Between 1948 and 2001, uranium mining in France produced around 163 million tons of mine tailings—waste material left after extracting valuable minerals. Nearly half of these tailings were placed in the Limousin region, where they were commonly used as fill material for parking lots, schoolyards, rural roads, and private gardens. These materials contain residual radioactivity and continue to emit radon, an invisible, odorless, and radioactive gas that can seep through asphalt and concrete, leading to dangerous levels of radiation exposure. Notably, radon levels exceeded safety thresholds in kindergarten schools in Bessines (1991) and Limoges (1997), raising concerns about public health. At the time, these tailings were treated as ordinary fill materials, no more hazardous than gravel or dirt. As a result, they were widely used to stabilize the ground, fill in depressions, or serve as foundations for public buildings, including kindergartens. It wasn’t until systematic radiation measurements were conducted in these areas that the risks became apparent. Radon is produced by the natural decay of uranium and its byproducts, which remain in the rock even after the main ore has been extracted. The gas can pass through surfaces and accumulate in poorly ventilated spaces, such as basements or ground-level classrooms, increasing the risk of long-term exposure. Limousin, especially the Haute-Vienne department, has the highest concentration of this issue in France due to the region's long history of uranium mining. The Bellezane storage site, for example, highlights the limitations of early containment efforts, as some radioactivity has seeped into the surrounding environment. Additionally, it is estimated that approximately 176,000 barrels of contaminated "yellow cake"—a concentrated uranium compound—were scattered across Limousin and other regions after the mines gradually closed. This practice was not limited to Limousin. In the Morbihan region, tailings from ten of the twenty-six mines operating until the 1980s were also used as fill material in four communes. An official circular later acknowledged that this use was widely accepted at the time, though it was eventually banned in 2002. This admission shows that the practice was widespread and accepted for decades across France’s mining areas. In response to growing concerns from environmental groups like CRIIRAD and France Nature Environnement, the former mining company, now known as Orano, has been conducting systematic identification of affected areas. A government directive has mandated the inventory of all potentially contaminated locations, relying on a public database managed by the Institute for Radiological Protection and Nuclear Safety. Each suspected site—parking lots, farmyards, or public buildings—is tested for radiation levels, and if high readings are confirmed, decontamination efforts are initiated. These may involve removing the contaminated material or covering it with an insulating layer to block radiation, all under the supervision of the Nuclear Safety Authority. Despite these efforts, the project remains far from complete, even thirty years after the first warnings. The contrast between the unassuming appearance of a parking lot or schoolyard and the hidden dangers beneath has become a key takeaway from this issue. What was once considered harmless fill material is now recognized as a legacy of industrial activity, with its full impact still being assessed. As investigations continue, the question lingers: how many of these seemingly ordinary places still require identification and cleanup?