With every breath, it is clear that air is an essential natural resource. This mixture of gases is invisible, but it is all around us. Clean air gives us the oxygen we need to live, but the mixture is always changing. Pollution from cars and factories changes the quality of our air. So do natural disasters, like volcanic eruptions. But with the right balance, Earth thrives. Natural resources like air are a gift, but we must use Earth''s gifts responsibly. Just as Earth takes care of us, we must take care of its air. This book will drive home all these points for your readers. Color photographs, fact boxes, a hands-on activity, and "Words to Know" are also included in this earth science book.