Measurement of Radon Exhalation Rates from Different Rock Types and Construction Materials (Gaza Strip, Palestine)

Indoor radon increases the health hazard due to long-term exposure. Most building materials of natural origin contain small amount of naturally occurring radioactive materials. The building materials of natural origin reflect the geology of their site origin. This study was carried out to assess the radon activity concentration in rock and building materials used in construction purposes in the Gaza Strip, southwestern of Palestine. Fourteen different construction materials of imported (international) and local origin were tested, using solid state nuclear track detectors (CR-39). After 55 days of exposure, CR-39 detectors were etched chemically and then counted under an optical microscope. The radon concentration level of studied samples ranges from 94.4 to 642.5 Bq/m3. The sands (from north of Gaza Strip), black cement, gray granite and the marble show relatively highest levels with values about 642.5, 285.0, 283.6, and 257.2 Bq/m3, respectively. These values are above the international standard limits, and they are not safe for use in construction purposes. According to Ubeid and Ramadan (2017), the highest value in sands are referred to black sands, agricultural run-off and urban areas, discharges from mining activities, factories and municipal sewer systems, leaching from dumps and former industrial sites. While, the high value in gray granite is related to high percentage of silica and potassium contents, the high value of radon concentration in the marble is interpreted to high contents of organic matter in the original limestone before the metamorphism. On the other hand, values on radon concentration in the waste-dust of marble and granite from industrial quarry were 399.7 and 257.2 Bq/m3, respectively. They were above the international standard limit, and generally the ambient is not safe for workers.