Smoke alarms are one of the best ways to protect loved ones. Nearly two-thirds of deaths from home fires happen where there are no working smoke alarms, according to the National Fire Protection Association.

Not all smoke alarms are created equal, though. At UL, samples of smoke alarms are tested to determine whether they meet national standards. When you find the UL Mark on a particular model, it tells you that representative samples of a smoke alarm have been evaluated by UL and have met safety requirements. UL then conducts proper follow-up evaluations.

The two main types of smoke alarms work off of two different scientific principles. Ionization models are best suited for rooms that contain highly combustible materials that can create flaming fires, while photoelectric models are best suited for detecting smoldering fires. UL tests ionization and photoelectric models both to the same standard, but since you can’t predict what type of fire might happen, installing both types of alarms in your home can enhance your family’s safety.

For example, you might choose ionization models for rooms that store flammable liquids, newspapers, and paint-cleaning solutions, while mounting photoelectric models in or near living rooms, bedrooms and kitchens, which often contain large pieces of slow-burning furniture, such as sofas, mattresses and counters. Some manufacturers also make dual-sensor units that use both technologies.

What else can you do to make sure you’re protecting your home and family from fire?

  • Have a smoke alarm on each floor of the house and in all sleeping areas. Alarms should be properly mounted high on the wall or on the ceiling, since smoke rises. If someone in the house is deaf or hard of hearing, look for alarms that combine lights or vibrations with the audible alarm.
  • Consider interconnected smoke alarms, with units in several areas of the home to alert people throughout the house, no matter where a fire starts.
  • Look for carbon monoxide (CO) alarms included in some smoke alarms. This additional equipment can signal if dangerous CO is building up from a malfunctioning space heater or water heater, for example.
  • Test and maintain your smoke alarms at least once a month unless otherwise noted by manufacturer instructions. Smoke alarms most often fail because of missing, dead or disconnected batteries. Replace the batteries when you change your clocks to and from daylight-saving time.