! The sea-level composition of air ! (in percent by volume at the temperature of 15°C ! and the pressure of 101325 Pa) is given below. ! ! Source: ! ! CRC Handbook of Chemistry and Physics ! by David R. Lide, Editor-in-Chief ! 1997 Edition ! ! ! Symbol Percent by Volume ! ! T= 1200.000 P= 10.1327e4 N2 74.523 O2 22.626 H2 2.851 !H2 1.999997 !CO2 0.0314 !NE 0.001818 !CH4 0.0002 !HE 0.000524 !KR 0.000114 !H2 0.00005 H 0.000 O 0.000