Pollutants Essay

Botkin (2010) primary pollutants are emitted directly to air. They are chemicals released directly into the air in a harmful form and are substances directly emitted from a process, such as ash from a volcanic eruption, the carbon monoxide gas from a motor vehicle exhaust or sulfur dioxide released from factories. Once emitted into the atmosphere, some of these primary pollutants can be altered by light energy, heat or the presence of other chemicals (e.g. oxygen) to form secondary pollutants. Primary pollutants include particulates, sulphur dioxide, carbon monoxide, nitrogen oxide and hydrocarbons. Primary pollutants are those, which are emitted directly into the atmosphere from different sources such as industrial stacks, household discharges

Nitrogen oxide (NOx)

Nitrogen oxides (NOx) especially nitrogen dioxide are emitted from high temperature combustion. Nitrogen dioxide is the chemical compound with the formula NO2. It is one of the several nitrogen oxides. This reddish-brown toxic gas has a characteristic sharp, biting odor. NO2 is one of the most prominent air pollutants. Nitrogen oxides (NO and

NO2, referred together as NOx) are highly reactive gases formed when oxygen and nitrogen react at high temperatures during combustion or lightning strikes. Nitrogen

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present in fuel can also be emitted as NOx during combustion. Emissions are dominated by fossil fuel combustion at northern mid-latitudes and by biomass burning in the tropics.

In the atmosphere NOx reacts with volatile organic compounds (VOCs) and carbon monoxide to produce ground-level ozone through a complicated chain reaction mechanism. It is eventually oxidized to nitric acid (HNO3). Like sulfuric acid, nitric acid contributes to acid deposition and to aerosol formation. NO2 is one of the most prominent air pollutants.

Nitrogen in coal, oil, and natural gas cannot be removed prior to combustion. Thus the removal of NOx is only possible during or after combustion has occurred.