A colorless, odorless and potentially deadly threat could be lurking in Amador County homes: carbon monoxide gas.

According to the U.S. Environmental Protection Agency, carbon monoxide, or CO, is formed when carbon in fuel such as gas, oil, kerosene, wood or charcoal is not burned completely.

"Hundreds of people die accidentally every year from CO poisoning caused by malfunctioning or improperly used fuel-burning appliances," said an EPA article titled, "Protect Your Family and Yourself from Carbon Monoxide Poisoning." Even more people die from CO poisoning caused by idling cars.

According to the federal Occupational Safety and Health Administration, inhalation of CO is harmful because it displaces oxygen in the blood.

"Large amounts of CO can overcome you in minutes without warning - causing you to lose consciousness and suffocate," said an OSHA fact sheet.

Initial symptoms of CO poisoning include tightening across the chest, headache, fatigue, dizziness, drowsiness and nausea, the fact sheet said. Prolonged exposure causes symptoms to worsen to the point of vomiting, confusion, collapse and muscle weakness.

The EPA advises that such symptoms should not be ignored, particularly if more than one person is experiencing them.

"You could lose consciousness and die if you do nothing," the EPA article said.

Fire Captain Terry East of the Sutter Hill CAL FIRE (formerly the California Department of Forestry and Fire Protection) station said although he has responded to only a few CO poisoning calls over the past few years, he has seen an increase in news stories on the topic during recent weeks.

"A couple days ago, some people were poisoned when they used a generator in their home for electricity," he said.

According to East, most of the CO poisoning cases he's seen have been caused by residential heating units. He cited improper use of equipment - as with the aforementioned case involving a generator - as another common cause of CO poisoning.

East said carbon monoxide poisoning has become less of an issue in recent years due to better detection technology and the improvement of building requirements and standards.

"We don't get a lot of calls on it, especially with all the detectors around these days, which are fairly cheap," he said.

The CAL FIRE Amador-El Dorado Unit issued a news release March 6 reminding people to check their smoke alarms and CO detectors.

"You should be doing this at least once a year and the U.S. Consumer Product Safety Commission usually recommends you do so when you reset your clocks, either when we spring forward to Daylight Saving Time or in the fall, when we revert to standard time zones," the release said. "So, if you didn't check these essential household protection devices over the weekend, take time to do so this week."

CAL FIRE recommends replacing detector batteries yearly and testing detectors to make sure they are working once a month. "And you should make sure there's an alarm on every level of your home, outside each sleeping area and inside each bedroom," the release said.

The age of CO and smoke detectors can also have an effect upon their performance.

"Some manufacturers recommend you replace smoke alarms every 10 years and CO alarms every five," the release said. "Their sensors can degrade from age and environmental contamination."

Tobie Edmonds, a public information officer for CAL FIRE, said anyone who has a propane or kerosene heater in their home should have a CO detector.

"Most companies who install those appliances usually include a CO detector in that purchase," he added.

But, warned the EPA, do not rely entirely on CO detectors.

"Carbon monoxide detectors are widely available in stores and you may want to consider buying one as a back-up - but not as a replacement - for proper use and maintenance of your fuel-burning appliances," the article said.

The EPA recommends purchasing detectors that have been certified by Underwriters Laboratories.

So how can county residents prevent CO poisoning? "Use CO alarm systems and do yearly maintenance and inspection on furnaces and heating systems," East said. "Older systems should be checked out more thoroughly and more often."

For more information on how to reduce the risk of CO poisoning, call the EPA at (800) 438-4318 or the Consumer Product Safety Commission at (800) 638-2772.