The CDC, MAYO CLINIC and many physicians recommend wearing a surgical mask in public during cold and flu season, or whenever you are sick. (See: big box of masks in the waiting room, ER, etc.)
Wearing a mask when you are infected with a cold or the flu helps contain infected germs from entering the air and infecting non-infected people. Wearing a mask during cold and flu season if you are not infected with an illness helps protect you from inhaling airborne germs carrying the flu virus or cold cooties.
So whether you are sick, or not, wearing a personal mask is an easy, responsible way to help prevent the spread of germs during cold and flu season.