The blocking effect of 222Rn gas and its progeny by various face masks has been determined using a measurement system with a parallel AlphaGUARD detector. The theoretical approach of diffusion rate for different particle sizes was calculated. The filtering effect of the different masks followed the order N99 > surgical > N95 > double cloth > double cellulose > cloth > cellulose masks, respectively. Overall the blocking effect percentage ranged between 7.65 and 22.66%. The study indicated that the effect of a mask with high quality in filtering the gas of 222Rn and its decay products is more than the double-layer masks.