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.
When using compressed gases, wear. appropriate protective equipment, such. as safety goggles or face shield, rubber. gloves, and safety shoes. Well-. ventilated barricades should be used in. extremely hazardous operations, such. as in the handling of fluorine. Gas masks should be kept available for immediate use when working with toxic gases. These masks should be placed in convenient locations in areas not likely to become contaminated, and should be approved by the U.S. Bureau of Mines for the service intended. Those involved in the handling of compressed gases should become