I think the main reason of Environmental Pollutions are due to increasing populations of human beings.
Due to increasing population we are cutting trees, which play big role in air purification for us.
We are gradually acquiring more and more apace for our demands without thinking about any other habitats, like animals.
Actually the main reason of Environmental Pollutions is due to our continuous disturbance against nature in the way of development facilities for us.
But, We are losing our nature which is not good.
Therefore we should always try to involve and interact with the nature.