الفهرس 
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Abstract
In the present work, radon gas were measured for some building materials which are used in Dakahlia Governorate, Egypt, by using nuclear track detectors of type CR-39 and LR-115 type1. Radon is considered as one of the most significant risks to human health after it was observed that exposure to radon can cause lung cancer disease. Forty samples of different building materials (ten kinds of building materials) like : black cement, white cement, gypsum, sand, ceramic, marble, bricks, stones, gravel and granite. After exposing nuclear track detectors (CR-39, LR-115 type1) for radon which emitted from the building materials for a period of 61 days, by using CR-39 detectors they were collected and chemically processed by using sodium hydroxide solution 6.25N and temperature 70 ± 1oC for 7 hours. As for the nuclear track detector type LR-115 type1 etched by using NaoH solution 2.5N at 60 ±1 oC for one hour. The average was number of tracks counted using optical microscope, which is used to calculate the concentration of radon of building materials. In the present work we calculated, (area exhalation rate, mass exhalation rate, working level, annual absorbed dose, annual effective dose). The results were obtained using by CR-39 detector as the follow : Radon concentration ranged from 47.88 Bq m-3 (white cement) to 820.51 Bq m-3 (granite), and area exhalation rate ranged from 61.84 mBq m-2 h-1 (white cement) to 1059.92 mBq m-2 h-1 (granite). The annual absorbed dose rate ranged from 0.60 mSvy-1 for samples white cement to 10.34 mSvy-1 for samples of granite, and the rate of annual effective dose from 1.45 mSvy-1 for samples white cement to 24.81 mSvy-1 for samples of granite. In the case of LR-115 type1 detector : Radon concentration ranges from 68.42 Bqm-3 for the samples to the white cement to 845.43 Bq m-3 of granite, and area exhalation rate ranges from 88.15 mBq m-2 h-1( white cement) to 1089.25 mBq m-2 h-1 ( granite). The annual absorbed dose rate ranged from 0.856 mSvy-1 for samples white cement to 10.66 mSvy-1 for samples of granite, and the annual effective dose rate ranged from 2.05 mSvy-1 for samples of white cement to 25.58 mSvy-1 for samples of granite. According to the above results, we found that the values of radon in granite samples have high concentration, the highest concentrations obtained and followed respectively (stones, sand, marble, black cement, bricks, gravel, ceramic, gypsum, white cement). They have been compared to concentrations obtained (ICRP) from 200 Bq m-3 to 600 Bq m-3. Generally we note that the concentrations obtained from the building materials are low to below the upper boundary of universal values with the exception of concentrations resulting from granite samples were outweigh the recommended values globally. Therefore it can be concluded that the samples of building materials used in this study are valid to be used as building material with a good ventilation systems inside buildings, but be careful when using granite as a building material because of its high concentrations of radon which may be serious.