A technique for measuring airborne concentrations of daughters of radon isotopes.

Describes a method of measuring airborne concentrations of radon daughters which distinguishes between the different isotopes. At the place of sampling, air is flowed through a millipore filter for five to ten minutes at approximately 12 litres per minute. The filter is counted during the period 2 to 12 minutes post sampling; the counts are integrated over each of four regions of energy and a second count made for the same regions during the period 15 to 30 minutes post sampling. Results are analysed by a BASIC computer program.