Dr. Howard Smith Oncall

  Vidcast:  https://youtu.be/W6oovAmIhHk   Masking singers and the bells of musical instruments significantly reduces CoVid-carrying aerosols, but keeping their performances safe requires limiting them to 30 minutes indoors and 60 minutes outdoors.  These conclusions stem from collaborative studies by engineers at the Universities of Colorado and Maryland.   The investigators compared the aerosol output from singers, woodwind instruments, and brass instruments utilizing flow visualization, anemometer measurements, and quantitative aerosol measurements.  Singers were masked with surgical masks, and instrument bells were covered with surgical masks or HEPA MERV 13 filters.   In general, brass instruments emitted more aerosols followed by singers and then woodwinds.  Masking provided near complete elimination of aerosols for singers, while instrument bell masks and HEPA filters couldn’t block aerosols escaping from keyholes and around mouthpieces.  As expected, aerosol accumulation reached critical levels faster