Are Smoke Detectors Harmful?

Are Smoke Detectors Harmful?

Last Updated on by Segun Ayo

Smoke detectors might look harmless, but are they truly harmless? That question would be answered in this guide. If you’ve had the same question, then lucky for you, your question would be answered in this guide. Read through to find out if smoke detectors are harmful.

What Is A Smoke Detector?

A smoke detector is a device that senses the presence of smoke in a building and warns the occupants, enabling them to escape a fire before succumbing to smoke inhalation or burns. Equipping a home with at least one smoke detector cuts in half the chances that the residents will die in a fire.

In 1992 the readers of R&D Magazine selected home smoke alarms as one of the “30 Products that Changed Our Lives.” Smoke detectors became widely available and affordable in the early 1970s. Prior to that date, fatalities from fires in the home averaged 10,000 per year, but by the early 1990s, the figure dropped to fewer than 6,000 per year.

Two basic types of smoke detectors are currently manufactured for residential use. The photoelectric smoke detector uses an optical beam to search for a smoke. When smoke particles cloud the beam, a photoelectric cell senses the decrease in light intensity and triggers an alarm.

This type of detector reacts most quickly to smoldering fires that release relatively large amounts of smoke.

The second type of smoke detector, known as an ionization chamber smoke detector (ICSD), is quicker at sensing flaming fires that produce little smoke. It employs a radioactive material to ionize the air in a sensing chamber; the presence of smoke affects the flow of the ions between a pair of electrodes, which triggers the alarm.

Ionization smoke alarms are generally more responsive to flaming fires.

How they work: Ionization-type smoke alarms have a small amount of radioactive material between two electrically charged plates, which ionizes the air and causes current to flow between the plates. When smoke enters the chamber, it disrupts the flow of ions, thus reducing the flow of current and activating the alarm.

Photoelectric smoke alarms are generally more responsive to fires that begin with a long period of smoldering (called “smoldering fires”).

How they work: Photoelectric-type alarms aim at a light source into a sensing chamber at an angle away from the sensor. Smoke enters the chamber, reflecting light onto the light sensor; triggering the alarm.

For each type of smoke alarm, the advantage it provides may be critical to life safety in some fire situations. Home fatal fires, day or night, include a large number of smoldering fires and a large number of flaming fires.

You can not predict the type of fire you may have in your home or when it will occur. Any smoke alarm technology, to be acceptable, must perform acceptably for both types of fires in order to provide early warning of fire at all times of the day or night and whether you are asleep or awake.

Between 80 and 90% of the smoke detectors in American homes are of this type. Although most residential models are self-contained units that operate on a 9-volt battery, construction codes in some parts of the country now require installations in new homes to be connected to the house wiring, with a battery backup in case of a power failure.

The typical ICSD radiation source emits alpha particles that strip electrons from the air molecules, creating positive oxygen and nitrogen ions. In the process, the electrons attach themselves to other air molecules, forming negative oxygen and nitrogen ions.

Two oppositely charged electrodes within the sensing chamber attract the positive and negative ions, setting up a small flow of current in the air space between the electrodes. When smoke particles enter the chamber, they attract some of the ions, disrupting the current flow.

A similar reference chamber is constructed so that no smoke particles can enter. The smoke detector constantly compares the current flow in the sensing chamber to the flow in the reference chamber; if a significant difference develops, an alarm is triggered.

Smoke alarms are a key part of a home fire escape plan. When there is a fire, smoke spreads fast. Working smoke alarms give you an early warning so you can get outside quickly.

  • A closed-door may slow the spread of smoke, heat, and fire. Install smoke alarms in every sleeping room and outside each separate sleeping area. Install alarms on every level of the home. Install alarms in Large homes may need extra smoke alarms.
  • It is best to use interconnected smoke alarms. When one smoke alarm sounds they all sound.
  • Test all smoke alarms at least once a month. Press the test button to be sure the alarm is working.
  • Today’s smoke alarms will be more technologically advanced to respond to a multitude of fire conditions, yet mitigate false alarms.
  • A smoke alarm should be on the ceiling or high on a wall. Keep smoke alarms away from the kitchen to reduce false alarms. They should be at least 10 feet (3 meters) from the stove.
  • People who are hard-of-hearing or deaf can use special alarms. These alarms have strobe lights and bed shakers.
  • Replace all smoke alarms when they are 10 years old.
  • Smoke alarms basement. Smoke alarms should be interconnected. When one sounds, they all sound.
  • are an important part of a home fire escape plan.

Seeing all the benefits of having a smoke detector, can this same equipment turn around and cause harm to the residents in the building it occupies?

Ionization chamber and photoelectric smoke detectors are the two most common types. Both work very well and are safe to use.

There are no health concerns with photoelectric smoke detectors because no radiation is involved. Photoelectric smoke detectors sound an alarm when smoke particles scatter a beam of light in the detection chamber. They respond quickly to fires with lots of smoke.

Ionization chamber smoke detectors contain a small amount of americium-241, a radioactive material. Smoke particles disrupt the low, steady electrical current produced by radioactive particles and trigger the detector’s alarm.

They react quickly to fires that give off little smoke. Ionization smoke detectors expose people to a tiny amount of radiation—about 1/100 of a millirem per year. This is well below the background radiation level of about 360 millirems a year. If a smoke detector contains radioactive materials, a printed notice on the packaging will say so.

Because of the long half-life of americium-241, the amount of radioactive material in an ionization chamber smoke detector at the end of its useful life will be about the same as when it was purchased. State and local requirements for the disposal of ionization smoke alarms vary.

Some States conduct an annual roundup of ionization smoke detectors similar to that for hazardous household chemicals. Others allow ionization smoke detectors to be thrown out with ordinary trash but recommend that used smoke alarms be returned to the supplier. Some states require that used smoke detectors be returned to the supplier.

Check with your local solid waste district, hazardous waste program, or health department to find out the procedures in your area. All manufacturers of ionization smoke detectors must accept returns—when in doubt, return the detector. Return addresses are listed in the product warranty or use instructions.

Smoke detector batteries should be disposed of as explained in What should I do with dead batteries?

However, you should note that:

Radiation safety

Radiation from natural sources is always present in the environment. It is in the food we eat, the air we breathe and the buildings we live in. This type of exposure is known as background radiation. Besides the radioactive materials that occur naturally in our environment, there are human-made radioactive materials. Americium-241 is one such material.

The dose rate from a domestic smoke alarm at a distance of one meter is less than one-thousandth of that from background radiation, which in Australia is on average 1.5 millisievert per year. At greater distances, the dose rate is much lower.

The dose rate to the hands when holding a smoke alarm is higher but is still less than one-tenth that from background radiation. As the hands are very much less sensitive to radiation than internal organs and the time of exposure is likely to be only a few minutes per year, no significant radiation exposure would occur.

The radioactive source in a smoke alarm is extremely insoluble and, if swallowed, would not be absorbed into the body but would pass through the digestive system.

In a house fire, temperatures are unlikely to exceed 1200°C. While such a fire temperature might be sufficient to melt the source it would not be enough to vaporize it and create an inhalation hazard.


Radiation can cause cancer and other problems, including defects in unborn children. Radiation produced during normal use of ionization smoke detectors is so low it has no noticeable effect. If the ceramic chamber containing the radioactive material is removed and swallowed, exposure is about six times the desirable yearly exposure—still too low to cause acute health effects.