Urban Air Pollution and Forests : Resources at Risk in the Mexiko City Air Basin (Ecological Studies Vol.156) (2002. XXI, 387 p. w. 87 b&w figs., 10 col. plates. 24 cm)

At present, roughly half of the world's population lives in urban centers. A consequence of this growing trend is that millions of people are being exposed to harmful levels of urban air pollutants caused mainly by emissions from motor vehicles and from industrial and domestic activities involving the combustion of fossil fuels.