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.