If every time you accidentally burn dinner the fire alarms in your home blare, chances are you think you’re sufficiently protected from a house or apartment fire. It’s what most consumers believe – that if their fire alarm activates with smoke, they are safe. Sadly, many prove defective in slow-burning fires, the most deadly kind, and do not give adequate time to escape.
You can find a poignant example on YouTube. An ionization fire alarm, a staple in approximately 90 percent of American homes, is placed into a sealed fish tank containing a smoking couch cushion and a carbon monoxide detector. Ionization fire alarms work by detecting invisible particles emitted by combustion called ions. When those ions are detected, like when your toast suddenly burns, the alarm sounds.
But in the demonstration, the ionization alarm never went off in the fish tank, even when the smoke was so thick you could not see through it and the carbon monoxide detector reached its max limit, more than enough to kill a human. However, when the other type of fire alarm, a photoelectric fire alarm, was placed in the tank, it went off within five seconds.
The fish tank demonstrates two important points about ionization smoke detectors. First, many modern product components create fewer ions when burned than the materials once used to build homes or make couch cushions. Second, slow smoldering fires produce ion particles that are usually too large and heavy to rise to where ionization smoke detectors are normally located.
However, photoelectric alarms can detect those particles that are too large and cool for an ionization alarm to detect because they detect smoke rather than ions. When smoke scatters a light beam in the detector, the alarm sounds.
While most homes only have ionization fire alarms to protect them, the National Fire Protection Agency (NFPA) recommends installing both ionization smoke alarms and photoelectric smoke alarms in your home.
“For each type of smoke alarm, the advantage it provides may be critical to life safety in some fire situations,” the NFPA states. “Home fatal fires, day or night, include a large number of smoldering fires and a large number of flaming fires. You cannot predict the type of fire you may have in your home or when it will occur.”
In addition, the U.S. Department of Homeland Security explains smoke and toxic gases from house fires kill more people than flames do, making the photoelectric fire alarm a necessity because, again, ionization fire alarms do not actually detect smoke. In fact, the International Association for Fire Fighters and the World Fire Safety Foundation both recommend the use of photoelectric fire alarms versus using ionization fire alarms or combination fire alarms, which combine elements of the two. Both Vermont and Massachusetts require new builds to contain photoelectric-only fire alarms, and the Ohio Fire Chiefs’ Association endorses photoelectric smoke alarms.
You can tell if your alarm is an ionization fire alarm, which most likely it is, by looking for an indication of radioactive material on the outside or possibly on the inside of the detector if you take it apart. Ionization alarms contain a trace amount of radioactive material to create the current used to detect the small subatomic particles created from combustion.
Why are ionization fire alarms so popular if they are not effective? The public has been misled. Under the guise of providing safety, manufacturers of ionization fire alarms have sold products that do not actually detect smoke and are known to not function effectively during a common form of fire without any notice to consumers. It is a deception by omission that has cost numerous lives.
Department of Defense
National Fire Protection Agency
The United States Fire Administration
Ohio Fire Chiefs Association
World Fire Safety Foundation