High-quality randomized trials and cohort analyses revealed no significant longitudinal association between PM2.5 or CO exposure from biomass cooking and severe pneumonia in infants.
Evidence from the multinational HAPIN trial showed that despite substantial PM2.5 exposure reductions with liquefied petroleum gas (LPG) stoves, incidence of severe infant pneumonia remained unchanged.
Contrasting earlier observational studies, prenatal CO exposures showed sex-specific associations with pneumonia risk, suggesting complex exposure-response dynamics potentially mediated by infant lung function impairment.
Insufficient exposure reductions in some interventions and methodological heterogeneity may underlie discrepancies in observed health outcomes, underscoring the need for comprehensive exposure assessment and mechanistic understanding.
