Can you provide any evidence of this claim? A bandana can be any textile and certainly doesn't filter exhaled air. Being made largely of cotten and rarely washed, they also become virus spreaders if someone infected yet asymptomatic saturates a mask and proceeds to aerosol it around all day like a chum trail of plague.
Bandana is the worst option, especially compared to many vented masks actually use N95 filters preventing the inhalation of covid to begin with - and much more securely than your earloop equivalent
Bandana is the worst option, especially compared to many vented masks actually use N95 filters preventing the inhalation of covid to begin with - and much more securely than your earloop equivalent