What is a feasible and efficient policy to regulate air pollution from vehicles? A Pigouvian tax is technologically infeasible. Most countries instead rely on exhaust standards that limit air pollution emissions per mile for new vehicles. We assess the effectiveness and efficiency of these...

This paper provides the first causal evidence that hostile activities online lead to physical violence. Given the recently documented relationship between pollution and social media, I exploit exogenous variation in local air quality as the first step to instrument for online aggression. In an...

Carbon leakage provides an efficiency argument for unilateral climate policy to differentiate emission prices in favor of emission-intensive and trade-exposed sectors. At the same time, differential emission pricing can be (mis-)used as a beggar-thy-neighbor policy to exploit terms of trade....