Composition of Air
Component |
Symbol
|
Volume |
Nitrogen |
N2
|
78.084% |
99.998% |
Oxygen |
O2
|
20.947% |
Argon |
Ar
|
0.934% |
Carbon Dioxide |
CO2 |
0.033% |
Neon |
Ne
|
18.2 parts per million |
Helium |
He
|
5.2 parts per million |
Krypton |
Kr
|
1.1 parts per million |
Sulfur dioxide |
SO2
|
1.0 parts per million |
Methane |
CH4
|
2.0 parts per million |
Hydrogen |
H2
|
0.5 parts per million |
Nitrous Oxide |
N2O
|
0.5 parts per million |
Xenon |
Xe
|
0.09 parts per million |
Ozone |
O3
|
0.07 parts per million |
Nitrogen dioxide |
NO2
|
0.02 parts per million |
Iodine |
I2
|
0.01 parts per million |
Carbon monoxide |
CO
|
trace |
Ammonia |
NH3
|
trace |
Human Respiration
The air that leaves a person's lungs during
exhalation contains 14% oxygen and 4.4% carbon dioxide.
Atmospheres with oxygen concentrations below 19.5
percent can have adverse physiological effects, and atmospheres with
less than 16 percent oxygen can become life threatening.
|