Still Your Grandfather’s Boiler: Estimating the Effects of the Clean Air Act’s Grandfathering Provisions
研究了美国清洁空气法案中针对新旧锅炉的差异化规制（祖父条款）如何导致老旧锅炉延迟退役、增加运行时间，并造成高达25亿美元的年度社会损害。
While vintage differentiation is a highly prominent feature of various regulations, it can induce significant biases. We study these biases in the context of New Source Review—a program within the US Clean Air Act imposing costly sulfur dioxide (SO2) abatement requirements on new boilers but not existing ones. Leveraging a novel dataset covering state-level SO2 regulations, we show that the regulatory differentiation decreased the probability of a grandfathered boiler retiring in a given year by 2.4 percentage points (i.e., 60% smaller) and increased their operations by around 1,150 hours annually. Conservative back-of-the-envelope calculations suggest annual societal damages of up to $2.5 billion associated with additional SO2 emissions caused by delayed retirements, higher utilization, and higher emission rates in the years considered. The results imply that long after their passage and in the presence of many subsequent, more stringent environmental policies, grandfathering provisions continued to have strong perverse impacts.