Loose-fitting facepiece means a respiratory inlet covering that is designed to form a partial seal with the face.
Deck means a floor or platform on which seats are provided for the accommodation of passengers;
Tunnelling means the construction of any tunnel beneath the natural surface of the earth for a purpose other than the searching for or winning of a mineral
Tight-fitting facepiece means a respiratory inlet covering that forms a complete seal with the face.
Motorized bicycle or "moped" means any vehicle that either has two tandem wheels or one wheel in the front and two wheels in the rear, that may be pedaled, and that is equipped with a helper motor of not more than fifty cubic centimeters piston displacement that produces no more than one brake horsepower and is capable of propelling the vehicle at a speed of no greater than twenty miles per hour on a level surface. "Motorized bicycle" or "moped" does not include an electric bicycle.