Over the past twenty years there has been a deadly resurgence of coal workers' pneumoconiosis (CWP), commonly known as black lung disease. While increased prevalence of the disease is alarming, these data only capture cases where CWP has been officially recognised. We argue that many more cases of the disease are going unreported. Drawing from contested environmental illness literature, we examine issues surrounding diagnostic uncertainty and medical surveillance. We draw from qualitative data on black lung that includes in-depth interviews, observation and document analysis. Findings indicate ongoing ambiguity and contestation over diagnosis of the disease, ranging from clinical and legal debates to concerted efforts to limit official recognition. While health screenings are currently available to miners, our results indicate low participation rates based on disincentives for early detection, logistical problems, and economic fears. Miners fear workplace discrimination and retaliation for participation in black lung screening programmes. Implications for public health policy and future research are discussed.