SARS-CoV-2 pandemic lockdown: Effects on air quality in the industrialized Gujarat state of India

Abstract

Two weeks after the world health organization described the novel coronavirus (SARS-CoV-2) outbreak as pandemic, the Indian government implemented lockdown of industrial activities and traffic flows across the entire nation between March 24 and May 31, 2020. In this paper, we estimated the improvements achieved in air quality during the lockdown period (March 24, 2020 and April 20, 2020) compared to the pre-lockdown (January 1, 2020 and March 23, 2020) by analyzing PM _2.5, PM ₁₀, SO ₄, CO, NO ₂ and O ₃ data from nine different air quality monitoring stations distributed across four different zones of the industrialized Gujarat state of western Indian. The Central Pollution Control Board (CPCB)-Air Quality Index (AQI) illustrated better air qualities during the lockdown with higher improvements in the zones 2 (Ahmedabad and Gandhinagar) and 3 (Jamnagar and Rajkot), and moderate improvements in the zones 1 (Surat, Ankleshwar and Vadodra) and 4 (Bhuj and Palanpur). The concentrations of PM _2.5, PM ₁₀, and NO ₂ were reduced by 38–78%, 32–80% and 30–84%, respectively. Functioning of the power plants possibly led to less reduction in CO (3–55%) and the declined emission of NO helped to improve O ₃ (16–48%) contents. We observed an overall improvement of 58% in AQI for the first four months of 2020 compared to the same interval of previous year. This positive outcome resulted from the lockdown restrictions might help to modify the existing environmental policies of the region.

Graphical abstract

Highlights

• •

  Reduction of 30–84% in NO ₂ during COVID-19 lockdown in western India.

• •

  Increasing O ₃ (16–58%) was mainly due to less NO emission.

• •

  Overall improvement of Air Quality Index (AQI) by 58% compared to 2019.

• •

  Populated cities with more industrial activities showed higher improvement in air quality (AQI: +60–75%).