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A majority of Indian are ranked very poorly in air quality with high levels of pollutants being a cause of worry. Lucknow, the capital of Uttar Pradesh, is a city plagued with extreme levels of air pollutants. The concentration of PM2.5, NO2 and SO2 is way above the prescribed levels of WHO for safe ambient air pollution levels in the city which affects the huge urban pollution. When lockdown was imposed in the town owing to the COVID 19 crisis, the city should have registered lower levels of pollution owing to reduced anthropogenic activity. The present study investigates the impact of lockdown on pre and post-lockdown levels of pollutants in Lucknow city.

It is evident that man-made activities like burning of fossil fuels, specially vehicles in an urban environment and industrial activities play a crucial role in the concentration of PM2.5, NO2 and SO2. To prevent the spread of the COVID-19 pandemic, an unprecedented statewide lockdown limiting human activity was enforced in March 2020. As a result, anthropogenic emissions reduced significantly, particularly in the transportation and manufacturing sectors. As a natural experiment with significant research value, this provides a valuable opportunity to comprehend the evolution of pollution through the use of stringent controls.

The national capital of Delhi which is one of the worst polluted cities in the world saw the levels of air quality improve during the lockdown phase (Srivastava et al., 2020; Chaudhary, 2021; Antil, Yadav and Chaudhary, 2022). Authors also concluded that reduced anthropogenic activity led to reduction in the city of Lucknow (Srivastava et al., 2020) and the air quality index (AQI) improved to moderate and good. This study investigates the impact of lockdown on air pollution indices in Lucknow from a scientific standpoint. With an area of 349 km2 and a population of 2.82 million, Lucknow is the capital city of Uttar Pradesh. Since two to three years ago, it has been well-documented that the city has heavy pollution days in early winter. During 5 November 2019, the air quality index (AQI) in Lucknow ranged between 283–500 to 267–486, which, according to the National Air Quality Index, was poor (Unhealthy) to severe. This study investigated air pollution indices for the city of Lucknow before and after the lockdowns were placed in the city. The months of February (before lockdown) and April (after lockdown) are taken as the reference months for comparing the impact of lockdown on the concentration of PM 2.5, SO2 and NO2. WHO recommends levels of 10 μg/m3 (PM2.5) 40 µg/m3 (NO2) and 20 µg/m3 (SO2) for safe concentration of various pollutants.

Pre and post lockdown data for various pollutants is obtained from National Air Quality Index, Central Pollution Control Board of India website. The data is then preprocessed and plotted in MS-Excel for analysis. The results are shown in Table 1
Table 1: Average monthly values of various pollutants and WHO recommended safe limits in µg/m³

The analysis reveals a significant change in pre and post lockdown levels in the concentration of various pollutants. In this context, Figure 1 depicts declining PM2.5 concentrations, indicating how the forced shutdown of factories, vehicles, and construction activities has facilitated the environmental adjustment of pollution. The trends in variation SO2 and NO2 for February and April are also shown in Figure 1. Similar findings have been reported for the city of Lucknow by other authors (Srivastava et al., 2020). The greatest change is observed in the concentration of NO2 which decreased by almost 60% post lockdown while SO2 showed the minimum change. The levels of PM2.5 almost halved to 65 µg/m³. Despite the significant reduction in anthropogenic activities during lockdown, the levels of PM2.5 was way higher than the WHO prescribed safe limit of 10 µg/m³. However, the levels of NO2 dropped below the safe limit of 40 µg/m³ to 17.38 µg/m³. 

 Figures : Charts depicting the concentrations of PM2.5, SO2 and NO2 in µg/m³ during February (pre-lockdown) and April (post-lockdown).

The present study provides conclusive impacts of anthropogenic activities on the concentration levels of air pollution in the form of sharp drop from pre to post lockdown period. There is no denying that the intense levels of air pollution are a cause of worry, however, the lockdown period proved that regulated activities can play a significant role in reducing the ambient air pollution levels more safe.

1. Antil, R., Yadav, S. and Chaudhary, S. (2022) ‘Assessment of impact of COVID-19 lockdown on air quality in national capital region of New Delhi, India’, The holistic approach to environment, 12(2), pp. 70–78. doi: 10.33765/thate.12.2.2. 2. Chaudhary, S. (2021) ‘Air Quality Before and After COVID-19 Lockdown Phases Around New Delhi , India’, (July). doi: 10.5696/2156-9614-11.30.210602. 3. Masum, M. H. and Pal, S. K. (2020) ‘Statistical evaluation of selected air quality parameters influenced by COVID-19 lockdown’, (June). doi: 10.22034/GJESM.2019.06.SI.08. 4. Srivastava, S. et al. (2020) ‘21 ‑ Day Lockdown in India Dramatically Reduced Air Pollution Indices in Lucknow and New Delhi , India’, Bulletin of Environmental Contamination and Toxicology, 105(1), pp. 9–17. doi: 10.1007/s00128-020-02895-w. 5. Zhang, M. et al. (2021) ‘Impact of reduced anthropogenic emissions during COVID-19 on air quality in India’, Atmospheric Chemistry and Physics, 21(5), pp. 4025–4037. doi: 10.5194/acp-21-4025-2021.