Two sets of observations run through the text of this book. First, many acts of development in the Third World have left a series of environmental problems; and second, the environment operates as an integrated system, so any type of modification, even if it is local in nature, may start a chain of events resulting in multifarious effects, regional in scale. Examples of this can be seen in some of the cases discussed: the deforestation of the tropical rainforest; construction of dams across rivers; groundwater depletion to meet urban demands. Such effects could even be global in some cases, as exemplified by the stratospheric ozone depletion and global warming.
It should be pointed out that different types of environmental degradation may arrive with different kinds of economic activities. Air pollution, for example, occurs where a large amount of fuel combustion and industrial activity take place. In that sense, the chapters in this book are arranged progressively in order of more complicated and extensive environmental degradation. Most Third World countries suffer from the effects of resource extraction or the expansion of agriculture to marginal areas. Only the more technologically advanced and populated ones pollute the water and air to a high degree. The non-uniform availability of information must also be noted. A high frequency of examples from a country not only indicates that cases of environmental degradation are common, but also that such ecological modifications are known, perhaps are being monitored, or even that some preventative measures are being taken. Absence of examples does not necessarily indicate good environmental