Sunday, May 03, 2020

Wearing a cloth mask outdoors is like wearing a helmet in your car

I wrote this first on Twitter:
Outdoor masking is the equivalent of wearing a helmet in your car. Indoor masking is the equivalent of wearing a seatbelt in your car... 
 ... Formula 1 drivers wear helmets in their cars. Makes sense for them. For rest of us net gain is just background risk noise... 
... It took decades of struggle to get Americans to use seatbelts. Even now some don’t. Despite overwhelming value... 
... If you get hung up on wearing helmets in cars people will think you are nuts and ignore the seatbelts.
The best science I've seen on outdoor communication is the Chinese tracing analysis. We aren't going to see much more science -- experts consider the risk too low to be worth researching given all we don't know about indoor transmission (including transit).

There are two valid objections I know of to this stance:
  1. Outdoor masking is of low value but it helps set social expectations that make indoor masking acceptable.
  2. If you don't wear a helmet in your car the risk is on you, if you don't wear a mask outside the risk is on me.
To which I would say - True. But ...
  1. We would never have gotten seatbelts in cars (high value) if we'd insisted that helmets were equally important (much lower value). If we don't have science we have nothing against the forces of stupidity.
  2. Yeah, that does suck. Happily the risk to you is extremely low. As a matter of politeness we should give anyone wearing an outdoor mask a 10 foot space. It's a signal of strong personal concern.
Outdoor masking has a cost beyond damaging expert credibility. It's very uncomfortable to exercise wearing a cloth mask. The physical and mental health benefits of exercise dwarf the non-existent value of the outdoor cloth mask.

Indoor masking is where we should be putting our energy. We should be developing N95 equivalent reusable masks for at risk persons to wear indoors in place of the cloth masks most of us wear.

True story. My father, who was a geek before his time, specced seatbelts on his 1950s company car (to the chagrin of his boss no doubt). They came as 4 point restraints. When he showed up in the car for a date his guest refused to enter the car. Anyone with seatbelts in the car must drive like a maniac.

PS. Regarding those "outdoor plume" studies --- viral reproduction does not scale with respiration. That is, if you breathe 3 times as much you don't exhale 3 times as many viruses.

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