Posted Friday, November 16, 2012 - 8:00 a.m.

MADISON, Wis. (AP) -- With temperatures starting to dip, Wisconsin safety officials remind residents to protect their families from carbon-monoxide risks.

The Centers for Disease Control and Prevention says carbon monoxide is the leading cause of accidental poisoning deaths in the U.S. Nearly half of those deaths happen during the winter.

Carbon monoxide is an invisible, odorless gas that can be emitted from aging or unvented furnaces or other gas-powered home appliances. Exposure can cause headaches, dizziness or nausea, and can be fatal to people who are sleeping.

The Wisconsin Department of Health Services says state law requires that every house have a carbon-monoxide detector in the basement and on every floor. Health officials remind residents to test their detectors regularly, change the batteries annually and make sure all heating appliances are well-vented.

Copyright 2012: Associated Press