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Comprehensive analysis of ambient air quality during second lockdown in national capital territory of Delhi.

ABSTRACT: The lockdown imposed in Delhi, due to the second wave of the COVID-19 pandemic has led to significant gains in air quality. Under the lockdown, restrictions were imposed on movement of people, operation of industrial establishments and hospitality sector amongst others. In the study, Air Quality Index and concentration trends of six pollutants, i.e. PM_2.5, PM₁₀, NO₂, SO₂, CO, and O₃ were analysed for National Capital Territory of Delhi, India for three periods in 2021 (pre-lockdown: 15 March to 16 April 2021, lockdown: 17 April to 31 May 2021 and post-lockdown: 01 June to 30 June). Data for corresponding periods in 2018-2020 was also analysed. Lockdown period saw 6 days in satisfactory AQI category as against 0 days in the same category during the pre-lockdown period. Average PM_2.5, PM₁₀, NO₂ and SO₂ concentrations reduced by 22%, 31%, 25% and 28% respectively during lockdown phase as compared to pre-lockdown phase, while O₃ was seen to increase. Variation in meteorological parameters and correlation of pollutants has also been examined. The significant improvement arising due to curtailment of certain activities in the lockdown period indicates the importance of local emission control, and helps improve the understanding of the dynamics of air pollution, thus highlighting policy areas to regulatory bodies for effective control of air pollution.

SUBMITTER: Sharma GK

PROVIDER: S-EPMC9427329 | biostudies-literature | 2022 May

REPOSITORIES: biostudies-literature

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Comprehensive analysis of ambient air quality during second lockdown in national capital territory of Delhi.

Sharma Gautam Kumar GK Tewani Ankush A Gargava Prashant P

Journal of hazardous materials advances 20220420

The lockdown imposed in Delhi, due to the second wave of the COVID-19 pandemic has led to significant gains in air quality. Under the lockdown, restrictions were imposed on movement of people, operation of industrial establishments and hospitality sector amongst others. In the study, Air Quality Index and concentration trends of six pollutants, i.e. PM2.5, PM10, NO2, SO2, CO, and O3 were analysed for National Capital Territory of Delhi, Indi ...[more]

PMID: 36919145

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Project description:Globally, since the end of December 2019, coronavirus disease (COVID-19) has been recognized as a severe infectious disease. Therefore, this study has been attempted to examine the linkage between climatic variables and COVID-19 particularly in National Capital Territory of Delhi (NCT of Delhi), India. For this, daily data of COVID-19 has been used for the period March 14 to June 11, 2020, (90 days). Eight climatic variables such as maximum, minimum and mean temperature (°C), relative humidity (%), bright sunshine hours, wind speed (km/h), evaporation (mm), and rainfall (mm) have been analyzed in relation to COVID-19. To study the relationship among different climatic variables and COVID-19 spread, Karl Pearson’s correlation analysis has been performed. The Mann–Kendall method and Sen’s slope estimator have been used to detect the direction and magnitude of COVID-19 trends, respectively. The results have shown that out of eight selected climatic variables, six variables, viz. maximum temperature, minimum temperature, mean temperature, relative humidity, evaporation, and wind speed are positively associated with coronavirus disease cases (statistically significant at 95 and 99% confidence levels). No association of coronavirus disease has been found with bright sunshine hours and rainfall. Besides, COVID-19 cases and deaths have shown increasing trends, significant at 99% confidence level. The results of this study suggest that climatic conditions in NCT of Delhi are favorable for COVID-19 and the disease may spread further with the increasing temperature, relative humidity, evaporation and wind speed. This is the only study which has presented the analysis of COVID-19 spread in relation to several climatic variables for the most densely populated and rapidly growing city of India. Thus, considering the results obtained, effective policies and actions are necessary especially by identifying the areas where the spread rate is increasing rapidly in this megacity. The prevention and protection measures should be adopted aiming at to reduce the further transmission of disease in the city.

Project description:BackgroundThe COVID-19 pandemic has had a deep global impact, not only from a social and economic perspective, but also with regard to human health and the environment. To restrict transmission of the virus, the Indian government enforced a complete nationwide lockdown except for essential services and supplies in phases from 25 March to 31 May 2020. Ambient air quality in and around New Delhi, one of the most polluted cities of world, was also impacted during this period.ObjectiveThe aim of the present study was to assess and understand the impact of four different lockdown phases (LD1, LD2, LD3 and LD4) on five air pollutants (particulate matter (PM) PM2.5, PM10, nitrogen oxide (NOx), sulfur dioxide (SO2) and ozone (O3)) compared to before lockdown (BLD) at 13 air monitoring stations in and around New Delhi.MethodsSecondary data on five criteria pollutants for 13 monitoring stations in and around New Delhi for the period 1 March to 31 May 2020 was accessed from the Central Pollution Control Bard, New Delhi. Data were statistically analyzed across lockdown phases, meteorological variables, and prevailing air sources around the monitoring stations.ResultsPollutant concentrations decreased during LD1 compared to BLD except for O3 at all stations. PM2.5 and PM10 remained either close to or higher than the National Ambient Air Quality Standards (NAAQS) due to prevailing high-speed winds. During lockdown phases, NO2 decreased, whereas O3 consistently increased at all stations. This was a paradoxical situation as O3 is formed via photochemical reactions among NOx and volatile organic compounds. Principal component analysis (PCA) extracted two principal components (PC1 and PC2) which explained up to 80% of cumulative variance in data. PM2.5, PM10 and NO2 were associated with PC1, whereas PC2 had loadings of either O3 only or O3 and SO2 depending upon monitoring station.ConclusionsThe present study found that air pollutants decreased during lockdown phases, but these decreases were specific to the site(s) and pollutant(s). The decrease in pollutant concentrations during lockdown could not be attributed completely to lockdown conditions as the planetary boundary layer increased two-fold during lockdown compared to the BLD phase. Such restrictions could be applied in the future to control air pollution but should be approached with caution.Competing interestsThe authors declare no competing financial interests.

Project description:Graphical abstract Highlights • Air quality of major cities of Kerala State (India) during the COVID-19 lockdown.• Substantial reduction of NO2 (-48 %) NOx (-53 % to -90 %) and CO (-24 % to -67 %).• Significant decrease in PM2.5 (-24 % to -47 %) and PM10 (-17 % to -20 %) levels.• Increase of O3 levels in Northern Kerala during lockdown period.• Indications of multiple sources (other than traffic and industry) of air pollution. This study assesses the effect of lockdown, due to the coronavirus disease (COVID-19) pandemic, on the concentration of different air pollutants and overall air quality of a less industrialized region (Kerala) of India. We analysed data from four ambient air quality stations over three years (January to May, 2018–2020) with pairwise comparisons, trend analysis, etc. Results indicated unprecedented reduction in the concentration of the air pollutants: nitrogen dioxide, NO2 (-48 %), oxides of nitrogen, NOx (-53 % to -90 %), carbon monoxide, CO (-24 % to -67 %) and the particulate matter (-24 % to -47 % for particulate matter with a diameter of less than 2.5 ?m, PM2.5; -17 % to -20 % for particulate matter with a diameter of less than 10 ?m, PM10), as well as the reduction of the National Air Quality Index (NAQI). These reductions indicate an overall improvement of the ambient air quality due to restrictions on transportation, construction, and the industrial sectors during lockdown, even in an area considered less industrial. Despite the general decreasing trend of the concentration of various air pollutants from January to May, suggesting seasonal influences, the trend was intensified in the year 2020 due to the added effect of the lockdown measures. Comparison of the results with those from larger and more industrialized cities suggests that the effects of lockdown are more variable, and focused on the levels of gaseous pollutants. Findings from this study demonstrate the far-reaching effects and implications of the COVID-19 lockdown on ambient air quality, even on less industrialized and less urbanized regions.

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Comprehensive analysis of ambient air quality during second lockdown in national capital territory of Delhi.

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Comprehensive analysis of ambient air quality during second lockdown in national capital territory of Delhi.

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