The Indian government imposed a countrywide lockdown on 25 March 2020 to contain the COVID-19 virus. The lockdown has led to a tremendous economic loss because of the closing of all industries and other activities. However, it has brought a brighter side to environmental quality improvement. This study assesses the influence of lockdown on Delhi-NCR's air and water quality. The earth system rejuvenated during the lockdown. An effort is made to understand the water quality of the Yamuna River in Delhi and the air quality of the Delhi-National Capital Region (Delhi NCR) during the lockdown. In the Yamuna River surrounding Delhi, a reduction of 1-10%, 33-66%, 51%, 45-90%, and 33-82%, respectively, in pH, EC, DO, BOD, and COD has been observed compared to the pre-lockdown. Similarly, the particulate matter concentration reduced by 31-53% in PM10 and 22-48% in PM2.5 during the lockdown of 2020 in comparison to the earlier years (2018 and 2019). Hence, the periodic lockdown has positively impacted the air and water quality in Delhi NCR.
TopIntroduction
The COVID-19 has forced the global lockdown to contain the spread of the virus in several nations (viz., France, Germany, Italy, Spain, China, India, etc.). The lockdown led to the closing of power plants, transportation, and other industries, that caused a severe reduction in concentration of GHGs (NO2, SO2 and CO) and particulate matters (PM2.5, PM10). An increase in the ozone concentration, mainly in Europe and many Chinese cities (Monserrate et al., 2020; EEA, 2020; Nie et al., 2021; Shi and Brasseur. 2020; Li et al., 2020). The lockdown in the USA to comprehend the COVID-19 pandemic considerably declined the concentration NO2 and CO and other atmospheric pollutants under reduced transportation and utility demands. The impact of the first phase was more pronounced to the urban than suburban air quality (Chen et al., 2020). During the COVID-19 lockdown, there has been a significant lowering of particulate matters (PM10 and PM2.5), NOx, SO2 and CO over different parts of the world, viz. the Yangtze River Delta Region and Hangzhou megacity (Li et al., 2020; Yuan et al., 2020). The USA observed a reduction of NO2 (49%) and CO (37%) during the lockdown (Chen et al., 2020). A similar improvement in the air quality was observed in Rio de Janeiro, Brazil, during the partial lockdown to the comparable period of 2019 (Dantas et al., 2020). The PM10, NO2 and CO of the Sao Paulo and Rio the Janeiro showed a reduction under lockdown with a very high reduction in the CO, which would be related to light-duty vehicular releases (Siciliano et al., 2020). The restricted public mobility and industrial closure in Sale city (North-Western Morocco) have also impacted air quality improvement (Otmani et al., 2020). The Hangzhou city of China showed a reduced concentration of black carbon during the lockdown (Xu et al., 2020). California basin displayed a decrease of 27% in NO2 concentration as compared to the last five years. (Parker et al., 2020) whereas 10–30% reduction in NO2 has been reported in central and eastern China during early 2020 (Patel, 2020) in comparison to the average value of 2005-2019. A deterioration in PM2.5 over major cities of the world has been reported by Singh and Chauhan (2020). It is interesting to note that the river water quality of India became cleaner throughout the lockdown (Garg et al., 2020).
The COVID-19 epidemic has become a challenge to humanity. It is not only posing a health crisis but also a social crisis. In the several previous pandemics, life is unlikely to be the same after the pandemic is over. It will impose changes on individuals, families, communities, states, nations, international relationships. Apart from this, it will also depend on how it is dealt with humans and environmental situations. Any disasters require emotional health counselling to distress, and the vulnerabilities are associated with the way society and government deals with the situation. There remains a vital role for socio-economic interventions for food, healthcare, shelter, etc., for coping with the pandemic.