Effects of air pollution on meteorological parameters during Deepawali festival over an Indian urban metropolis Upal Saha a, b , Shamitaksha Talukdar b , Soumyajyoti Jana b , Animesh Maitra a, b, * a Institute of Radio Physics and Electronics, University of Calcutta, 92 Acharya Prafulla Chandra Road, Kolkata 700009, West Bengal, India b S.K. Mitra Centre for Research in Space Environment, Institute of Radio Physics and Electronics, University of Calcutta, 92 Acharya Prafulla Chandra Road, Kolkata 700009, West Bengal, India highlights Both long-term and short-term study reveals an increase in pollutant concentration. PM10 has been found to be the most dominant air pollutants during this Deepawali. Boundary layer is affected by retained change in lapse rate and low relative humidity. Windrose diagram also validated the cause of severe urban Deepawali pollution. Increased pollution is a serious concern on the changing pattern of environment. article info Article history: Received 15 July 2014 Received in revised form 9 September 2014 Accepted 10 September 2014 Available online 16 September 2014 Keywords: Festival Fireworks Air pollution Lapse rate Relative humidity Visibility abstract Atmospheric pollutants (NO 2 , SO 2 , PM10, BC, CO, surface O 3 ), emitted during reworks display, have signicant effects on meteorological parameters like air temperature, relative humidity, lapse rate and visibility in air over Kolkata (22 65 0 N, 88 45 0 E), a metropolitan city near the landeocean boundary, on the eve of Deepawali festival when extensive reworks are burnt. Long-term trend (2005e2013), in- dicates that the yearly average concentrations of both primary and secondary air pollutants have increased, exceeding the National Ambient Air Quality Standard (NAAQS) limit, on the respective Deepawali days. Short-term study (2012e2013) during the festival shows that the average pollutant concentrations have increased too compared to normal days. This study also reveals the immediate ef- fects of the increased air pollutants on the boundary layer meteorology. PM10 has been found to be the most dominant atmospheric pollutants during this period. As a result of an increase in atmospheric heat content with elevated surface air temperature, a signicant increase in the environmental lapse rate bears a signature of the inuence of pollutants on the boundary layer temperature prole. A change in the diurnal pattern of relative humidity as well as in the vertical temperature prole is due to the change of the lapse rate during the festival days. Thus, the atmospheric pollutants during this festival over the urban region have signicant effect on the boundary layer meteorology with bearings on environmental hazards. © 2014 Elsevier Ltd. All rights reserved. 1. Introduction In recent times, short-term air quality degradation episodes are drawing increased attention of the scientic community as they considerably affect human health through long-term adverse ef- fects (Pope et al., 2002; Pope and Dockery, 2006; Nastos et al., 2010; Singh et al., 2010; Samoli et al., 2011; Bapna et al., 2013; Bhuyan et al., 2014). Burning of reworks during festivals are signicant contributors to air pollution in India, which are of increasing concern in terms of health hazards and effects on environment. Fireworks during celebrations like Deepawali in India, Lass Fallas in Spain, Lantern festival in Beijing, New year celebration belong to same category and have been reported to be signicant sources of anthropogenic aerosols all over the world (Mandal et al., 1997; Drewnick et al., 2006; Vecchi et al., 2008; Wang et al., 2007; Nishanth et al., 2012; Vyas and Saraswat, 2012; Cheng et al., 2014). Deepawali festival experiences the most extensive burning of reworks in India causing a major concern for environmental * Corresponding author. Institute of Radio Physics and Electronics, University of Calcutta, 92 Acharya Prafulla Chandra Road, Kolkata 700009, West Bengal, India. E-mail addresses: animesh.maitra@gmail.com, am.rpe@caluniv.ac.in (A. Maitra). Contents lists available at ScienceDirect Atmospheric Environment journal homepage: www.elsevier.com/locate/atmosenv http://dx.doi.org/10.1016/j.atmosenv.2014.09.032 1352-2310/© 2014 Elsevier Ltd. All rights reserved. Atmospheric Environment 98 (2014) 530e539