Vol. 10, Issue 9, Part D (2024)

Abstract
Unburned hydrocarbons pollute the urban air due to result of uncompleted combustion and the evaporation of solvents and liquid fuels. Volatile organic compounds (VOCs) and other organic substances including hydrocarbons are readily vaporized. Free radicals are added in the urban air with major reactive hydrocarbons which contain a C = C bond. Warmth, ample sunlight, and a stagnant of air are also required for the formation of the Photochemical Smog. Nitrogen dioxide (NO2), ozone (O3), PAN (per-oxy acetyl nitrate), and chemical compounds that contain the –CHO group (aldehydes) are the major undesirable components of photochemical smog. Major cities in the World are subjected to smog. The cities are the obvious substantial sources for the emission of sufficient NOx, different hydrocarbons and other volatile organic compounds into air. Smog makes some plant damage, health hazards, and eye irritations to human beings if their concentrations are sufficiently high.