Impact of comminution and resuspension of tephra by vehicular activity on ambient PM10 levels in urban areas: insights from a pilot experimental study on Mt. Etna volcano, Italy

Abstract

Fine volcanic ash can have an adverse health impact. It is readily produced during explosive eruptions but also can be generated in large quantities by secondary processes. We evaluated the production and resuspension of sub-10 μm volcanic particulate matter (PM 10 ) by road traffic as these processes may generate an increased respiratory exposure hazard. We conducted experiments on the slopes of Etna volcano, where we drove with a small SUV-type car over an area of road artificially covered with tephra and investigated the resulting grain size distribution (GSD) and concentration of PM 10 in the air as a function of (1) the number of car passages, (2) the starting thickness of the tephra deposit, and (3) vehicle speed. Our data show that increasing the number of car passages, deposit thickness, and vehicle speed rapidly induces a decrease in the GSD of tephra deposits and results in increased airborne PM 10 . We show that vehicles will cause comminution (i.e., reduction to a smaller average particle size) and resuspension of basaltic ash, so local communities can expect that, after an eruption, concentrations of PM 10 may increase with time and affect exposures close to roads.

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