Prenatal Household Air Pollution Is Associated with Impaired Infant Lung Function with Sex-Specific Effects. Evidence from GRAPHS, a Cluster Randomized Cookstove Intervention Trial

Abstract

Rationale: Approximately 2.8 billion people are exposed daily to household air pollution from polluting cookstoves. The effects of prenatal household air pollution on lung development are unknown.

Objectives: To prospectively examine associations between prenatal household air pollution and infant lung function and pneumonia in rural Ghana.

Methods: Prenatal household air pollution exposure was indexed by serial maternal carbon monoxide personal exposure measurements. Using linear regression, we examined associations between average prenatal carbon monoxide and infant lung function at age 30 days, first in the entire cohort (n = 384) and then stratified by sex. Quasi-Poisson generalized additive models explored associations between infant lung function and pneumonia.

Measurements and main results: Multivariable linear regression models showed that average prenatal carbon monoxide exposure was associated with reduced time to peak tidal expiratory flow to expiratory time (β = -0.004; P = 0.01), increased respiratory rate (β = 0.28; P = 0.01), and increased minute ventilation (β = 7.21; P = 0.05), considered separately, per 1 ppm increase in average prenatal carbon monoxide. Sex-stratified analyses suggested that girls were particularly vulnerable (time to peak tidal expiratory flow to expiratory time: β = -0.003, P = 0.05; respiratory rate: β = 0.36, P = 0.01; minute ventilation: β = 11.25, P = 0.01; passive respiratory compliance normalized for body weight: β = 0.005, P = 0.01). Increased respiratory rate at age 30 days was associated with increased risk for physician-assessed pneumonia (relative risk, 1.02; 95% confidence interval, 1.00-1.04) and severe pneumonia (relative risk, 1.04; 95% confidence interval, 1.00-1.08) in the first year of life.

Conclusions: Increased prenatal household air pollution exposure is associated with impaired infant lung function. Altered infant lung function may increase risk for pneumonia in the first year of life. These findings have implications for future respiratory health. Clinical trial registered with www.clinicaltrials.gov (NCT 01335490).

Trial registration: ClinicalTrials.gov NCT01335490.

Keywords: household air pollution; lung development; lung function; pneumonia; sex-specific effects.

Figures

Figure 1.

Representative plot of a maternal prenatal personal exposure assessment. This figure demonstrates personal carbon monoxide (CO) exposures (in parts per million) plotted against time, for a 72-hour exposure assessment period. The Lascar EL-CO-USB Data Logger measured CO levels every 10 seconds and was worn in the participant’s breathing zone. Peaks correspond to reported cooking periods; CO exposures outside of these periods were largely zero. Data for this study used the first 48 hours, to avoid cases where battery issues or field pick up schedules could have resulted in missing a cooking event on the last day. For this session, the 48-hour average CO exposure is 1.01 ppm (range, 0–94.65 ppm).