wearing a mask exposes you to elevated levels of co2 (due to re-breathing exhaled air)
source: https://associationofanaesthetists-publications.onlinelibrary.wiley.com/doi/full/10.1111/j.1365-2044.2006.04767.x

elevated co2 is what they use in clinical lab settings to induce anxiety and panic attacks
source: https://pubmed.ncbi.nlm.nih.gov/10450339/

Anxiety disorders often go hand in hand with depression
https://www.cdc.gov/tobacco/campaign/tips/diseases/depression-anxiety.html

increased morbidity and mortality associated with depression
source: https://pubmed.ncbi.nlm.nih.gov/12377296/