Introduction: Exposure to radon gas, with about two-third of background radiation, is considered as the greatest source of community irradiation, which increases the risk of lung cancer with Alpha radiation, so as it is recognized as the second cause of lung cancer in the US after smoking. Although radon evaluation has been carried out in Europe more than the developing countries, measuring radon concentration in the mines is being increased worldwide such as Ghyasy, Ishimori, Fisne and Kobal's studies in the lead mines. Since there are a noticeable number of mines as well as mine staff in Yazd province, the present study aimed to determine the concentration of radon gas in the lead and zinc mines in Yazd.

Materials and Methods: In this analytical-cross sectional field study, the radon concentration of radon of three zinc and lead mines were measured in Yazd province via active method using RAD7 device (range between 4- 400000 Bq/m³) in summer. The study data were entered into SPSS software (ver.16) and radon-created Alpha particles were measured.

Results: According to the results, the highest concentration of radon was observed in mine 3 (413.3 Bq/m³) and the lowest concentration was detected in mine 1 (57 Bq/m³) and the average radon concentration in mines 1,2,3 were 848.5, 125.83 and 1667.4 Bq/m³, respectively. In addition, the concentration mean of radon gas in workers' work place, resort area and both rest area and the outside environment of the mines were 2068.2, 219.9, and 19.75 Bq/m³, respectively. The correlation between radon gas concentration and lead mine grade was also reported -0.899.

Conclusions: The findings of the present study indicated that the concentration of radon in 62.5% places were less than the action level, 12.5% of places were higher than the action level and less than the maximum permissible limit, and only 25% of places were higher than the maximum permissible limit. The place and station of measurement were the most influential factors in regard with radon concentration in the present study.