•Studied aerosol optical depth at urban and rural locations (2005–2018) in Indo-Gangetic Plains
•Observed positive trend of aerosol optical depth over both urban and rural areas
•Aerosol optical depth over a rural area is increasing at 0.50–0.67% per year.
•Crop residue burning increases aerosol optical depth during post-monsoon season.
•Established empirical relation between aerosol optical depth and PM10 for the region
(Tanbir Singh, Khaiwal Ravindra, Pawan Gupta, Harjinder Sembhi, Sachchida Nand Tripathi, and Suman Mor are other authors of this paper.)