While epidemiological investigations have documented elevated health harms associated with public injecting, further ethnographic research focused specifically on public injecting settings is required to develop greater understanding of how these environments influence the production of drug-related harm. We undertook preliminary ethnographic research, incorporating a structured environmental survey, observations and interviews with 50 local injectors, in Vancouver's Downtown Eastside (DTES). Our study aimed to document the physical locations and social context of public injecting settings, exploring how such venues interplay with injection-related health risks. Findings show that DTES public injecting locations comprise a large network of alleyways, which are often unsanitary and constrain efforts to inject in a hygienic fashion. Due to fears of being intercepted by the police, physically assaulted, or robbed, injectors are preoccupied with "hurrying and worrying" when injecting in public. Although individuals are concerned with matters of hygiene and avoiding infections associated with injecting, the perceived risks of public injection settings are primarily related to the presence of street predators and the police. Ecological features of public injecting environments serve to complicate the task of injecting, encourage 'rushing' during the injection process, and decrease the likelihood that public injectors will employ safer injecting practices. Future interventions must specifically target these micro risk environments. Innovative strategies are urgently needed to ensure that police operations in the open drug scene do not compromise public injectors' efforts to protect their health. Additionally, structural factors which perpetuate the large public injecting scene should be addressed through policy interventions that increase access to housing and public toilets as well as expanding the scope and capacity of the local drug consumption facilities.