The ICU Doc from NYC who is treating this disease said that you get the disease through droplets that you get on your hand and then you touch your face. So if you are infected and wear a mask it can help prevent the droplets from reaching surfaces and other people. If you are not infected, a mask can help save you from transmitting the disease to yourself through touching your face (nose and eyes especially). You have to be in CLOSE proximity to an infected person who is sneezing or coughing etc. to get exposure to the droplets directly.