While a bird nesting in a chimney flue might sound like a cozy arrangement for the summer, the blockage could be deadly when the fireplace below is used.

Carbon monoxide, produced when wood and fossil fuels burn, can start accumulating. Residents breathing the poisoned air might develop headaches and feel sick. Eventually, they might fall unconscious and even die.

Blockages and malfunctioning heating equipment are common reasons for problems with the gas that it often noted for being both colorless and odorless, according to Pat McJunkin, a Casper Fire-EMS spokesman.

With winter approaching and one Natrona County family narrowly avoiding the worst outcome of carbon monoxide exposure only a week ago, officials say it is a good time to have heating systems inspected and to consider purchasing a home carbon monoxide detector.

A local family's unpleasant brush with carbon monoxide came on Sept. 22. Deputy Shane Rinker was called that morning to a home on Salt Creek Highway to assist with a medical problem. After arriving, according to reports, Rinker noted a strange smell and watched as family members started collapsing.

Rinker immediately started to evacuate the family of four from the house.

Sheriff Mark Benton said Rinker will receive formal recognition for his work that day.

"He did a great job," Benton said. "We're really happy nobody died."

The odor Rinker noted in the Salt Creek Highway home is difficult to explain. While other gases with detectable smells could be released by a malfunctioning appliance, carbon monoxide is said to be odorless.

McJunkin, said his department is called to check for dangerous levels of carbon monoxide a handful of times a year. The most common time for such calls, he said, is in the early fall as people start heating their homes for the first time in months.

To stay safe, McJunkin suggests installing carbon monoxide detectors and having heating systems checked each year.

Bird nests are only one of the ways flues can become blocked, he said, and such blockages can be difficult to detect.

Another winter danger comes from the temptation to warm cars in a sealed garage. If a car must be left running, McJunkin advised, leave it in a well ventilated area.

Reporter Anthony Lane can be reached at (307) 266-0593 or at anthony.lane@casperstartribune.net.