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816 Confined Space Safety in Construction
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Hazardous Atmospheres

A hazardous atmosphere affects the air in the space and can cause death or acute illness, or impair the ability of workers to escape.

Safety Brief: Hazardous Atmospheres

Hazardous atmospheres include:

  • Corrosive atmospheres: Corrosive atmospheres accumulate from some manufacturing processes and biological or chemical reactions. Some cause immediate damage to the skin and eyes; some have no immediate effect, but cause cancer with prolonged exposure.
  • Flammable or explosive gasses, liquids, vapors, mists, fibers, or dusts: Flammable gases such as acetylene, butane, propane, hydrogen, and methane are common in permit spaces. Grain, nitrated fertilizers, and ground chemicals can produce combustible dusts.
  • Air or oxygen displacement: Some substances (such as inerting gasses) can displace air or oxygen in a confined space; examples include nitrogen, helium, steam, Freon, argon, and carbon dioxide.

Knowledge Check Choose the best answer for the question.

1-4. What is a characteristic of a hazardous atmosphere?