Imagine being able to detect the faintest of radionuclide signals from hundreds of miles away. That’s the capability created by scientists at Pacific Northwest National Laboratory who have contributed much of the nuclear science that underlies an international monitoring system designed to detect nuclear explosions worldwide. The system constantly collects and analyzes air samples for signals that would indicate a nuclear explosion, perhaps conducted secretly underground. Incredibly, the system can detect just a small number of atoms from nuclear activity anywhere on the planet. In terms of sensitivity, the capability – in place for decades – is analogous to the ability to detect coronavirus from a single cough anywhere on Earth.