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.
The commonly known N-95 filtering facepiece respirator or dust mask is one type of particulate respirator, often used in hospitals to protect against infectious agents. Particulate respirators are airpurifying respirators because they clean particles out of the air as you breathe.