The dramatic growth in health expenditures is an important health policy concern worldwide. Therefore, understanding the factors that increase health expenditures provides policy makers with evidence for decision-making. We aim to examine long-term effects of carbon dioxide emission, urbanization rate and GDP per capita on health expenditures. This study investigates the effect of carbon dioxide emission, urban population, and GDP per capita on health expenditure for 21 OECD countries over the period 1992–2018. Panel ARDL Approach and Gengenbach, Urbain and Westerlund Panel Co-integration Test have been used in the article. Test results indicate the long-run relationship among health expenditure and carbon dioxide emission, urban population, and GDP per capita. Effect of carbon dioxide emission (CO₂), urban population, and GDP per capita is significant and positive on health expenditure. Rapid economic growths of OECD countries recently and environmental pollution have increased health expenditures in the long term.