Specifically, a team from the University of Bath and King’s College London believes that the gas could be used to treat difficult nail infections. One common nail infection, called paronychia, occurs when bacteria enters the skin through the cuticle or nail fold. Topical treatments that are applied right on the nail are safer, but can sometimes take years to work. Hydrogen sulfide, a small and naturally occurring gas that is known for that “rotten egg” smell, offers a potential new treatment. In lab tests, the team used a chemical that releases the hydrogen sulphide gas into the nail.