For the past five years, the Pyhäsalmi mine in central Finland has been using passive high-frequency RFID tags to record when workers enter or leave a mine shaft. Since that time, says Kimmo Luukkonen, the mine's managing director, the technology has improved management's visibility into who is underground and when, and hence has increased its safety program's efficiency and accuracy. The company plans to expand that RFID solution to monitor who carries explosive detonators into the mine.