In an air sterilization system that includes a UV kill chamber for sterilizing air that is to be supplied to users, the effectiveness of killing or neutralizing pathogens is increased by including not only a UV light source of a certain intensity but also including a particle filter and providing short duration high intensity UV radiation. In the case of a user specific system that includes a face mask to supply air to a specific user, exhaled air from the face mask may be sterilized as well, either by using the same kill chamber or by using a separate kill chamber.