中文摘要
氮氧化物（NOx）是近地面臭氧的前体物；近地面臭氧是一种危害人类健康和生态系统的有害污染物。尽管历经数十年的监管，NOx排放量也急剧下降，但间歇性高臭氧事件仍使许多地区无法达到空气质量标准。理论上，与统一排放价格相比，在空间或时间上实行差异化排放价格可以更具成本效益地减少此类事件。为检验这一预测，我们利用美国环境保护署（EPA）和美国国家海洋和大气管理局（NOAA）2001—2019年的数据，采用新颖的实证策略估计：（1）每小时排放量与高臭氧事件之间的联系；（2）每小时边际减排成本。这些估计构成了比较统一排放定价与差异化排放定价模拟分析的基础。与经济理论一致，差异化定价在减少高臭氧事件方面的成本效益显著更高，但这一优势取决于所估计的NOx—臭氧关系的准确性。仅在日间实施排放定价，可以比统一排放定价以低42%的成本实现同等幅度的臭氧事件削减；按发电厂和一天中的不同时段实行差异化排放定价，则可以以低88%的成本实现同等幅度的削减。
Abstract
Nitrogen oxides (NOx) are a precursor to ground-level ozone, a pernicious pollutant that is harmful to human health and ecosystems. Despite decades of regulations and a precipitous decline in NOx emissions, episodic high-ozone events prevent many areas from attaining air quality standards. Theoretically, spatially or temporally differentiated emissions prices could be more cost effective at reducing such events than a uniform price. To test this prediction, with data from EPA and NOAA spanning 2001–2019, we use novel empirical strategies to estimate (1) the link between hourly emissions and high-ozone events and (2) hourly marginal abatement costs. These estimates form the basis for simulations that compare uniform and differentiated emissions pricing. Consistent with economic theory, differentiated pricing is substantially more cost effective at reducing high-ozone events, though this advantage depends on the accuracy of the estimated NOx–ozone relationship. A daytime-only emissions price can achieve the same ozone-event reductions as a uniform emissions price at 42 percent lower cost; an emissions price that varies by power plant and hour of the day can achieve the same reductions at 88 percent lower cost.