[LostInBayport]

Get some "masks". They sell incredibly thin disposable masks. You hardly know you are wearing one.

I had to wear one for a significant amount of time not long ago. I chose a biker's mask, figuring if they wear them cycling they must be easy to breathe in. After I while I forgot I had it on. Walked all the way to my car before I realized I still had it up.

[cuban leaf]

Balaclava. I used to wear one when bicycle commuting in the winter. You can breathe through them no sweat. Google it.

And as a bonus, you can use it to make unauthorized withdrawals at the bank.

[waterhill]

A neck gaiter. I wear one while fishing to keep the sun reflecting on the water from burning me up. Along with hat, glasses and lightweight longsleeves.

Very breathable.

[Steven Tyler]

Grab a ratty old t-shirt, thinner the fabric the better.
Cut out the short sleeve.

Pull over your head

[BunnySlippers]

I see them called GAITERS here in the stores:

https://www.google.com/search?client=safari&rls=en&q=gaiters&ie=UTF-8&oe=UTF-8