Impact of lockdown (COVID-19) and unlocking period on ambient air quality and human health in Lucknow city, India

Lucknow is one of the most polluted metro-city in India with increasing vehicular density and fuel consumption in the last three decades. The study was conducted during years 2019–2021 for measurement of fine particulate matter (PM_2.5), nitrogen dioxide (NO₂), sulphur dioxide (SO₂), respirable particulate matter (PM₁₀), and noise levels at nine selected sites; 4 residential, 4 commercial, and 1 industrial, encompassing prior-to-lockdown, during-lockdown, and after-lockdown periods. Values of PM₁₀ for prior-to-lockdown, during-lockdown, and after-lockdown period ranged from 133.2 to 197.4, 77.0 to 135.0, and 91.4 to 148.0 µg/m³, respectively while values of PM_2.5 were 66.5 to 93.6, 41.9 to 67.5 and 49.5 to 98.6 µg/m³, respectively. Corresponding values of SO₂ ranged from 8.7 to 12.8, 5.5 to 7.6, and 11.4 to 17.6 µg/m³, respectively while values of NO₂ were 24.6 to 57.0, 20.5 to 32.8, and 26.1 to 43.8 µg/m³, respectively. Order of the trace metals associated with PM_2.5 is Co < Cd < As < Cr < Ni < Cu < Pb < Mn < K < Zn, Co < Cd < As < Cr < Cu < Ni < Pb < Mn < Zn < K and Cd < Co < As < Cr < Cu < Ni < Pb < Mn < K < Zn in the same periods. Statistical data evidenced that the air quality of the city witnessed drastic improvement during the COVID-19 pandemic. WHO AIRQ + was utilized to calculate attributable health risk and post-neonatal disease burden; showing 1447 ± 768 estimated number of cases attributable to ambient PM₁₀ per lakh of population. Regulatory authorities need to establish new benchmarks for the prevention and management of public health risks for urban resilience and environmental management for episodic events in the near future.