i think there are about 8.000t of man made orbital objects up there right now.
The earth has 510.100.000 square km of surface.
That boils down to 15g of material per square km.
Now be assured...if u life in a city, or even near a street with car traffic you are allready living with way way higher levels of polution than orbital objects could cause....unless a Rorsat with a nuklear reactor decides to crash in your backyard.
Orbital littering is a real problem, but its dwarfed by the gigantic amount of trash and polution we allready have on earth...even if all the orbital objects would come down tomorrow...u would not notice the increase of polution.