A helmet comprising a face shield and a device for supplying atmospheric air to the interior of the helmet. The device has filters for removing dust particles and noxious substances from the atmospheric air to be drawn in and supplied to the inner surface of the face shield....http://www.google.es/patents/US4502480?utm_source=gb-gplus-sharePatente US4502480 - Helmet equipped with device for supplying atmospheric air
Helmet equipped with device for supplying atmospheric air
