Energy Intelligence and Sustainability ISSN (Online): 3139-4051 Volume-2 Issue-3 June-2026
  1. 2
    Citations
Assessing the short-term air quality improvements during the COVID-19 lockdown

Rushda Khanam1, Danish Ali1, Rajeev Singh1, Henna Gull2 and Sirajuddin Ahmed1

Department of Environmental Sciences,Faculty of Engineering and Technology, Jamia Millia Islamia,New Delhi-110025,India1
Division of Environmental Science and Engineering,Pohang University of Science and Technology, 77 Cheongam-Ro, Nam-Gu,Pohang 37673,South Korea2
Corresponding Author : Sirajuddin Ahmed

Recieved : 27-May-2026; Revised : 18-June-2026; Accepted : 25-June-2026

Abstract

Clean air is essential for protecting human well-being while supporting sustainable economic and societal development. This study aims to investigate the air quality trends in Delhi by comparing the pre-COVID, COVID, and post-COVID periods. The Daily air quality index (AQI) shows a significant improvement during the lockdown period, dropping by 46.8% from about 228 in the pre-COVID period to 122 in the COVID period. In the pre-COVID period, moderate and poor AQI categories dominated, taking almost 73%, whereas the satisfactory category was less common. On the other hand, during the COVID period, the satisfactory AQI category became more prevalent, reaching 51.3%. The PM₁₀ concentrations fell from 288 µg/m³ in pre-COVID to 138 µg/m³ during the COVID period, and PM₂.₅ decreased from 98 µg/m³ to 49 µg/m³. Non-parametric tests were used to analyze the statistical difference between the periods. Kruskal–Wallis H test showed that AQI, PM₂.₅ and PM₁₀ differed significantly during the pre-COVID, COVID, and post-COVID periods (p < 0.001). Pairwise comparisons using the Dunn-Bonferroni post hoc test further identified significant differences between the periods. However, even after these improvements, exceedance analysis indicates that Delhi’s PM concentrations largely exceed the guidelines set by WHO for particulate matter. In conclusion, although short-term measures to reduce emissions have been shown to greatly improve air quality, their effects are temporary. Better policies and strict enforcement are required to ensure that global air quality standards are met in the long run.

Keywords

COVID-19 Lockdown, Air quality index (AQI), PM10, PM2.5, Statistical analysis.

Cite this article

Khanam R, Ali D, Singh R, Gull H, Ahmed S. Assessing the short-term air quality improvements during the COVID-19 lockdown. Energy Intelligence and Sustainability. 2026;2(3):22-31. DOI : 10.19101/EIS.2026.11001

References
[1]
Choudhary A, Kumar P, Shukla A, Singh S, Singh AK. Characterization of trace gases and green house gas in megacity New Delhi. In EPJ web of conferences 2020 (p. 03008). EDP Sciences.
[Crossref] [Google Scholar]
[2]
Garg A, Kumar A, Gupta NC. Comprehensive study on impact assessment of lockdown on overall ambient air quality amid COVID-19 in Delhi and its NCR, India. Journal of Hazardous Materials Letters. 2021; 2:100010.
[Crossref] [Google Scholar]
[3]
Maji S, Ahmed S, Siddiqui WA, Ghosh S. Short term effects of criteria air pollutants on daily mortality in Delhi, India. Atmospheric Environment. 2017; 150:210-9.
[Crossref] [Google Scholar]
[4]
Sanderson P, Su SS, Chang IT, Saborit JD, Kepaptsoglou DM, Weber RJ, et al. Characterisation of iron-rich atmospheric submicrometre particles in the roadside environment. Atmospheric Environment. 2016; 140:167-75.
[Crossref] [Google Scholar]
[5]
Gupta S, Sharma SK, Tiwari P, Vijayan N. Insight study of trace elements in PM2. 5 during nine years in Delhi, India: seasonal variation, source apportionment, and health risks assessment. Archives of Environmental Contamination and Toxicology. 2024; 86(4):393-409.
[Crossref] [Google Scholar]
[6]
Jha AK, Jhamaria C, Yadav M, Singh NK, Singh PK, Jindal MK, et al. Temporal analysis of atmospheric pollutant concentrations with specific regard to NAAQS compliance in an industrial cluster of New Delhi, India. Mapan. 2024; 39(2):261-73.
[Crossref] [Google Scholar]
[7]
Maheshwari A, Prasad V, Gudi RD, Biswas P. Systems engineering based advanced optimization for sustainable water management in refineries. Journal of Cleaner Production. 2019; 224:661-76.
[Crossref] [Google Scholar]
[8]
Karimi B, Shokrinezhad B. Air pollution and the number of daily deaths due to respiratory causes in Tehran. Atmospheric Environment. 2021; 246:118161.
[Crossref] [Google Scholar]
[9]
Maji S, Ahmed S, Kaur-Sidhu M, Mor S, Ravindra K. Health risks of major air pollutants, their drivers and mitigation strategies: a review. Air, Soil and Water Research. 2023; 16:11786221231154659.
[Crossref] [Google Scholar]
[10]
Rani A, Kumar M. Investigating the impact of land use, vegetation index, and seasonal variability on air pollutant concentrations in the megacity Delhi, India. Environmental Monitoring and Assessment. 2025; 197(11):1274.
[Crossref] [Google Scholar]
[11]
Dumka UC, Tiwari S, Kaskaoutis DG, Soni VK, Safai PD, Attri SD. Aerosol and pollutant characteristics in Delhi during a winter research campaign. Environmental Science and Pollution Research. 2019; 26(4):3771-94.
[Crossref] [Google Scholar]
[12]
Guttikunda SK, Dammalapati SK, Pradhan G, Krishna B, Jethva HT, Jawahar P. What is polluting Delhi’s air? a review from 1990 to 2022. Sustainability. 2023; 15(5):4209.
[Crossref] [Google Scholar]
[13]
S. RS, Krüger OO, Sharma A, Panda U, Pöhlker C, Walter D, et al. Planetary boundary layer height modulates aerosol—water vapor interactions during winter in the megacity of Delhi. Journal of Geophysical Research: Atmospheres. 2021; 126(24):e2021JD035681.
[Crossref] [Google Scholar]
[14]
Tiwari S, Hopke PK, Pipal AS, Srivastava AK, Bisht DS, Tiwari S, et al. Intra-urban variability of particulate matter (PM2. 5 and PM10) and its relationship with optical properties of aerosols over Delhi, India. Atmospheric Research. 2015; 166:223-32.
[Crossref] [Google Scholar]
[15]
Deshwal V, Kumar V. Study of coronavirus disease (COVID-19) outbreak in India. The Open Nursing Journal. 2021; 15(1).
[Crossref] [Google Scholar]
[16]
Gautam S. The influence of COVID-19 on air quality in India: a boon or inutile. Bulletin of Environmental Contamination and Toxicology. 2020; 104(6):724-6.
[Crossref] [Google Scholar]
[17]
Singh B, Pandey P, Wabaidur SM, Avtar R, Kumar P, Rahman S. Substantial changes in Gaseous pollutants and health effects during COVID-19 in Delhi, India. Environmental Science. 2023; 11:e14489.
[Crossref] [Google Scholar]
[18]
Mahato S, Pal S, Ghosh KG. Effect of lockdown amid COVID-19 pandemic on air quality of the megacity Delhi, India. Science of the total environment. 2020; 730:139086.
[Crossref] [Google Scholar]
[19]
Kumar P, Hama S, Omidvarborna H, Sharma A, Sahani J, Abhijith KV, et al. Temporary reduction in fine particulate matter due to ‘anthropogenic emissions switch-off’during COVID-19 lockdown in Indian cities. Sustainable Cities and Society. 2020; 62:102382.
[Crossref] [Google Scholar]
[20]
Nigam R, Pandya K, Luis AJ, Sengupta R, Kotha M. Positive effects of COVID-19 lockdown on air quality of industrial cities (Ankleshwar and Vapi) of Western India. Scientific Reports. 2021; 11(1):4285.
[Crossref] [Google Scholar]
[21]
Maji S, Ghosh S, Ahmed S. Association of air quality with respiratory and cardiovascular morbidity rate in Delhi, India. International Journal of Environmental Health Research. 2018; 28(5):471-90.
[Crossref] [Google Scholar]
[22]
Bhatti UA, Zeeshan Z, Nizamani MM, Bazai S, Yu Z, Yuan L. Assessing the change of ambient air quality patterns in jiangsu province of China pre-to post-COVID-19. Chemosphere. 2022; 288:132569.
[Crossref] [Google Scholar]
[23]
Dwivedi P, Radha RS, Kumar D. Seven-year trends in ambient air quality and ozone dynamics in Delhi: COVID-19 lockdown lessons and future pathways from GAINS/ECLIPSE projections. International Journal of Environment and Climate Change. 2026; 16(2):56-84.
[Crossref] [Google Scholar]
[24]
Singh RP, Chauhan A. Impact of lockdown on air quality in India during COVID-19 pandemic. Air Quality, Atmosphere & Health. 2020; 13(8):921-8.
[Crossref] [Google Scholar]
[25]
Soydan O. Effects of landscape composition and patterns on land surface temperature: Urban heat island case study for Nigde, Turkey. Urban Climate. 2020; 34:100688.
[Crossref] [Google Scholar]
[26]
Sharma S, Zhang M, Gao J, Zhang H, Kota SH. Effect of restricted emissions during COVID-19 on air quality in India. Science of the Total Environment. 2020; 728:138878.
[Crossref] [Google Scholar]
[27]
Garsa K, Khan AA, Jindal P, Middey A, Luqman N, Mohanty H, et al. Assessment of meteorological parameters on air pollution variability over Delhi. Environmental Monitoring and Assessment. 2023; 195(11):1315.
[Crossref] [Google Scholar]
[28]
Ali D, Singh M, Khan AA, Vidyarthi AK, Ahmed S. Impact of meteorological drivers on air quality index: a case study from Delhi. Environmental Pollution. 2026; 388:127324.
[Crossref] [Google Scholar]
[29]
Maji S, Ahmed S, Ghosh S, Garg SK. Evaluation of air quality index for air quality data interpretation in Delhi, India. Current Science. 2020; 119(6):1019-26.
[Crossref] [Google Scholar]
[30]
Mohan M, Kandya A. An analysis of the annual and seasonal trends of air quality index of Delhi. Environmental Monitoring and Assessment. 2007; 131(1):267-77.
[Crossref] [Google Scholar]
[31]
George N, Prasad JB, Varghese E, Rajesh R, Kumar A. Impact of lockdown on air quality in the most polluted cities of India. Indian Journal of Community Medicine: Official Publication of Indian Association of Preventive & Social Medicine. 2024; 49(1):96.
[Crossref] [Google Scholar]
[32]
Popli S, Yadav E, Singh A, Singh G. Comprehensive assessment of air quality dynamics in Delhi: a tri-phased analysis spanning pre, during, and post-lockdown periods. In E3S web of conferences 2024 (p. 01010). EDP Sciences.
[Crossref] [Google Scholar]
[33]
Mallik C, Gadhavi H, Lal S, Yadav RK, Boopathy R, Das T. Effect of lockdown on pollutant levels in the Delhi megacity: Role of local emission sources and chemical lifetimes. Frontiers in Environmental Science. 2021; 9:743894.
[Crossref] [Google Scholar]
[34]
Shandilya K, Bansal SN, Gupta GK, Srivastava R, Singh NP, Maity B, et al. COVID-19 lockdown altered atmospheric pollutant dynamics across major Indian cities. Discover Atmosphere. 2026; 4(1):15.
[Crossref] [Google Scholar]