5. Conclusion
The main purpose of this study was tofind a relationship
between the ambient atmosphere, especially its humidity and
radon and thoron exhalation rates. Two different materials with
high radium (brick) and high thorium (granite) concentrations
were chosen for measurements. Thefindings are summarized
below.
(1) The obtained results showed that for both materials radon and
thoron exhalation rates increased and that above a certain
level they decreased or reached a plateau; these trends were
consistent with results of previous studies.
(2) The results showed the same trends of exhalations for both
materials with different structural characteristics (porosity and
density) regardless of their weight.
(3) It was concluded that effective dose could be changed by the
factor of 2 due to humidity.
(4) The present results indicated that humidity should be taken
into consideration to calculate the equivalent dose from radon
and thoron