The Effects of COVID-19 Lockdown on Air Quality and Health in India and Finland

The COVID-19 lockdowns worldwide provided a prospect to evaluate the impacts of restricted movements and emissions on air quality. In this study, we analyze the data obtained from the ground-based observation stations for six air pollutants (PM₁₀, PM_2.5, CO, NO₂, O₃ and SO₂) and meteorological parameters from March 25th to May 31st in 22 cities representative of five regions of India and from March 16th to May 14th in 21 districts of Finland from 2017 to 2020. The NO₂ concentrations dropped significantly during all phases apart from East India's exception during phase 1. O₃ concentrations for all four phases in West India reduced significantly, with the highest during Phase 2 (~38%). The PM_2.5 concentration nearly halved across India during all phases except South India, where a very marginal reduction (2%) was observed during Phase 4. SO₂ (~31%) and CO (~41%) concentrations also reduced noticeably in South India and North India during all the phases. The air temperature rose by ~10% (average) during all the phases across India when compared to 2017-2019. In Finland, NO₂ concentration reduced substantially in 2020. Apart from Phase 1, the concentrations of PM₁₀ and PM_2.5 reduced markedly in all the Phases across Finland. Also, O₃ and SO₂ concentrations stayed within the permissible limits in the study period for all four years but were highest in 2017 in Finland, while the sulfurous compounds (OSCs) levels increased during all the phases across Finland. The changes in the mobility patterns were also assessed and were observed to have reduced significantly during the lockdown. The benefits in the overall mortality due to the reduction in the concentrations of PM_2.5 have also been estimated for India and Finland. Therefore, this research illustrates the effectiveness of lockdown and provides timely policy suggestions to the regulators to implement interventions to improve air quality.