$NO$, $N_{2}O$ and $N{O}_2$ are produced during combustion of fossil fuels and fuels in automobiles. Tolerable level of $N{O}_X$ is______ ppm. 

 

The oxides of nitrogen are the main components in air. These are produced during the combustion process and also by automobile engines. When the fossil is burnt in automobiles, dinitrogen and dioxygen combine to yield substantial quantities of oxides of nitrogen, $NO$ and$N{O}_2$. The red irritant smog in the traffic and crowded areas we see is caused by the nitrogen oxides. So, there should be a tolerance level of the gases. The maximum permissible concentration or tolerable level of $N{O}_X$ in combustion process is 10ppm.