Finally, Holzinger et al. (2008) observed a rapid convergence of environmental policy between 1970 and 2000. Growing international interdependence has led the environmental policy of industrialized countries to more resemblance, comprehensiveness and rigour. International harmonization and communication within international institutions appear to play an important role in the convergence of environmental policies. The development and strengthening of international standards could therefore help mitigate the negative effects of trade on carbon. “The United States and our trading partners will benefit if trade is open, transparent, regular, and fair, and respects labor and environmental standards.” — President Obama, May 6, 2009, of the proclamation of World Trade Week 2009. Analytical reports: oecd Trade and Environment Working Papers The second hypothesis is called the factor endowment (FEH) hypothesis. Based on this assumption, trade flows are determined by the quantity and nature of resources held by trading partners, which corresponds to the Heckscher Ohlin Vanek theory of comparative advantage. Developed economies are often endowed with physical capital, while emerging countries are generally endowed with labour capital.
 For this way, developing countries tend to produce more labour-intensive goods, while developed countries tend to produce more capital-intensive products, which require more energy consumption (Copeland & Taylor 2013). As a result, free trade agreements can cause more pollution to industrialized countries. Johnson, P.M., &Beaulieu, A. (1996). Environment and NAFTA: understanding and implementation of the new continental legislation. Presse-l`île. Nemati et al (2016) empirically examined the relationship between free trade agreements and GHG emissions depending on the nature of the agreement. To this end, the authors focus on three case studies: mercosur, an agreement signed only between developing countries, NAFTA, where the parties are both developed and developing countries, and the Australian-American Free Trade Agreement (AUSFTA) which was signed only between industrialized countries. They found that free trade agreements signed only between developing countries (MERCOSUR) or only industrialized countries (AUSFTA) each have a positive effect and do not have environmental damage to the global environment.
However, NAFTA has increased global greenhouse gas emissions and supported PHH.  Based on a gravity framework, Yao et al (2019) found a positive influence of free trade agreements on bilateral carbon dioxide pollution. In addition, the authors find mixed evidence of free trade agreements when conducting an income-based country-by-country analysis. The agreements appear to be beneficial to high-income countries, while they are detrimental to the environment of high- and low-middle-income economies. The first hypothesis is the Pollution Haven (PHH) hypothesis, developed by Johnson and Beaulieu (1996). This assumption assumes that as a result of a free trade agreement, developing countries will have more pollution due to their lax environmental legislation, given that polluting industries will be relocated from countries subject to strict environmental rules to developing countries. . .