AZ Allows Smoke Alarms Baned in Other States

Will your Smoke Alarm sound off with smoke alone?

Currently, ionization-type smoke detectors are banned in three states: Massachusetts, Iowa, and Vermont as well as at least two cities in California. However, elsewhere, including in Arizona, they are the dominant type of smoke detector, due to their low price.Smoke Detector REALLY? I checked at Home Depot and Lowes and the difference in price between two similar models was about $2.00. (There I go again, thinking like a home inspector)

Now, what many people are unaware of is that there is a very serious problem with ionization-type smoke detectors: they are very poor at detecting slow smoldering fires. Ionization-type smoke detectors can take 15 to 30 minutes longer to sound than a photoelectric-type smoke detector, and sometimes won’t even sound at all. Slow smoldering fires account for more deaths than fast flaming fires annually, most of which occur during the overnight hours.

I estimate that at least 10,000-15,000 people have died unnecessarily in smoldering house fires since 1990 because they relied on ionization detectors.”

Jay Fleming, Deputy Fire Chief , Boston, MA.

FEMA states: America’s fire death rate is one of the highest per capita in the industrialized world. Fire kills approximately 3,000 and injures approximately 20,000 people each year.

The majority of deaths are in homes without a working smoke alarm. A smoke alarm greatly reduces your chances of dying in a fire.

Firefighters pay a high price for this terrible fire record as well; approximately 100 firefighters die in the line of duty each year. Direct property losses due to fire reach almost $11 billion a year. Most of these deaths and losses can be prevented!

Ionization type smoke detectors account for well over 90% of the smoke alarms installed in residential construction in the US. I would guess that number is higher in the Phoenix area based on what I see during home inspections. On average, ionization units respond about 30 seconds faster to an open-flame fire than photoelectric type alarms. However, in a smoldering fire, ionization units respond on average 30 to 60 minutes slower than a photoelectric unit. In some cases, they may not respond at all. Most residential fire fatalities occur at night and are result of smoke inhalation. The flash-over point in a fire is basically the point where the fire goes critical. Twenty to thirty years ago, the flash-over point in a fire occurred in as little as 12-14 minutes.  Due primarily to the increased use of synthetic and engineered materials, flash-over now often occurs in as little as 2-4 minutes. This leaves the occupants significantly less time to safely exit their home in a fire.

“Kidde recommends for maximum protection that both ionization and photoelectric smoke alarms be installed. Ionization technology is faster at detecting fast flaming fires that give off little smoke. Photoelectric technology is faster at responding to slow smoldering, smoky fires.”

Since Kiddie is one of the largest manufactures of both types of alarms, maybe they have a point, or maybe they want to sell more units.

Of course, there also exists dual sensor smoke detectors, which contain both a photoelectric and an ionization sensor,  I will have more on that in a minute.

The issue with ionization alarms is more than just the inferior response times. A recent Alaskan study shows that ionization units are up to 8 times more likely to be non-functional in the first year after installation. Because ionization units are very prone to nuisance tripping from cooking, etc., people become frustrated and intentionally disable the units – i.e. they remove the battery, etc. This leaves the home unprotected. Homes with non-functional smoke alarms account for around 2/3’s of all fire deaths. Statistically, ionization alarms are the most likely to be disabled. Most of the other 1/3 of fire deaths occur in homes where a functional alarm is installed. However, in far too many cases, the alarm sounds too late to alert the occupants.

Don’t just take my word for it, watch the video below.

One of the most disturbing aspects of this is that it is not new information. There is significant research going back to the mid-1970’s showing that ionization “may not operate in time to alert occupants early enough to escape from smoldering fires.” (source AFAC)

“We put 50 million smoke detectors in buildings in America in a two year period and our fire loss and death rate goes up. We’re having a little trouble explaining these things.”

Gordon Vickery, former head of the US. Fire Administration

Source: Fire engineering magazine, September 1980

Fire Fighters Don’t Like them

August 2008: The 292,000 member, International Association of Fire Fighters (IAFF), has changed their position on smoke alarms to formally endorse photoelectric smoke detectors. IAFF members protect over 85% of the population in the US and Canada.

The IAFF’s Official Position is to:

a) ONLY Recommend Photoelectric Smoke Detectors/Alarms
RESOLVED, That the IAFF propose and support the mandate of only photoelectric smoke detectors in United States and Canadian federal law, in all state, provincial and local legislation, and in all standard development organizations’ building fire and life safety codes and standards . . .”

b) NOT Recommend Combination Alarms
WHEREAS, dual alarms, also called combination alarms, that contain both technologies are available but the benefit over photoelectric in the response to fires is marginal. They are more costly, and they will experience the same nuisance problem as ionization smoke alarms . . .”

How do you know which smoke alarm you have?

It’s not always possible to know. In general, if the unit has a Hush feature, it is an ionization unit. If the label says anything about radioactive materials, Americium-241 or the model number ends in an “I” – then it is an ionization unit. When there is any doubt, there is better than a 90% chance it is an ionization unit. To be safe, simply replace all unknown units with photoelectric units.

There are also combination photoelectric/carbon monoxide (CO) alarms. These combination units are more expensive. The NFPA recommends, smoke alarms be replaced every 8 years. Most carbon monoxide detectors should be replaced every 5 years. So your either replacing the smoke alarm portion more often than needed or relying on a CO detector that is past its replacement date. Separate units simply make more sense.

As a Home Inspector serving the Phoenix and Scottsdale area, I am require by the State of Arizona to report on the presence of, and test smoke alarms. However home inspectors are not required to test them with smoke. Think about it, do you want some stranger walking around the home with a cigar? No, we are required to test them with the test buttons only.

Remember pushing the test button only checks the horn function, not the units ability to detect smoke and most units recommend that they be tested weekly.


Click here to see AZ current laws regulating Smoke Alarms (as of the time of this post. Different city’s may adopt different regulations at different times)

Please take this information and pass it on to others, feel free to post comments or contact me (480-636-7400)
Scott Warga, is the Qualifying party for ACSI American Construction Specialists and Investigations LLC,(ROC216772) a dual licensed residential and small commercial contractor. He is also a qualified Phoenix home inspector certified by the Arizona Board of Technical Registration (#38062) and was appointed to the Arizona Board of Technical Registration’s Enforcement Advisory Committee. He has 9 years construction experience and has performed residential and commercial property inspections for over 8 years. He has specialized in forensic inspections, investigating failed, damaged and defective construction for over 4 years. He is a member of the American Society of Home Inspectors, (#205826) and currently sits on their board of directors. He has been an instructor of home inspection at Mesa Community College, for Inspection Training Associates, a Kaplan Professional School and Arizona Sun-Tech Home Inspection School. He has served as District Chairman & Vice President for the Arizona chapter of the American Society of Home Inspectors and an approved instructor for both them and the Arizona Department of Real Estate. If you need an Arizona Home Inspector, he is your guy.


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  1. Great article Scott, wasn’t aware of the dangers of ionization type smoke alarms. Do you check for these types of alarms when inspecting? Do you note in your reports type of smoke alarms in the home?

    I just checked mine and they are ionization alarms, and I will be replacing them with photoelectric.

    Thank you for teaching me something new today!

    Mary Ann Chiquete

    • Mary Ann,
      Thanks for stopping buy.

      To answer your question, I do not check each unit to see what type they are, but I normally check one unless I can tell they are over 8 years old, then I just recommend they all be replaced with Photo electric units.

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