Abstract: The present disclosure provides for devices and methods that actively circulate air into a helmet and around a wearer's face and head. Advantageously, the devices described herein can be added to off-the-shelf protective helmets and can leverage existing passive ventilation features to actively circulate fresh air without compromising protection against mechanical forces. The devices can be added to helmets on a temporary, permanent, or semi-permanent basis and can be used alongside additional protective accessories such visors, lenses, and/or face guards. The devices and methods described herein are be suitable to virtually all protective helmets (e.g. athletic or safety helmets). The devices described herein are portable, non-restrictive, and fully contained in the interior of the helmet. Helmets with integral forced-air circulation are also provided.