As to the question of rules regarding when and where peaceful protests may be held, that's highly dependent on the specific location of the protest.
The venturi mask, also known as an air-entrainment mask (and sometimes by the brand name VentimaskÂ®), is a medical device to deliver a known oxygen concentration to patients on controlled oxygen therapy.
If the wearer needs a combination surgical mask. and a particulate respirator, they should use a product that is both cleared by FDA as a surgical mask and tested by. NIOSH as a particulate respirator. An in-depth comparison of surgical masks and respirators is outlined in table 1.