Cesium compounds if present in atmosphere, can affect human health as well as the ecosystem due to their highly hazardous nature. Interaction of cesium compounds with abundantly available atmospheric salts can modify the hygroscopic behaviour in sub-saturation relative humidity (RH) domain. Any marked modification in growth factor (GF) for the mixed particle state in comparison to the single particles ultimately affects the settling rates and hence the deposition flux. This work studies the hygroscopic behaviour of two important cesium bound fission product aerosols (CsI, CsOH) internally mixed with some common atmospheric particles viz. $NaCl,{(N{H}_4)}_{2}S{O}_4$ and NaNO₃ for a fixed dry particle size of 100 nm. Experimental measurements, performed with Hygroscopic tandem differential mobility analyzer in the range of 20-94% RH, have been compared with the predictions made from Zdanovskii-Stokes-Robinson (ZSR) approach. Apart from the single/pure particle state for the constituents (i.e. mixing ratios 1:0 and 0:1), three other mixing ratios 1:4, 1:1 and 4:1 have been considered. The results show that the GF vs RH pattern for mixed particles is different from that for single CsI and CsOH particles. The intrinsic water uptake behavior for these cesium compounds was found to be perturbed for some of the chosen combinations as well. Deliquescent transition for the mixed particles was observed at lower RH compared to the single electrolytes. Relative differences noticeable for the chosen mixing ratios could be related to the available fractions in the mixed state. Overall, ZSR method was found to be capturing the trend of increasing GFs with increasing RH. Terminal gravitational settling velocities calculated from the measured GFs were also found to be different for single and mixed particles. The relative difference was significant for some combinations and test conditions. Any modification in settling velocity ultimately impacts the deposition flux estimations. Hence neglecting the presence of atmospheric salts affects the accuracy of the source term estimates for a postulated nuclear reactor accident scenario.

铯化合物如果存在于大气中，由于其高度危险的性质，会影响人类健康和生态系统。铯化合物与大量可用的大气盐的相互作用可以改变亚饱和相对湿度 (RH) 域中的吸湿行为。与单个颗粒相比，混合颗粒状态的生长因子 (GF) 的任何显着改变最终都会影响沉降速率，从而影响沉积通量。这项工作研究了两种重要的铯束缚裂变产物气溶胶（CsI、  CsOH）与一些常见的大气粒子内部混合的吸湿行为，即。$N\mathrm{一种}C升,{(N{H}_4)}_2秒{哦}_4$和NaNO ₃的固定干燥粒径为 100 nm。使用吸湿串联差分迁移率分析仪在 20-94% RH 范围内进行的实验测量与 Zdanovskii-Stokes-Robinson (ZSR) 方法的预测进行了比较。除了成分的单一/纯粒子状态（即混合比 1:0 和 0:1）外，还考虑了其​​他三个混合比 1:4、1:1 和 4:1。结果表明，混合粒子的 GF vs RH 模式与单一CsI和CsOH 的模式不同粒子。发现这些铯化合物的固有吸水行为对于某些选定的组合也受到干扰。与单一电解质相比，在较低 RH 下观察到混合颗粒的潮解转变。所选混合比的显着相对差异可能与混合状态下的可用分数有关。总体而言，发现 ZSR 方法捕捉了随着 RH 增加而增加 GF 的趋势。还发现根据测量的 GF 计算的终端重力沉降速度对于单个和混合颗粒是不同的。对于某些组合和测试条件，相对差异是显着的。沉降速度的任何修改最终都会影响沉积通量估计。