The smallest one I know of is the kids' Flo Mask.

Thanks! I'll pass this along to Simon who leads our swab sampling work.

On reusable respirators, they're worse to significantly worse for intelligibility than disposables. If you're only talking about what to wear when not talking (ex: listening to talks) then this doesn't matter, but if you're considering masking for 1:1s or group discussions it becomes pretty important.

This is probably a regional thing: I don't see the 3M 4251 or other disposable respirators for sale in the US. My guess is the cost difference you're seeing is due to comparing a US-market (6200) vs UK-market (4251) masks on UK Amazon?

Definitely! Storing replacement filters in addition to the masks themselves seems good.

If you're trying to flag something engineered, I think the general public makes more sense than people who work with animals. What we do at the NAO (we really need to write up a page on this!) is visit busy public places, put out a sign, and ask if people are interested in swabbing their nose for science. People swab their own noses, drop them in a shared container, and we pay a small amount per swab. It's under IRB, and if you were looking to do something similar we could share our IRB documentation?

also use it to not spread random colds / flu / covid

If your goal is not spreading ("source control") then you should wear one that filters the output (no valve). I think the ElastoMask Pro is a good option there: manufacturer, Amazon.

Efficacy drops pretty slowly: the mask body itself shouldn't degrade, and the filters mostly degrade by being clogged with dust (which in normal environments is at least 6m). You can get extra filters cheaply.

how bad is it if I sneeze inside

Not an expert in this, but my understanding is it's gross but not dangerous. You could consider also having some disposable masks to wear when you're sneezy?

Amazon also sells imitation ones that don't say 3M and are probably not certified: example. They're much cheaper, and could even be worth buying.

I don't have any special knowledge on whether the ones that say 3M are also not 3M, but I'd doubt it?

I think it may still be too expensive to make sense, but in poorer areas I think nasal swabs + Nanopore does much better than wastewater for pathogen-agnostic detection:

• The costs of collecting the swabs (both the people collecting and compensation to participants) are lower.

• Nanopore sequencing is cheaper if you don't need massive sequencing depth, and for swabs you probably don't.

Thanks! I'm glad this has 1 + 0 + 1 + 1 = ω − 1, but I'm going to need to go read more to understand why ;)