In this study, we adopted a novel objective measure of attitude strength based on observable responses, and empirically tested the role of attitude strength in the relationship between environmental attitude and willingness to pay (WTP) for improving air visibility. We proposed the moderating role of environmental attitude strength in the relationship of environmental attitude to WTP, and empirically tested it in a survey on air visibility on a sample of 652 residents in Beijing, China. Our main finding was that the translation of environmental attitude into WTP was 61% less when the same level of environmental attitude was weakly held rather than strongly held. We also investigated the relationships of individual difference variables to environmental attitude strength, showing the interaction of value orientation, environmental knowledge, need for cognitive closure, and demographic factors.