[en]On the one hand, the adoption of polluting technologies can enhance the factor productivity; on the other hand, pollution lowers the stock of human capital by weakening physical and mental performances, and short-ening the life expectancy at the end. To capture the impact of pollution on economic growth, we compute the optimal policy in an endogenous growth model `a la Lucas (1988) and we study the effects of pollution in the short and the long run.[/en]