Each year portable space heaters cause an estimated 1,700 home fires, 180 injuries, and 70 deaths, according to the U.S. Consumer Product Safety Commission. Does that mean they’re unsafe. It depends on the heater and how you use it.

Propane and kerosene heaters create the most heat but because of their open flames, higher surface temperatures, and the carbon monoxide and carbon dioxide released, shouldn’t be used indoors, except during a power outage. Even then the heater must be used with caution and placed in the center of a well-ventilated room equipped with battery-powered CO and smoke alarms.

Portable electric space heaters are the top selling type by far, and while they don’t pose air quality concerns, burns and fires are potential hazards. The models in our space heater Ratings have a sensor that shuts them off if they overheat. Some also have tip-over switches, hot-surface alerts, timers and remote controls. Here’s our advice on using a portable electric space heater:

• Look for the safety-certification label, such as the UL mark from Underwriters Laboratories, the ETL label from Intertek, or certification from CSA International.
  
• Check the power cord for cracks, fraying, loose connections, and broken plugs; repair or replace the heater if you find any damage. Most manufacturers do not recommend using extension cords.
  
• Place the heater on a level surface—not where kids and pets can reach it. And don’t leave the heater running unattended or while you’re sleeping.
  
• Keep flammable items such as furniture and curtains at least three feet from the heater.