Mass and elemental concentrations of airborne dust inside and outside of a dwelling house were measured at four seasons over a year. The airborne dust samples were collected by using low volume air samplers and the elemental concentration was determined by INAA method. The mass concentration varied remarkably over a year. On the other hand, it was found that the shielding factor (mass ratio of the outside to the inside) does not change. The elemental concentration showed same trend to the mass one. The shielding factor for individual element, however, was classified into two groups according to the size distribution of dust particles. These results indicate that the shielding function of a dwelling house depends mainly on the dust particle size. To obtain a correlation between wind and mass concentration, simultaneous measurments were carried out employing a computerised wind vane and an anemometer, as well as a piezobalance dust meter
