How to Dispose of Smoke Detectors Properly
Many Americans don’t know the ugly truth about the smoke detectors installed inside their homes. There are two types of smoke detectors; ionization smoke detectors and photoelectric type smoke detectors. Most modern smoke detectors are “dual sensor” types which detect smoke both ways. The photoelectric sensor is generally more sensitive than ionization smoke detector technology at sensing large smoke particles, which tend to be produced in greater amounts by smoldering fires. These fires may smolder for hours before bursting into flame. Ionization smoke detectors are generally more sensitive than photoelectric technology smoke detectors at sensing small particles, which tend to be produced in greater amounts by hot, flaming fires which consume combustible materials rapidly and may spread quickly. For maximum protection, most manufacturers incorporate both sensors in their smoke detector design.
Ionization smoke detectors utilize a small amount of radioactive material called Americium-241 which is a man-made element discovered by American scientist during the Manhattan Project. The Americium emits alpha particles which the smoke detector uses to determine if smoke is present in the ionization chamber.
The ionization chamber is basically two metal plates a small distance apart. One of the plates carries a positive charge, the other a negative charge. Between the two plates, oxygen and nitrogen molecules are ionized when electrons removed from the molecules by alpha particles from the radioactive material. The result is oxygen and nitrogen atoms that are positively charged because they are short one electron; the free electrons are negatively charged.
In the smoke-free chamber, positive and negative ions create a small current as they migrate to charged plates. Smoke particles and combustion gases interact with the ions generated by the alpha particles, restoring them to their original electronic state and decreasing the electrical current passing through the cell. This disrupts the current flow and triggers the alarm.
The Americium-241 is contained inside the airflow chamber (Aluminum cap with slots)
The problem is that most people don’t read the instructions on the smoke detectors to see if they contain Americium. The ingredient is shielded by a metal chamber within the plastic casing of the detector. On your wall, this material poses little threat; however, when a detector is broken open in an incinerator or a landfill, it can present a health hazard. For this reason, all detectors, by law, must be labeled as to radioactive content. Detector companies must accept returned radioactive detectors for disposal as hazardous waste. The Americium is harmful if inhaled, but it will actually pass through your digestive track safely.
The Nuclear Regulatory Commission, NRC, and the EPA have published standards for manufacturers and users for the use of smoke detectors containing radioactive materials.
Many smoke alarm companies do not manufacturer smoke alarms in the U.S. The smoke detectors may be manufactured abroad and imported or "transferred" to the U.S. When ionization smoke alarms are imported into the U.S., the company must meet the NRC license requirements for gas and aerosol detectors at 10 CFR 32.26.
Any smoke alarm that you buy that contains radioactive material should contain a notice on the packaging. For example, a typical package labeling might read:
"This product is designed to detect products of combustion using ionization technology. It contains 0.9 micocurie of Americium 241, a radioactive material"
" Distributed under US NRC License No. _________. Manufactured in compliance with U.S. NRC safety criteria in 10 CFR 32.27"
Disposal and Recycling
According to the Nuclear Regulatory Commission, the amount of radiation that escapes the detector is roughly 3000x less than normal background radiation exposure rates, at 1 meter from the alarm. The only possible health risk is if the Americium 241 is inhaled. Do not disturb, poke or attempt to remove the ingredient in your ionization detector. Do not crush smoke detector.
Although it is legal to dispose of your ionization detector in the trash, you should return the product back to the manufacturer. They are mandated by the Nuclear Regulatory law 10 CFR 32.27 to see that the radioactive waste is disposed at a nuclear waste disposal facility. Send the smoke detector back intact, DO NOT remove any components. The entire smoke detector needs to be returned to the manufacturer or store by UPS ground mail, not FedEx or airmail. The batteries should be removed and properly disposed of or recycled. Place the entire smoke detector in a sealed box wrapped in paper to prevent it from being damaged.
If you can’t return smoke detector to manufacturer, remove battery from smoke detector and deliver battery to household hazardous waste disposal event or facility. Hopefully you won’t have to dispose of it in the trash.
Most alarms installed today have a life span of about 8-10 years. After this time, the entire unit should be replaced. It is a good idea to write the date of purchase with a marker on the inside of your alarm so you will know when to replace it. Some of the newer alarms already have the purchase date written inside. In any event, always follow the manufacturer’s instructions for replacement. The Americiums useful life is slightly longer than 10 years and begin to break down which is another good reason to recycle them.