Background One key structural dimension in the distribution of drug-related harm associated with injecting drug use is the injecting environment. Epidemiological evidence associates elevated blood-borne viral risk with injecting in ‘public’ and ‘semipublic’ environments. Yet the quality of evidence on public injecting and related viral risk is variable, and is lacking in many countries such as the United Kingdom. Aim This commentary considers the micro-injecting environment as a critical dimension of risk, exploring the need for ‘safer injecting environment interventions’. Methods We draw upon published research evidence and qualitative case examples. Results We note the limits in epidemiological evidence on public injecting and emphasize the need for ethnographic research to determine the ‘social relations’ of how drug users and risk practices interact with injecting environments. We identify three main forms of ‘safer environment intervention’: purpose-built drug consumption rooms; interventions within existing spatial relations; and spatial programming and urban design. While drug consumption rooms find evidence-based support, they are not a panacea. We emphasize the potential of interventions embedded within existing spatial and social relations. These include low-cost pragmatic interventions enhancing facilities and safety at public and semipublic injecting sites and, primarily, peer-based interventions, including peer-supervised injecting sites. We caution against spatial programming and urban design interventions which can cause the displacement of socially marginalized populations and the redistribution of harm. Conclusions Public health interventions in the addictions field have in the past focused upon individual behavioural change at the cost of social interventions and environmental change. We wish to focus greater attention on reducing risks related to public injecting and encourage greater debate on ‘safer environment interventions’ in harm reduction. (Authors)