An investigation of environmental Kuznets hypothesis in Asian Productivity Organization (APO) using three air pollution indicators.

The threat of climate change over the past decades has become more prominent among environmental experts. As a result, economists and environmental researchers are more likely to pursue environmentally-friendly economic growth. The present study examines the variables of open trade, population, GDP, and its square to study the Kuznets environmental hypothesis regarding carbon dioxide, methane, and nitrogen oxide emissions in three separate equations, which have, to the authors' best knowledge, been rarely addressed in the literature. The study period was from 1990 to 2016 conducted on 20 countries in the Asian Productivity Organization (APO). This hypothesis has not been studied regarding air pollution among APO members states. The panel ARDL method was used regarding the panel data applied for the structure of the research data. According to the results, the Kuznets environmental hypothesis was approved as reversed U for carbon dioxide and methane gases in the long run, but not for nitrous oxide. The short-term results also indicate the rejection of the Kuznets environmental hypothesis among the studied countries. The variable of trade had a negative correlation with the emission of all three greenhouse gases. Also, the earning elasticity estimated for CO2, N2O, and CH4 at 0.4, 0.38 and 0.04, respectively show that the effect of GDP growth on CO2 emissions is higher than that of N2O and CH4 emissions, indicating the importance of CO2, which causes more air pollution than other greenhouse gases and will have an important impact on the quality of the environment. Therefore, it is recommended to consider more measures for curbing carbon dioxide than for other greenhouse gases to prevent its emissions. [ABSTRACT FROM AUTHOR]