Pollution and city size: can cities be too small?
研究了城市系统模型中污染与城市规模的关系，发现当污染是全局性的且人均污染随城市规模下降时，大城市可能规模不足，对美国城市的校准显示最大城市可能偏小3-4%。
Abstract We study optimal and equilibrium sizes of cities in a city system model with pollution. Pollution is a function of population size. If pollution is local or per-capita pollution increases with population, equilibrium cities are too large under symmetry; with asymmetric cities, the largest cities are too large and the smallest too small. When pollution is global and per-capita pollution declines with city size, cities may be too small under symmetry; with asymmetric cities, the largest cities are too small and the smallest too large if the marginal damage of pollution is large enough. We calibrate the model to US cities and find that the largest cities may be undersized by 3–4%.