As a Realtor, I get the opportunity to visit many homes on a weekly basis. On a regular basis, I notice that the smoke detectors have yellowed significantly. While it may seem like a cosmetic concern, these yellow detectors may actually present a risk to the homeowners.
Smoke detectors and other consumer products are injected with bromine to reduce the flammability. A side effect of the bromine is that it causes the plastic to yellow over time with exposure to light, oxygen and heat.