[jltsiren]

Disposable masks have been routinely used in healthcare since at least the 1960s. I would be extremely surprised if there are no studies of the long-term health effects of mask use. Especially since the people who could do such research are the ones who would suffer most from any adverse effects.

[gjsman-1000]

There are some, even from this pandemic. They aren't great.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8072811/