The US refining industry is a leading producer of sulfur oxide and nitrogen oxide emissions. As a result of the Clean Air Act, it has been subject to a host of environmental regulations that prescribe the production processes firms can employ and limits their emissions based on the permits they...

Demand for air quality depends on health impacts and defensive investments that improve health, but little research assesses the empirical importance of defenses. We study an important cap-and-trade market, which dramatically reduced NOx emissions, a key ingredient in ozone formation. A rich...