In the modern world, more than 300 air polluting substances are emitted into the air which are increasing in number day by day due to the introduction of new manufacturing processes and technologies. The most common pollutants which causes injury in plants are ozone, sulfur dioxide, fluorides, chlorine, peroxy-acetyl nitrate (PAN), and ethylene. The impact of air pollutants on plants depends on the physiological and biochemical characteristics of the affected plant, the type of the pollutants. Due to toxic concentration of pollutant in air reductions of growth parameters in plants occur, such as height, diameter, leaf and root biomass, leaf area length and width of stomata, length of the stomatal pore, and stomatal density. These pollutants affect plants even at low concentrations (0.1 to 55 ppm) by causing chronic or acute injury.