Originally Posted by
mrt2you
because the UV rays help break down the plastic and stryofoam. there are no UV rays buried in a landfill.
do a test for yourself. take a piece of old styrofoam cooler. cover 1/2 of it so the sunlight can't hit it. them leave it out in the sun for a month or so. you will easily see damage in the exposed area over the non exposed area.
i don't replace my helmet every 3-4 years. i give my helmet a good visual inspection every month or so. once i see the plastic starting to crack, dry out i replace the helmet.i usually have to do this about the 6th or 7th year.
people don't ride outside 24 hours a day for a month like your test
rather than doing that, do the same test, but only expose the Styrofoam an hour or two a day, and don't forget rest days, or other days you may not ride, so no exposure at all on several days
then on the days you don't expose it to the sun, take it inside like you would your helmet