When responders suspect a hazardous unknown liquid could be TIH, which PPE option best reflects standard practice?

• A. Level A PPE provides maximum protection for unknown TIH.
• B. Level B PPE provides maximum protection for unknown TIH.
• C. Level C PPE provides maximum protection for unknown TIH.
• D. Level A or Level B PPE is used when unknown TIH is suspected.

Answer: (D)

When you suspect a hazardous unknown liquid could be TIH, the priority is to prevent inhalation exposure and protect the skin while you assess the scene. Unknown TIH means you can’t safely assume the level of hazard, so you choose the highest or near-highest level of protection available. Level A PPE offers the most protection: a fully encapsulated suit with a labeled self-contained breathing apparatus (SCBA) and complete skin protection, which minimizes both inhalation and contact risks. Level B PPE also provides strong protection, with an SCBA and a splash-protective suit, but it isn’t fully encapsulated, giving you high inhalation protection plus significant skin protection while allowing more mobility. In practice, responders select Level A or Level B based on the scene assessment, the concentration and volatility of the unknown TIH, and the need for mobility versus maximum protection. Level C PPE, which uses air-purifying respirators, would not be appropriate here because unknown TIH hazards could be inhaled at dangerous concentrations, and the protection wouldn’t guarantee safety.