I’m a fully-vaxxed low-risk (young, no co-morbidities) inhabitant of Los Angeles and I recently decided to start gong back to group fitness classes, specifically, spinning (in-door exercise bike classes).
The owner of the studio closest to my house is dutifully enforcing LA’s indoor mask mandate at all times…however she is handing out face shields (see link if you don’t know what I mean) at the front desk and encouraging their use in lieu of actual masks. The instructors are taking off their masks when class starts and replacing them with face shields as well.
While I appreciate that it’s rather unpleasant to do intense cardio with any sort of proper mask and that a face shield is must nicer, this seems unsafe to me as the shields are not intended to prevent the wearer from getting other people sick.
Just how unsafe is this practice? And in addition to conflicting with common sense, does it likely also violate the city’s mask mandate?
They’re decidedly not masks. They’re as effective as holding up a clear plastic page protector in front of your face. They don’t filter any germs. If your city mask mandate specifies masks, then the studio is violating it.
They are effective at stopping stuff splashing on your face and in your eyes, which is what they are designed for.
They are partially effective at reducing big-droplet emission, as you can easily see when wearing one.
However, current thinking is that there is significant fine-droplet transmission, which this kind of face shield is not effective at blocking.
My city’s (otherwise very strict) mask mandate exempts fitness studios when doing cardio. From my reading of the reference above, I thing that wearing a face shield would be better than nothing for protection.
There is so much bad science and poor application of masking (e.g. people wearing masks pulled down to expose the nostrils) that I don’t know that face shields versus ‘masks’ if questionable utility really matters. Realistically, a N95 respirator or close-fitting KN95-type mask is what you need to actually assure that you are receiving any useful measure of protection, and those would obviously be very uncomfortable if not impractical to wear during heavy exertion. Woven cloth masks may help prevent aerosols from being spread (at least, until they point that they are saturated with moisture) but likely provide a very low amount of protection to the wearer in an enclosed environment. And it only takes one infected person to remove their mask for a few tens of seconds to wipe away sweat or snot to essentially fill the room with aersolized breath.
I would not go into an enclosed environment with poor ventilation (e.g. HVAC being blown down from above, pushing exhaled breath back down) with people breathing hard for an extended period of time even with a N95 respirator and being vaccinated. It is clear that the severity of illness correlates with the viral load exposure, and an asymptomatic SARS-CoV-2 carrier who is producing virions at the rate that ‘Delta’ variant carriers have been observed at could pose a risk to even a fully vaccinated person as has been seen.
Cardio in a mask is hard. I went to my dance class twice, but I was the only one in the whole place wearing any mask at all. I stopped going. My instructor now has COVID.
Just thinking about the mechanics of it, it seems to me that a face shield would surely reduce the spread of droplets simply and solely by virtue of the fact that it imposes a physical barrier to straight-line travel.
Whether that reduction is enough to be significant, I have no idea.
Last year, there was a superspreader event in Switzerland at a restaurant where servers wearing masks were not infected but servers wearing face shields were.
As @Melbourne stated, face shields do a good job at blocking droplets and aerosols coming right at you in the short term. So they are a nice supplement to the mask you are wearing if you have to get close to people. Plus they protect your eyes. That’s why hospital workers will wear both if they don’t have those big respirators. However, aerosols that have accumulated in a room will easily float up around the shield. Also, your aerosols will easily move around the shield. A shield without a mask is completely useless for the gym.