Answer to Question #6454 Submitted to "Ask the Experts"

Q

What effect does a house fire have on the radioactive material in smoke alarms? Would the material melt and/or vaporize and, if so, would it release radioactive material into the surrounding environment? How dangerous would this be to firefighters, those demolishing the house later on, and people living close by?

A

The short answer to your question is that the presence of smoke alarms in a house fire presents no hazard to the firefighters, workers demolishing or cleaning up the burnt house, or people living nearby. This issue has been studied and tested in great detail. Most of the original research was done in the 1970s, the decade when the use of smoke detectors increased dramatically in U.S. households. I have listed below a number of references with some of the original research in case you are interested in studying the technical details. One of the most thorough studies was published in 1981 (O'Donnell et al.—reference number 1 below) but the report is not electronically available. A more recent document published by the U.S. Nuclear Regulatory Commission summarizes the research data. This document is NUREG-1771, Systematic Radiological Assessment of Exemptions for Source and Byproduct Materials, published in June 2001. I direct your attention specifically to Section 2.15.4.4 on pages 2-222.

The technical analyses included scenarios such as (1) a neighborhood hero trying to rescue a person from a residential fire, (2) firefighters responding to a warehouse fire, assuming that the warehouse stores 36,000 smoke detectors and the firefighters spend eight hours in the building with a low-ventilation rate, (3) a worker cleaning up a residential fire and not wearing a respirator, (4) a fire inspector who spends 25 percent of his time (63 work days) inspecting residential fires, not wearing respirators, and (5) other scenarios including disposal and future land use. Even though fires melt the plastic casing and can damage the metal casing, and a very small fraction (0.01 percent) of the material can become airborne during such fires, the resulting radiation dose in all of the above scenarios is trivial and presents no health hazard. The radiation doses in these scenarios is three to five orders of magnitude (that is 1,000 to 100,000 times) LESS than radiation dose we receive from our natural environment every year.

The only scenario when a smoke detector may present a nontrivial dose is if a person deliberately breaks open the smoke detector casing, separates the source foil from its metal mount, and swallows it whole on purpose. In that unrealistic scenario, the dose will be comparable to the dose from a medical CT (computed tomography) exam. That means no health effect is expected even when that extreme and deliberate measure is taken. Reference number 3 below, which you can get from your science library, is a case study of a woman who swallowed two smoke detectors and received an insignificant radiation dose.

You can check the U.S. EPA (Environmental Protection Agency) Web site for some general information about smoke detectors and radiation. If you are interested in technical details of the smoke detector safety studies, you may see references below.

Armin Ansari, PhD, CHP

References

1. O'Donnell FR, Etnier EL, Holton GA, Travis CC. An assessment of radiation doses from residential smoke detectors that contain Americium-241. ORNL-5807, Oak Ridge National Laboratory; 1981.
2. Cutshall NH, Larsen IL, Case FN. High temperature testing of smoke detector sources. NUREG/CR-0403 (ORNL/NUREG/TM-246); 1978.
3. Rundo J, Fairman WD, Essling M, Huff DR. Ingestion of ²⁴¹Am sources intended for domestic smoke detectors: Report of a case. Health Phys 33(6):561-566; 1977.