The Illinois State Fire Marshal is reminding residents to make sure their carbon monoxide detectors are in good working order and to replace alarms that are more than three years old.

"People may believe that a beep coming out of their CO alarm means it's time for a battery change, when in fact it means the device needs to be replaced," said Illinois State Fire Marshal Larry Matkaitis. "The replacement of a dead carbon monoxide alarm is a life saver."

Since January 2007, Illinois law requires homes with an attached garage and/or fossil fuel burning capabilities to have properly placed and functioning CO alarms. The alarms must have battery power as the primary or secondary power supply. They cannot be powered solely by electricity.

The state fire marshal recommends any household with carbon monoxide detectors that have been installed for more than three years replace them and reminds consumers that alarms manufactured before August 2009 may not have had the end-of-life beeping feature.

Carbon monoxide is the number one cause of poisoning death in the United States, with about 300 people dying from carbon monoxide poisoning every year, according to the National Fire Protection Association. The colorless, odorless, tasteless gas can be produced by gas or oil appliances such as furnaces, clothes dryers, water heaters, ovens, space heaters, fireplaces and wood burning stoves.

More information about carbon monoxide poisoning can be found at www.sfm.illinois.gov or at the website of the National Fire Protection Association at www.nfpa.org.