confinedspace

Confined space is a space that is large enough for a person to enter and perform work but has limited or restricted means for entry or exit and is not designed for continuous occupancy. Such spaces may have poor ventilation, limited access, or physical hazards that create safety risks for workers.

Confined spaces are commonly categorized as non-permit and permit-required. Permit-required confined spaces pose at least one of the following hazards: a hazardous atmosphere (for example, low oxygen or toxic or flammable gases), the potential for engulfment or entrapment, an internal configuration that could trap or asphyxiate an entrant, or other serious safety risks. Examples include storage tanks, vessels, vaults, sewers, pits, pipes, manholes, silos, boilers, and underground utility spaces.

Hazards in confined spaces include hazardous atmospheres, oxygen deficiency, toxic or flammable gases, vapors, and maybe chemical or physical hazards. Other risks include engulfment by liquids or granular materials, sudden movements of machinery, heat stress, and limited means of rescue or escape. Because of these hazards, work in confined spaces is typically governed by specialized safety procedures.

Safety measures and procedures aim to prevent incidents and include hazard assessment, atmospheric testing before and during entry, ventilation, isolation and lockout of energy sources, proper lighting, use of entry permits, trained entrants and attendants, clear communication, and a rescue plan. In many jurisdictions, non-entry methods are preferred when possible, and entry is subject to strict permit systems and rescue readiness.

Regulatory context varies by country. In the United States, OSHA’s permit-required confined spaces standard (29 CFR 1910.146) applies to general industry, with construction-specific rules in 29 CFR 1926 Subpart AA. Other regions rely on national safety regulations and guidance such as industry standards and NFPA guidelines.