Composition of the EarthÕs Atmosphere

 

Gas

Percent (By Volume Dry Air)

Nitrogen (N)

78.08 %

Oxygen (O)

20.95 %

Argon (Ar)

0.93 %

Neon (Ne)

0.0018 %

Helium (He)

0.0005 %

Hydrogen (H2)

0.00006 %

Xenon (Xe)

0.000009 %

Other Particles

 

Water Vapor (H2O)

0-4 %

Carbon Dioxide (CO2)

0.036 %

Methane (CH4)

0.00017 %

Nitrous Oxide (N2O)

0.00003 %

Ozone (O3)

0.000004 %

Particles (dust, soot, etc.)

0.000001 %

Chlorofluorocarbons (CFCs)

0.00000002 %