Exhalation of radon from naturally occurring radioactive materials (NORM) in Nigeria

Radon-222 mass exhalation rate, E_M, and surface exhalation rate, E_A, 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 E_A 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 E_M and E_A of the building materials were higher than those of other countries. For the fertilizers, the E_M and E_A 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. (authors)