This study investigates the possibility of primary biological aerosol (PBA) influencing cloud processes. In particular, pollen grains are studied using a combined laboratory and modelling approach. The hygroscopicity and wettability of pollen grains are measured under subsaturated conditions. From these measurements the response of pollen to supersaturated conditions are parameterized using kappa-Köhler theory and implemented into a cloud box model. The model output data suggests that under certain atmospheric conditions the activation of pollen grains can interfere with the activation of the fine aerosol mode thus changing cloud dynamics.