* Nitrogen: 78%

* Oxygen: 21%

* Argon: 0.93%

* Carbon Dioxide: 0.039%

* Neon: 0.0018%

* Helium: 0.00052%

* Methane: 0.0002%

* Krypton: 0.00011%

* Hydrogen: 0.00005%

* Nitrous Oxide: 0.00003%

* Carbon Monoxide: 0.00001%

In addition, there are trace amounts of other gases, such as ozone, sulfur dioxide, and ammonia.