From a USC virologist who has been investigating coronavirus (SARS, MERS) since 1970s....
"This virus is spread in large droplets by coughing and sneezing. This means that the air will not infect you! BUT all the surfaces where these droplets land are infectious for about a week on average - everything that is associated with infected people will be contaminated and potentially infectious. The virus is on surfaces and you will not be infected unless your unprotected face is directly coughed or sneezed upon. This virus only has cell receptors for lung cells (it only infects your lungs) The only way for the virus to infect you is through your nose or mouth via your hands or an infected cough or sneeze onto or into your nose or mouth." stop touching your face, wash your hands with >60% alcohol sanitizer (eg. Purell) and the mask does more to prevent you from touching your face than it does preventing you from catching it.
