Dry powder inhalation, part 1: ancient history and precursors to modern dry powder inhalers.

Inhalation does not necessarily require active creation of inhalable aerosols, smokes or fumes. Inhaling 'healthy air' with volatile and gaseous components, or fine aerosols in pine forests, on volcano slopes and at the seaside must be considered as inhalation therapy too. From this viewpoint, inhalation therapy may have been much more common and widespread and have a longer history than is currently known from written evidence.