What may be released when using a fire extinguisher that could be hazardous?

When using a fire extinguisher, particularly those that contain chemicals such as halon or carbon dioxide, a chemical that causes oxygen displacement can be released. This occurs because these types of extinguishing agents work by displacing the oxygen in the vicinity of the fire, depriving it of the oxygen it needs to continue burning. While effective in putting out fires, this displacement can lead to a hazardous environment, particularly in enclosed spaces, as it can cause suffocation or lead to unconsciousness if oxygen levels drop significantly.

The other options, while they may present risks in certain contexts, do not specifically pertain to the use of fire extinguishers in the same way. For instance, burning residue is a result of combustion rather than the extinguishing process. Extremely high temperatures can occur during a fire or after a fire is extinguished, but they are not a byproduct of the extinguishing agent itself. Toxic smoke is primarily a concern during active combustion rather than as a direct consequence of using a fire extinguisher.