Environmental and nutritional risks for child growth in Nairobi’s informal settlements: the role of household air pollution

Child undernutrition remains a public health challenge in Kenya, particularly in urban informal settlements, yet the role of household air pollution (HAP) in child stunting has received little longitudinal attention. This study examines the association between HAP and linear growth among under-five children living in Kibera, an informal settlement in Nairobi. Using two waves of household survey data collected six months apart, height-for-age z-scores (HAZ) and stunting (HAZ < –2) were assessed. Random-effects linear and logistic regression models, supplemented by correlated random-effects (Mundlak) and quantile regression analyses with multiple robustness checks, were used to estimate associations. Stunting prevalence was high (39.8%), with a higher rate among children in polluting-fuel households (44.0%) than in clean-fuel households (36.3%). After adjustment for child, maternal, and household characteristics, polluting cooking fuel use was associated with lower HAZ (approximately 0.356 SD lower) and higher odds of stunting. The results were robust to additional adjustment for household food consumption score (FCS). Quantile regressions suggested that the negative association between polluting-fuel use and HAZ was strongest at the lower and upper tails of the HAZ distribution. Overall, the findings highlight household air pollution as an under-recognised correlate for child stunting in informal urban settings and support further evaluation of clean-cooking interventions as part of broader strategies to address child undernutrition in informal urban settings.