Air pollution is a serious environmental issue that has been long recognized. Whereas government policies attempt to reduce air pollution by controlling various pollution sources, research on risk perception of air pollution tends to treat air pollution as a single unified risk and neglects the complication of the polluting sources. Previous research consistently demonstrates that lay people have an inaccurate understanding of air pollution and are unwilling to change their behaviors to decrease pollution. However, these findings can hardly be employed in policy making because researchers and policy makers treat air pollution differently. The aim of the present study is to obtain a nuanced understanding of people's risk perception of air pollution from different sources. Moreover, we propose a new risk dimension, Self-Relevancy, and try to understand people's reluctance to change their behaviors to reduce pollution. Three main findings emerged. First, we demonstrated that people perceived each air pollution source Downloaded by [Athabasca University] at 05:36 28 June 2016 ACCEPTED MANUSCRIPT ACCEPTED MANUSCRIPT 2differently. Second, factor analysis of risk characteristics showed that ratings of self-relevancy questions mainly loaded on the same factor, which indicates the robustness of the Self-Relevancy risk dimension. Finally, we found that people's ratings of Self-Relevancy positively predicted their perceived risk for some of the pollution sources. These findings highlight the importance of investigating sub-categories of risks and exploring the risk dimension of Self-Relevancy in future risk perception research to provide detailed and informative data for policy makers.