All,

I could have sworn this had come up already but after browsing through every DCHAS email since March 1^st I couldn’t find an answer. We have received several questions from labs about the risk of solvent vapors being “trapped” in cloth face masks. Some seem to be concerned that they will just be trapped in the breathing space, others are worried that they’ll “stick” to the masks and desorb later. Here’s what I’ve been thinking so far:

• If there is sufficient vapor to cause concern, the work should be done in a fume hood.
• If it’s in a fume hood and there is still a sufficient quantity of solvent to cause health concerns, then there is either an issue with the fume hood or with how the user is operating, which should have become apparent in previous times without face masks.
• The air in the cove should be largely the same as the room air; while these masks may stop certain sizes of solid particles or liquid droplets, gas exchange should not be inhibited. So, you’re back to the first point: if the room’s air is hazardous, you have a bigger problem than your mask.
• As a side note to the above, I think similar logic can be applied to chemical compatibility/fire resistance questions. If a researcher is worried that a face covering could catch fire or react with something, then their bigger problem is that their face is on fire or has acid on it or something. Most of the clothing a researcher has is probably susceptible to fire or acids, but they still wear that into lab.

To be clear, not wearing a face covering is not an option. This isn’t in our hands, our county government has mandated it and, to my understanding, is uninterested in making exceptions. Thanks in advance for the help/advice.

Sincerely,

Jack Reidy (he/him)

Research Safety Specialist, Assistant Chemical Hygiene Officer

Environmental Health & Safety

Stanford University

484 Oak Road, Stanford, CA, 94305

Tel: (650) 497-7614