Radiation from Smoke Detectors and Exit Lighting

After natural disasters, homeowners, business owners, and response personnel may encounter some items containing radioactive materials, most notably smoke detectors and commercial exit lights. Smoke detectors are ubiquitous in most buildings, including residential, commercial, and institutional facilities, since there are code requirements to have them in most jurisdictions. Most smoke detectors use a very small radioactive source, generally americium-241. However, the level of radiation emitted from a smoke detector is insufficient to create a public health hazard, and there are no federal regulatory requirements for disposal. 

Dislocated or damaged smoke detectors may or may not suitable for reinstallation. Because smoke detectors save lives, if there is any doubt about the suitability of a device, it may be prudent to exercise precaution and purchase a new smoke detector unit. In general, if damaged or unusable, the recovered smoke detector should be returned to the manufacturer if at all possible. Consult local fire protection agencies for advice. 

Tritium exit lights are generally found in some commercial and institutional facilities, especially in locations where electrical power is not available or difficult to run. Tritium exit signs are devices similar in appearance to exit signs operated by AC or DC electrical circuits, but the difference is that tritium exit signs provide illumination from sealed glass tubes inside the unit that contain tritium gas, a radioactive isotope of hydrogen. The tritium gas emits beta particles that interact within the tube to produce the illumination. 

As long as the glass tube within the sign remains unbroken, there is little risk of radiation exposure. However, if this internal glass tube becomes broken, there is some risk of exposure. If the word “Exit” is not fully or partially illuminated, this is an indication that the tritium gas has escaped. As a gas, the tritium will dissipate over time. The rate of dissipation depends on the ventilation rate in the vicinity. 

The greatest risk to people occurs when the tritium exit sign first breaks or there is an indication that there is escaping gas leakage. If a tritium exit sign is broken, leave the area immediately. Consult an industrial hygienist, safetyprofessional, or the state radiation office.

Disposal of tritium exit signs is highly regulated. They must not be disposed in normal trash or abandoned. If you encounter a displaced tritium exit light, consult with an industrial hygienist or contact the state radiation office in the link above.

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