Investigating the aerosol optical depth variation during a persisting mass gathering event of Kumbh-2019 in India

The Kumbh mela is a huge public gathering event in Hindu tradition. During 2019 Kumbh which was organized at Prayagraj/Allahabad, India, large infrastructure was created to facilitate the visitors. To monitor impact of such gathering and infrastructure on the atmospheric composition, a road campaign was conducted from Nagpur (21.15 N, 79.03 E) to Prayagraj (25.42 N, 81.87 E) during 17–23 February 2019 with a hand-held microtop sun photometer as a primary instrument. Data revealed AOD variation to be higher by about 19% at the centre of the event. The derived angstrom exponent suggests that the mass gathering and large infrastructure may have raised the dust level in the ambient atmosphere which was reflected in the enhanced Aerosol optical depth values and size distribution. •It is noted that large establishments were created for the convenience of pilgrims during the Kumbh Mela held at Prayagraj during January–March 2019.•The mass gathering and large establishments may have raised the dust level in the ambient which was reflected in the enhanced Aerosol optical depth values and size distribution.•The ozone content was found to peak at Kumbh area during the land campaign. However, the peak in ozone and water vapor variations may not necessarily be associated with the Kumbh event.