Why didn't the emergency responder find CO gas after an alarm?

If your carbon monoxide alarm went off, it detected a dangerous level of CO gas. Here are some reasons why a responder may not find CO during an investigation:

  1. Carbon monoxide gas dissipated in fresh air. If windows and doors open before a responder arrived, the same concentration of CO gas may no longer be present. Be safe first and vent dangerous carbon monoxide gas to the outside. The responder can try to recreate the conditions.
  2. The alarm may have been caused by an on-again, off-again problem. CO alarms measure gas exposure over time, so the exact conditions that cause an alarm may be difficult to duplicate in an investigation.