Sulphur-gas concentrations in volcanic and geothermal areas in Italy and Greece: Characterising potential human exposures and risks

Passive samplers were used to measure the atmospheric concentrations of SO2 naturally emitted at three
volcanoes in Italy (Etna, Vulcano and Stromboli) and of H2S naturally emitted at three volcanic/geothermal
areas in Greece (Milos, Santorini and Nisyros). The measured concentrations and dispersion patterns varied
with the strength of the source (open conduits or fumaroles), the meteorological conditions and the area
topography. At Etna, Vulcano and Stromboli, SO2 concentrations reach values that are dangerous to people
affected by bronchial asthma or lung diseases (>1000 μg m−3). H2S values measured at Nisyros also exceed
the limit considered safe for the same group of people (>3000 μg m−3). The data obtained using passive
samplers represent time-averaged values over periods from a few days up to 1 month, and hence concentrations
probably reached much higher peak values that were potentially also dangerous to healthy people. The
present study provides evidence of a peculiar volcanic risk associated with tourist exploitation of active
volcanic areas. This risk is particularly high at Mt. Etna, where the elderly and people in less-than-perfect
health can easily reach areas with dangerous SO2 concentrations via a cableway and off-road vehicles