How do you get rid of mildew odor from plastic sheets/plastic outdoor gear?

I have used vinegar with good effect to get out of water bottles. It may work on sheets etc

I use the sterlising fluid for babies stuff. Great for bringing coffee or tea stained mugs looking brand new too.
The Sock

and that would be...?

Try a weak (2-3%) bleach solution, if it does not work increase to 5%-10% allow to sit for a short while (30 minutes) and rinse well with clean water and allow to fully dry (windy and sunny day the best) before returning to storage.

Pete

I'd second the bleach idea. But good luck, I have stuff (altho most not plastic) I brought home from Panama in the 60's that still has that lovely odor built in...

Fod absorbing odor, I've used and would try that box sitting in the frig. That baking soda. Make a slurry, slop it on, spread it out, let it sit for a while, and see how it does. It's cheap and does absorb odors. Heck I use it to get the taste of last night's cigar smoke out, because it helps.

A weak solution of common chlorine bleach and just enough of a mild non-toxic detergent, like Simple Green or dish soap, to aid wetting in warm water has always done it for me. Apply, scrub off any soil, rinse. Reapply rinse. Air dry.

In enclosed spots where it is difficult or impossible to scrub I have had good luck immersing the object and use denture tablets as a soak.

Sterilising fluid is called that in the UK. It's for 'babies bottles and equipment' ask any mother what it's called in the US.
The Sock

Try sunlight.

Sue