“The smoky factory chimney is a favorite example simply because it appears to limit itself so conveniently to spreading dirt within a locality; the additional costs of keeping one's person and one's clothes clean in the polluted areas can easily be estimated and added to the private costs in order to yield an estimate of the social costs of production. The costs of water pollution by one or more factories is also amenable to calculation of this sort since the authorities usually have estimates of the damages being caused and of the higher costs of alternative sources of pure water. Some of the simpler nuisances, on the other hand, such as excessive engine noise and emission of noxious fumes, may be tackled most economically by enacting compulsory noise-muffling measures and compulsory installation of anti-fume devices, as in several states of the US. However, more general social afflictions such as industrial noise, dirt, stench, ugliness, urban sprawl, and other features that jar the nerves and impair the health of many are difficult both to measure and to impute to any single source -- which is, of course, no reason for treating them with resignation.”