This study investigated the level of natural radioactivity and radiological risks of 40 different ceramic tiles through gamma-ray spectroscopy using a high-purity germanium detector.The calculated activity concentrations were evaluated to determine their potential radiological risks to human health.Furthermore,the activity concentrations were subjected to the RESRAD-BUILD computer code to assess the effect of ventilation rate,dweller position,and room size and direction on the total effective dose (TED).The simulated TED received by a receptor when changing the ventilation rate in a room ranged from 0.26 ± 0.01 to 0.61 ± 0.01 mSv/y;however,the percentage variations in the TED due to dweller position and room size are 34,31,and 35％ and 33,27,and 40％ for the x-,y-,and z-directions,respectively.The overall TED received by the dweller based on room size and direction is 0.75 mSv/ y.The calculated radiological risk parameters were all below the recommended maximum limit.However,the TED received by the dweller is significantly affected by the directions of the measurement,position,room size,and ventilation.Therefore,estimating the TED from one direction would underestimate the total dose received by the dweller.