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.
Full face mask. Lower pressure settings can often be treated with nasal masks or nasal pillows. The other major factor for consideration is if the patient will keep their mouth open, making it more difficult to maintain a constant pressure. In this case, a full face mask is often used. See the video below for examples.