Abstract
Abstract. To mitigate the impacts of the pandemic of coronavirus disease 2019 (COVID-19), the Indian government implemented lockdown measures on 24 March 2020, which prohibited unnecessary anthropogenic activities, thus leading to a significant reduction in emissions. To investigate the impacts of this lockdown measure on air quality in India, we used the Community Multi-Scale Air Quality (CMAQ) model to estimate the changes of key air pollutants. From pre-lockdown to lockdown periods, improved air quality is observed in India, indicated by the lower key pollutant levels such as PM2.5 (−26 %), maximum daily 8 h average ozone (MDA8 O3) (−11 %), NO2 (−50 %), and SO2 (−14 %). In addition, changes in these pollutants show distinct spatial variations with the more important decrease in northern and western India. During the lockdown, our results illustrate that such emission reductions play a positive role in the improvement of air quality. Significant reductions of PM2.5 concentration and its major components are predicted, especially for secondary inorganic aerosols that are up to 92 %, 57 %, and 79 % for nitrate (NO3-), sulfate (SO42-), and ammonium (NH4+), respectively. On average, the MDA8 O3 also decreases 15 % during the lockdown period although it increases slightly in some VOC-limited urban locations, which is mainly due to the more significant reduction of NOx than VOCs. More aggressive and localized emission control strategies should be implemented in India to mitigate air pollution in the future.
Highlights
India, the second-most populous country in the world, has been suffering from severe air pollution along with rapid urbanization and industrialization in recent decades (Karambelas et al, 2018), and 13 Indian cities were among the world’s top 20 most polluted cities according to the World Health Organization (WHO) (WHO, 2018)
To counter the fast contagion of COVID-19, a 3-week nationwide lockdown was imposed in India on 24 March, which was extended until 30 June
We explored the synergetic impacts from the meteorological conditions and anthropogenic emissions during the pre-lockdown and lockdown periods
Summary
The second-most populous country in the world, has been suffering from severe air pollution along with rapid urbanization and industrialization in recent decades (Karambelas et al, 2018), and 13 Indian cities were among the world’s top 20 most polluted cities according to the World Health Organization (WHO) (WHO, 2018). The Indian government has been promoting effective emission control strategies such as the conversion of fossil fuels to clean fuels in the nationwide Clean India Mission (CIM). Such long-term or short-term reduction strategies seem to show insufficiency in the restoration of ambient air quality (Beig et al, 2013; Purohit et al, 2019; Banerjee et al, 2017). Due to the pandemic of coronavirus disease 2019 (COVID-19), nationwide or partial lockdown measures have been implemented in many countries (Chintalapudi et al, 2020; Dantas et al, 2020; Ehrlich et al, 2020).
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