This obviously distressed UK doctor confirms the presence of parasitic worms in blue face-masks, those worn mostly by NHS employees.  She experimented with seven different types, all were contaminated with some 'worm' that was invisible to the eye but showed under a microscope. The 'worms' were still but came to life with carbon dioxide from human breath and wriggled away from water or alcohol.   Disturbing - but perhaps a way to refuse wearing masks for those who feel unable to stand