The vast Indo-Gangetic Plains (IGP) in South Asia, a highly productive agricultural area and densely populated area suffer from heavy atmospheric pollution. Now new evidences suggest that pollution is increasing in the adjacent Hindu Kush-Himalayan (HKH) mountain regions as well. More recently, there has been growing concern about what happens upwind of the mountain region, for example over highly populated and heavily polluted IGP; and about how the changes upwind, especially emissions of atmospheric pollutants, are linked to environmental changes in the mountain regions and their socio-economic implications within and beyond mountain Himalayan regions. Though the HKH mountain regions are truly a global resource in terms of goods and services they provide, these regions still remain as one of the least sampled regions of the world in terms of atmospheric pollution. This session presents recent advances in our understanding, through a combination of field measurements and atmospheric simulations, of the sources, ambient concentrations, spatial and temporal variations, transport and transformation, and removal of gaseous and particulate air pollutants in complex topography as well as their impacts on air quality, public health, crop lose, regional circulations, cryosphere, and climate of the HKH and IGP region. They will include findings from several recent studies in the region, including the SusKat-ABC international air pollution measurement campaign in Nepal in 2013, and the Nepal Air Monitoring and Source Testing Experiment (NAMaSTE) 2015.