In the construction industry, OSHA estimates an annual rate of 6.44 worker fatalities and 967 injuries in the United States out of 641,000 entries by workers into confined spaces. This unacceptable toll resulted in the proposed rule, 29 CFR Part 1926, Confined Spaces in Construction, released on November 28, 2007.

The reference to confined space entry in construction, 29 CFR 1926.21, states that all employees required to enter into confined or enclosed spaces shall be instructed as to the nature of the hazards involved, the necessary precautions to be taken, and in the use of protective and emergency equipment required. The employer shall comply with any specific regulations that apply to work in dangerous or potentially dangerous areas. OSHA’s construction regulations also contain requirements regarding confined space hazards in underground construction (Subpart S), underground electric transmission and distribution work (1926.956), excavations (Subpart P), and welding and cutting (Subpart J).

Confined space hazards on construction sites
While the proposed rule is a step in the right direction, its limitations have come under scrutiny by some within the construction industry because it fails to address the specific hazards construction workers may encounter, and it creates confusion in identifying and reporting specific hazards. In order to address these challenges, it is necessary to become familiar with the language of the regulation.

A confined space is defined as any space big enough for an employee to enter and perform work. It has limited openings for entry and exit and is not intended for continuous occupancy.

Permit-required confined spaces as stated by the general industry definitions may contain one or more of the following dangers:
  • Hazardous air (atmosphere).
  • A material that might engulf the entrant as it shifts or gives way.
  • An internal structure that could cause an entrant to be trapped or asphyxiated by inwardly converging walls or a floor which slopes downward and tapers to a smaller cross section.
  • Any other safety or health hazard.
Confined spaces on a construction site can include storage tanks, process vessels, bins, boilers, sewers, ventilation or exhaust ducts, underground utility vaults, tunnels, pipelines, and open top spaces more than four feet deep, such as pits, tubs, vaults and vessels.

Proposed standard adds protections
The proposed OSHA standard does not replace the more hazard-specific construction standards already in place. Rather, it requires additional protections when employees are working in or near a confined space and includes requirements for training, hazard analysis, classification, entering, working, exiting and rescue.

Employers would be required to classify each confined space subject to a hazard as one of the following four types:
  • A Continuous System-Permit-Required Confined Space (CS-PRCS) is part of, and contiguous with, a larger confined space (for example, sewers) that the employer cannot isolate from the larger confined space. It is also subject to a potential hazard release from the larger confined space that would overwhelm personal protective equipment and/or hazard controls, resulting in a hazard that is immediately dangerous to life and health.
  • A Permit-Required Confined Space (PRCS) has any one of the following: a hazardous atmosphere that ventilation will not reduce to and maintain at a safe level; inwardly-converging, sloping or tapering surfaces that could trap or asphyxiate an employee; or an engulfment hazard or other physical hazard.
  • A Controlled-Atmosphere Confined Space (CACS) is a confined space where ventilation alone controls atmospheric hazards at safe levels. Note also that a confined space cannot be classified as a CACS if it has a physical hazard (unless that hazard has been isolated).
  • An Isolated-Hazard Confined Space (IHCS) is one where the employer has isolated all physical and atmospheric hazards. “Isolated” means the elimination or removal of a physical or atmospheric hazard by preventing its release into a confined space. It includes, but is not limited to, the following methods: blanking and blinding; misaligning or removing sections of lines, pipes, or ducts; a double-block-and-bleed system; locking out or tagging out energy sources; machine guarding; and blocking or disconnecting all mechanical linkages.
Definitions add to the confusion
As defined in the proposed rule, the “controlling contractor” is the employer who has overall responsibility for construction at the worksite. According to the rule, if a “host employer” has overall responsibility for construction at the worksite, then it is both a “host employer” and a “controlling contractor.” There often is one contractor with overall authority of the construction site including the authority to change worksite conditions and alter work practices with regard to safety. Under this proposed standard, there are specific duties that would apply to the controlling contractor as distinguished from the host employer and the contractor.

The term “employer” refers to an employer whose employees are exposed to confined-space hazards.

Employers whose own employees are exposed to a hazard addressed by this proposed standard would be required to comply with the provisions that identify an obligation of “the employer.”

Some contracting companies believe the proposed rule will make it more costly and confusing to work in common construction site spaces, such as trenches and manholes. For example, confusion might arise in determining who classifies the confined space. The “employer” as defined above makes the determination on the classification of the confined space; however, the “controlling contractor” has the ultimate responsibility for the site. Although it does give employers more flexibility, leaving the duty of classification of the confined space to the employers may prove to add more confusion to the mix. The complete proposed rule can be found at OSHA’s Web site,