The grain size of building materials products has a great influence on the radon release level.The release amount of radon is the greatest when the grain size is 5 mm

and the release levels will reduce for any other dimensions.Temperature has also important effect on the release of radon from building materials products.The concentration of radon will double when temperature raises 5℃ at 20℃ or higher

especially

when temperature is higher than 25℃

the concentration rises even more rapidly.The activation energy Ea of radon release for the fly ash samples is measured to be 77194.19 J.mol-1

and the factor A is 4.54×1015 s-1.The concentration of radon increases gradually with time

the release and decay of radon will reach equilibrium 36 h later

and the relative standard deviation of the fluctuating value of radon concentration is 2.1% at that moment.The relative standard deviation of the rate of preventing radon for the radon prevention coating is 3.8%.The results are reliable when the method is used in the research of radon prevention mortar and putty.