Background: With the rapidly economic development and urbanization in Yan’an city

more building materials were consumed in building construction.While the natural radioactivity level of building materials from Yan’an is limited in the literatures.Purpose: The main objective of this study is to determine the natural radioactivity level and to analyze the associated radiation hazards of building materials in Yan’an.Methods: The specific activities of natural radionuclides 226Ra

232Th and 40K in various building materials from Yan’an city were determined using low-background gamma-ray spectrometry

and their radiation hazards were evaluated according to the standard methods.Results: The results show that the specific activities of 226Ra

232Th and 40K in the building materials are 9.4 73.1

11.5 86.9 and 258.9 1055.1 Bq/kg

respectively.The activities of 226Ra and 232Th

except for sand and gravel aggregate

in all other building materials are higher than the corresponding means of local soil

and the activities of 40K in hollow brick

red-clay brick

sand and gravel aggregate exceed the means of 40K in soil.However

the values of internal exposure index

external exposure index and gamma radiation index in all investigated building materials are less than 1.Conclusions: The radiation levels of all analyzed building materials are within the national safety standard

which indicates that all analyzed building materials can be used anywhere and they can’t cause radiation hazard to the local residents.