In America leafy greens are responsible for over a fifth of all food-borne illnesses (more than any other food), despite processing that often involves nasty chemicals and unpopular irradiation treatments. Dr Demokritou believes electrospraying could be used from farm to fork to reduce pathogens like E.coli, salmonella and listeria, as well as yeasts and fungi that cause food to spoil.

Thomas Webster, director of the Nanomedicine Laboratory at Northeastern University in Boston, is impressed with the preliminary results but says the main concern is toxicity. “You have to do a good job looking at these materials and not just in the lungs,” he says. Wider environmental effects have to be considered, and whether they kill friendly bacteria.

The researchers are now planning further safety tests and will also experiment to see if electrosprayed nanoparticles can be effective against viruses like influenza. Most nanoparticles might still be too toxic to use against bacteria within the body, but if they can reduce the chance of catching an infection in the first place, that is nothing to be sneezed at.