Now that classes are done, I have more time to blog and to scribble academic stuff. One new paper of mine (joint with Joel Schwartz) that I'm mildly excited about is titled: "Urban Air Pollution Progress Despite Sprawl: The “Greening” of the Vehicle Fleet". This paper uses a variety of California vehicle emissions data bases to explain why average vehicle emissions have been falling over time. Why is this interesting?
Your intuition tells you that as people grow richer and as more people move to California, California's urban air pollution will grow worse. More people, more cars driving more miles means more smog. But!!!, technological advance has reduced the average vehicle's emissions enough to offset these scale effects. I'm fascinated about this "battle" between capitalism's quantity effects versus its "quality" effects. My forthcoming book "Green Cities" spends a fair bit of time on this point.
Here is part of the Kahn and Schwartz Conclusion that merits future work:
By documenting the role played by technological advance and diffusion of technologies in reducing vehicle emissions, this paper touches on a broader theme in urban economics. Technological advance has reduced many of the social costs of city bigness. It has reduced both air emissions and noise emissions associated with urban economic activity. Information technology has allowed cities to start road pricing programs reducing the transaction costs of tracking which vehicle has entered what zone at what time. Like many big cities, New York City has used a spatial mapping program called “CompStat” to monitor the spatial distribution of crimes. This has allowed police forces to allocate scarce resources to troubled “hot spots” and holds police precinct commanders accountable for surprising crime trends.