Impacts of environmental changes at Pune, India during the lockdown period imposed due to the Covid-19 pandemic, on the characteristics of the atmospheric ions and the new particle formation (i.e. the formation of molecular clusters and their subsequent growth to larger sizes) and shrinkage events have been investigated. The increase in the small and big cluster ion concentrations and the decrease in intermediate ion concentrations observed during the lockdown period have been associated with the decrease in the aerosols and precursor gases, respectively. During the NPF events, the nucleation mode particles of both polarities grow in size. However, during the unique shrinkage events observed here, particles increase in concentration but do not grow in size during the morning-to-noon period and shrink in the noon-to-evening period during the lockdown period. Simultaneously, the concentration of particles of >25 nm decrease i during the morning hours and increase during the afternoon hours .On the shrinkage event days, solar irradiance is higher and relative humidity is lower throughout the day than on the NPF/no-event days. Occurrence of shrinkage events has been proposed to be associated with the change in saturation vapour pressure of different chemical species with temperature/solar irradiance.

由于 Covid-19 大流行而导致的封锁期间印度浦那的环境变化对大气离子的特征和新粒子的形成（即分子簇的形成及其随后增长到更大的尺寸）和收缩的影响事件已被调查。在锁定期间观察到的小簇离子和大簇离子浓度的增加和中间离子浓度的减少分别与气溶胶和前体气体的减少有关。在 NPF 事件期间，两种极性的成核模式粒子的尺寸都会增大。然而，在这里观察到的独特收缩事件中，在锁定期间，颗粒浓度增加，但在早上到中午期间不会增大，在中午到晚上期间会缩小。同时，>25 nm 的粒子浓度在上午减少 i 并在下午增加。在收缩事件日，全天太阳辐照度较高，相对湿度低于 NPF/无事件日. 已经提出收缩事件的发生与不同化学物质的饱和蒸气压随温度/太阳辐照度的变化有关。与 NPF/无事件日相比，全天的太阳辐照度更高，相对湿度更低。已经提出收缩事件的发生与不同化学物质的饱和蒸气压随温度/太阳辐照度的变化有关。与 NPF/无事件日相比，全天的太阳辐照度更高，相对湿度更低。已经提出收缩事件的发生与不同化学物质的饱和蒸气压随温度/太阳辐照度的变化有关。