Nitrogen Asphyxiation in a Confined Space

A vessel is purged with nitrogen to keep oxygen out. A worker enters or reaches in without confirming breathable air and is overcome in seconds; a would-be rescuer rushes in and is overcome too.

CSB identified 85 nitrogen incidents in the U.S. (1992–2002) causing 80 deaths (CSB Nitrogen Asphyxiation Bulletin 2003); nitrogen is odorless and colorless — an oxygen-deficient atmosphere gives no warning and is detectable only with an instrument .

1. Verify O₂ with a calibrated meter before any entry or reach-in.
2. Enter only under permit, with ventilation and an attendant.
3. Use supplied air where the atmosphere cannot be verified safe.
4. If someone collapses, call trained rescue — never attempt an impulsive self-rescue.

CSB: 85 nitrogen incidents / 80 deaths over 1992–2002 (~8 deaths/yr) (CSB Bulletin 2003); more broadly, BLS counted 1,030 confined-space occupational deaths 2011–2018 (~129/yr, range 88–166) (BLS fact sheet,…

Collapse within one or two breaths below ~10% O₂; frequent multiple fatalities because rescuers follow — ~60% of confined-space fatalities are would-be rescuers (NIOSH-derived figure via safety-industry compilations); contractors were 60%+ of CSB's nitrogen…