What are the gases that make up the atmosphere? Ninety-nine percent of air is nitrogen and oxygen. The other one percent is a mixture of water vapor, argon, carbon dioxide, and other gases. Without the atmosphere, there would be no life on our planet.
 
It is important that the amounts of nitrogen and oxygen in the atmosphere never change. If either changed very much, life could not survive. But the amounts of the other gases do change a little. These changes do not harm us.
 
The amount of water vapor in the air is always changing. It is always different over different parts of the world. It may change over a certain place within a period of a day or even a few hours. Water vapor may make up as much as four percent of the atmosphere.

Ozone is a gas. It is made of three oxygen atoms. It always has the same chemical structure, no matter where it is located. But location does matter if you're talking about "good" or "bad" ozone. Good ozone is found miles above the ground. Bad ozone is found near the ground.