Originally Posted by dszombiex

^^^ Check that link.

Btw composition of the earth's atmosphere:

Nitrogen (N2) 780,840 ppmv (78.084%)
Oxygen (O2) 209,460 ppmv (20.946%)
Argon (Ar) 9,340 ppmv (0.9340%)
Carbon dioxide (CO2) 387 ppmv (0.0387%)
Neon (Ne) 18.18 ppmv (0.001818%)
Helium (He) 5.24 ppmv (0.000524%)
Methane (CH4) 1.79 ppmv (0.000179%)
Krypton (Kr) 1.14 ppmv (0.000114%)
Hydrogen (H2) 0.55 ppmv (0.000055%)
Nitrous oxide (N2O) 0.3 ppmv (0.00003%)
Xenon (Xe) 0.09 ppmv (9 × 10−6%)
Ozone (O3) 0.0 to 0.07 ppmv (0% to 7 × 10−6%)
Nitrogen dioxide (NO2) 0.02 ppmv (2 × 10−6%)
Iodine (I) 0.01 ppmv (1 × 10−6%)
Carbon monoxide (CO) 0.1 ppmv (0.00001%)
Ammonia (NH3) trace