This article examines the politics of formal representations of environmental hazards. Certain environmental hazards are made publicly invisible when their formal representations are misaligned with what can be measured in practice under the existing socioeconomic and technoscientific conditions. Conversely, better aligning formal representations and measurement capabilities helps reveal the scope of such hazards. Such (mis)alignment of formal representations is a relative, dialogical, and historically specific process. It requires not only experts and their specialized knowledge, but also contextual knowledge of the actual local conditions. The work of alignment of formal representations requires public ?un-black-boxing? of these formalisms. It also depends on much infrastructural work, which I describe as the invisible work of making visible. (Mis)alignment of formal representations is illustrated here with the examples of three successive concepts of radiation protection in Belarus, a former Soviet Union republic that was covered with much of the Chernobyl fallout. Revisions to the radiation protection concept first expanded and then dramatically shrank the scope of the officially recognized and publicly visible radioactive contamination in Belarus.