'Public concern', a ubiquitous notion used in descriptive and explanatory modes by policy makers, academics and the media, is often presented as axiomatic. However, the variability with which it is deployed in different contexts, for example, as justification for policy attention or having equivalence with what is considered 'newsworthy', belies this status. This article presents an empirical analysis of emails and phone calls from the UK public to UK government agencies, reporting suspected cases of ash dieback disease - a tree health issue which attracted intense media and policy attention in the United Kingdom in 2012. We challenge the view that public attentiveness is necessarily indicative of public concern, or that media attention can be taken as its proxy. Examination of concern at macro and micro levels reveals heterogeneous processes with multiple dimensions. Understanding the nature of public concern is crucial in enabling more effective policy development and operational responses to risk-related issues.