The current situation of haze and PM 2.5 has been heavily discussed in Thailand. The problem causes adverse effects on the lives and health of the citizens. The causes of the problem include internal and external factors. The internal factors, among others, consist of wildfires, daily routine emissions, and the burning of agricultural fields. The transboundary haze is primary concern for the external factor. The state needs to carry out domestic environmental measures to reduce and prevent internal emissions together with establishing international collaboration with neighbouring countries to tackle the transboundary haze. There have been studies of environmental law in international dialogues and domestic laws to develop
national environmental laws and policies. Geneva Convention on Long-range Transboundary Air Pollution is one of the models for international collaboration whereas the Clean Air Act of 1990 of the United States exemplifies national air pollution control and management. Studying these laws does not benefit only to the language competency, but also provide advantages to broaden the perspective on the principles and practices of both environmental laws.