What is the CL2 IDHL value?

• A. 5 ppm
• B. 15 ppm
• C. 20 ppm
• D. 10 ppm

Answer: (D)

Understanding the exposure threshold that signals immediate danger is key. IDLH stands for Immediately Dangerous to Life or Health, and it marks the concentration where breathing the atmosphere could cause death or severe health effects in a short time, guiding respirator selection and emergency response.

For chlorine gas, that life-threatening threshold is 10 ppm. So the correct value is 10 ppm. The other numbers are not the IDLH for chlorine; they may be other exposure references or simply not the standard IDLH value. 5 ppm is below the dangerous threshold, while 15 or 20 ppm exceed it, but the official IDLH concentration defined for chlorine gas is 10 ppm.