 Deep inside this concrete labyrinth, a linear accelerator is creating radiation which is used to battle some of the world's most toxic pollutants. Electron beams are already a proven tool for treating industrial wastewater, such as from the textile dying industry. Many complex chemicals cannot be broken down by bacteria in the normal wastewater facilities so they are very hard to dispose of. However, electron beams are powerful and effective in breaking down their chemical bonds allowing us to discharge them very safely. This technology can also be used to clean even more toxic materials. For example, in Slovakia, a channel contaminated with the cancer-causing chemicals known as PCBs is feeding into the huge lake Zemplin. Medical scientists who have been using e-beams to sterilise medical equipment have now set their sights on a more ambitious goal. We want to use the irradiation to clean the polluted mud before it gets to the lake. We are bringing samples of the mud to our laboratories, irradiating it and we are already seeing strong results. The team hopes that irradiating the contaminated river mud on site will stop the slow trickle of pollution into the lake. Using e-beams for treating the most tenacious industrial pollutants is fast, effective and ecologically sound and could offer a sustainable solution for governments and industries.