Relation of body mass index and waist-to-height ratio to cardiovascular disease risk factors in children and adolescents: the Bogalusa Heart Study. Freedman DS, Kahn HS, Mei Z, Grummer-Strawn LM, Dietz WH, Srinivasan SR, Berenson GS. [PubMed-indexed for MEDLINE].
Smelling salts release ammonia (NH3) gas, which triggers an inhalation reflex (that is, causes the muscles that control breathing to work faster) by irritating the mucous membranes of the nose and lungs. Although these hypothetical mechanisms have been discussed, it is likely that smelling salts are not effective.
My understanding of epsom salts would be no. Epsom salts are reported to have therapeutic value in relaxing muscles and joints because of their mineral content that is different from other types of salt. And like any salt, they do have some detoxifying qualities but only at the skin level, which is why your skin could feel dry afterwards.