Kibera is a densely populated informal settlement in Nairobi, Kenya, facing significant environmental health challenges such as indoor air pollution from traditional cookstoves. A mixed-method approach including baseline surveys, household inventories, and follow-up interviews to evaluate changes before and after the programme implementation. Baseline data indicated an average of 1200 ppm CO levels in households; post-programme reductions were observed with 85% of participants reporting a decrease to below 600 ppm. The clean cookstove programmes have significantly reduced indoor air pollution, aligning with health improvement trends among residents. Continue support for ongoing maintenance and further research on long-term sustainability impacts.