Worldwide spread out of COVID-19 in a short-time has brought a significant decline of road traffic, tourist flow and industrial ventures. During this emergency period, the restricted human dealings with nature have appeared as blessing for health of the total environment. The variation of atmospheric O₃ may modulate the range of UV index (UVI) at any region of the earth. The objective of the study is to examine the variation of UV index over the megacities of India with respect to tropospheric O₃ level modification during COVID-19 lockdown. The meteorological or environmental data (temperature in °C, gust in km/h, wind speed km/h, relative humidity in %, air pressure in mb and cloud cover in okta) of four selective megacities of India (Kolkata, Chennai, Delhi, Mumbai) during and pre lockdown period have been obtained to comprehend about the variation of UV index and tropospheric O₃. The descriptive statistical applications i.e. standard deviation, standard errors and K-means clustering have been done through standard statistical software. In the present study, t-test has been used to understand level of significance of surface O₃ and UVI during pre-lockdown (2019) and lockdown (2020) phase. The result shows that the four major megacities in India namely New Delhi, Mumbai, Kolkata and Chennai have experienced the vibrant diminution in terms of the concentration of UV index with slightly increasing the tropospheric O₃ level during the lockdown phase. The higher accumulation of O₃ during the lockdown in the lower atmosphere of four megacities does not exceed the permissible limit. The excess amount of O₃ has remarkably contributed to trap the harmful UV radiation which has lowered the UVI in these worst polluted megacities of India. In the meantime, the prominent reduction of NO_x during the lockdown period decreases the titration impact to O₃ and this mechanism helps to revitalize the ozone concentration level. The uniqueness of the current study is highlighted the ground reality regarding reduction of UV index and amplification of tropospheric O₃ concentration during lockdown phase. This study definitely assists to make new environmental policy, act and law for recover the health of the total environment.

COVID-19 在短时间内在全球范围内蔓延，导致道路交通、旅游流量和工业企业大幅下降。在这个紧急时期，限制人类与自然的交往似乎是对整个环境健康的祝福。大气中 O ₃的变化可能会调节地球任何区域的紫外线指数 (UVI) 范围。该研究的目的是检查印度特大城市紫外线指数相对于对流层 O _3的变化COVID-19 锁定期间的级别修改。印度四个特大城市（加尔各答、钦奈、德里）的气象或环境数据（温度（°C）、阵风（km/h）、风速（km/h）、相对湿度（%）、气压（mb）和云量（okta）） , Mumbai) 已获得封锁期间和封锁前的数据，以了解紫外线指数和对流层 O ₃的变化。描述性统计应用，即标准偏差、标准误差和K-means 聚类已通过标准统计软件完成。在本研究中，t 检验已用于了解表面 O _{3的显着性水平}和锁定前（2019 年）和锁定（2020 年）阶段的 UVI。结果表明，印度的四大特大城市新德里、孟买、加尔各答和钦奈在封锁阶段经历了紫外线指数浓度的剧烈下降，而对流层 O _{3水平略有增加。四个特大城市的低层大气封锁期间O 3}的较高积累不超过允许的限度。过量的 O ₃显着有助于捕获有害的紫外线辐射，从而降低了印度这些污染最严重的特大城市的紫外线指数。同时，锁定期间NO _{x的显着减少降低了滴定对O 3的影响}这种机制有助于恢复臭氧浓度水平。当前研究的独特性突出了在锁定阶段减少紫外线指数和放大对流层 O _{3浓度的地面现实。}这项研究无疑有助于制定新的环境政策、法案和法律，以恢复整体环境的健康。