A large discrepancy between simulated and observed black carbon (BC) surface concentrations over the densely populated Indo-Gangetic plain (IGP) has so far limited our ability to assess the magnitude of BC sanitary impacts in terms of population exposure, morbidity, and mortality. We evaluate these impacts using an integrated modeling framework, including a successfully predicted BC surface concentration in a high-resolution chemical transport model CHIMERE with observationally-constrained BC emissions, combined with consistent health functions for BC. Population exposure to BC is noteworthy, with more than 60 million people identified living over hotspots of BC concentration (wintertime mean > 20 μg m−3). A fraction of 62% of the total cardiovascular diseases mortality (CVM) burden for the megacity is found attributable to wintertime BC exposure. The semi-urban area has 50% of the CVM burden attributable to BC exposure in the total population over the IGP. More than 400 thousand lives can potentially be saved from CVM annually, by implementing prioritized emission reduction from the combustion of domestic biofuel in the semi-urban area, and diesel oil in transportation and coal in thermal power plant and brick kiln industries in megacities.