Abstract: A protective helmet of the type which substantially completely surrounds the wearer's head to provide maximum protection from otherwise hazardous conditions encountered during sand blasting, steam or high pressure water jet cleaning, welding, and other operations requiring protection from dust, fumes, gases, and other dangerous environmental conditions is disclosed, wherein improved air distributing means is provided within the helmet to achieve improved air circulation at a reduced noise level which is not obnoxious or harmful to the wearer. In addition, the air supply hose is provided which enters the helmet from the downwardly facing open end thereof, so that the hose does not project from the sides or top of the helmet. The air supply hose is, further, conveniently anchored to a belt around the wearer's waist. An apron or skirt can be removably attached to the perimeter of the downwardly facing opening of the helmet to hang down from the helmet over the shoulders and upper torso of the wearer.