Erlkönig: COVID-19 and Masks

2020-03-23

So, after watching FOX "news" tell its unfortunate viewers that masks were ineffective (2020-03-23) because they're too stupid to sort out the facts, here are some facts... Caveats: I am not a doctor, though every medical person I've told these to agreed, and were often unaware of the details. It doesn't help that the West almost entirely misunderstands why masks are worn by people in Japan - to protect others against the mask wearer, and so the clueless Westerners wear the wrong masks to defend themselves, and get infected anyway.

Respirator

These are face-fitting masks that force all inhalation through a significant filter. These may be flexible, shaped masks like air pollution masks, pre-molded doctor's N95 respirators, or some sturdier struction like a painter's mask with replacable filters, gas mask, or full face mask with both a mount/nose gasket and upper-face gasket

N95

This refers to the NIOSH N95 air filter certification. All occurrences of N95 below can be upgraded to N99, N100, or R99, R100, or P99, P100 (best). The R and P filters also protect against oily environments (although R for a much shorter time than P). PM2.5 filters (common in shaped air pollution masks) also appear to be largely equivalent to N95 respirators. HEPA level 11 also appears to be equivalent to N95 (e.g. if one wants to try making respirators out of vacuum cleaner HEPA bags)

Doctor's mask

A typical doctor's procedure mask or surgical mask, characterized by being rectangular and pleated before use, and which are generally not close-fitting enough to have any hope of protecting the wearer, which is not their purpose - they're intended to protect others

For more info, see the Wikipedia entry for NIOSH air filtration rating

The bad examples to avoid - masks wasted

• Uninfected people wearing mere doctors' masks (procedural or surgical mask)
• Uninfected people - especially medical personnel - wearing a N95 respirator or better but no face shield
• Infected people wearing no mask
• Infected people wearing a mask/respirator lacking exhaust filtration, such as a painter's respirator where the exhaust is raw exhalation air

The good examples to follow

• Infected person in doctor's mask (without face shield)
• Uninfected persons in respirator + face shield
• An untested person in a face shield + a respirator that filters both intake and exhaust

What to know about masks/respirators on other people

• Respirators
  • only protect the wearer - not you
  • don't tell you whether the wearer's infected
  • (wear this type until you're infected)
• Doctor's masks
  • protect you from the wearers - but not them from you
  • (you can switch to this type once you're infected)

What to do

If you are uninfected, to defend yourself

• Wear an N95 or better respirator over your nose and mouth
• Wear eye protection against tiny water droplets carrying the virus
• Ideally wear a combined respirator that pulls filtered air in over the eyes (through one-way vents) and through a second set of one-way vents for the inhale, and finally exhausts your exhalation through another one-way vent
• Painter's respirators can be good fits for this use case

But

• This type of respirator, unless modified, only defends you, not people near you
• Wearing the mount+nose respirator without eye protection is ineffective for defending yourself against the virus, which can invade through the eyes

If you are infected, to defend others from yourself

• You don't need eye protection
• You don't need inhalation protection
• Wear a respirator over your nose+mouth for N95+ filtration of exhalation. Doctor's masks generally fit this case, but are not as effective as protecting others
• Skip the masks with one-way valves - those are usually set up to filter inhalation, which isn't relevant if you're already infected

But

• Most respirators DO NOT filter exhalations - those near you are NOT protected unless extra steps are taken to filter the exhaust

If you don't know if you're infected, to protect yourself and others

• Follow all the guidelines for protecting yourself with one addition
• Add an N95 filter over the exhalation vent!

Other safety notes

Donning / removing respirators and face shields

The outside of both respirators and both sides of face shields should be treated as contaminated surfaces after use. As should all other clothing worn, and any skin - particularly all skin not under your respirator.

Facial Hair

Facial hair reduces the effectiveness of the rubber or silicone seals, it's recommended to be bare-faced, or to use vaseline along the line where hair and seal are in contact

Gloves

Gloves transmit the virus as easily as hands, and hands are not considered to be infection targets. In other words, gloves are generally useless outside of minor corner cases like being able to peel them off to make clean hands available (once), or as flimsy reminders to NOT TOUCH YOUR FACE. If you're only wearing gloves (no mask), you're in deep trouble.

Fast food

Many drive through food vendors, fast food, etc, apparently believe gloves are sufficient protection. In actuality, they do nothing to protect the customer from COVID-19. Hand washing with even basic doctor's masks would be more effective.

Instead of judging safety based on whether gloves are present (although gloves may protect against other threats), consider whether the food preparation method tends to sanitize the food anyway, and whether there's much opportunity for that to be abridged before you have the food yourself. Pizza, for example, is oven transferred directly from oven into a box and never touch again by staff before it's received by a custom.