时间：2023-04-26
中文摘要：
机动车限行政策根据机动车牌照的尾号决定车辆哪天能上路。这篇论文评估了河南省各地市从2017年至2019年间的限行政策对空气污染的影响。作者记录了市政府宣布限行时是否宣布了解除限行的日期，并以此对限行城市进行了划分。作者为限行政策起止日期的外生性提供了一些支持性的证据，同时，运用双重固定效应模型，发现了限行有效性的显著的异质性。在常态化限行的城市，限行减少了颗粒物浓度，但在临时采用限行的城市却没有影响。为了从理论上解释这一不同，作者构建了一个简单的经济学模型，推演出针对当地居民的两个假设：第一，常态化的限行政策更能促使当地居民采用一个具有高固定成本的替代开汽油车的出行方式，以减少通勤时间；第二，限行只能作为应对临时采用的限行政策的短期解决方式。在理论上，这两类规避限行的行为均能影响限行减少空气污染的有效性。论文证实了公共政策的期限和人们对此期限的预期能够决定政策的有效性。
研究意义：
限行能否减少空气污染？什么样的限行能减少空气污染？中外学者尚未在这两个问题上达成一致结论。文章为更好的回答这两个问题做出了两点贡献：第一，与多数文献一次只研究一个限行城市的做法不同，文章把多个限行城市纳入了统一的分析框架，对比分析了限行的有效性；这些限行城市充分的代表了限行有效性的各种潜在驱动因素可能存在的各类表现，让确定限行有效性的主要驱动因素成为可能。第二，文章提出了限行常态化这一限行有效性的潜在驱动因素，并以限行为例展示了公共政策常态化在政策有效性中可以扮演的角色。
The Effect of China’s Driving Restrictions on Air Pollution:
The Role of a Policy Announcement Without a Stated Expiration
Resource and Energy Economics, Vol. 72, 2023, Article 101360
Wenbo Li
Abstract:
Driving restrictions keep cars off the street largely on the basis of the last digit of the license plate number. This paper evaluates how different driving restriction policies affected the air quality of the 17 cities in Henan, one of China's most populous provinces, from 2017 to 2019. I offer a novel way to categorize driving restrictions by making a distinction between cities that announced driving restrictions without a stated expiration and other cities that announced driving restrictions with a stated expiration. I provide some suggestive evidence on the exogeneity of timing, and using two-way fixed effects, I find significant heterogeneity in policy effectiveness. The policy reduced particulate matter concentration in cities that announced driving restrictions without a stated expiration, but had no effect in cities that announced driving restrictions with a stated expiration. To explain this difference, I build a model, which implies that driving restrictions announced without a stated expiration can induce people to pay a high fixed cost in exchange for a low transit time and not to choose non-compliance, two behavioral changes with the potential to further reduce air pollution. Thus, managing the duration of a policy and people's expectations of its duration can matter crucially for the policy's effectiveness.
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