If you are infected, the use of surgical face masks may reduce the risk of you infecting other people. On the other hand there is no evidence that face masks will effectively prevent you from becoming infected with the virus. In fact, it is possible that the use of face masks may even increase the risk of infection due to a false sense of security and increased contact between hands, mouth and eyes while wearing them. The inappropriate use of masks also may increase the risk of infection.
In many countries, face masks are only advised for medical personnel. People who work with (possibly) infected people use professional face masks. These face masks only help if they are used correctly; they must fit closely over the nose and mouth and they must be changed regularly. The simple (paper) face masks that most people use do not protect the wearer against the virus.
- If you are healthy, you only need to wear a mask if you are taking care of a person with suspected 2019-nCoV infection.
- Wear a mask if you are coughing or sneezing.
- Masks are effective only when used in combination with frequent hand-cleaning with alcohol-based hand rub or soap and water.
- If you wear a mask, then you must know how to use it and dispose of it properly.
- Before putting on a mask, clean hands with alcohol-based hand rub or soap and water.
- Cover mouth and nose with mask and make sure there are no gaps between your face and the mask.
- Avoid touching the mask while using it; if you do, clean your hands with alcohol-based hand rub or soap and water.
- Replace the mask with a new one as soon as it is damp and do not re-use single-use masks.
- To remove the mask: remove it from behind (do not touch the front of mask); discard immediately in a closed bin; clean hands with alcohol-based hand rub or soap and water.
Information from the CDC in the USA: In light of new data about how COVID-19 spreads, along with evidence of widespread COVID-19 illness in communities across the country, CDC recommends that people wear a cloth face covering to cover their nose and mouth in the community setting. This is to protect people around you if you are infected but do not have symptoms. Some more FAQ from the CDC is given here.