Laws, Regulations and Consensus Standards
The legal hierarchy
The OSH Act of 1970 created three obligations: the General Duty Clause, Section 5(a)(1), requiring each employer to furnish a workplace free from recognized hazards likely to cause death or serious physical harm; Section 5(a)(2), requiring compliance with promulgated standards; and the employer's duty to employees. Regulations sit in 29 CFR - Part 1910 for general industry, 1926 for construction, 1904 for recordkeeping. State plans must be at least as effective as the federal program; they need not be identical, and some cover public employees that federal OSHA does not.
Know the difference between a statute (Congress), a regulation/standard (rulemaking, enforceable), and a consensus standard (ANSI/ASSP, NFPA, ASTM, ISO - voluntary until adopted or incorporated by reference). Guidance documents, letters of interpretation, and NIOSH criteria are not enforceable standards, though letters of interpretation carry weight in enforcement.
Exposure limits
OSHA PELs are enforceable. NIOSH RELs and ACGIH TLVs are recommendations; TLVs are health-based and frequently lower than PELs. A permissible exposure limit is a legal ceiling on exposure, not a guarantee of safety.
Traps
- Saying a consensus standard is law when it has only been incorporated by reference into a rule.
- Confusing the General Duty Clause (no specific standard exists) with a specific standard violation.
- Assuming state plans must mirror federal rules exactly.
- Citing a TLV as if it were a legal limit.
Worked example
Anhydrous ammonia: OSHA PEL 50 ppm (8-hr TWA); ACGIH TLV 25 ppm; NIOSH IDLH 300 ppm. A measured 40 ppm exposure is a legal compliance question at 50 ppm but exceeds the TLV, so a defensible program targets 25 ppm and treats 300 ppm as the evacuation trigger.
Rule of thumb
Rank the numbers: PEL = enforceable, TLV/REL = advisory, IDLH = life-threatening, not a work limit.