By bringing together work of two IIASA programs, we develop a more holistic insight into the impacts of environmental investments on human well-being. We link IIASA’s GAINS (greenhouse gas – air pollution interactions and synergies) model with the SEDIM model that explores the impacts of human capital on economic growth. We find that that environmental investments into air pollution control in developing countries have only very small net impacts on economic growth as improved health conditions will increase labour force and productivity. If measured with the Human Development Index, the large increase in longevity outweighs the small decreases in per-capita GDP.