If you look at some plastic that has been outside in the sun for a while (a year or five) such as a toy or a plastic bag, it gets very fragile. If it's thin lik

If you look at some plastic that has been outside in the sun for a while (a year or five) such as a toy or a plastic bag, it gets very fragile. If it's thin like a plastic bag, just the wind can break it apart. For thicker plastic parts, probably rain is enough to flush off the outer layer or powdered plastic every now and then.