Governs work in compressed air environments (tunnels, caissons and other pressurised compartments). A competent person designated by the employer, familiar with this subpart and responsible for full compliance, must be present at all times, and every employee is instructed in the safety rules affecting them. Medical: the employer retains one or more licensed physicians experienced in compressed air medicine and decompression illness, available whenever work is in progress, physically fit and willing to enter pressure. No one enters compressed air until examined and reported fit; workers absent 10 days, or absent through sickness or injury, are re-examined before returning; continuous workers are re-examined at an interval set by the physician but not longer than 1 year. The physician keeps full records of examinations, decompression illness, incapacitating illness or injury and deaths; records are open to the Secretary, and a copy goes to OSHA within 48 hours after any such accident, death, injury or case of decompression illness. Each tunnel project has a fully equipped first aid station and litter-capable transport, with one at each portal where tunnelling proceeds from portals over 5 road miles apart. A medical lock is maintained whenever working chamber pressure exceeds normal atmosphere: at least 6 feet headroom, two or more compartments, ready for at least 5 hours after anyone leaves the working chamber, designed for 75 p.s.i.g., able to reach 75 p.s.i.g. from 0 in 5 minutes with oil-free and CO-free air, held between 70 and 90 degrees F, with observation port, gauges, override controls, manual sprinkler, closed-circuit oxygen that shuts off when the fire system operates, and an attendant under the physician's control. Every worker carries an identification badge (name, medical lock address, physician phone, instruction to rush the wearer to the lock) on and off the job, with a permanent issue record. Communications (bells, whistles or telephones) link face, man lock inside and out, lock attendant, compressor plant, first aid station and any emergency lock or special chamber. Decompression times are posted in each man lock on the superintendent-signed form, signal codes are posted, and for each 8-hour shift an employee outside the lock records time under pressure and decompression time, with a copy to the physician after each shift. Compression: new workers are taught to avoid discomfort; a rise of at most 3 p.s.i.g. during the first minute, with holds at 3 and 7 p.s.i.g., then no faster than 10 p.s.i. per minute; if discomfort persists after 5 minutes the pressure is reduced, down to atmospheric if needed. Pressure above 50 p.s.i. is prohibited except in emergency. Decompression must follow the Appendix A Decompression Tables, which are mandatory: two to four stages by working pressure and exposure time, stage 1 at no more than 5 pounds per minute and never below 4 pounds, later stages no faster than 1 pound per minute, no interpolation (use the next higher pressure or time). The physician sets procedures for more than one exposure in 24 hours and for decanting, with no more than 5 minutes at atmospheric pressure between decompression and recompression. Locks: automatic decompression controls unless working chamber pressure stays under 12 p.s.i.g. with manual override and an inside emergency control; clock, thermometer and continuous 4-hour recording gauge outside each man lock, charts sent to the physician after each shift; separate man and materials locks for caissons over 150 square feet and tunnel bulkheads where the diameter is 14 feet or greater (unless pressure stays under 12 p.s.i.g. with no rapid flooding danger); minimum 5 feet headroom and 30 cubic feet per occupant; 70 degrees F minimum; a special decompression chamber when decompression exceeds 75 minutes (7 feet headroom, 50 cubic feet, 4 square feet walking and 3 square feet seating per person, posted capacity). Air supply: a gauge tender at all times (up to two headings from one location, one per caisson), two independent power sources for low air, duplicate feedlines to within 100 feet of the face, check valves. Air is analysed at least once each shift with records kept on site and results held within Subpart D limits and 10 percent of the LEL, ventilation not less than 30 cfm, chamber temperature not over 85 degrees F. Also covered: dual electric lighting at 10 foot-candles minimum, sanitation (one shower per 10 employees per shift and one toilet per 15), fire protection including 2-inch water lines with hose outlets every 200 feet, intermediate bulkheads with locks or safety screens where rapid flooding is a danger, noncombustible hanging walkways with railings in tunnels of 16 feet diameter or more, and bulkhead testing where practicable.
The graph holds this control, the 0 it maps to, and the evidence behind each claim, over MCP and REST.