As the common saying goes: All's well that ends well. This research was the first to explore whether the end effect could be observed in the perception of air pollution and further examined the effect of perceived difference on the end effect. In Experiment 1, participants went through a short trial of 30 severe air pollution pictures and a long trial of 45 pollution pictures containing 15 extra moderate pollution pictures at the end. The results showed preference for the long trial as well as more willingness to experience it again, which verified the end effect. In Experiment 2, the long trial was adjusted to 45 severe air pollution pictures, which caused the end effect to disappear. In Experiment 3, it was confirmed that perceived difference had an impact on the end effect, as the end effect worked when subjects cognitively focused on the variated pollution extent but disappeared when they focused on the air pollution quality. These results advance our understanding by directly demonstrating the influence of perceived difference on the end effect as well as providing a useful view to intervene in people's perception of air pollution. Further theoretical and practical implications are discussed.