High natural radiation areas in the coastal and peninsular India were studied for airborne thorium and resultant population exposure due to inhalation.
Four locations covering three states viz., Ayiramthengu and Neendakara in Kerala, Kudiraimozhi in Tamil Nadu and Bhimilipatnam in Andhra Pradesh were investigated.
External gamma radiation fields 1 m above the monazite ore bodies ranged from 200 to 3000 nGyh-1.
Soil samples showed 232Th specific activity varying from 0.1 to 1.5 Bq g-1 with surface alpha activity in the range of 1.0-12.5 Bq cm-2.
Suspended particulates in the samples ranged from 60-140 mug m - 3 with 232Th showing a wider variation of<0.03-0.3 mBq m-3.
There was poor correlation between suspended particulates and long-lived alpha airborne activity (r=-0.3).
The resuspension factors for 232Th were in the range of 1.5 x 10-8-7.9 x 10-7 cm-1, Higher resuspension was correlated with dry sand dunes.
The upper limits for Committed Effective Dose (CED) due to inhalation of airborne 232Th at the respective high natural radiation areas were estimated to range from 50 30 to 300 ± 130 muSv (5-30 mrem) per year per adult member of public assuming an activity median aerodynamic diameter of 1 mum for the airborne particulates.
Mots-clés Pascal : Inde, Asie, Pollution air, Pollution radioactive, Pollution origine naturelle, Thorium, Particule en suspension, Radioactivité, Teneur air, Dosimétrie, Homme, Radioactivité gamma, Rayonnement alpha
Mots-clés Pascal anglais : India, Asia, Air pollution, Radioactive pollution, Natural origin pollution, Thorium, Suspended particle, Radioactivity, Air content, Dosimetry, Human, Gamma radioactivity, Alpha radiation
Notice produite par :
Inist-CNRS - Institut de l'Information Scientifique et Technique
Cote : 98-0360415
Code Inist : 001D16C04D. Création : 25/01/1999.