Confined spaces include areas that are large enough for worker entry but have limited access, are not designed for occupancy, and could contain hazards such as oxygen deficiency, flammable atmospheres, or toxic gases. Permit-required confined spaces must have written procedures for safe entry. Before entry, hazards must be identified and eliminated or controlled. Atmospheric testing must verify adequate oxygen (19.5-23.5 percent), no flammable gases below 25 percent of lower explosive limit, and no toxic gases above exposure limits. Continuous atmospheric monitoring must continue throughout the entry. Engineering controls such as ventilation must maintain safe atmospheric conditions. Personal protective equipment including respirators must be provided if hazards cannot be controlled. Rescue equipment and procedures must be in place before entry in case a worker becomes incapacitated. A trained attendant must remain outside the space monitoring the entrant and ready to summon rescue. Communication equipment must allow the attendant to maintain contact with entrants. Training must cover confined space hazards, atmospheric testing, respiratory protection, rescue procedures, and appropriate use of PPE. Only trained and authorized personnel may enter confined spaces. Medical evaluation must determine fitness for the physical demands of confined space work and respiratory protection use. Documentation of atmospheric test results and entry procedures must be maintained.