What is the minimum number of crew members located outside the IDLH atmosphere required to initially monitor and provide emergency rescue until a larger rapid intervention crew is created?

• A. One
• B. Two
• C. Three
• D. Four

Answer: (B)

In an IDLH environment, there must be a standby rescue capability outside the danger zone to protect interior workers and enable rapid intervention. The minimum arrangement is a dedicated outside monitor plus a second person who is ready to perform emergency rescue if needed. This pairing provides two essential functions at once: ongoing monitoring and communication, and an immediate rescue capability if interior crew members become incapacitated. A single outside person cannot reliably fulfill both roles, so having a second standby rescuer ensures there is always someone ready to act right away while the larger rapid intervention crew is organized. As operations scale, the outside team can be reinforced, but this two-person setup is the smallest capable of maintaining safety and rapid response.