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Smoke Detectors

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This page discusses how a radioactive sources is used in some smoke detectors.

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Overview

Smoke detectors are common household items. One type, ionization smoke detectors, uses a small radioactive source as a key component in detecting smoke particles. Photoelectric smoke detectors use a light and sensor to detect smoke. Ionization smoke detectors are more effective at detecting flash fires, while photoelectric smoke detectors are more effective in detecting smoldering fires. Both cost about the same, and many smoke detector models use both ionization and photoelectric features to achieve maximum detection.

Remember
Always use a smoke detector in your home!

The radionuclide used in ionization smoke detectors is an oxide of americium-241, which is bonded to a metallic foil and sealed in an ionization chamber. As long as you use the smoke detector as directed and do not open it, it poses no radiation health risk to humans--always use a smoke detector in your home.

Americium-241 is a man-made radioactive metal, first discovered during the Manhattan project, the national program that first developed atomic weapons during World War II. Americium-241 emits alpha particles and low-energy gamma rays. The smoke detector alarm goes off when the flow of alpha particles is interrupted by smoke particles.

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Who is protecting you

The States

Each state has one or more programs that address radiation protection and the use and disposal of radioactive material in consumer products.

U.S. Nuclear Regulatory Commission (NRC)

NRC establishes regulations for the licensing of the sale, use and disposal of radioactive material. The requirements for a license for the use of radioactive material in a consumer product are based on the quantity of the radioactive material and the specified level of radiation.

U.S. Environmental Protection Agency (EPA)

EPA’s Clean Materials program is designed to monitor the ways radioactive sources enter the environment or the nation's metal supply through improper management. EPA also works with the National Conference of Radiation Control Program Directors to develop ways to keep unnecessary radioactive material out of consumer products.

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What you can do to protect yourself

Remember
Never take an ionizing smoke detector apart.

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Resources

Americium
March 30, 2012. U.S. Environmental Protection Agency, Radiation Protection
This page provides basic scientific information on americium as well as information on human exposure, health effects, and protecting people from radiation.
Ionization Technology
March 30, 2012. U.S. Environmental Protection Agency, Radiation Protection
This site provides information on how ionization sensor smoke alarms use americium.
Conference of Radiation Control Program Directors exit EPA
April 13, 2012. CRCP
On this site, you can learn about the work of CRCPD and how to contact your state’s radiation control program.

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