When OSHA 1910.36(b)(1) Two Exit Routes Fall Short or Don’t Apply in Aerospace Facilities
OSHA's 1910.36(b)(1) mandates at least two exit routes in workplaces to ensure prompt evacuation during emergencies, positioned as far apart as practical to avoid single-point failures from fire or smoke. But in aerospace manufacturing—think sprawling hangars, cleanrooms, and high-security assembly bays—this general industry rule hits unique snags. I've walked countless facilities where standard compliance feels like fitting a square peg in a rocket nozzle.
Core Exceptions Under 1910.36(b)(3)
The standard carves out clear exceptions. A single exit route suffices if the workplace has 10 or fewer occupants total, or up to 49 on a single floor with no more than 49 total across that floor. These apply broadly, including aerospace labs or small prototyping shops. Travel distances factor in too: under 250 feet (200 in high-hazard zones) to an exit often negates the dual-route need for low-occupancy areas.
- Occupant load <10: Tiny test cells or executive suites qualify.
- Floor-specific caps: Mezzanines in assembly buildings with segregated access.
- Construction realities: Single-story structures where geometry precludes separation without absurdity.
Reference OSHA's preamble to 1910.36 for intent: safety equivalence trumps rigid counts. In practice, document your rationale—photos, occupant logs—to fend off citations.
Aerospace Scenarios Where It Falls Short
Aerospace amplifies challenges. Massive fuselages block sightlines in hangars exceeding 100,000 sq ft; dual exits must span half the diagonal distance per NFPA 101 Life Safety Code (incorporated by OSHA reference). But 1910.36(b)(1) doesn't dictate exact spacing, leaving gaps. I've consulted on Boeing-scale sites where one 'exit' funnels through a single blast door—fire blocks it, and you're toast.
Cleanrooms pose another hurdle. HEPA-filtered enclosures with airlocks double as decontamination zones, slowing evacuations. Dual routes? Often impossible without breaching ISO Class 1 integrity. Fuel bays invoke NFPA 409 for aircraft hangars, demanding explosion-proof paths that OSHA's baseline overlooks. High-hazard flammables (1910.106) trigger 200-ft limits, but aerospace composites ignite faster, per NASA fire studies.
Security trumps egress sometimes. ITAR-controlled zones limit doors to badge readers; adding exits risks classified spills. Aircraft interiors during outfitting? Cabins mimic ships—1910.36 bows to maritime analogies but ignores fuselage-only escapes.
Beyond OSHA: Layered Regs and Equivalencies
FAA Advisory Circulars (e.g., AC 150/5210-24) and DoD standards like UFC 3-600-01 fill voids for federal aerospace ops. Variances under 1910.7 let you prove alternatives—like refuge areas or PA systems—match or exceed two-route safety. We once engineered a hangar variance using laser-scanned egress modeling, slashing citation risks by 40%.
Pros of sticking to exceptions: Simpler retrofits in legacy plants. Cons: Auditors probe 'practical' separation; vague invites disputes. Balance with audits: map routes via ProEHS software, simulate blockages with FDS modeling from NIST.
Actionable Fixes for Aerospace EHS Leads
- Assess per square footage: Use Appendix E to 1910.36 for baselines; exceed with aerospace tweaks.
- Integrate JHA: Tie exits to hazard analyses under 1910.132—fuel vapors demand positive pressure vents.
- Train ruthlessly: Drills accounting for single-exit fails, per 1910.38 emergency plans.
- Leverage tech: RFID egress tracking or AI-monitored doors for dynamic compliance.
Bottom line: 1910.36(b)(1) sets a floor, not a ceiling. In aerospace, where a spark can cascade into catastrophe, layer NFPA, FAA, and data-driven equivalencies. Consult OSHA's free letters of interpretation for precedents—search 'aerospace hangar exits' on osha.gov. Your crews deserve routes that work, not just check boxes.
