All around the world, trees are dying. This is happening because of a kind of pollution called acid rain.
When coal, oil and natural gas are burnt, they give off sulfur dioxide and nitrogen oxides. These gases dissolve in rainwater to form sulfuric acid and nitric acid. This makes the rain into acid rain. It can be as acidic as lemon juice.

The picture shows how acid rain forms. The acid rain drains into lakes and makes the water in them acidic.

How does acid rain affect the environment?

Soil contains nutrients that keep plants healthy. Plants take in nutrients through their roots. But acid rain washes nutrients out of the soil.
The lack of nutrients weakens plants.
They grow slowly and their leaves fall off.
Plants need leaves to make food.
With fewer leaves, plants make less food.
Even large trees are damaged by acid rain. Pest attack can kill them because they are so weak and their branches die back.
Eventually the trees die.