SALT LAKE CITY -- Utah's Poison Control Center has now issued a reminder about the dangers of a killer usually associated with winter. It comes on the heels of a tragic summer weekend.

"If you're asleep, you may never know you've got carbon monoxide," said Kathy Chambers, with the Salt Lake Valley Health Department.

That's likely what happened to a young girl and a man from Colorado who were discovered dead after sleeping in a tent at a Utah campsite. They slept next to a propane tank hooked to a heater.

"They thought this is a good way to stay warm, so they used it. And you may think in a tent [it] isn't air tight, but they are," Chambers said.

A man and his grandson barely escaped the same outcome at Fish Lake. They'd put a cover on the boat to stay dry and unintentionally trapped exhaust fumes. The man passed out.

"Even a single exposure can cause permanent brain damage," said Dr. Lindell Weaver, medical director for hyperbaric medicine at Intermountain Medical Center. "The best treatment is prevention."

It's a warning doctors and safety advocates have issued so Utahns will be mindful of carbon monoxide risks all year round. They urge people to:

• Install CO detectors on boats, houseboats and RVs.
• Stay away from the engine exhaust areas of boats. CO from boat motors is much more concentrated because catalytic converters aren't required. Concentrations behind a houseboat, for example, can be lethal within seconds.
• Recognize the symptoms of CO poisoning: headache, nausea, dizziness or loss of consciousness.

"First thing you need to do is get out the area, the confined space where you're having the symptoms, and get into fresh air," Chambers said.

CLICK HERE for more information on CO safety in the summer months.

CLICK HERE for CO safety tips specific to the use of portable generators.

E-mail: dwimmer@ksl.com