ASSESSMENT OF LUNG DEPOSITION AND BREATHING RATE OF UNDERGROUND MINERS IN TAJIKISTAN

Deposited gamma ray activity in miners' lungs and airborne concentrati ons of Rn-222 decay products were measured in a metal mine in Tadjikis tan. Measurements for about 100 miners were performed, using filtered air samples to estimate their decay product exposures and a field gamm a ray system to determine corresponding chest activities. These two qu antities yielded the deposited lung activity per unit exposure, which is proportional to the product of the average minute volume and the fr actional lung deposition, called here the 'filtration ability of lungs ' (FAL). The group average FALs were found to be, for drillers, assist ant drillers, and inspection personnel, respectively, 0.0079, 0.0067, and 0.0052 m(3) . min(-1), with approximately 20% standard error. Inde pendent measurements were also made, for a group of mine workers engag ed in light work, not only of FAL, but also of breathing rate (minute volume), permitting estimation of the lung deposition fraction, found to average 0.34 +/- 0.03. Finally, this value was used together with t he group FALs noted to yield upper-bound estimates of the average minu te volumes for these job categories, respectively, 0.023 +/- 0.004, 0. 020 +/- 0.004, and 0.015 +/- 0.003 m(3) . min(-1).