DANVILLE — It’s colorless, odorless and, at the right level, toxic to the people inhaling it. And right now is the exact time residents need to start preparing for it in their homes.

Carbon monoxide is the result of incomplete burning of fuels ranging from wood and coal to kerosene and natural gas. It’s also created by engines, such as vehicles and portable generators.

November already has produced a small spike in the carbon monoxide calls to city firefighters, who have responded to four calls in the first two weeks, with three coming just during the weekend. A total of six checks for the gas were reported in the entire month of October.

Fire Deputy Director Bobby Lillard said the department sees more calls during this time of year as people begin to turn on their furnaces because of dropping seasonal temperatures.

Furnaces can sometimes be the source of the gas, as was the case during the weekend. Frank Wright of Wright’s Heating and Air said his company was called to one of the homes reporting carbon monoxide. The family left its home for the night and stayed in a hotel while their furnace was taken care of.

“They were blessed,” he said. “Carbon monoxide can lead to death.”

Wright said the furnace did not need repair and only required a simple task to allow the family to return home again.

“It was a problem that a simple cleaning check would have taken care of,” he said.

Many people are calling companies for furnace checks this time of year, with Wright saying 12-13 hour days are the norm up until the week before Christmas as people wait until for temperatures to turn pretty cold before looking to their furnace for warmth.

Lillard said getting your furnace checked is important, as well has having a carbon monoxide detector in your home. The devices are similar to a smoke detector and send up an alarm when detecting a certain level of carbon monoxide.

The fire department carries monitors with it to carbon monoxide calls and begins looking for a source for the gas if levels are detected at 20 parts per million, Lillard said. Furnaces, and stoves, are often the first to be checked, but it’s not always an easy search.

“We had one case where we couldn’t find it at all,” he said. “Later we found out there was an attached garage. (The homeowners) were idling their car in there and it was circulating through the house system.”

Other times, Lillard said detectors simply need a new battery or have dust collecting inside.

A 2007 law states that detectors must be placed within 15 feet of each room used for sleeping in a home, Lillard said.

Initial symptoms of exposure to carbon monoxide are similar to the flu, but without a fever. Those include nausea, headaches, fatigue and shortness of breath. Higher gas levels can cause mental confusion, vomiting, loss of muscular coordination and, finally, death.

Carbon monoxide is the leading cause of poisoning deaths in the nation, with more than 500 attributed to the gas each year.

SAFETY TIPS

There are several ways to cut the possibility of carbon monoxide danger in your home, including:

--Have the heating system professionally inspected and serviced annually to ensure proper operation. The inspector also should check chimneys and flues for blockages, corrosion, partial and complete disconnections and loose connections.

--Never leave a car running in an attached garage, even with the garage door open.

--Never operate a portable generator or any other gasoline engine-powered tool either in or near an enclosed space such as a garage, house, or other building. Even with open doors and windows, these spaces can trap CO and allow it to quickly build to lethal levels.

--Install a CO alarm in the hallway near every separate sleeping area of the home. Make sure the alarm cannot be covered up by furniture or draperies.