Assessment of occupational exposure to radon-222 in water treatment and production plants in Ogbomoso, South-western, Nigeria

The transfer of dissolved radionuclide in water into the indoor air is one of the major pathways for radon-222 (222Rn). In water treatment and production plants (WTPPs), there is a risk that radon degasses from the water and enters into the indoor air. Hence, this study assessed different WTPPs to determine the amount of 222Rn workers are exposed to as a result of their occupation.

An Electret Passive Environmental Radon Monitor (E-PERM®) device was used to investigate the indoor radon levels in the processing, packaging, and storage rooms of five (5) well-known and active WTPPs in Ogbomoso, Nigeria, and descriptive statistics was used for the analysis of data obtained.

The radon concentration obtained varies between 44 - 149 Bq/m3 with an average of 69.28 ± 20.06 Bq/m3 in the processing rooms, 27 – 44 Bq/m3 with an average of 36.02 ± 4.05 Bq/m3  in the packaging rooms and 34 – 144 Bq/m3 with an average of 71.15 ± 42.81 Bq/m3 in the storage rooms. The average annual effective dose obtained for each of the WTPPs varies between 1.00 mSvy-1 and 2.00 mSvy-1.

The results showed that all the investigated WTPPs had high radon concentration and annual effective dose when compared with the action level proposed by local and international organizations. Hence, the workers are at risk to 222Rn during water treatment and production processes.