The Thimphu Outcome summarizes the key discussions and recommendations from the Second Regional Science Policy Dialogue on Air Quality Management in the Indo-Gangetic Plain and Himalayan Foothills (IGP-HF) held on June 26-27, 2024. The dialogue highlighted the critical impact of poor air quality on health, environment, economy, and social well-being in the IGP-HF region, which is one of the most polluted airsheds globally. The discussions underscored the need for a collaborative airshed management approach involving regional, national, and sub-national levels to address cross-border pollution sources, including transport, industry, power generation, waste burning, and agriculture. The dialogue concluded with key recommendations for advancing air quality management, including operationalizing the “Kathmandu Road Map,” renaming the forum to include financial aspects, setting ambitious air quality targets, forming technical committees and working groups, fostering regional cooperation, sharing knowledge, and mobilizing funding for green technologies and capacity building. The outcome aims to catalyze coordinated actions across sectors and borders for a cleaner and healthier region.