It is my intention here, to get the word out about WHY photoelectric smoke detector technology is a major priority folks need to know about.  By the time you reach the end of this post, you will know the basics.



When you are in the midst of planning for the best in smart home security and safety—you are looking for peace of mind, confidence, convenience and “cool”.   I also know that you want to know your
chosen system is  ready to fully take care of your family’s needs.

However, it isn’t easy keeping up with all the “bells and whistles” and new gad-
getry introduced monthly into home security offerings.  Guess what?  In the continuous flood of new technology, this most important, basic device is for-
gotten in too many home security kits.  It’s the WIRELESS SMOKE DETECTOR!  Wireless, so you won’t have to hire a professional to run wires through your
walls, ceilings and floors.

Let me include myself in this.  What if you and I put time and energy in our research, and spend our money selecting a smart home package, then after installation fall victim to our house on fire
and lose everything . . . because we did not include smoke detectors in the kit?

I cannot overstate the importance of installing and maintaining reliable, currently functioning smoke detectors throughout your home.


Smoke detectors in USA Home Fires

According to the National Fire Protection Association records kept in 2009-2013:

  • 3 of every 5 home fire deaths resulted  in homes with NO SMOKE DETECTORS (38%) or no working smoke alarms (21%);
  • In fires in which the smoke alarms were present but did not operate, almost half (46%) of the smoke detectors had missing or disconnected batteries;
  • Your home is 10 times more likely to have a fire than to be burglarized.
  • Most fire deaths are the result of smoke inhalation (up to 80%) and not burning flesh.
  • Often smoke incapacitates people so quickly that they cannot get to the nearest available exit in time!
  • Smoke detectors provide an early warning of a fire, giving families additional escape time to get out.

Please note that home fire sprinklers are thought by many to be 24/7 firemen in your house.  Pricing varies around the country, by the size and design of the house, whether it is new construction or a retrofit and several other factors.  The pricing in the USA will range between $1.50 and $2.50 per square foot—think about it!



It is very important to understand the 2 types of technologies used in detectors:  Ionization and Photoelectric.

You change your “smoke” detector batteries 2 times a year and press the button on the detector every month to be sure everything is working as it should be—but do you know what  type of detector you have?   Knowing the brand  (First Alert, Firex, Kidde, Panasonic, Honeywell, Nest, etc.) is not nearly as important as knowing the TECHNOLOGY—it may SAVE YOUR LIFE!  There are 2 types, Photoelectric and Ionization and each has a sensor that detects smoke and fire differently.


What Is An Ionization smoke Detector?

An ionization smoke detector contains a small amount of radioactive material.  The radiation passes through an ionization chamber which is an air-filled space between 2 electrodes and permits a small, constant current between the electrodes.   Any particles of combustion that enter the chamber absorb the alpha particles, which reduces the ionization and interrupts the current setting off the alarm.   This detector is generally more responsive to flaming fires and particles of combustion, than smoke.

  • Swiss physicists Walter Jaeger and Ernst Meili, together discovered the technology for Ionization Smoke Detectors in 1939.
  • These these detectors work well in “flaming fires” but lead to more false/nuisance alarms from frying bacon, toasters, boiling water, or steam from showers—so people shut them off or remove the batteries and if a fire develops, because the detectors are deactivated, lives are lost.
  • According to some studies, ionization detectors are 8 time more likely to be intentionally disabled than photoelectric detectors, because of nuisance tripping.
  • Ionization alarms generally respond to fast-flame fires 30 to 90 seconds faster than photoelectric smoke detectors.    In smoldering fires, ionization alarms respond about 15 to 50 minutes slower than photoelectric alarms, and fail to activate between 20-25% of the time.
  • The units can be paired together (2 units side by side), or both technologies combined in a single unit.  Recent studies now indicate that most combined units are very reliable and should be combined for maximum safety.  As a matter of fact, reliable photoelectric smoke detectors as a single unit, in the last couple of years have slowly been disappearing from the market.
  • Statistically, 2/3 of fire deaths occur in homes where there are no alarms, the only alarms are ionization detectors and they have not been maintained, replaced when needed, or have been intentionally disabled.  The remaining 1/3 of residential deaths occur because the ionization alarm has sounded too late and the victims have already been overcome by smoke and poison gasses.

What Is A Photoelectric Smoke Detector?

A photoelectric smoke detector uses a light beam source and a photoelectric sensor.  When smoke enters the optical chamber and crosses the path of the light beam, some of the light is scattered by the smoke particles, disbursing it away from the sensor, setting off the alarm.  This detector is generally more responsive to fires that begin with a long period of smoldering.

  • Duane Pearsall and Stanley Peterson introduced the first Photoelectric Smoke Detector in 1965.
  • As of 2012, over 90% of US homes have ionization smoke alarms installed, 5% have photoelectric alarms and the rest have no alarms.
  • Photoelectric detectors lead to less false alarms from frying bacon, toasters, boiling water, or steam from showers, so they continue to be operational rather than disabled because of frequent false alarms.
  • Regulatory agencies are increasingly requiring the unit to have a 10-year life and a sealed 10-year lithium, non-replaceable, non-rechargeable battery.
  • Keep in mind most fire deaths are the result of smoke inhalation (up to 80%) and not burning flesh.  Children age 10 and under and adults over 70 are most vulnerable to the effects of smoke inhalation in a home fire.    At the present time, photoelectric smoke detectors are the best and most effective answer to providing life-saving protection “in real-world fatal home fires!”
  • In recent years, because of the extensive use of synthetics in building materials, furnishings, and personal items found in residential settings, the smoke from a home fire is strikingly more toxic than in years gone by.    Plastics, nylons, Orlons, polyurethanes and polymers such as Styrofoam™ and polyurethane have had a significant impact on combustion, fire behavior, and especially on the dramatically increased danger of smoke for both residents and and first responders.
  • The 5 major, toxic/lethal smoke products responsible for home fire deaths, are:

Carbon Monoxide (CO)—results in headache, fatigue, dizziness and finally unconsciousness and death;

Carbon Dioxide (CO2)—stimulates breathing and thereby increases the inhalation of all the toxicities in smoke;

Hydrogen Cyanide (HCN)—arrests the activity of all forms of living matter;

Hydrogen Chloride (HC1)—damages the upper respiratory tract and leads to asphyxiation and death;

Nitrogen Dioxide (NO, N2O, NO2 and N2O4)—irritates the mucous membranes and upper respiratory tract.


Photoelectric Smoke & Carbon monoxide alarm
with voice & location

is the only early-responsive, reliable, SAFE Alarm, with high reviews, in 2019. 





“Photoelectric VS Ionization Smoke detectors:

In Real-World Fires
the Differences Are



Skip Walker, is an ICC Certified Combination Residential Building Inspector, an ICC Certified California Residential Building and Plumbing Inspector, a CREIA Master Inspector, an ASHI Certified Inspector, and a FIRE Certified Fireplace Inspector. He has presented at a number of local, state regional and national ASHI and CREIA conferences, the National Association of Realtors®, the California Association of Realtors® and the New York City Council Building and Safety Committee on smoke alarm performance and CO poisoning issues.

Skip has served in numerous capacities for CREIA and ASHI and written extensively on smoke detectors, CO issues, deck safety and general inspection issues.   He is the recipient of the 2014 ASHI Philip C. Monahan Award, ASHI’s highest honor, the 2014 ASHI President’s Award, the 2014 CREIA John Daly Award, CREIA’s highest honor and the 2011 CREIA Inspector of the Year. At the 2016 CREIA Conference, he was named to the list of the 40 Most Influential Inspectors of the Last 40 Years.  Skip’s home has ONLY photoelectric alarms installed in it.