...
Compressed air environments are those in which air has been mechanically compressed to a point where the air pressure is higher than the pressure of the atmosphere. Compressed air environments are most often associated with underwater diving but can also affect construction workers during tunnel construction to prevent flooding and toxic substance buildup.
During compressed air activities, the pressure and force on the body increase, and though the human body can typically withstand the pressure increase, bodily gases aren’t as adaptive. Compressed air occupies less space in the lungs, so divers, for example, need more of it to fill their lungs at depth. As a result, they consume air more quickly underwater than they do at the surface, placing their bodies at great risk.
Scope
Occupational exposure to compressed air increases a worker’s risk of decompression sickness and air gas embolism. Therefore, job sites may require onsite hyperbaric chambers and medical teams depending on the specific conditions, depth of the work, and duration of exposure. For divers, decompression sickness happens when they come up to the surface too quickly. The rapid change in pressure causes gases like nitrogen, which were absorbed into the body at depth, to form bubbles in the blood and tissues. These bubbles can block blood flow and damage organs.
Sometimes, these bubbles get into the arteries, which can lead to a serious condition called arterial gas embolism. This effect is similar to opening a shaken soda bottle: if opened quickly, bubbles rush out and overflow; if opened slowly, the pressure equalizes and fewer bubbles form. A lack of gradual decompression can cause stroke-like symptoms such as confusion, vision problems, trouble speaking, paralysis, or even unconsciousness. Additional effects include hearing and balance issues, difficulty breathing, and stomach upset, with severe incidents resulting in death.
The increasing demand for underground tunnels across America has construction workers working in compressed air environments also. Tunnel-boring machines use compressed air so workers can complete tasks under extreme pressure. Hyperbaric operations are crucial for regular maintenance, safety checks, and handling emergencies.
OSHA regulations require that during the compression of employees, the pressure shall not be increased to more than 3 p.s.i.g. within the first minute. The pressure must then be held at 3 p.s.i.g. and again at 7 p.s.i.g. long enough to determine if the worker(s) are experiencing discomfort. After the first minute, pressure must be raised uniformly and at a rate of not more than 10 p.s.i. per minute.
If at any time, a worker complains of discomfort, the pressure shall be held to determine if the symptoms are relieved. If, after 5 minutes, the discomfort doesn’t disappear, pressure must be gradually reduced the worker indicates there is no longer any discomfort. If discomfort doesn’t subside, pressure must be reduced to atmospheric.
Regulatory citations
- 29 CFR 1926.803 (construction)
- 29 CFR 1904 — Recording and reporting occupational injuries and illnesses
- 29 CFR 1910 Subpart I — Personal Protective Equipment (PPE)
- 29 CFR 1910.1020 — Access to employee exposure and medical records
Key definitions
- Atmospheric pressure: The force exerted by the weight of the air in every direction by the Earth’s atmosphere.
- Compressed air environment: An environment in which air has been mechanically compressed to a point where the air pressure is higher than the pressure of the atmosphere.
- Decompression sickness: A medical condition caused by the dissolving gases within the body due to rapid changes in pressure; also known as “the bends.”
- Embolism: A medical emergency caused by clots or blockages in an artery or blood vessel.
- Exposure: Subjecting a worker to a hazardous drug by any route of entry, such as inhalation, ingestion, skin contact, or absorption. Exposure includes potential (e.g., accidental or possible) exposure.
- Hyperbaric chamber: A machine or pressurized room or capsule where the air pressure is higher than normal atmospheric pressure. It's used to deliver pure oxygen into the bloodstream to reduce clots or relieve decompression sickness.
- Pounds per square inch gauge (p.s.i.g.): A unit of pressure on a gauge that is expressed relative to atmospheric pressure.
Summary of requirements
- Conduct hazard assessments to identify operations or activities within compressed air environments.
- Consult with medical professionals, industrial hygienists, or other occupational health and safety professionals for guidance, as necessary.
- Develop and implement a written program to reduce exposures to compressed air environments.
- Retain one or more licensed physicians familiar with and experienced in the physical requirements and the medical aspects of compressed air work and the treatment of decompression illness who will be available at all times while compressed air work is occurring.
- Implement monitoring protocols that include worker discomfort monitoring, compression and decompression, and postings of decompression in each man lock.
- Establish reliable means of communication that are maintained during the entire duration of compressed air work.
- Implement controls and procedures for fire prevention and protection, sanitation, ventilation, and flood prevention.
- Provide appropriate PPE necessary to protect workers from exposure.
- Train workers in chemical and material handling hazards and required protective measures.
- Investigate any worker incidents or near misses to find root causes and implement corrective actions to prevent future occurrences.