It's estimated at least 95 % of homes have at least one smoke detector.
Credited with saving lives, some now say the type of smoke detector hanging in most homes may not be saving as many lives as once thought.
Just this past Thanksgiving two Liberty County women lost their lives in this mobile home fire. Investigations show there was a smoke detector but some firefighters say it didn't alert the women soon enough. The fire investigator thinks the women's lives might have been saved if they'd had a different kind of smoke detector.
In a Three on Your Side Special Report Alice Massimi has more on the deadly delay of some smoke detectors.

Many people aren't even aware there are different kinds of smoke detectors but as it turns out, there are.
The most common and least expensive is Ionized.
The Ionized technology uses a small amount of radioactive material between two charged plates, when the air inside changes, it sets off the alarm.
These kinds of detectors are best at detecting flaming, fast moving fires.
Then there are Photoelectric.
Not very well known, they use technology in which a light source is aimed into a sensing chamber. When smoke enters, it bounces back light and triggers the alarm.
Photoelectric detectors are more responsive to smoldering fires.
Then there are Dual detectors, which have both technologies.
Some firefighters have a problem with Ionized detectors, claiming they are not as responsive as Photoelectric. Actually they think they should be taken off store shelves.
Wanting to see why these detectors are deemed to be so unsafe, we did a test of our own.

Armed with three different types of smoke alarms, Ionized, Photoelectric, and Dual - we were on a mission.
With the help of the Savannah Fire Department, we wanted to know whether ionized smoke detectors were as useless as some claimed.
So we attached all three detectors to a board, labeled them and hung them up in our makeshift room.
Knowing Ionized is supposed to respond the best to fast moving fires, that's the first kind we started.
A lit cigarette is dropped into a wastebasket of paper, within minutes, flames are seen.
The Ionized alarm does go off first.
Thirteen seconds later, the dual alarm kicks in and forty-seven seconds after the Ionized first went off, the Photoelectric alarm is heard.
Now it's time for the smoldering fire, the most common household fire and the type of fire some firefighters claim is not detected very well by ionized detectors.
For this one, we place a cigarette in between some couch cushions.
The Photoelectric goes off first, thirty-nine seconds later, the dual and a minute and five seconds after the Photoelectric sounded, the Ionization sounded.
“The Photoelectric did activate faster with a smoldering fire and the Ionization did happen faster with a free burning fire,” explains Savannah Fire Captain Matt Stanley who assisted with the test.
But while our test did not show much lag time in the ionized response, tests done of the federal level have.
“In the smoldering the Photoelectric was approximately 30 minutes on average faster than the ionization that in itself is important enough,” points out Boston Fire Deputy Chief Jay Fleming. “The really important thing they found, not in every case but in a sizeable amount of cases, the smoldering fires the ionization wasn't responding till after the smoke was too thick to allow someone safely egress.”
Yet the alarms are what is found in most homes and even handed out free of charge by many fire departments.
Fleming is looking to change that, “I think having the photoelectric again might be able to save anywhere between 15 to 20 percent of the people who are dying with the working smoke detectors.”
Fleming admits ionized go off an average of 50 seconds earlier than Photoelectric detectors in flaming fires, but he says Photoelectric is still the safest bet for everyone.
“Every night I fall asleep saying a prayer because I suspect there is going to be two or three people who die that night who don't have to,” says Fleming.
But Chief Fleming says he is slowly making headway. In the state of Massachusetts, the Fire and Building Code does not allow ionized smoke detectors in homes and the Governor’s of Vermont and New Hampshire are expected to sign similar legislation later this week.
Chief Fleming and Captain Stanley say if you can't afford to buy new detectors right now, at least make sure you have fresh batteries in your existing detectors.

Click here for our special Deadly Delay page with more resources.