For tunnel, shaft and underground construction crews and supervisors: access and check-in/check-out, safety instruction, communications, self-rescuers and emergency provisions, gassy classifications, air monitoring, ventilation, fire prevention and ground support.
Based on OSHA 29 CFR 1926.800 · about 6 min read
Need proof of training? The full course (30 min) adds practice questions, a job scenario, the final quiz and a certificate your employer can verify.
Safe access and egress are provided to all work stations, protected from excavators, haulage machines, trains and other mobile equipment. Access to openings is controlled to prevent unauthorized entry.
A check-in/check-out procedure lets above-ground personnel know an accurate count of all persons underground in an emergency. The procedure is not required once underground facilities designed for human occupancy are complete enough that the permanent environmental controls are effective, and the remaining construction will not cause any environmental hazard or structural failure within the facilities.
All employees are instructed in recognizing and avoiding underground hazards, as appropriate: air monitoring, ventilation, illumination, communications, flood control, mechanical equipment, PPE, explosives, fire prevention and protection, and emergency procedures including evacuation plans and check-in/check-out.
Oncoming shifts are told of hazardous occurrences such as gas, equipment failures, slides, cave-ins, flooding, fires or explosions.
Shafts being developed or used for personnel access or hoisting have two effective means of communication, at least one of them voice. Communication systems are tested upon initial entry of each shift and as often as necessary later.
Anyone working alone in a hazardous location, out of voice range and unobserved, has an effective way to get help.
NIOSH-approved self-rescuers are immediately available at work stations where employees might be trapped by smoke or gas.
At least one designated person above ground keeps an accurate count of employees underground and secures immediate aid.
Each employee has a hand lamp or cap lamp for emergencies unless other lighting allows escape.
Rescue teams: with fewer than 25 underground, at least one 5-person team on site or within half an hour; with 25 or more, two teams (one within half an hour, one within 2 hours).
A competent person performs all air monitoring. The atmosphere must contain at least 19.5 percent and no more than 22 percent oxygen, and oxygen is tested before contaminants. Toxic gases (CO, NO2, H2S and others) and flammable gases are tested as often as necessary.
5 percent of the LEL (methane or other flammable gas): increase ventilation or otherwise control the gas, unless the employer is already operating under the potentially gassy or gassy operation requirements.
10 percent of the LEL near welding, cutting or other hot work: suspend the hot work.
20 percent of the LEL: withdraw all employees (except those needed to eliminate the hazard) to a safe location above ground, and cut power except to acceptable pumping and ventilation equipment.
Hydrogen sulfide: at 5 ppm or more, the affected area is tested at least at the beginning and midpoint of each shift until it has been below 5 ppm for 3 consecutive days. Above 10 ppm, a continuous sampling and indicating monitor is used and employees are informed. The monitor gives a visual and aural alarm at 20 ppm.
Operations are classified potentially gassy if monitoring shows 10 percent or more of the LEL (measured 12 inches from the roof, face, floor or walls) for more than a 24-hour period, or if the history of the area or geological formation indicates that level is likely. They are classified gassy if monitoring shows that level for three consecutive days, if methane or other flammable gas from the strata has ignited, or if the operation is connected to a work area classified as gassy and is subject to a continuous course of air containing the flammable gas. In gassy operations, entrances are posted, smoking is prohibited, and matches and lighters are collected.
Fresh air is supplied to all underground work areas in quantities that prevent harmful accumulations. Mechanical ventilation is used unless natural ventilation is shown to be sufficient.
At least 200 cubic feet of fresh air per minute is supplied for each employee underground, and the linear velocity of air flow is at least 30 feet per minute where blasting or rock drilling is conducted, or where other conditions likely to produce dust, fumes, mists, vapors or gases in harmful or explosive quantities are present.
Mechanical air flow must be reversible.
After blasting, smoke and fumes are exhausted to the outside before work resumes.
If ventilation was shut down with all employees out, only authorized competent persons go underground until ventilation is restored and areas are tested and declared safe.
Open flames and fires are prohibited underground except for permitted hot work. Readily visible signs prohibiting smoking and open flames are posted in areas having fire or explosion hazards.
No more than a 24-hour supply of diesel fuel is stored underground. Gasoline is not carried, stored or used underground.
Oil, grease and diesel fuel stored underground are kept in tightly sealed containers in fire-resistant areas at least 300 feet from underground explosive magazines and at least 100 feet from shaft stations and steeply inclined passageways. Flammable or combustible materials are not stored above ground within 100 feet of any access opening. Where space limits make that not feasible, they are kept as far as practicable from the opening, and either a fire-resistant barrier of at least one-hour rating is placed between them and the opening or other precautions protect them from ignition sources.
Leaks and spills of flammable or combustible fluids are cleaned up immediately.
No more than a 24-hour supply of fuel gas and oxygen cylinders is allowed underground, and noncombustible barriers go below hot work in or over a shaft or raise.
A competent person inspects the roof, face and walls at the start of each shift and as often as necessary, while protected from loose ground.
Loose ground that might be hazardous is taken down, scaled or supported. Rock bolt torque is checked as a competent person determines.
Damaged or dislodged supports that create a hazardous condition are promptly repaired or replaced, with new supports installed before damaged ones are removed.
Shafts and wells over 5 feet deep that employees enter are supported by a steel casing, concrete pipe, timber, solid rock or other suitable material. After blasting in shafts, a competent person determines if the walls, ladders, timbers, blocking or wedges have loosened.
Fact-checked against the regulation text on October 09, 2026. This certificate records completion of awareness training based on OSHA 29 CFR 1926.800(b) through (k), (m), (n) and (o). It is not an OSHA card or license, it does not make anyone a competent person or a rescue team member, and it does not by itself meet the training requirements of 29 CFR 1926.800(d). Your employer must still instruct all employees in the recognition and avoidance of hazards associated with underground construction activities including, where appropriate, air monitoring; ventilation; illumination; communications; flood control; mechanical equipment; personal protective equipment; explosives; fire prevention and protection; and emergency procedures, including evacuation plans and check-in/check-out systems. Rescue team members must also be qualified in rescue procedures, the use and limitations of breathing apparatus, and the use of firefighting equipment, as required by 29 CFR 1926.800(g)(5)(iii).
This guide explains the rule in plain words. Always read the regulation itself and your employer's site-specific procedures.