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 self-inflating bag-valve mask system is the most commonly used system for emergency department and pre-hospital resuscitation. An appropriate mask is one that does not cover the patient's eyes and does not extend beyond the chin. Typically, this mask is of anatomic design, with the pointed portion over the nose.