Thread by @StartsWithABang

Earlier this month, I traveled by air for the first time during the pandemic.

Even though I'm "healthy" by all accounts, I live with at least one highly vulnerable person, and it's very important to me to not bring #covid into my house.

Here's what I've learned since. 🧵

(1/n)

First: if you're someone who cares about #covid safety, you will wear a mask every time you're indoors, period.

But not all masks are equal, and not all indoor environments are equally safe/dangerous.

I know you know this, but I'm going to go in depth here. Hang tight!

(2/n)

For most indoor spaces, wearing a well-fitting, NIOSH certified N95 mask is totally sufficient.

Note that I said "N95" and not KF94 or KN95.

The horizontal straps create far fewer air pockets than over-the-ear straps do, and fit more people far better.

Heads > ears.

(3/n)

Are you still wearing a cloth mask? Or a surgical mask?

It was time to upgrade long ago; the second best time to upgrade is right now. Well-fitting N95s are consistently only about $1-to-$1.50-per-mask, even with inflation.

But there's much more to the story.

(4/n)

Many KN95 and KF94 masks are counterfit; they are not made in the USA and are rarely NIOSH certified. You get much more consistency with an N95.

If you can afford them, there's no reason to go with _less_ protection with so many people being so lax about protection.

(5/n)

But even an N95 won't protect you for long if there are infected people in your indoor spaces that aren't wearing a mask at all.

If you're going to be indoors for any length of time, "everyone masked, preferably with an N95" is the safest environment.

(6/n)

The more people are unmasked, the less air flow there is, and the greater the density of people, the riskier the environment is.

Smaller spaces = more danger.

Higher person density = more danger.

Fewer/worse masks = more danger.

The worse your mask fits = more danger.

(7/n)

My "trip" that I took was for work; I flew to LAX for the American Astronomical Society's annual big conference: #AAS240.

We had over ~2k attendees.

Masks were mandatory for all indoor events.

Vaccination was mandatory for in-person attendance.

Only 18 cases, total.

(8/n)

This is the way to do a conference. And yet, even with all that, nearly 1% of people attending still got infected.

The most likely culprit of how/where they got infected?

Not from other people at the conference; it's most likely they got it from flying.

(9/n)

I know a number of the individuals who caught #covid, and they were among the most responsible people when it comes to safety precautions.

Unfortunately, the "airplane" experience, despite what airlines, CEOs, and even unionized employees are saying, is a virus's dream.

(10/n)

There are two factors that make it so:

1.) A lack of a mask mandate. Unmasked, infected "breathers" spread their germs everywhere, and quickly.

2.) The amount of time spent in the cabin _on the ground_. The stagnant air is terrible, and an ideal super-spreader recipe.

(11/n)

One proxy that you can use to see "how stagnant is the air in here, and how much of other people's exhaled breath am I inhaling?" is to monitor CO2 levels.

When an airplane is flying, CO2 levels are pretty normal; airflow is good!

(12/n)

But when the plane is on the ground, stationary, and you're just sitting in your seat, CO2 levels will spike. They can rise to many times (I've seen up to 12x!!!) the normal concentration.

Even with an N95 mask, less than 1 hour of exposure can easily infect you.

(13/n)

Unless everyone is masked -- and that includes flight attendants, who are (sadly) excellent disease vectors on flights -- an N95 is not sufficient to protect you.

It's very likely that most or even all of the infections at my meeting originated from airplanes.

(14/n)

THIS DOES NOT MEAN YOU SHOULDN'T FLY!

It means you need to take better precautions.

One recommendation is: get a fitted N95. This takes work and effort on your part, and for me, I'd have to shave my beard to make a sufficient seal.

That offers an improvement, for sure.

(15/n)

But there's an even better option: get a P100 mask or respirator system.

Yes, they're big, bulky, and annoying. But also, you will be far safer, especially in an airplane's cabin, than with any other option.

An N95 blocks 95% of particles; a P100 blocks like 99.98%.

(16/n)

Do not remove the P100 during the flight, if possible. Eat and drink before and after, not during the flight.

And if you must take it off, only do so when you're in the air. Do not, under any circumstances, remove it or compromise the seal when you're on the ground.

(17/n)

Properly wearing a better mask/respirator is how you play responsible defense. It's the best front-line defense.

But you can do even better if you like: by protecting the mucous membranes in your eyes from COVID as well.

(18/n)

Some P100s come with full-head protection; others come with goggles as well.

Be careful with the latter category; some masks with goggles have compromised respiratory seals _because_ of the goggles!

If the seal is bad, you're not protected anymore!

(19/n)

But there's good news as well; even wearing regular eyeglasses offers substantial additional protection against #covid.

It's also a brilliant test of your respirator's seal; if your glasses don't fog up, you've got a good seal! If they do, you don't!

(20/n)

If your goal is to be as safe as possible, you can up your PPE game in the riskiest of environments.

For most safety-conscious people, the riskiest environment you'll put yourself in is the airplane itself.

Upgrade to a P100. Don't take it off. Wear glasses (or better).

(21/n)

If I knew a few weeks ago what I now know, I would have done this prior to the #AAS240 meeting.

We can't control the bad behavior of others, but we can be the example of good behavior we want to see in the world.

You can bet I'll be doing it from this point forward.

(22/22)