Even though carbon monoxide alarms may meet the U.L. 2034 listing standard they are not all equal in sensor quality or performance.

Acid based electrochemical sensors have the highest degree of performance and accuracy. Households should have at least one of these in place. 

U.L. 2034 standards do not require alarming to levels less than 70 parts per million of carbon monoxide; PLEASE READ THE INSTRUCTIONS AND INFORMATION ON EACH PACKAGE WHEN PURCHASING. They do not meet OSHA workplace compliance standards. 

If the concentration in the air is over 70 ppm and under 150 ppm of CO the device is supposed to alarm between 60 and 240 minutes. If the concentration drops below 70 PPM within that period the time starts over again. 

Specifically written on the outside of the package it states:

• At 70 PPM, unit must alarm within 60-240 min.
• At 150 PPM, unit must alarm within 10-50 min.
• At 400 PPM, unit must alarm within 4-15 min.

An additional small print WARNING suggests that people of vulnerable health should use a more sensitive and accurate alarm. COSA describes these people to include: Pregnant women, infants and people with heart or respiratory complications.

Ask your medical physician or practitioner to test you for carbon monoxide if you think you may have been exposed or have symptoms associated with the poisoning. 

The test button only lets you know that when you depress it and the audible sound is heard that the electrical connection to the alarm works NOT that the sensor works.