If air monitoring indicates that the oxygen level in the atmosphere is below 19.5 percent:

• A. The IC or Incident Safety Officer should be notified.
• B. The team should proceed as planned.
• C. Ventilation is not necessary.
• D. Ignore the reading.

Answer: (A)

Air that is oxygen-deficient (below 19.5 percent) is a hazardous environment because not enough oxygen can impair thinking, coordination, and survival. In SAR operations, decisions about hazardous atmospheres are made by the incident command and the Incident Safety Officer, who are responsible for implementing controls to keep responders safe. Notifying the IC or ISO right away allows them to stop entry, evaluate options, and arrange proper ventilation or respiratory protection before anyone proceeds. Moving forward as planned or ignoring the reading would expose the team to serious risk, and ventilation or other mitigations should only be carried out under authorized safety management. So, the best immediate action is to alert the IC or ISO.