Smoke detectors at the end of their lifespan, which is about eight to 10 years according to Earth911, cannot be recycled; many of them are ionization smoke detectors, which have small amounts of radioactive material, Americium 241. The Solid Waste Agency of Northern Cook County (SWANCC) states on its Smoke Detectors page that “all smoke detectors contain the mail-back address to send used units with radioactive chips,” but now recommends that residents dispose of smoke detectors in their regular trash.
A list of manufacturers that may accept old and used smoke detectors for disposal can be found here: Smoke Detector Disposal Info. However, according to SWANCC, the manufacturers that they contacted simply throw them away and advise residents to just throw them away themselves. Since the amount of radioactive material in ionization smoke detectors is so limited, the EPA does not require special disposal methods for them.
While both Earth 911’s No Smoking and disposal tips page mention Household Hazardous Waste (HHW) collection events as acceptable options for smoke detector disposal, both SWANCC and the Illinois Environmental Protection Agency state that smoke detectors will not be accepted at such events.
Fire extinguishers also are ineligible for disposal at HHW events, but there are numerous disposal, recycling, and reuse options available to residents. SWANCC states on its Fire Extinguishers page that “[t]hey cannot be discarded curbside,” but they can be recharged, recycled at various locations, possibly through the fire-extinguisher manufacturers and local fire departments, and even in regular residential recycling as long as all contents are discharged and the head is removed—the steel body can then be recycled. However, the Mt. Prospect Fire Department does not recharge, recycle, or otherwise dispose of fire extinguishers and refers people to SWANCC for more information.