Country	Mean activity concentration (Bq・kg⁻¹)			References
Country	²²⁶Ra	²³²Th	⁴⁰K	References
Al Rakkah East of Saudi Arabia	23	20	233	Present study
Riyadh, Center of Saudi Arabia	14.5	11	225	[28]
Tayma, north west of Saudi	30.77	27.59	161.8	[14]
Albaha, South of Saudi Arabia	37	32	343	[30]
Jeddah, West of Saudi Arabia	9.3	7.4	369	[31]
Kuwai, North region	66.6	11.3	384.5	[15]
Kuwai, south region	13.6	2.4	110.4	[15]
Oman	29.7	15.9	225	[16]
Qatar	23.2	4.5	127.1	[32]
Jordan	49	27	291	[13]
Syria	23	20	270	[3]
Iran	28	22	640	[3]
India	26.4	51.2	5.6	[9]
Pakistan	25.8	49.2	561.6	[7]
Pakistan	73.9	152.2	325.3	[5]
China	38.5	54.6	584	[10]
Japan	29	28	310	[3]
Yemen	44	58	823	[33]
Egypt, National range	37	18	320	[3]
Nigeria	7.8	29.4	229	[34]
Turkey	37	40	667	[35]
Algeria	50	25	370	[3]
Sweden	42	42	680	[3]
China	32	41	440	[3]
India	41	29	400	[3]
United State	40	35	370	[3]
World average	32	45	420	[3]