A:Answer Nest Protect Peak CO levels, during CO alarms, range from 70 parts per million (ppm) to 1,964 ppm, with a median of 142 ppm based on field studies. After a CO event, Nest Protect will tell you the highest level of CO that it detected. You can find the peak CO level in Protect History.
Nest Protect is not a low-level carbon monoxide monitor and will alert you to carbon monoxide only in a Heads Up or Emergency Alarm event.