OKLAHOMA CITY - As the temperature drops, a hazard associated with the cold weather may be on the rise in your home.
In fact, 500 deaths occur in the United States every year from carbon monoxide poisoning, often from leaks in heating units.
Carbon monoxide is a toxic gas that is colorless and odorless.
It suffocates victims by depleting them of oxygen, which can happen in less than an hour.
Experts at Hill & Company say inside your furnace, the problem often begins in "heat exchangers."
They're hot pieces of metal that warm the air before it's circulated in your home.
If those heat exchangers become rusty or cracked, they can leak carbon monoxide.
Another problem is that roofers can accidentally cover up heating vents with shingles, pumping carbon monoxide back into your home.
Hill & Company workers say they remember testing levels at one family's home where they thought the cold weather was making them sick.
"When I put my detector in one of the floor vents, it was 198 parts per million and still climbing," said Dennis Martin, a consultant with Hill & Company. "400 parts per million is death within two hours. So they were halfway to dead and they thought they had the flu."
He recommends having several carbon monoxide detectors that have fresh batteries at all times.
An annual maintenance check on a furnace costs anywhere from $59 to $79, which can also buy peace of mind.