Indoor air pollution (IAP) from cooking fuels is a significant health concern in Nairobi slums, affecting maternal health outcomes. A mixed-methods approach was employed, including household surveys, anthropometric measurements, and qualitative interviews with mothers. Data were analysed using descriptive statistics and thematic analysis. Household surveys revealed a reduction of 30% in IAP exposure among participants who received cooking fuel subsidies compared to controls (n=500; p<0.01). The study highlights the effectiveness of targeted interventions in reducing IAP and improving maternal health outcomes. Further research should focus on scaling up successful programmes and exploring long-term impacts on child development.