EXHALATION OF RADON FROM NATURALLY OCCURRING RADIOACTIVE MATERIALS (NORM) IN NIGERIA

Radon-222 mass exhalation rate, EM, and surface exhalation rate, EA, have been determined for some building materials and fertilizers in Nigeria by accumulation method using AlphaGUARD radon monitor. The building materials include granite, cement, tile, white marble, brick, concrete and sand. The mean EM of the building materials varied from 0.06 ± 0.03 for white marble to 0.23 ± 0.15 Bq kg-1 h-1 for brick. The mean EA ranged between 1.06 ± 0.56 Bq kg-1 h-1 and 3.15 ± 1.52 Bq m-2 h-1 for white marble and brick, respectively. Most of the EM and EA of the building materials were higher than those of other countries. For the fertilizers, the EM and EA ranged from 0.13 ± 0.01 to 0.42 ± 0.03 Bq kg-1 h-1 and 2.11 ± 0.56 to 4.81 ± 1.24 Bq m-2 h-1 with mean values of 0.25 ± 0.07 Bq kg-1 h-1 and 3.24 ± 0.93 Bq m-2 h-1, respectively. The radon mass and surface exhalation rates of the fertilizers were higher than those of the building materials.