Effect of Don Muang Tollway to Concentrations of Pb-214 and Bi-214 in Kasetsart University Atmosphere

Abstract

²¹⁴Pb and ²¹⁴Bi concentrations in the Don Muang Tollway atmosphere were measured using gamma spectrometer. Air particles were collected on glass fiber filters by using a high volume jet air sampler for 3 hours. The 540 air samples from six different locations in the Don Muang Tollway 2 times each for 3 months (7 Dec 1998-26 Feb 1999 and 1 Mar-21 May 1999) were monitored for gamma activities using a Hyper Pure Germanium (HPGe) detector. The average concentrations of ²¹⁴Pb and ²¹⁴Bi were (2.283 ± 0.015) × 10^-11μg/m³ and (2.683± 0.036) × 10^-11 μg/m³, respectively. The concentration of ²²²Rn in secular equilibrium condition was also calculated from the concentration of ²¹⁴Pb, giving an average value (4.867 ± 0.032) × 10^-9 μg/m³. which are lower than the maximum values of the safety standards (1 × 10^-8 μg/m³ for ²¹⁴Pb and ²¹⁴Bi, 2 × 10^-7μg/m³ for ²²²Rn). The result of this study showed that ²¹⁴Pb and ²¹⁴Bi concentrations after building the Don Muang Tollway were about 10 times higher than the former condition in 1990. This also corresponds with the properties of the Earth atmosphere.