Revisiting the environmental Kuznets curve: Evidence from West Africa

This paper analyzes the revenue-pollution relationship by revisiting the Environmental Kuznets Curve (EKC) hypothesis for West African countries over the period of 1980–2014. The study approximates the income measurement by GDP per capita and uses carbon dioxide (CO2), nitrogen oxide (NO2), and methane emissions as various environmental quality measures. The paper uses parametric and non-parametric estimation techniques to test the EKC hypothesis. The results support the existence of the U-inverted relationship between income and methane emission, on one hand, and between income and nitrogen dioxide emission on the other. The estimates also show a mixed result for the U-inverted hypothesis between income and carbon dioxide emissions. Thus, the verification of the curve depends on the estimation techniques and the measurement of the pollutant used. The obtained results led to the conclusion that the EKC hypothesis is validated for West African countries.