The aim of this study is to examine the effect of green investments on air quality for developed and developing European countries. In this context, the short- and long-term effects of green investments on air quality were examined by panel generalized method of moments (GMM) and panel causality method. As a result of the GMM analysis, it has been determined that green investments negatively affect the air quality for both developed European countries and developing European countries in the short term, but this effect turns positive in developed countries in the long term. As a result of the panel causality analysis, two-way causality was determined between air quality and green investments.