This study examines the Income Inequality and Health Hypothesis (IINH) in an environmental context across 27 OECD countries between 1990 and 2018. The Pooled Mean Group-ARDL (PMG-ARDL) model is employed to assess the joint short- and long-run effects of income inequality and CO₂ emissions on life expectancy (LE), controlling for health expenditure and mortality rates. The results indicate that income inequality significantly reduces life expectancy in the long run, while CO₂ emissions negatively affect LE across both short- and long-term horizons. Health expenditure is found to increase life expectancy in the long run. In addition, the Emirmahmutoglu and Kose (2011) panel Granger causality test shows that both the existence and direction of causal relationships among variables vary across individual OECD countries.
Pelin Gençoğlu (Thu,) studied this question.