MISSISSIPPI STATE -- A chill in the air often makes its way into homes and offices, prompting the use of a potentially dangerous heat source.

Herb Willcutt, a safety specialist with Mississippi State University's Extension Service, said portable space heaters are safe when used properly. Incorrect use can cause damage to homes and offices, or even deadly fires.

"The biggest safety concern with any temporary heat source, whether it be electric, gas or others, is operating them in close proximity to combustible materials like furniture, draperies, newspapers and other household or office items," Willcutt said. "All heaters have a recommended clearance between the heater and any combustible item. Those recommendations always should be followed, with no exceptions."

Willcutt also emphasized that space heaters are meant to provide temporary, not permanent, heat. Using space heaters as a source of permanent heat increases the risk of fires.

"Never leave a temporary heat source unattended. If you're going to leave your home for any period of time, turn it off," Willcutt said. "By all means, do not go to sleep with it on in a bedroom or anywhere else in the home."

Mississippi's State Chief Deputy Fire Marshal Millard D. Mackey said space heaters should not be used with extension cords because they can overheat and start a fire. Mackey also stressed the importance of following the instructions that come with a space heater.

"The units themselves are not that dangerous if they are used in accordance with the manufacturer's instructions. They can be used safely as a temporary source of heat," Mackey said. "Those instructions usually are located not only in the operator's manual, but also on the heating unit itself."

Mackey said he has investigated fires that resulted from space heaters being left plugged into office walls overnight.

"A lot of times, people will turn the thermostat about halfway up so it comes on in the morning. During the day, they'll turn it down but not off. In the middle of the night, the thing comes back on and something is set on fire," Mackey said. "This situation could be avoided if the unit was used correctly: it shouldn't be left plugged in and it shouldn't be left near combustible materials, such as under a desk."

The U.S. Consumer Product Safety Commission offers several tips for selection, safe use and maintenance of gas, wood, kerosene and electric space heaters. Select a space heater with a guard around the flame area or heating element and one that is the correct size for the intended area of use. Look for a heater that has been tested and certified by a nationally recognized testing laboratory.

Keep doors open to the rest of the house when using an unvented, fuel-burning space heater. This helps to prevent pollutant buildup and promotes proper combustion.

"When using any kind of heat source, it's a good idea to have working smoke alarms and carbon monoxide detectors on each floor of your home and near sleeping areas," Willcutt said. "Keep at least one dry-powder operative, ABC-type fire extinguisher in the home at all times. Also, develop a family fire escape plan before a fire occurs."

Place heaters on level, hard, non-flammable surfaces. Keep heaters in safe working condition, and have necessary repairs done by a qualified person. Never use or store flammable liquids around a space heater.

"Space heaters are a potential source of burns for small children and pets," Willcutt said. "Teach children to stay away from space heaters, and do not allow children to adjust the controls or move space heaters."