Assessment of 7Be concentration in outdoor ambient air.

7Be is a cosmogenic radionuclide with a half-life of 53.3 d produced mostly in the stratosphere by cosmic ray spallation of nitrogen and oxygen and entering the lower troposphere by atmospheric circulation processes. 7Be emits gamma rays of energy 477.6 keV and its concentration in the ambient air can be measured by gamma spectrometry. In the present study, the activity concentration of 7Be in outdoor ambient air of Lahore city, Pakistan, has been measured employing two air samplers and using a high purity germanium [HP(Ge)] detector. The 7Be activity concentration was found in the range from 1.6 to 11.3 mBq m(-3) with a mean value of 5.4 mBq m(-3).