In this paper we analyse the reasonings that people deploy in explaining and rationalising their behaviour in relation to the collective environmental and health-risk problem of urban air quality. We draw on an empirical study of public perceptions of air pollution to identify a range of 'vocabularies of motive' or discourses that serve to move responsibility to act away from the individual and onto other groups. We consider how far each of these 'vocabularies' can be interpreted as a mode of blaming, and draw conclusions linking our analysis to wider relational and moral tensions. Our analysis suggests that blame, although conceptually powerful, falters under empirical scrutiny. On this basis we argue for a more sensitive reading of responsibility discourses in academic debate and enquiry. Conclusions and policy implications are developed, linking our interpretation to the (confrontation of) wider relational and moral tensions, which characterise collective-risk situations.