Exposure to household air pollution has been linked to adverse health outcomes among women aged 40-79. Little is known about how shifting from biomass cooking to a cleaner fuel like liquefied petroleum gas (LPG) could impact exposures for this population. We report 24-h exposures to particulate matter (PM), black carbon (BC), and carbon monoxide (CO) among women aged 40 to <80 years participating in the Household Air Pollution Intervention Network trial. 209 participants were randomized to the intervention and received an LPG stove and continuous fuel supply; controls used biomass ( = 209). Exposures were measured up to six times; we used mixed-effects models to estimate differences between intervention and control groups. Preintervention exposures between groups were comparable; median postintervention exposures were 62% (76.3 vs 29.3 μg/m), 73% (10.4 vs 2.8 μg/m), and 57% (1.4 vs 0.6 ppm) lower for PM, BC, and CO among LPG users than for controls. Reductions were similar across countries; 70% of PM exposures after intervention were below the annual WHO interim target I (IT-1) value of 35 μg/m. We provide evidence that implementing an LPG intervention can reduce air pollution exposure over an 18-month period to at or below the annual WHO IT-1 guideline.