| well,humans use many products wich pollute the earth,even when humans breath it realeses a small ammount of co2,wich polutes the air.but just that isint enough to effect us in any way,its when we make factory's and burn lots of coal,and release polution,wich damages the atmospere,messing up the greenhouse effect,allowing more heat.
but of course,there is natural pollution,like volcanoes and such |