least for local public goods like water and air quality, and the focus needs to remain on economic production.

The “pollute now and clean up later” argument suffers from a number of weaknesses. Indeed, there are several situations in which early action may be desirable.

First, it may be more economical to start reducing or preventing pollution at an early growth stage rather than incurring all the cleanup costs at later stages, even when discounting is taken into account. This question is related to the role of technology and infrastructure lock-in, and is particularly important in developing countries where most of the infrastructure will be built in the next decades.

Second, it ignores the role of environmental irreversibility. When reversal is not possible, investments in environmental quality protection are necessary over the short term. This is the case for example in Kenya, where traditional forests are destroyed for bio-energy or agriculture. It is possible to restore their “water tower” and other functions through replanting but not their bio-diversity and tourism industry potential.

Third, the influence of environmental quality and welfare is often indirect, so people may not link water or soil quality to the health issues they are confronted with.<sup>17</sup> Alternatively, populations may not internalize the public health benefits of a healthier environment. With better information on these indirect effects, they may ask for higher environmental quality at earlier stages of development. Public intervention may be needed to internalize the externality.

Fourth, even when they care (and evidence abounds that they do, given that they tend to be very vulnerable to environmental harm), poor communities may not have the “voice” to make their concerns heard. Implemented policies in developing countries may be more representative of the preferences of elites than those of the poor or reflect institutional constraints such as those imposed by poorly defined property rights (as in open access resources). More generally, it is difficult to infer preferences about collective goods from individual behavior. If cities offer many more jobs and opportunities than rural areas, but also much higher levels of local pollution, the fact that people move from rural areas to cities does not mean they would not prefer slightly less opportunities and higher environmental quality in cities. Their preferences are not completely revealed by the binary choice “moving or not to the city”, because they do not have a continuum of choices of increasing opportunities and decreasing environmental quality. More generally, this example shows the limits of inferring individual preferences from observed behaviors, justifying the use of other tools such as surveys.

Finally, empirical evidence suggests that the hump-shaped environmental Kuznets curve applies to local pollution with short-term and visible impacts, but rarely to natural resource depletion (water resources) which have a long-term component or to global pollutants such as greenhouse gases (which combine a long-term component with a global scale). It seems likely that local environmental issues with short term manifestations get solved spontaneously as countries develop (e.g., local air and water pollution),

> 17 In some case, even specialists debate the importance of these relationships.

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