There are several discussions about face masks in the last few page. Below are some information regarding what face mask to use for 2019-nCoV.
Public should use surgical masks, not N95 masks, to guard against Wuhan virus spread: Experts
Below is a YouTube video by US Occupational Safety and Health Administration (OSHA) explaining the difference between respirators and surgical masks.
When purchasing surgical masks, look for ones that are rated by ASTM. Below is an explanation of the different ratings. The two most important factors are the BFE (Bacterial Filtration Efficiency) and PFE (Particle Filtration Efficiency). I was going to insert the table "Guide to Face Mask Selection and Use" here. But the file is too big to uploaded. So I provide a link below.
Hope the above information helps.