## Facts

- Pratt & Whitney operated a manufacturing plant with electroplating lines using multiple open surface tanks containing, among other substances, acids, cyanides, hydrogen peroxide, glacial acetic acid, and heated slushing oil.
- Each tank had an individual exhaust duct, but ducts within each plating line merged into a common exhaust duct that vented through a roof stack.
- OSHA cited Pratt & Whitney for a serious violation of 29 C.F.R. § 1910.94(d)(7)(iii), which prohibits connecting two or more operations to the same exhaust system when the substances removed, alone or combined, may create a fire, explosion, or chemical reaction hazard in the duct system.
- The Secretary alleged that exhausting acid mists and cyanide mists into the same duct could generate hydrogen cyanide gas, and that certain combinations involving hydrogen peroxide (with heated slushing oil and/or acetic acid) could create explosive hazards.
- An ALJ upheld the citation in substantial part, and OSHRC affirmed a serious violation using a “realistic possibility” approach to hazard proof.
- Pratt & Whitney petitioned for judicial review in the Second Circuit.

## Issues

1. Whether the Secretary may establish a violation of 29 C.F.R. § 1910.94(d)(7)(iii) by showing a “realistic possibility” of a hazardous reaction in a common exhaust duct.
2. Whether application of the cited OSHA standard requires proof that the cited condition presents a “significant risk” consistent with OSHA’s statutory limits.

## Decision

- The Second Circuit vacated OSHRC’s order and remanded.
- The court held that OSHRC applied an impermissibly low risk threshold by treating a “realistic possibility” of harm as sufficient.
- The court directed OSHRC to determine on remand whether the cited venting configuration created a “significant risk” of fire, explosion, or chemical reaction hazard under § 1910.94(d)(7)(iii).
- The court did not resolve whether Pratt & Whitney’s system in fact posed a significant risk on the existing record.

## Legal Principles

- OSHA enforcement under specific standards must be confined to conditions presenting a significant (non-trivial) risk, not speculative or remote hazards.
- An agency interpretation that extends an OSHA standard to conditions posing insignificant risks exceeds OSHA’s statutory scope.
- For § 1910.94(d)(7)(iii), chemical possibility alone does not establish a violation; the Commission must assess whether, under actual operating conditions, the likelihood and magnitude of the postulated reaction amount to a significant risk.

## Conclusion

The Second Circuit set aside OSHRC’s serious-violation finding because the Commission relied on a “realistic possibility” test, and it required a remand for application of a significant-risk standard before § 1910.94(d)(7)(iii) could be enforced against Pratt & Whitney’s common-duct ventilation system.


Pratt & Whitney Aircraft v. Sec’y of Lab., 649 F.2d 96 (2d Cir. 1981)