R iver pollution represents a classic negative externality that spills across political boundaries. The source region generates emissions that pollute the river, but social costs are borne downstream. In cases ranging from Western Europe to China, empirical studies have documented significant free riding along interjurisdictional river boundaries (Cai, Chen, and Qing 2013;Sigman 2002Sigman , 2005and Sandler 2006). 1 Sigman (2002) compares pollution in domestic and international rivers. She finds that stations immediately upstream of international borders have higher levels of biochemical oxygen demand (BOD) than similar stations elsewhere. Gray and Shadbegian (2004) find that near the Canadian-United States border BOD discharges are higher and that fewer inspections take place. Using Toxic Release Inventory data from 1987to 1996, Helland and Whitford (2003 show that facilities' water emissions are higher in counties that border other states. Sigman (2005) finds that free riding gives rise to a 4 percent degradation of water quality downstream of authorized US states. Lipscomb and Mobarak (2013) exploit a Brazilian natural experiment in which county borders are redrawn frequently and consequently changes strategic polluting behavior around borders. They conclude that solutions to cross-boundary spillovers require active regulatory involvement by upper-level governmental officials.

No abstract

Cover: A transmission electron microscope image of microgel particles that consist of welldefined temperature-sensitive poly(N-isopropylacrylamide) cores with pH-sensitive chitosan shells is shown. The microgels are obtained directly from aqueous graft copolymerization of N-isopropylacrylamide and N,N-methylenebisacrylamide from chitosan. The unique coreshell nanostructure exhibits tuneable responses to pH and temperature.Further details can be found in the Communication

No abstract

China’s urbanites continue to be exposed to high levels of air pollution. Such pollution exposure raises mortality risk, lowers the day-to-day sentiment of the population and lowers outdoor worker productivity. Using a unique set of data for Chinese judges, we document that local air pollution also lowers the productivity of high skilled government officials who work indoors. Our new evidence on the effects of air pollution highlights both the challenge that pollution poses for quality of life and workforce productivity and indicates that the Chinese urban elites gain co-benefits when their cities burn less fossil fuel.