(4) Lead is the most toxic ‘metal’pollutant in automobile exhaust; the other pollutantsbeing Hydrocarbons, Nitrogenoxides, Carbon Monoxide,Carbon Dioxide, etc. Carbonmonoxide has 210 times greateraffinity for hemoglobin thanoxygen which makes it highlytoxic and lethal as well. It isthe commonest cause of accidentalpoisoning.Photochemical smog is a termused to describe air pollutionthat is a result of the interactionof sunlight with certainchemicals in the atmosphere.One of the primary componentsof photochemical smog isozone. While ozone in thestratosphere protects earthfrom harmful UV radiation,ozone on the ground is hazardousto human health.Ground-level ozone is formedprimarily from vehicle exhaustandvolatile organic compounds(from paints, solvents,and fuel evaporation) interactin the presence of sunlight.