I've been using a cloth mask I bought in Europe. I cut out the back portion and any extra sections they add, so it's as thin as possible (you can basically see through it!)

Non-stop travel, and 50+ countries later. No issues. (it clearly does nothing, you can see right through it)

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Just ordered a couple masks from Fake Mask, so I'm excited to try those.
Have heard they are the most breathable.

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Other solution, is fly Qatar Q Suites. They don't make you wear a mask, so, problem solved!