Dr. Howard Smith Oncall

  Vidcast:  https://youtu.be/H2aYiqRdCC0   If you make a mask, put at least 2 layers and ideally 3 in that mask.  Australian researchers make that recommendation after high speed photographic studies of aerosols emanating from a subject through masks of various constructions.   The investigators used cotton fabric with a thread count of 170 to create one and two layered masks to compare with a 3 layered surgical mask.  The visual recording system captured still and video images while the healthy subject was speaking, coughing, and sneezing.   The single layered mask reduced aerosol spread with speaking and coughing but not with sneezing.  The 2 layered mask was better but not as good as the 3 layer surgical mask.   https://thorax.bmj.com/content/early/2020/07/24/thoraxjnl-2020-215748   #covid #mask #cotton #surgicalmask