This paper presents the results of identification of natural ionizing irradiation in the vicinity of Nikola Tesla B power plant ash disposal field. The investigations have comprised the determination of natural gas (radon and thoron) activities with a passive discriminative nuclear track detector (CR 39) in the air column of the depth of 80 cm in the soil. The determination of gamma dose rate has been given as well, including the corresponding GPS coordinates of 28 measuring points.