We recommend choosing CO2 alarms that have the most accurate sensing technology available. CO2 alarms are designed to alert you when carbon monoxide levels have begun to accumulate over a period of time, and will sound before most people would experience any CO poisoning symptoms. The more accurate the alarm, the greater chance you and your family have of responding appropriately to the problem.

Below are key factors to look for when purchasing a CO2 alarm.

Electrochemical sensor: Alarms with electrochemical sensors are more stable during humidity and temperature changes and resist reacting to common household chemicals that may cause false readings.

End-of-life warning: This feature alerts consumers when it's time to replace the alarm.

UL or CSA Listed: CO2 alarms should meet the strict third-party standards set by Underwriters Laboratories (UL) or Canadian Standards Association (CSA). A UL Listed or CSA Listed label should be printed on the product's packaging.

Also, be sure to consider these major features:

Accuracy: Look for a statement on the package about the alarm's accuracy level. If the CO2 alarm is UL Listed, then the accuracy statement will have been certified by UL, too.

Battery-Operated: Consumers who live in areas prone to power outages or who own a gas-powered generator should consider a battery-powered CO2 alarm with a backlit digital display. Battery-powered units offer 24-hour-a-day CO2 monitoring when power is interrupted. The backlit digital display allows the user to view the CO2 level in the dark. The alarm can also be placed on a shelf or wall or moved from room to room.

Digital Display: A digital display screen clearly shows the level of CO2 detected in the home, and updates the reading every 15 seconds.

Peak-Level Memory: This feature records the highest level of CO2 present. Knowing the CO2 level in the home can help emergency personnel determine treatment.

Plug-in with Battery Backup: Easy to plug into any electrical socket, these alarms include a 9V battery for protection during short-term power outages.

Voice Warning: This feature clearly announces the threat present in the home, in addition to emitting the traditional alarm beep. It is often a feature of combination smoke/CO2 alarms.