Which PPE level provides the highest level of protection for unknown hazardous substances?

• A. Level A
• B. Level B
• C. Level C
• D. Level D

Answer: (A)

Unknown hazards call for the highest level of protection to prevent both skin contact and inhalation of unknown substances. The best choice is a fully encapsulating chemical protective suit with a self-contained breathing apparatus. This setup seals the wearer from head to toe, including the hands and feet, and provides an independent air supply, so vapors or liquids cannot reach the skin or be breathed, even when you don’t know what the substance is. The full encapsulation minimizes the chance of dermal absorption and inhalation, which is crucial when the exact chemical, concentration, or potential reactions are not known.

Other levels offer good protection, but they don’t cover all bases as comprehensively. A non-encapsulating ensemble with a breathing apparatus still leaves gaps that vapors or splashes could penetrate, and air-purifying respirators depend on the contaminant being known and present in safe concentrations. Levels with minimal or no respiratory protection are inadequate for unknown hazards, since there’s no guarantee the air is safe to breathe.