Face Visors for Caving?

[Bob Mehew]

As I understand it the hazard of concern is someone spraying out an aerosol containing droplets of what ever containing the virus which might get into your eyes and hence into you body.  So eye protection is recommended for activities where aerosols are likely to be generated.  Thus goggles are better than visors as they seal off the eyes.  But having watched a number of carers over the past week have trouble with misting up due to poor seals between face mask and goggles (because the two inevitably overlap), I can understand why visors are preferred by many people.

So the first step surely is to prevent the aerosol which could be done by a face mask on the other person.  But as I see it, face masks are not practical for many cave or mine environments.  (Indeed I have written that into the upcoming revision of Radon Underground.)

The next step is social distancing.  Again I guess one could be in a situation where that is not possible.  And there are concerns that the 2m rule is possibly optimistic for underground environments.  My expectation is that without a face mask, you are more likely to breath in a load of floating viruses compared to having them projected into your eyes.  A visor will hardly prevent that scenario.  So all in all, I don't see visors as a useful protection reducing the risk by any significant amount.  Sorry about that.

 

[domestos bend]

Don't get too close to the person in front's aerosol 

 

[Andy Walsh]

I've used glasses(old ones)for caving + in very muddy digs no problem (unless I forget and leave sunglasses on)
An Inglesport (other shops available) balaclava works quite well and useful in a cave /out side on a bike as a face mask +keep you warm(just use bottom bit if into a shop or bank!!
A simple tip from a corvid expert if you suddenly cannot avoid someone just hold your breath

 

[HardenClimber3]

Aerosols and droplets.
Lie on your back with a syringe and squirt it up in the air. That is droplets.
Lie on your back with an aerosol spray (if you admit to having one) and spray it up in the air. That is an aerosol.

There is considerable debate about the relative roles of droplets vs aerosols and airborne transmission of the coronavirus. A lot of effort has been put into showing airborne transmission is not significant (note the phrasing).
In normal contexts most of what we expel is droplets rather than aerosol. (As an aside, a serious laboratory guideline was produce, which included in the list of AGP's - aerosol generating procedures - 'induced laughter').

Perhaps we should think of two metre spacing as a volume of air around us when it comes to moving in passages etc.
Indoors 2 metre spacing reduces transmission. Outdoors who knows.
A face mask will further reduce likelihood of transmission. (any face mask, though obviously some are more effective than others)(and remember, an important role of masks is to protect others from the wearer ..... ie it depends on 'herd altruism'.
Eye protection appears to give a further increment although the evidence is less strong and data usually comes as an additive hierarchy. Face shields alone are not great, it would appear.

Touch....it seems caves might be quite good places for viruses to survive...particularly nice clean caves...

So, practicalities, Mistral the entrance is a bit contact prone but has a good draught...just make sure you wait long enough not to join a queue in the entrance passage. It would help is people left organic waste in any static water...(viral survival is better in 'clean' water. Perhaps, after Alum Pot might be better...lots of air, scope to distance between  pitches

(how effective are the face shields against metal splinters from hammering etc?)