Nitrogen oxides (${\mathrm{NO}}_{\mathrm{x}}$) are another major pollutant of the atmosphere, particularly in large cities. 
Nitrogen monoxide is formed by the reaction of nitrogen and oxygen inside the hot engine of cars and other vehicles. Complete the following equation for the reaction producing nitrogen monoxide.

${\mathrm{N}}_2+{\mathrm{O}}_2\to \mathrm{\_\_\_NO}$

Nitrogen oxides (${\mathrm{NO}}_{\mathrm{x}}$) are another major pollutant of the atmosphere, particularly in large cities. 

When leaving the car, nitrogen monoxide in the exhaust fumes reacts further with oxygen in the air to produce the brown gas which can be seen in the atmosphere over large cities. This gas is nitrogen dioxide. Balance the equation for the production of this gas.

Nitrogen monoxide$+$oxygen$\to$nitrogen dioxide

$\mathrm{NO}+{\mathrm{O}}_2\to {\mathrm{NO}}_2$
 

The use of fossil fuels in industry and transport also produces carbon dioxide. What is the reasoning behind the slogan painted on these freight containers seen waiting to be loaded on to a freight train outside a major UK station? Outline the argument behind the slogan.