This study investigates the position of the environmental Kuznets curve in 25 OECD countries for three pollutants (SO<sub>2</sub>, NO<sub>2</sub> and CO) and analyses the impacts of Environmental Policy Stringency and energy consumption per capita on the environmental quality. Therefore, the originality of this paper lies in the attempt to better understand theoretically and empirically the specificities of the concept related to the environmental Kuznets curve. The study used a dynamic panel model with the system Generalized Method of Moments (GMM) estimator and an autoregressive distributed lag (ARDL) model with alternative panel estimators. We consider that the results of this paper are very interesting. The found results confirm that: i) firstly, the Environmental Kuznets Curve (EKC) hypothesis is well supported for all three major pollutant emissions in OECD. ii) Secondly, the positive effects of energy consumption on various pollutant emissions are confirmed. iii) Finally section analyses the Environmental Policy Stringency negatively effects the pollutant emissions. We consider that the results of this paper are very interesting, The policy instruments will help in realizing a balanced environment. Public authorities are encouraged to implement more and more of the regulatory instruments to protect the environmental quality.