Why is it that during changing weather, one is advised to avoid closed, crowded and airconditioned places like cinema halls etc. ?

During changing weather, one is advised to avoid closed, crowded and air- conditioned placed like cinema halls, etc., because during this period the infectious agents are more prevalent as moist condition is favourable for growth of microbes and people which are more vulnerable as their body system is busy with adapting changing environmental condition of temperature, humidity,etcand they infected easily.