The long-term lockdown due to COVID-19 has beneficial impact on the natural environment. India has enforced a lockdown on 24th March 2020 and was subsequently extended in various phases. The lockdown due to the sudden spurt of the COVID-19 pandemic has shown a significant decline in concentration of air pollutants across India. The present article dealt with scenarios of air quality concentration of air pollutants, and effect on climatic variability during the COVID-19 lockdown period in Kolkata Metropolitan Area, India. The result showed that the air pollutants are significantly reduced and the air quality index (AQI) was improved during the lockdown months. Aerosol concentrations decreased by − 54.94% from the period of pre-lockdown. The major air pollutants like particulate matters (PM_2.5, PM₁₀), sulphur dioxide (SO₂), carbon monoxide (CO) and Ozone (O₃) were observed the maximum reduction ( − 40 to − 60%) in the COVID-19 lockdown period. The AQI has been improved by 54.94% in the lockdown period. On the other hand, Sen’s slope rank and the Mann–Kendal trend test showed the daily decreased of air pollutants rate is − 0.051 to − 1.586 μg /m3. The increasing trend of daily minimum, average, and maximum temperature from the month of March to May in this year (2020s) are 0.091, 0.118, and 0.106 °C which is lowest than the 2016s to 2019s trend. Therefore, this research has an enormous opportunity to explain the effects of the lockdown on air quality and climate variability, and it can also be helpful for policymakers and decision-makers to enact appropriate measures to control air pollution.

由于 COVID-19 造成的长期封锁对自然环境产生了有益的影响。印度已于 2020 年 3 月 24 日实施封锁，随后分阶段延长。由于 COVID-19 大流行的突然爆发而导致的封锁表明，印度各地的空气污染物浓度显着下降。本文讨论了印度加尔各答都会区 COVID-19 封锁期间空气污染物的空气质量浓度情景以及对气候变化的影响。结果表明，在封锁期间，空气污染物显着减少，空气质量指数（AQI）有所改善。气溶胶浓度比封锁前下降了 − 54.94%。颗粒物等主要空气污染物（PM _2.5 , PM ₁₀)、二氧化硫 (SO ₂ )、一氧化碳 (CO) 和臭氧 (O ₃）观察到在 COVID-19 锁定期间的最大减少（- 40 至 - 60%）。在锁定期间，AQI 改善了 54.94%。另一方面，Sen 的斜率秩和 Mann-Kendal 趋势检验表明，空气污染物率的每日下降幅度为 - 0.051 至 - 1.586 μg /m3。今年（2020s）3~5月份日最低、平均、最高气温的上升趋势分别为0.091、0.118、0.106℃，低于2016~2019s的趋势。因此，这项研究为解释封锁对空气质量和气候变化的影响提供了巨大的机会，也有助于政策制定者和决策者制定适当的措施来控制空气污染。