Insights into India's temporary air pollution relief: A systematic review for green recovery amid and post-COVID-19

Abstract

The outbreak of the novel coronavirus disease (COVID-19) has profoundly impacted human health, the environment, and the economy. Numerous studies have explored the relationship between COVID-19 and the air quality index, yet a comprehensive critical review addressing the reduction in air pollutants post-challenges and green opportunities in India remains absent. Concurrently, a systemic review has been conducted to analyze the significant relationship between meteorological/climatic factors and COVID-19 transmission. The findings of this review unveil remarkable reductions, reaching up to 87% for PM₁₀ and 81% for PM_2.5 during lockdown periods in India. Gaseous pollutants, including CO, CO₂, SO₂, and NO₂, exhibited reductions surpassing 75%, 54%, 72%, and 78%, respectively, during these lockdowns. Notably, while particulate and gaseous pollutants experienced drastic declines, there was a slight increase observed in O₃ levels during lockdown periods. This review underscores a discernible correlation between fluctuations in meteorological parameters and the transmission dynamics of COVID-19. Moreover, it delves into post-COVID-19 challenges and potential avenues for green recovery amidst the pandemic. Additionally, it outlines specific research inquiries to address these future research areas.

Graphical abstract

Highlights

The significant reductions were observed for particulate and gaseous pollutants across Indian cities during COVID-19 lockdowns.

The ozone level was observed slightly increasing during the COVID-19 lockdowns.

The temporary air quality improvements underscore the need for sustainable urban planning to maintain long-term benefits.

The pandemic has sped up the move toward sustainability, creating a chance to invest in green infrastructure and renewable energy.

Discussion

The observed reductions in air pollutants especially in PM₁₀ and PM_2.5 levels during the COVID-19 lockdowns were limited to a specific period and geographic locations, making it difficult to generalize the findings to other times or regions with different environmental and socio-economic conditions. At the same time, other pollutants such as (SO₂ and O₃) increased in some areas despite overall reductions in emissions suggesting that current pollution control strategies may need to be re-evaluated to address complex atmospheric chemistry and secondary pollutant formation. The temporary improvements in air quality during lockdowns raise provocative concerns about the sustainability of such gains and whether current environmental policies are sufficient to maintain long-term air quality without causing economic and social disruptions.