| Summary: | Fine particulate matter (PM<sub>2.5</sub>) is a major criteria pollutant affecting the environment, health and climate. In India where ground-based measurements of PM<sub>2.5</sub> is scarce, it is important to have a long-term database at a high spatial resolution for an efficient air quality management plan. Here we develop and present a high-resolution (1-km) ambient PM<sub>2.5</sub> database spanning two decades (2000–2019) for India. We convert aerosol optical depth from Moderate Resolution Imaging Spectroradiometer (MODIS) retrieved by Multiangle Implementation of Atmospheric Correction (MAIAC) algorithm to surface PM<sub>2.5</sub> using a dynamic scaling factor from Modern-Era Retrospective analysis for Research and Applications Version 2 (MERRA-2) data. The satellite-derived daily (24-h average) and annual PM<sub>2.5</sub> show a <i>R</i><sup>2</sup> of 0.8 and 0.97 and root mean square error of 25.7 and 7.2 μg/m<sup>3</sup>, respectively against surface measurements from the Central Pollution Control Board India network. Population-weighted 20-year averaged PM<sub>2.5</sub> over India is 57.3 μg/m<sup>3</sup> (5–95 percentile ranges: 16.8–86.9) with a larger increase observed in the present decade (2010–2019) than in the previous decade (2000 to 2009). Poor air quality across the urban–rural transact suggests that this is a regional scale problem, a fact that is often neglected. The database is freely disseminated through a web portal ‘satellite-based application for air quality monitoring and management at a national scale’ (SAANS) for air quality management, epidemiological research and mass awareness.
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