When should a Level A suit be used?

A Level A suit should be used when there is a high risk of exposure to vapors, gases, or harmful materials that necessitate full-body protection. This type of suit provides the highest level of protection against hazardous substances, including those that are toxic and can be absorbed through the skin or inhaled.

The design of a Level A suit includes a vapor-tight enclosure, which ensures that no harmful chemical agents can penetrate the suit and impact the wearer. It is equipped with a self-contained breathing apparatus (SCBA) to protect against inhalation hazards, making it suitable for environments where there are significant risks of exposure to very hazardous contaminants.

In situations where there is uncertain or known presence of highly toxic materials, the complete physical barrier and respirator combination provided by Level A suits is crucial for ensuring the safety of personnel who need to operate in such an environment. This is why Level A suits are essential for dealing with scenarios that involve potentially dangerous exposures, which aligns perfectly with option C's description.