Tucson, AZ- IRENE HSIAO, Tucson Citizen

Get air.

And a carbon monoxide detector.

Frosty temperatures are pressing more furnaces into service, and with them comes the threat of carbon monoxide poisoning.

A scare yesterday at Sonora Behavioral Health Hospital, 6050 N. Corona Road, prompted fire officials to warn the public about the deadly gas, a product of combustion. Carbon monoxide is suspected in the death of a 27-year-old father and his infant son last week in Nogales.

Furnaces or other appliances that aren’t completely burning their fuel produce the gas. So do fireplaces, nonelectric stoves, internal combustion engines and candles. Poor ventilation allows carbon monoxide to build up.

The danger is often highest at night, when heaters are in use and people are asleep.

“Nobody knows it’s present until it’s too late,” said Capt. Adam Goldberg, a Northwest Fire/Rescue District spokesman.

Firefighters evaluated 17 people yesterday morning at Sonora Behavioral Health, where a staff member and a patient complained of nausea and reported the smell of natural gas.

Fourteen were taken to nearby Northwest Medical Center; none was admitted. Firefighters were not able to determine what caused their symptoms.

The smell of natural gas comes from an additive that produces a rotten-egg aroma. Carbon monoxide is produced when such gas or other fuels are incompletely burned. It has no odor.

Poisoning symptoms can include vomiting, weakness, dizziness, trouble seeing, lethargy and unconsciousness, Goldberg said. The immediate remedy: fresh air.

Detectors cost about to $30 to $50. Annual furnace inspections are recommended.