Estimates of inhalation doses resulting from the possible use of phospho-gypsum plaster-board in Australian homes.
Current materials used as internal lining in Australian buildings are based on natural gypsum of low radium content. A study was carried out to estimate the contribution to the annual effective dose due to airborne contamination from chemical by-product gypsum plaster-board of higher radium content if it were used as an internal lining. The 226Ra content and 222Rn exhalation rate were measured for several samples of the plaster-board, and the behavior of 222Rn and its progeny (218Po, 214Pb, 214Bi, and 214Po) in a typical building was modeled numerically, using the results of the exhalation rate measurements as input. For building ventilation rates greater than approximately 0.5 air changes per hour, the contribution to the total annual effective dose from inhalation of 222Rn and its progeny exhaled from the phospho-gypsum plaster-board is estimated to be below 1 mSv. This contribution is reduced if the surface of the plaster-board is coated with paint or cardboard, or if the very fine particles are removed from the phospho-gypsum during manufacture of the plaster-board. The effective doses arising from dust generation during the installation of the plaster-board are also estimated to be below 1 mSv. The recommended action level of 200 Bq m-3 for radon in air in Australia corresponds to an annual effective dose of approximately 6 mSv. The study indicates that the suggested acceptable level of 185 Bq kg-1 for the 226Ra concentration in the plaster-board may be too restrictive under Australian conditions.
O'Brien
R S
RS
Australian Radiation Laboratory, Yallambie, Victoria.
Peggie
J R
JR
Leith
I S
IS
D000396:Air Pollutants, Radioactive / Q000032:analysis*; D016902:Air Pollution, Indoor / Q000032:analysis*; D001315:Australia; D002133:Calcium Sulfate; D003252:Construction Materials; D006801:Humans; D008433:Mathematics; D008962:Models, Theoretical; D010758:Phosphorus; D011886:Radon / Q000032:analysis*; D017687:Radon Daughters / Q000032:analysis*; D012119:Respiration; D014691:Ventilation
D000396:Air Pollutants, Radioactive; D017687:Radon Daughters; C077769:phosphogypsum; D010758:Phosphorus; D011886:Radon; D002133:Calcium Sulfate