Primary and secondary pollutant

Primary pollutant:

Emitted into the atmosphere directly from the source of the pollutant Not undergo any chemical or physical transformation Retains the same chemical form Examples of Primary Pollutants:

• Car exhaust, smokestacks (CO, SO2, NO)•Particulate material (soot, ash)•Toxic metals (lead, mercury)•Volatile organic compounds (VOCs)(methane, propane, CFCs, etc.)

Secondary pollutant:

Formed by chemical reactions among primary pollutants and normally present atmospheric constituents.

Undergo a chemical change once they reach the atmosphere Examples of secondary pollutants:

• Atmospheric acids (H2SO4,HNO3)•Photochemical oxidants (NO2)

Hazardous Air pollutants (HAPs)

Chemical which known or suspected as carcinogens have high usage and emissions in a wide variety of industries, including printing, metal

fabrication, automotive repair, wood finishing, dry cleaning. the EPA has determined that emissions of these chemicals present a threat to human health

or the environment. Example: Acetamide, Asbestos, Benzene, Chloroform, Formaldehyde, Hexane etc.

Conclusion

Air Pollution is the substance in the air that present at high enough concentrations, produces a detrimental environmental effect (health effects or welfare effects).

Primary air pollutants are emitted directly into the air from sources. They can have effects both directly and as precursors of secondary air pollutants (chemicals formed through reactions in the atmosphere).

Developed Countries have reduced emissions recently by:

•increased efficiency of cars, factories, power plants

•pollution-control technologies

Developing Countries still struggling with:

•dust, smoke, dirt 10x higher than safe levels