arm (OR=1.23; 95% CI: 0.46, 3.32) had similar odds of LRTI vs. control. Geometric mean PM2.5 concentrations were similar to control in the education arm (11.77% higher; 95% CI: -16.57, 49.72) and air filtration arm (6.96% lower; 95% CI: -30.50, 24.55). In the exposure-response analysis, odds of LRTI were 1.45 times higher (95% CI: 1.02, 2.05) per interquartile range (25μg/m3) increase in mean indoor PM2.5.

DISCUSSION: We did not observe meaningful differences in LRTI or indoor PM2.5 in the air filtration or education arms compared with the control arm. Results from the exposure-response analysis provide further evidence that biomass air pollution adversely impacts childhood LRTI. Our results highlight the need for novel, effective intervention strategies in households heated with wood stoves. https://doi.org/10.1289/EHP9932.

PMID:35394807 | DOI:10.1289/EHP9932

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