Step-by-step explanation:
I think it depends on how long you wear the same mask. Because you won't get sick as fast as the others in the room. They could cough without covering or anything and as long as you wash your hands and avoid touching your face you would be fine. The mask just helps prevent germs circulating the air from reaching your system. However, overtime I am sure it will start wearing off it's effects so it's always wise to change it once a day or so since the germs from the other side would still be on it.