Household Air Pollution and Child Lung Function: The Ghana Randomized Air Pollution and Health Study

Rationale: The impact of a household air pollution (HAP) stove intervention on child lung function is poorly described. Objectives: To assess the effect of a prenatal to age one HAP stove intervention on, and exposure-response associations with, age four lung function. Methods: The Ghana Randomized Air Pollution and Health Study (GRAPHS) randomized pregnant women to a liquefied petroleum gas (LPG), improved biomass, or open fire (control) stove through child age one. We quantified HAP exposure by repeated maternal and child personal carbon monoxide (CO) exposure measurements. Children performed oscillometry, an effort-independent lung function measurement, at age four. We examined associations between GRAPHS stove assignment and prenatal and infant CO measurements and oscillometry via generalized linear regression models. We used reverse distributed lag models (rDLMs) to examine time-varying associations between prenatal CO and oscillometry. Measurements and Main Results: The primary oscillometry measure was reactance at 5 Hertz, X5, a measure of elastic and inertial lung properties. Secondary measures included total, large and small airway resistance (R5, R20, R5-20), area of reactance (AX) and resonant frequency (Fres). Of the 683 children who attended the lung function visit, 567 (83%) performed acceptable oscillometry. Two hundred and twenty-one, 106, and 240 children were from the LPG, improved biomass and control arms, respectively. Compared to control, the improved biomass stove was associated with lower reactance at 5 Hertz (X5 z-score, beta=-0.25, 95% CI -0.39, -0.11), higher large airway resistance (R20 z-score, beta=0.34, 95% CI 0.23, 0.44) and higher area of reactance (AX z-score, beta=0.16, 95% CI 0.06, 0.26) suggestive of overall worse lung function. The LPG stove was associated with higher X5 (beta=0.16, 95% CI 0.01, 0.31) and lower small airway resistance (R5-20 z-score, beta=-0.15, 95% CI -0.30, 0.0) suggestive of better small airway function. Higher average prenatal CO exposure was associated with higher R5 and R20 and DLMs identified sensitive windows of exposure between CO and X5, R5, R20 and R5-20. Conclusions: These data support the importance of prenatal HAP exposure on child lung function. Clinical trial registration available at www.clinicaltrials.gov, ID: NCT01335490.