It is well recognised all over the world that inhalation of indoor radon (222Rn), thoron (220Rn) and their progeny contribute a major fraction of the total radiation dose to human beings from natural sources. In the present work, an attempt has been made to assess the levels of radon and thoron in some dwellings of the seismic-prone North-Eastern region of India, using a special type of twin-chamber dosimeter. The results show a non-signifi cant increase in radon and thoron concentration during the winter season compared to summer of nearly 1.6 times and 1.3 times, respectively.
United Nations Scientific Committee on the Effects of Atomic Radiations: Sources and Effects of Ionizing Radiation. UNSCEAR1993, p 73.
2.
Icrp: Protection against 222Rn at home and at work. ICRP Publ No 65. 1993, p 23.
3.
United Nations Scientific Committee on the Effects of Atomic Radiations: Sources and Effects of Ionizing Radiation. No A/AC/82/R-441. New York, United Nations, UNSCEAR, 1986.
4.
Monnin M., Tommasino L.: Inter-countries cooperative research program regarding geophysical studies performed through radon measurements. Proc Int Workshop on Radon Monitoring. Radioprotection, Environmental Radioactivity and Earth Sciences, ICTP, Trieste , 1989, pp 583-588.
5.
Dwivedi KK, Ghosh S.: Prospects and potential of radon monitoring in North-Eastern India . Workshop on Radon Monitoring. Radioprotection, Environmental and Earth Sciences, Trieste, 1991, pp 317-327.
6.
Kumar S., Gopalani D., Jodha AS: Indoor radon levels in India. Bull Radiat Protect1994;17: 41-45.
7.
Dwivedi KK, Ghosh S., Srivastava A., Lalramengzami R., Laldawngliana C., Sinha D., Ramachandran TV: Measurement of potential alpha energy exposure (PAEE) of radon and its progenies in dwellings in North-Eastern India. Radiat Meas1996;26:291-296.
8.
Dwivedi KK, Srivastava A., Ghosh S., Sinha D., Laldawngliana C., Lalramengzami R., Saxena A.: Measurements of indoor radon in some dwellings in Aizawl (India). Indoor Environ1995;4: 362-364.
9.
Nagarathan A. : Radon: A historical overview. Bull Radiat Protect1994;17:1-9.
10.
Subbaramu MC , Ramachandran TV, Muraleedharan TS, Shaikh AN: Indoor radon daughters in some high background areas in India. Radiat Protect Dosimetry1989 ;30:41-44.
11.
Mayya YS, Eappen KP, Nambi Ksv: Parametric methodology for inhalation dosimetry due to a mixed field of radon and thoron using passive detectors. Proc 12th Natl Symp on RadiatPhysics, Jodhpur, 1998, pp 28-30.
