Some methods for measurement of radon and radon progeny are reviewed in this paper.

(1) Filter method for the measurement of radon progeny. A general formula was developed for the filter method

which can be used conveniently. All the formula related with the filter method are the special cases of our formula and could be obtained by using a magnetic card and a TI-59 calculator.

(2) Two-filter method for the measurement of radon. A general formula was developed for the two-filter method

which is a direct result of the formula given in ref. (12). J. W. Thomas' result could be obtained easily from it by using the reasonable diffusion coefficient.

(3) Balloon method for the measurement of radon. Balloon method for the measurement of radon was developed in 1974. The air containing radon was taken into a nylon balloon with a sampling time t

1

and sampling rate Q

1

. Radon progeny activity was removed by a filter. After a certain duration t

2

the air was taken out from the ballon with the time t

3

. When air was taken out

it passed the another filter. The

a

counts on this filter in the time interval T

1

→T

2

canbe calculated by a general formula. For one sampling

the measurement can be finished within 25 mins with the sensitivity of 0.01~0.005 pCi/I

which is much more sensitive than the two-filter method

and also

faster and more convenient.

The calculated results are compared with the experimental values and the agreements are quite good.