最適環境與貿易政策──考慮不完全競爭的市場結構及跨國性汙染

Optimal Environmental and Trade Policies: A Case of Imperfect Competition and Cross-Border Pollution

This paper discusses the optimal environmental and tariff policies in the case where a country must choose among various alternatives designed to mitigate pollution level abroad. A greater tariff on foreign import will reduce the pollution level by decreasing the output. The optimal tariff ought to be lower on the import from advanced economy where anti-pollution policy is more rigorously enforced. Because the production activity often occurs in foreign countries where direct monitoring and control on pollution is necessary to lessen the production externalities. In this setting, a pollution tax imposed by foreign government is shown to be optimal in absence of coordination between two governments. In the presence of coordination, the optimal policy is indeterminate, i.e., it can be a tax or subsidy. 本文探討當存在跨國性污染時，本國如何制定最適環境與關稅政策，較高關稅可以降低污染程度，對於執行反污染政策愈嚴格的國家，應課予較低的關稅。在本國關稅固定的假設下，外國與本國政府若不進行合作，則外國會對廠商課污染稅，但在合作的情況下，外國可能課稅或補貼。

本文探討當存在跨國性污染時，本國如何制定最適環境與關稅政策，較高關稅可以降低污染程度，對於執行反污染政策愈嚴格的國家，應課予較低的關稅。在本國關稅固定的假設下，外國與本國政府若不進行合作，則外國會對廠商課污染稅，但在合作的情況下，外國可能課稅或補貼。