note: MSM doesn't tell you want those toxic chemicals are in the masks:
Source:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10112860/ Formaldehyde((methanal)formyl group), acetaldehyde(formyl group), and propionaldehyde (formyl group)
2,4-dinitrophenylhydrazine(methanol and some concentrated sulfuric acid) and Acetonitrile (methyl cyanide)
formyl group
https://en.wikipedia.org/wiki/Aldehyde Nothing like sucking in methanal, concentrated sulfuric acid and cyanide all day long.