Silver linings in the dark clouds of COVID-19: Improvement of air quality over India and Delhi metropolitan area from measurements and WRF-CHIMERE model simulations

Dumka, U. C.; Kaskaoutis, Dimitris G.; Verma, Shubha; Ningombam, Shantikumar S.; Kumar, Sarvan; Ghosh, Souradip

doi:10.1016/j.apr.2020.11.005

Cited by 41 publications

(35 citation statements)

References 106 publications

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“…Numerous studies around the world, as in China and East Asia [13][14][15], India [16][17][18], Southeast Asia [19,20], Europe [21][22][23][24][25][26], North America [27,28] and South America [29,30], have analyzed the effect of COVID-19 lockdowns in spring 2020 on concentrations of particulate matter (PM) and gaseous pollutants (NO x , CO, O 3 , SO 2 , NH 3 , etc.). All these studies agree on an unprecedented reduction of air pollution worldwide due to drastic limitations in traffic and industrial activity [31][32][33]. Focusing on the AOD, a significant reduction (20-60%) was obtained in eastern China, while southeast Asia, eastern US and most European regions experienced a reduction reaching 40% [19,34,35].…”

Section: Introductionsupporting

confidence: 70%

Assessment of the COVID-19 Lockdown Effects on Spectral Aerosol Scattering and Absorption Properties in Athens, Greece

et al. 2021

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COVID-19 is evolving into one of the worst pandemics in recent history, claiming a death toll of over 1.5 million as of December 2020. In an attempt to limit the expansion of the pandemic in its initial phase, nearly all countries imposed restriction measures, which resulted in an unprecedented reduction of air pollution. This study aims to assess the impact of the lockdown effects due to COVID-19 on in situ measured aerosol properties, namely spectral-scattering (bsca) and absorption (babs) coefficients, black carbon (BC) concentrations, single-scattering albedo (SSA), scattering and absorption Ångström exponents (SAE, AAE) in Athens, Greece. Moreover, a comparison is performed with the regional background site of Finokalia, Crete, for a better assessment of the urban impact on observed differences. The study examines pre-lockdown (1–22 March 2020), lockdown (23 March–3 May 2020) and post-lockdown (4–31 May 2020) periods, while the aerosol properties are also compared with a 3–4 year preceding period (2016/2017–2019). Comparison of meteorological parameters in Athens, between the lockdown period and respective days in previous years, showed only marginal variation, which is not deemed sufficient in order to justify the notable changes in aerosol concentrations and optical properties. The largest reduction during the lockdown period was observed for babs compared to the pre-lockdown (−39%) and to the same period in previous years (−36%). This was intensified during the morning traffic hours (−60%), reflecting the large decrease in vehicular emissions. Furthermore, AAE increased during the lockdown period due to reduced emissions from fossil-fuel combustion, while a smaller (−21%) decrease was observed for bsca along with slight increases (6%) in SAE and SSA values, indicating that scattering aerosol properties were less affected by the decrease in vehicular emissions, as they are more dependent on regional sources and atmospheric processing. Nighttime BC emissions related to residential wood-burning were slightly increased during the lockdown period, with respect to previous-year means. On the contrary, aerosol and pollution changes during the lockdown period at Finokalia were low and highly sensitive to natural sources and processes.

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Section: Introductionsupporting

confidence: 70%

Assessment of the COVID-19 Lockdown Effects on Spectral Aerosol Scattering and Absorption Properties in Athens, Greece

et al. 2021

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“…The changes in the emissions of both primary or/and secondary particles can reduce particulate matter content. The primary PM refers to natural and anthropogenic activities such as wind erosion and road traffic in urban areas (Dumka et al 2021 ; Kerimray et al 2020 ; Pei et al 2020 ; Srivastava et al 2021 ), while the two main secondary PM components are nitrate and sulfate, formed in the air from precursors of NO 2 and SO 2 . As a result, the reduction in the emissions of NO 2 and SO 2 could indirectly reduce the secondary ambient PM formation (Tables 3 – 4 and Figure 5 ).…”

Section: Resultsmentioning

confidence: 99%

Assessment of potential benefits of traffic and urban mobility reductions during COVID-19 lockdowns: dose-response calculations for material corrosions on built cultural heritage

Broomandi

Tleuken

Zhaxylykov

et al. 2021

Environ Sci Pollut Res

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Air pollution, particularly in urban areas, puts human health in danger and has adverse impacts on the built environment. It can accelerate the natural corrosion rate of cultural heritages and monuments, leading to premature aging and lowering their aesthetic value. Globally, at the beginning of 2020, to tackle the spread of novel COVID-19, the lockdown was enforced in the most hard-hit countries. Therefore, this study assesses, as a first time, the plausible benefits of traffic and urban mobility reductions on the natural process of deterioration of materials during COVID-19 lockdown in twenty-four major cities on five continents. The potential risk is estimated based on exceeding the tolerable degradation limits for each material. The notable impact of COVID-19 mobility restrictions on air quality was evidenced in 2020 compared to 2019. The introduced mobility restrictions in 2020 could decrease the surface recession rate of materials. Extremely randomized trees analysis showed that PM 10 was the main influencing factor for corrosion of portland, copper, cast bronze, and carbon steel with a relative importance of 0.60, 0.32, 0.90, and 0.64, respectively, while SO 2 and HNO 3 were mainly responsible for corrosion of sandstone and zinc with a relative importance of 0.60 and 0.40, respectively. The globally adverse governed meteorological conditions in 2020 could not positively influence the movement restrictions around the world in air quality improvements. Our findings can highlight the need for additional policies and measures for reducing ambient pollution in cities and the proximity of sensitive cultural heritage to avoid further damage. Supplementary Information The online version contains supplementary material available at 10.1007/s11356-021-16078-5.

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“…Similarly, Nakada et al (2020) conducted in São Paulo, Brazil, noted that reduction in pollutants during lockdown was not influenced by changes in meteorological and dispersion conditions. In a recent study conducted by Dumka et al 2020 for the region of Delhi NCR also reported that drastic change in pollutant concentrations during lockdown period could be attributed to limited anthropogenic emissions and effect of meteorological conditions were minimum. Hence, based on the above literature, it was assumed that the role of meteorological parameters in reduction of pollutant concentrations was minimum.…”

Section: Methodsmentioning

confidence: 96%

“…Singh et al ( 2020c ) estimated the temporal and diurnal changes of criteria pollutants like PM 2.5 , PM 10 , NO 2 , CO, O 3 and SO 2 for regions across India by using real-time monitoring data from CPCB and observed significant reductions in particulate pollutants, NO 2 and CO, while the results of SO 2 and O 3 showed mixed variation. In a recent study presented by Dumka, 2020 used WRF-CHIMERE model and observed that reductions in PM 10 , PM 2.5 , NO 2 during lockdown in Delhi NCR region ranged between 27 to 59%. Similarly, Biswal et al ( 2020a , 2020b ) observed decrease in NO 2 concentrations during lockdown period compared to last year using satellite-based ozone monitoring instrument sensor data for India.…”

Section: Literature Reviewmentioning

confidence: 99%

Short-term impacts of air pollutants in three megacities of India during COVID-19 lockdown

Ganguly

Sharma

Kumar

2021

Environ Dev Sustain

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Lockdown was imposed by the Indian government in the month of March 2020 as an early precaution to the COVID-19 pandemic which obstructed the socio-economic growth globally. The main aim of this study was to analyse the impact of lockdown (imposed in March and continued in April 2020) on the existing air quality in three megacities of India (Delhi, Mumbai and Kolkata) by assessing the trends of PM 10 and NO 2 concentrations. A comparison of the percentage reduction in concentrations of lockdown period with respect to same period in year 2019 and pre-lockdown period (February 14–March 24) was made. It was observed from the study that an overall decrease of pollutant concentrations was in the ranges of 30–60% and 52–80% of PM 10 and NO 2 , respectively, in the three cities during lockdown in comparison with previous year and pre-lockdown period . The overall decrease in concentrations of pollutants at urban sites was greater than the background sites. Highest decline in concentrations of PM 10 were observed in Kolkata city, followed by Mumbai and Delhi, while decline in NO 2 was highest in Mumbai. Results also highlighted that capital city Delhi had the worst air quality amongst three cities, with particulate matter (PM 10 ) being the dominant pollutant. Although COVID-19 has significantly affected the human life considering the mortality and morbidity, lockdowns imposed to control the pandemic had significantly improved the air quality in the selected study locations, although for the short amount of period.

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Silver linings in the dark clouds of COVID-19: Improvement of air quality over India and Delhi metropolitan area from measurements and WRF-CHIMERE model simulations

Cited by 41 publications

References 106 publications

Assessment of the COVID-19 Lockdown Effects on Spectral Aerosol Scattering and Absorption Properties in Athens, Greece

Assessment of the COVID-19 Lockdown Effects on Spectral Aerosol Scattering and Absorption Properties in Athens, Greece

Assessment of potential benefits of traffic and urban mobility reductions during COVID-19 lockdowns: dose-response calculations for material corrosions on built cultural heritage

Short-term impacts of air pollutants in three megacities of India during COVID-19 lockdown

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