Impact of air pollution on stunting among children in Africa

Background: Undernutrition is a global public health crisis, causing nearly half of deaths for children under age 5 years. Little is known regarding the impact of air pollution in-utero and early childhood on health outcomes related to undernutrition. The aim of our study is to evaluate the association of prenatal and early-life exposure to PM_2.5 and child malnutrition as captured by the height-for-age z-score (HAZ), and stunting in 32 countries in Africa. We also evaluated critical windows of susceptibility during pregnancy to each environmental risk.

Methods: We linked nationally representative anthropometric data from 58 Demographic and Health Surveys (DHS) (n = 264,207 children < 5 years of age) with the average in-utero PM_2.5 concentrations derived from satellite imagery. We then estimated associations between PM_2.5 and stunting and HAZ after controlling for child, mother and household factors, and trends in time and seasonality.

Results: We observed lower HAZ and increased stunting with higher in-utero PM_2.5 exposure, with statistically significant associations observed for stunting (OR: 1.016 (95% CI: 1.002, 1.030), for a 10 μg/m³ increase). The associations observed were robust to various model specifications. Wald tests revealed that sex, wealth quintile and urban/rural were not significant effect modifiers of these associations. When evaluating associations between trimester-specific PM_2.5 levels, we observed that associations between PM_2.5 and stunting was the largest.

Conclusions: This is one of the first studies for the African continent to investigate in-utero and early-life exposure to PM_2.5 is an important marker of childhood undernutrition. Our results highlight that PM_2.5 concentrations need to be urgently mitigated to help address undernutrition in children on the continent.