Pollution

Daly, A. and P. Zannetti. 2007. An Introduction to Air Pollution – Definitions, Classifications, and History. Chapter 1 of AMBIENT AIR POLLUTION (P. Zannetti, D. Al-Ajmi, and S. Al-Rashied, Editors). Published by The Arab School for Science and Technology (ASST) (http://www.arabschool.org.sy) and The EnviroComp Institute (http://www.envirocomp.org/).

Chapter 1

An Introduction to Air Pollution – Definitions, Classifications, and History
Aaron Daly and Paolo Zannetti
The EnviroComp Institute, Fremont, CA (USA) [e-mail] and [e-mail]
Abstract: Definitions and classifications used in the study of air pollution are introduced. Also introduced are a brief history of air pollution, its regulation, and trends of its ambient concentrations and emissions. Keywords: Anthropogenic, biogenic, geogenic emissions; primary and secondary pollutants; criteria, hazardous, radioactive, indoor pollutants; sulfur smog, photochemical smog; UN-ECE, US-EPA, Clean Air Act.

1

The Natural Environment and Some Definitions of Air Pollution

The present-day atmosphere is quite different from the natural atmosphere that existed before the Industrial Revolution (circa 1760 1 ), in terms of chemical composition. If the natural atmosphere is considered to be “clean”, then this means that clean air cannot be found anywhere in today’s atmosphere. The chemical composition of the pre-industrial (i.e., before the 18th century), natural global atmosphere is compared to current compositions in Table 1:
1

T.S. Ashton, The Industrial Revolution, 1760-1830, London: Oxford University Press, 1948. 1

© 2007 The Arab School for Science and Technology (ASST) and The EnviroComp Institute

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Ambient Air Pollution Table 1. Atmospheric Chemical Compositions2.

Gas Nitrogen Oxygen Argon Neon Helium Krypton Xenon Carbon dioxide Methane Nitrous oxide Water Vapor

Symbol N2 O2

Ar Ne He Kr Xe CO2 CH4 N2O H2O

Percent by volume (Current Atmosphere) 78.1 20.9