Results from incomplete combustion or from burning in an enclosed area. It is produced primarily by motor vehicles. A silvery-white poisonous metallic element, liquid at room temperature. It is used in thermometers, barometers, vapor lamps and batteries and in the preparation of chemical pesticides. Results from the combustion of fossil fuels like coal, oil and gasoline.
Typical sources are motor vehicles, power plants, industrial boilers and other fuel-burning sources.
Ozone is also known as smog. Consists of solid particles like dust, soot and ash which are suspended in the air. It results from burning of fuels or materials or from dust-generating activities. It contributes to smog and acid rain. Major sources are motor vehicle exhaust, emissions from the use of solvents, and emissions from the chemical and petroleum industries.