Geological exploration of the shafts of ancient Laurion silver mines (Attica, Greece) have been carried out yearly since 2002, research being concentrated on the Spitharopoussi area. Among these shafts, remarkable for their regularity, are some which are vertical and deeper than 80m. Observations raised the problem of identifying the technology used to achieve sufficient circulation of air for respiration when sinking these shafts. This question is far from being answered in detail, and even the special case of a single vertical shaft has not previously received due attention. Our initial purpose is to establish what means were required to permit respiration below a certain depth in both winter and summer seasons. We then describe the two most common shaft types already explored, partitioned and twisted, and then some other oddly-shaped shafts. Finally, as work in progress, we report the measurements which are currently being recorded on site in order to develop further theoretical and numerical approaches.