Abstract
Natural radioactivity of soil samples has been studied in many countries of the Arabian Peninsula, including Saudi Arabia. Radiological indices based on soil radioactivity have been widely used in these studies. However, there are no available data about natural radioactivity of fine aerosol particles in such countries. The objective of this study is to determine the activity concentrations of K-40, Th-232 and U-238 in airborne PM2.5 and the associated internal inhalation radiation dose to the public in Jeddah City, Saudi Arabia. Twenty-four air samples in four locations throughout Jeddah were collected and analyzed for PM2.5 and the associated K, Th and U. The activity concentrations of the isotopes K-40, Th-232 and U-238 were calculated. High atmospheric PM2.5 concentrations (mean: 50.81 +/- 34.02 mu g/m(3)) were found. The natural radioactivity associated with PM2.5 due to the isotopes Th-232 and U-238 were 301.8 +/- 76.1, 11.8 +/- 4.2 and 10.8 +/- 3.4 Bq/kg, respectively, and the Ra-eq was calculated as 44.9 +/- 14.0 Bq/kg. The inhalation annual effective radiation dose to the public due to natural isotopes of the airborne PM2.5 was in the range 15.03-58.87 nSv/year, depending on the age group. Although these dose values were associated with the PM2.5 fraction only, they were higher than the world references values in air reported in the UNSCEAR, 2000 report. (C) 2014 Elsevier Ltd. All rights reserved.