If you get wet, getting out of wet clothes is essential; it is very important not to get chilled. Just as important, when you come in from the cold and step into an elevator or a classroom, you are subject to illness because your nasal cilia are not doing their job. Similarly you have the same system in your bronchial passages. If the cilia are stunned and not moving from the cold, they fail. Then the bacteria that lands in your nose remains in place.