In principle, counterfactual claims cannot be refuted. When inhaled, aromatic substances “could” improve lung function (or protect against hair loss, pimples, sweaty feet, etc.). There is no evidence that harmless food flavors turn into dangerous toxins when inhaled rather than consumed.
Quoted from: KARL FRANZENS UNIVERSITY GRAZ INSTITUTE OF PHARMACEUTICAL SCIENCES - Pharmacology and Toxicology - Head: 0. Univ.-Prof. Dr. Bernhard Michael Mayer