A very simply fix but proved to be effective. This had been on my mind for a very long time and I looked into chemical treatment and even replacing the vents, in the end I bought a can of gloss white spray paint and off I went. The hardest part was how to remove the vents from the ceiling, but once I worked that out it was incredibly quick and easy.
Materials
Gloss White spray paint
Tools
None. To remove the vents it was only a matter of pulling the vents down which released x3 holding clips.
Steps
Step 1
Removed vents from ceiling
Step 2
wiped vents down
Step 3
spray painted the vents
Step 4
re installed them into ceiling