Dinitrogen and dioxygen are main constitutents of air but these do not react with each other to form oxides of nitrogen because

Major component of atmosphere are dinitrogen and dioxygen. Both do not react with each other as nitrogen is an inactive gas. The triple bond in N₂ is very stable and its dissociation energy is very high. Both react with each other at very high temperature.
${\mathrm{N}}_2\left(\mathrm{g}\right)+{\mathrm{O}}_2\left(\mathrm{g}\right)\stackrel{3000°\mathrm{c}}{\to }2\mathrm{NO}\left(\mathrm{g}\right)$