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.
An oxygen mask is attached to a plastic tube and covers your nose and mouth. It is usually held in place by an elastic strap that wraps around the back of your head. You can use an oxygen mask if you need a lot of oxygen. Your caregiver may tell you to use a nasal cannula during the day, and a mask at night. A mask may help if your nose is dry or stuffy.