•This study explores young people’s behaviour intentions to reduce PM2.5 in China.•The extended theory of planned behaviour model has been adopted.•Personal moral norm is significantly related to intention to reduce PM2.5.•The indirect effect of subjective norm is greater than direct effect. Fine particulate matter (PM2.5) emissions have attracted extensive attention because of their severe negative impacts on human health and the national economy. Promoting public participation in reducing PM2.5, especially among young people, is one effective manner in which to control PM2.5 emissions. The present study explores the determinants that influence young people’s behavioural intentions towards reducing PM2.5 using an extended version of the theory of planned behaviour (TPB), which incorporates personal moral norms. Additionally, this paper evaluates and compares the direct and indirect relationships between subjective norms and PM2.5 reduction intentions. This study was tested empirically using survey data collected from 425 respondents in China. The results revealed that young people’s attitude towards reducing PM2.5, the subjective norm, was that behavioural control and personal moral norms significantly affect PM2.5 reduction intentions. Furthermore, the indirect effects of subjective norms on PM2.5 reduction intentions via other determinants were 2.5 times greater than the direct effect. In addition, the results also validated the appropriateness of the extended theory of planned behaviour for exploring young people’s PM2.5 reduction intention. Based on the results, implications and future research directions are also discussed.