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Your household smoke detectors

Smoke detectors are the most common consumer products that use nuclear technology to function. They are critical components of every household and workplace because of their ability to detect smoke in the air and identify potential fire hazards.

How do they work?

There are two primary technologies used in smoke detectors. One type uses a photoelectric sensor to detect the change in light level caused by smoke. The other uses the radiation from a small amount of radioactive material to sense smoke. These types of detectors, also referred to as ionization chamber smoke detectors, are the most commonly used because of their sensitivity and ability to identify a wider range of fire conditions.

The americium-241 in ionization chamber smoke detectors makes the air in the detector’s sensing chamber conduct electricity. When smoke enters the sensing chamber, it interrupts the electrical current, triggering the smoke detector’s alarm.

Ionizing smoke detectors are used in Canada because they are best at detecting quick burning fires, such as many of the fires which occur in North American buildings, which contain significant amounts of wood.

Household smoke detector

Household smoke detector

Radioactive properties

Most household detectors contain a very small amount of americium-241, a radioactive isotope. The slight amount of radiation that can be measured outside the unit does not pose any health risk. In fact, the average annual radiation dose from these devices per person represents 0.01 percent of the dose they receive from natural background radiation. The safe encapsulation and low amount of radioactive material make these devices completely safe under all conditions, even during or after a fire.

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Secure disposal

Consumers have three options when their ionizing smoke detector reaches its end of useful life:

  1. participating in municipal recycling programs for these devices
  2. contacting and returning their smoke detector to its manufacturer for disposal
  3. disposing household smoke detectors in regular municipal household garbage but not in recycling or composting waste, after the removal of its internal battery for proper disposal

There is no limit as to how many residential smoke detectors you may dispose of at one time. Most households do not have more than one or two at their disposal anyway. However, hiring a consultant is recommended for the disposal of large institutional quantities or industrial smoke detectors.

Quick safety tips

  • Batteries are used as either the sole or backup power source of the device, depending on the brand of smoke detector. Regardless of which kind of smoke detectors you have, it is a good idea to have batteries in them.
  • If you hear a chirping or beeping sound, it is usually an indication that you should replace them. To be safe, routinely test your household devices by pressing the “test” btn to ensure their functionality.
  • When it comes to the lifespan of the smoke detectors, different manufacturers may have varying replacement recommendations. 

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The CNSC’s role

Each smoke detector made in Canada must comply with strict radiation safety standards before their distribution. The CNSC is responsible for licensing the manufacturing and initial distribution of all smoke detectors containing a radioactive source in Canada. Check out our Household Smoke Detector Safety and Disposal Fact Sheet for more information.

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