Dear Sally, Plastic face shields are worn with cloth masks, not alone to reduce CV-19 spread. Droplets and aerosols from users' mouths or noses can drop under shields. Shields do not eliminate the risk of contaminated aerosols passing under the bottom edge of shields and reaching the wearer's mouth, nose, or other parts of the face. Using both mask and shield do.
The face masks may be a good idea to add to your students' use of cloth masks so that droplets from hazardous chemicals do not reach their faces. In all of the official reports from OSHA, CDC, NIH and anecdotal accounts on use of cloth masks, there has been no comment on the possibility of fumes "trapped" beneath cloth masks. Check the cloth mask literature.
Janet Baum, Instructor, T.H. Chan School of Public Health, Harvard University, Boston, MA
My teaching colleagues are concerned that cloth or surgical face masks worn by students or faculty in a chemistry lab setting where volatile chemicals are used, for example organic lab, could trap fumes within the masks and therefore be harmful to the user? They are wondering if face shields should be worn in labs instead of cloth face masks to prevent covid19 spreading, but mot allow chemical fume buildup.
We do have fume hoods for every student to use. Any guidance on this issue?
Thank you,
Sally Burgmeier
Chemistry Safety Officer
Augustana College
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