We present the first real attempt to directly and continuously measure GEM through a Lumex RA-915 M,designed for real-time detection of mercury vapor, mounted on an UAV (Unmanned Aerial Vehicle, namely aheavy-lift octocopter), inside and outside the former Hg-mining area of Abbadia San Salvatore (Mt. Amiata,Italy), known as a GEM source. We tested the effectiveness of the UAV-Lumex combination at different heights inselected sites pertaining to both mining facilities and surrounding urban zones, shedding light on the GEM spatialdistribution and concentration variability. The Lumex great sensitivity and the octocopter optimal versatility andmaneuverability, both horizontally and vertically, allowed to depict the GEM distribution in the atmosphere upto 60 m above the ground. The acquisition system was further optimized by: i) synchronizing Lumex and UAVGPS data by means of a stand-alone GPS that was previously synchronized with Lumex; ii) using a verticalsampling tube (1.20 m high) connected to the Lumex inlet to overcome the rotors strong airflows and turbulencethat would have affected GEM measurements; iii) supplying the octocopter with batteries for power supply to