Protective helmet with selectively covered aperture

摘要

Protective helmet comprising a two piece shell, an electric motor and impeller useful for creating a positive pressure environment in the head space, and a filter for removing particulates and other substances. The impeller introduces atmospheric air into an air channel defined by two detachably attached shell pieces. The air is pushed through a particulate filter in the air channel and then through at least one aperture into the head space. A heating element may be used to heat the air flow.