The observation of GEM depletion in dilute volcanic plumes has important implications for the atmospheric Hg budget and Hg deposition pathways, regardless of the underlying physical and chemical mechanisms, and regardless of whether GEM was converted into GOM or PBM within the plume. As both GOM and PBM are water-soluble and have atmospheric lifetimes significantly shorter than that of GEM, such a conversion would lead to larger Hg deposition and Hg exposure in regions close to degassing volcanoes. This is concerning, as it has been estimated that ~15% of the world's population lives within less than 100 km of a Holocene volcano (i.e. a volcano that has been active in the last ~10 000 years; Stand 2015) 110 .