system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why does tan plastic like used in phones and office equipment fade to that nasty yellowish color?
gpt
Those plastics (and modern ones) are made with anti-combustable materials. Over time and being exposed to UV light, those chemicals leech and coalesce at the surface of the plastic. Some computer parts also emit Ozone, with degrades to Oxygen, both of which are corrosive. Given enough time and exposure to these things, those plastics will turn yellow, then brown, and also become brittle.

All colors of plastic with be affected, but it's on white and tan that they are most noticeable.