This week, residents in the Northeast and Midwest are digging out of a major snow storm. Last week, temperatures plunged below minus 54 in northern Minnesota, and Florida citrus farmers coped with frozen orange groves.

As the temperature falls, the dangers of heating homes with space heaters grows. Consider these examples:

On Jan. 5, a home in Omaha, Neb., caught fire after the residents put a space heater in the living room and placed it too close to a couch, according to the residents. Everyone got out safely, KETV NewsWatch 7 reported.

A Jan. 14 fire in a two-story home in Milford, Del., caused $40,000 in damage. The state fire marshal believes an overloaded circuit serving an electric space heater caused the fire, according to WBAL-TV 11.

Toledo fire officials said two people died in a Jan. 16 house fire on the city's east side. An arson investigator believes a space heater caused the fire at the two-story home.

An elderly man died Jan. 17 in a fire in his trailer home in Albany, Ga. Fire investigators think a space heater might have caught the bed on fire in the trailer.

A trailer at the Fern Park, Fla., Mobile Home Park was destroyed in an early-morning fire Jan 17. WESH NewsChannel 2 reported that a teenage couple and their baby had to be rescued after their space heater started the blaze, investigators said.

In Louisville, Ky., firefighters continue to see fires on frigid days like because of space and kerosene heaters, wood stoves, dirty chimneys and even kitchen appliances that people are using to heat their homes, WLKY NewsChannel 32 reported.

Does this mean space heaters are dangerous? Not when they are used in the way manufacturers intend. But, firefighters report that thedevices are often used inappropriately.

"Supplemental heating things ... account for two out of three fires when heating equipment is used," said Okolona, Ky., Fire chief Rich Carlson.

The U.S. Consumer Product Safety Commission estimates that more than 25,000 residential fires every year are associated with the use of space heaters. More than 300 people die in these fires, and an estimated 6,000 people have to be taken to hospital emergency rooms for burn injuries.

Added Warmth

Space heaters are powered by electricity, kerosene or natural gas. A lot of people buy them as their primary heating source, "and they're not manufactured for that purpose," said Lt. John Thomas, of the Lancaster, Pa., Fire Department in an interview last winter with WGAL-TV.

After one nasty two-day cold snap last winter, a Home Depot store in Lancaster, Pa., sold twice as many electric space heaters as they did the entire week before. One customer said he had 10 space heaters in his home and was buying more to heat a friend's house.

"A lot of (people) are concerned. They're looking for something that's going to be more efficient than the traditional central air or kerosene heat and stuff like that," Home Depot's Mike Creegan told WGAL News 8.

The good news about space heaters is that they are very heat efficient, meaning that the heat they generate in a room stays in the room. Most well-maintained gas or oil burning furnaces lose at least some of their heat output as the warm air travels through the heating system and building.

The bad news is that while electric space heaters may save a lot of money on home heating oil or natural gas, they run off electricity, which can be the most expensive way to heat a home.

Still, savings are possible.

"Where the savings come in is if people lower the temperature in their home and then spot-heat the kitchen, bedroom or study with a space heater. Then, they can save some money," said Robert Iosue, who works for an energy company in Lancaster.

Many of today's space heaters have improved safety features over earlier models. Many are enclosed units that will shut off if they are tipped over or get too hot.

Electric heaters have been recalled by the CPSC because internal wiring can overheat, causing a fire or electrocution. That's what prompted a 2003 CPSC recall on 2,400 Weather Works Ventilaire Electric Heaters, for example

In Lancaster, kerosene space heaters are not allowed in buildings, both because of the fire hazards, and because of the potential for carbon monoxide poisoning.

Silent Killer

The dangers of space heaters are not limited to fire.

During a recent power outage in Jay, N.Y., when temperatures outside plunged well below zero, officials teamed up with the Red Cross to open a shelter at the town's community center. Officials there told WPTZ NewsChannel 5 that the cold weather may sometimes prompt people to try and stay warm using unsafe means.

"Back during the ice storm, we had numerous fatalities from people using generators inside or using stoves -- anything that throws off carbon monoxide," said Randy Douglas, Jay's town manager. Center

"I know a lot of people, including the elderly, don't like to leave their homes," said Lucy Wood, a Red Cross volunteer. "They think they're safe, but when the weather is this cold, they're not."

A Polk County, Fla. couple tried to stay warm during a power outage over a cold weekend at Christmas last year, but they were instead apparently poisoned by carbon monoxide, WESH NewsChannel 2 reported. A space heater was not the culprit this time – a gas-powered generator was running in the garage near the kitchen door. But the lesson is clear: Along with fire hazards, there's a hidden danger in carbon monoxide poisoning.

Carbon monoxide, or CO, is a flammable, colorless, odorless, tasteless toxic gas produced during incomplete combustion of fuel, including kerosene used in space heaters. It is the leading cause of accidental poisoning deaths in America, according to the Journal of the American Medical Association.

About 1,500 people die annually due to accidental carbon monoxide exposure, and an additional 10,000 seek medical attention. (Medical experts agree that it's difficult to estimate the total number of carbon monoxide incidents because the symptoms of carbon monoxide poisoning resemble so many other common ailments.)

CO gets into a home by sources other than space heaters, too. Any fuel-burning appliance, furnace, water heater, fireplace or woodstove can generate CO. Warming up vehicles in an attached garage, even with the garage door opened, can allow concentrated amounts of CO to enter your home through the car port door or nearby windows. Wind can also blow fumes back into the garage, and temperature differences between the indoors and outside can move CO back into your house or garage.

The gas is dangerous because it inhibits the blood's capacity to carry oxygen. In human lungs, it quickly passes into our bloodstream and attaches itself to hemoglobin, the oxygen carrying pigment in red blood cells. Once there, it replaces oxygen in the bloodstream, cutting off the needed oxygen to our organs and cells, causing various amounts of damage.

Low levels of carbon monoxide poisoning result in symptoms commonly mistaken for common flu and cold symptoms -- shortness of breath on mild exertion, mild headaches and nausea.

With higher levels of poisoning, the symptoms become more severe -- dizziness, mental confusion, severe headaches, nausea and fainting on mild exertion.

At high levels, a poisoning victim may become unconscious and die.

Avoiding Fuel Hazards

Anyone using a kerosene or propane heater in a home should buy and install a carbon monoxide detector.

Have gas and kerosene space heaters inspected annually by qualified technicians to ensure that they are properly adjusted and clean.

Keep the wick of the kerosene heater clean and properly adjusted. Appliances that are not working properly can release harmful and even fatal amounts of pollutants.

Be certain the heater is placed on a level, hard and nonflammable surface, not on rugs or carpets.

Keep the heater in a safe working condition. Replace missing guards and controls at once. Never operate a defective heater. Have all necessary repairs done by a qualified technician.

Never use gasoline in a kerosene heater. Even very small quantities of gasoline in the heater tank can cause a fire.

Kerosene should never be stored or carried in a container that has had gasoline because the residual gasoline is enough to increase the flammability of the kerosene.

Only use 1-K kerosene in kerosene heaters. Kerosene should be purchased from a dealer who can certify that it is 1-K grade kerosene. The fact that kerosene is “water clear” does not ensure that it is 1-K, since both 1-K and 2-K can appear clear.

CSPC has a more extensive set of kerosene tips here.

Avoiding Electric Hazards

Electric space heaters are the biggest sellers.

Use heaters on the floor. Never place heaters on furniture, since they may fall, dislodging or breaking parts in the heater, which could result in a fire or shock hazard.

Do not use heaters in wet or moist places, such as bathrooms; corrosion or other damage to parts in the heater may lead to a fire or shock hazard.

Do not hide cords under rugs or carpets. Placing anything on top of the cord could cause the cord to overheat, and can cause a fire.

Do not use an extension cord unless absolutely necessary. Using a light-duty, household extension cord with high-wattage appliances can start a fire. If you must use an extension cord, it must be marked #14 or #12 A WG; this tells the thickness or gauge of the wire in the cord. (The smaller the number, the greater the thickness of the wire.)

Be sure the plug fits snugly in the outlet, because a loose plug can overheat. Have a qualified repairman replace the worn-out plug or outlet. If the plug feels hot, unplug the heater and have a qualified technician check for problems. If the heater and its plug are found to be working properly, have the outlet replaced. Using a heater with a hot cord or plug could start a fire.

Broken heaters should be checked and repaired by a qualified appliance service center. Do not attempt to repair, adjust or replace parts in the heater yourself.

CSPC has a more extensive set of kerosene tips here.