Air quality improvement during triple-lockdown in the coastal city of Kannur, Kerala to combat Covid-19 transmission

PeerJ. 2020 Jul 31:8:e9642. doi: 10.7717/peerj.9642. eCollection 2020.

Abstract

The novel SARS-CoV-2 coronavirus that emerged in the city of Wuhan, China, last year has since become the COVID-19 pandemic across all continents. To restrict the spread of the virus pandemic, the Government of India imposed a lockdown from 25 March 2020. In India, Kannur district was identified as the first "hotspot" of virus transmission and a "triple-lockdown" was implemented for a span of twenty days from 20 April 2020. This article highlights the variations of surface O3, NO, NO2, CO, SO2, NH3, VOC's, PM10, PM2.5 and meteorological parameters at the time of pre-lockdown, lockdown and triple-lockdown days at Kannur town in south India using ground-based analyzers. From pre-lockdown days to triple-lockdown days, surface O3 concentration was found to increase by 22% in this VOC limited environment. NO and NO2 concentrations were decreased by 61% and 71% respectively. The concentration of PM10 and PM2.5 were observed to decline significantly by 61% and 53% respectively. Reduction in PM10 during lockdown and triple-lockdown days enhanced the intensity of solar radiation reaching the lower troposphere, and increased air temperature and reduced the relative humidity. Owing to this, surface O3 production over Kannur was found to have increased during triple-lockdown days. The concentration of CO (67%), VOCs (61%), SO2 (62%) and NH3 (16%) were found to decrease significantly from pre-lockdown days to triple-lockdown days. The air quality index revealed that the air quality at the observational site was clean during the lockdown.

Keywords: Air pollutants; Air quality; COVID-19; Kannur; Lockdown.

Grants and funding

This work was carried out with the support of ISRO- GBP (AT-CTM) program and Kerala State Council for Science Technology and Environment (KSCSTE) and the project sanction order no. Council (P) Order No. 186/2009/KSCSTE dated 17.2.2009. KT Valsaraj received support from the Charles and Hilda Roddey Distinguished Professorship in Chemical Engineering at LSU. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.