Oxygen Displacement

Oxygen deficiency can also happen when oxygen is displaced or replaced by other gases in the confined space. This can happen when:

• Another gas accumulates at the bottom of a space because it is heavier than normal air. For example, hydrogen sulfide will sink to the bottom of a tank and form an unbreathable layer.
• Inert gases are used to purge or clean a space. An inert gas is one that does not react with other materials at normal temperature and air pressure. While inert gases are nontoxic and nonflammable, they can displace oxygen so that there is not enough breathable oxygen present in the air.

To learn more about Firefighter Confined Space visit our Firefighter Confined Space Entry & Rescue Online Training web page.