Our study shows that perception- and attitude-related -variables, i.e. environmental concern, sensitivity and the ability to relax in polluted places, significantly affect the WTP estimates for both types of pollutants. These variables explain to some degree the differences in WTP estimates between countries. This stresses that benefit transfer from studies in one country to another should be performed with great care. In addition, the type of information provided (vignettes) influenced the WTP estimates. Qualitative information indicated higher WTP estimate for air pollution than for noise. In contrast, and contrary to expectation, avoiding a half year shorter life expectancy due to air pollution was valued lower than a 13% increase in severe annoyance by noise. The more policy relevant scenario of combined effects showed little difference between pollutants.