Non-degradable solid pollutants are
DDT
Plastics
Nearly half of all the DDT present in the air breaks down within two days. But that's not the problem.
In fact, DDT sticks to the soil, and there it is broken down slowly into DDE and DDD by microorganisms.
It takes 2-15 years for half of the DDT in the soil to break down, depending on the type of soil.
Different types/grades of plastic take different times to degrade. But the average time that a plastic bottle to degrade completely is at least 450 years! That is massive given we don't recycle at least 90% of plastics.