Table 9.1 Major Permanent Constituents of the Atmosphere Ga as Percent by volume parts per Million Nitrogen(N 7808 Oxygen(O2) Argon(Ar) 0.93 Neon(Ne) 18.2 Helium(He) 5.2 Krypton(Kr) ydrogen(H2) 0.5 In addition to these permanent gases, there are a number of others, such as water vapor, carbon dioxide, methane, carbon monoxide, ozone and ammonia, that fluctuate with time altitude and location Water vapor: <1%-3%Table 9.1 Major Permanent Constituents of the Atmosphere. In addition to these permanent gases, there are a number of others, such as water vapor, carbon dioxide, methane, carbon monoxide, ozone and ammonia, that fluctuate with time, altitude, and location. Water vapor: < 1% - 3%