There is no optimal environmental standard existing for entire world now because each nation would has different social priorities and environmental objectives and lastly it is costly and inefficient to impose environmental standards across the world. The nations could impose additional import tariff on environment polluting commodities which could stimulate the producers to improve the production process more eco-friendly and cleaner in order to avoid the extra tax. Furthermore, the importing nations could gain tax revenue from the exporter to disburse protection cost to the economy. Moreover, to avoid the protection cost, the nation could use the administrative and regulation to impose on imported commodities which dirty commodities could not be passed through the borders.