Large forests are important to us in many ways. They give us wood for building and heating. They are a home for many kinds of plants and animals. For many city people, forests are a place to go for a vacation. There they can learn about nature, breathe fresh air, and sleep in a quiet place. There is one more reason why forests are important for everyone. The leaves on trees help clean the air. Dirty air is a serious problem in many parts of the world. Without our forest this problem might be ever worse.