UNDERWRITERS LABORATORIES INC. UL2034
WHAT LEVELS OF CO CAUSE AN ALARM?
Underwriters Laboratories Inc. Standard UL2034 requires residential CO Alarms to sound when exposed to levels of CO and exposure times as described below. They are measured in parts per million (ppm) of CO over time (in minutes). UL2034 Required Alarm Points*:
Note* Approximately 10% COHb exposure at levels of 10% to 95% Relative Humidity (RH). The unit is designed not to alarm when exposed to a constant level of 30 ppm for 30 days.
IMPORTANT!
CO Alarms are designed to alarm before there is an immediate life threat. Since you cannot see or smell CO, never assume it’s not present.