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J Geophys Res Atmos

Title:		Impact of COVID-19 Pandemic Lockdown in Ambient Concentrations of Aromatic Volatile Organic Compounds in a Metropolitan City of Western India
Author(s):		Sahu LK; Tripathi N; Gupta M; Singh V; Yadav R; Patel K;
Address:		Physical Research Laboratory (PRL) Ahmedabad India. Indian Institute of Technology Gandhinagar Gandhinagar India. National Atmospheric Research Laboratory (NARL) Gadanki India. Indian Institute of Tropical Meteorology (IITM) Pune India
Journal Title:		J Geophys Res Atmos
Year:		2022
Volume:		20220323
Issue:		6
Page Number:		e2022JD036628 -
DOI:		10.1029/2022JD036628
ISSN/ISBN:		2169-897X (Print) 2169-8996 (Electronic) 2169-897X (Linking)
Abstract:		"The real-time Benzene, Toluene, Ethylbenzene, and Xylenes (BTEX) concentrations were measured in a metropolitan city of India during January to May of 2020 and 2014-2015-2018 to assess the impact of emission reduction during the COVID-19 lockdown. The total BTEX ( summation operatorBTEX) concentrations were 11.5 +/- 9.0, 15.7 +/- 16, 5.3 +/- 5.0, 2.9 +/- 2.0, and 0.93 +/- 1.2 ppbv in January-May 2020, respectively. The evening rush hour peaks of BTEX during lockdown decreased by 4-5 times from the same period of years 2014-2015-2018. A significant decline in background concentrations suggests a regional-scale reduction in anthropogenic emissions. The contributions of summation operatorTEX compounds to summation operatorBTEX increased from 42% to 59% in winter to 64%-75% during the lockdown under hot summer conditions. While emission reductions dominated during the lockdown period, the meteorological and photochemical factors may also have contributed. Meteorological influence on actual observed BTEX data was removed by normalizing with ventilation coefficient (VC). The actual ambient air reductions of 85%-90% and VC-normalized reductions of 54%-88% of the BTEX concentrations during lockdown were estimated compared to those during the same period of 2014-2015-2018. The estimated changes using nighttime data, which take into account BTEX photooxidation removal, are approximately 8% lower than the VC-normalized estimates using all data. These significant reductions in BTEX concentrations are consistent with the change in people's movement as inferred from mobility data during the lockdown. Although enforced, the significant decline in ambient BTEX levels during lockdown was a good change for the air quality. The study suggests a need for more effective science-based policies that consider local and regional factors"
Keywords:		Btex Covid-19 lockdown meteorology vehicle exhaust ventilation coefficient;
Notes:		"PubMed-not-MEDLINESahu, L K Tripathi, Nidhi Gupta, Mansi Singh, Vikas Yadav, Ravi Patel, Kashyap eng 2022/05/24 J Geophys Res Atmos. 2022 Mar 27; 127(6):e2022JD036628. doi: 10.1029/2022JD036628. Epub 2022 Mar 23"