The pollutants that account for most of the air pollution worldwide are called criteria air pollutants, $e.g.,$ carbon monoxide (CO), sulphur dioxide ($SO_{2}$), nitrogen oxides $(NO_{x})$, ozone $\left( O_{3} \right),\ H_{2}S$, particulate matters $(PM_{10})$ and lead (i) Carbon monoxide causes giddiness, headache, decreased vision, cardiovascular malfunction and asphyxia (ii) Hydrogen sulphide causes nausea, eye and throat irritation (iii) Sulphur dioxide causes respiratory tract diseases like asthma, bronchitis, cancer, emphysema, etc. (iv) $O_{3}$ is an oxidizing pollutant