OMAHA, Neb. (AP) — Experts at the Nebraska Regional Poison Center are reminding people about the dangers of carbon monoxide.

The odorless and colorless gas is produced when fuels don’t burn completely in furnaces. Carbon monoxide exposure can be fatal.

There are more than 400 deaths and 15,000 emergency room visits every year in the United States because of carbon monoxide. Problems are more common during the winter months.

The symptoms include sleepiness, headaches, dizziness and blurred vision.

The Poison Center recommends that everyone keep carbon monoxide detectors on every level of their homes. And make sure to inspect furnaces and other fuel-burning equipment annually.