Highly-concentrated gaseous ozone of 15 vol% was produced from an ozone-oxygen mixture (5 vol%), generated from a pure oxygen-fed discharge ozonizer, by using silica-gel as an adsorbent. The nonwoven fabrics of stainless steel fiber were treated with 15 vol% gaseous ozone for 60 min. As a result of the ozone treatment, the total amount of metal ions dissolved from the ozone-treated stainless steel fiber during immersion in pure water decreased by 70% compared with that from non-ozone-treated stainless steel fiber. X-ray photoelectron spectroscopic analysis showed that Fe and O were enriched...