Maxim Massenkoff asks a very good question. If pollution reduces birth weight as much as the micro studies on pollution suggest, why aren’t birth weights very low in very polluted cities and countries? Figure 1, for example, shows birth weights in a variety of highly polluted world cities. The yellow dashed and blue lines show “predicted” birth weights extrapolated from the well-known Alexander and Schwandt “Volkswagen study” which looked at the effects of increased pollution in the United States. Despite the fact that every one of the highly-polluted cities is much more polluted than the most polluted US city, birth weight is not tremendously lower in these cities. Indeed, there is no obvious correlation between birth weight and pollution at all.