Personnel entering or working in permit-required confined spaces may encounter any number of serious hazards that can affect their ability to safely work in or evacuate from a confined space. Serious physical damage is defined as an impairment or illness in which a body part is made functionally useless or is substantially reduced in efficiency. Such impairment or illness may be permanent or temporary and includes, but is not limited to, loss of consciousness, disorientation, or other immediate and substantial reduction in mental efficiency.