The use of electrostatic probes as a diagnostic tool of the dust particles in the tokamak edge plasmas is investigated. Probe measurements of electrostatic fluctuations in the scrape-off layer of the Frascati Tokamak Upgrade revealed that some features of the signals can be explained only by a local non-propagating phenomenon. These signal features are shown to be both in qualitative and quantitative agreement with ionization, and consequent extra charge collected by the probes, due to the impact of micrometre-sized dust at a velocity of the order of 10 km s−1. Electron microscope analysis of the probe surface yielded direct support for such an interpretation.