The radioactivity concentrations of

7

Be

212

Pb and

214

Pb in the atmosphere of Xi’an suburb were determined from April 2002 to April 2003.A high-volume air sampler and a high resolution gamma-ray spectrometer were used to measure the radioactivity.The annual average concentrations of

7

Be

212

Pb and

214

Pb were 6.68×10

-3

Bq·m

-3

0.65 Bq/m

3

and 16.06 Bq·m

-3

respectively.The

7

Be levels were higher in spring than those in other seasons

with a maximum concentration of 16.64×10

-3

Bq·m

-3

.They reflected obvious seasonal trends.The concentrations of

212

Pb and

214

Pb have strong seasonal trends.The maximum concentrations were 1.71 Bq·m

-3

for

212

Pb and 50.11 Bq·m

-3

for

214

Pb in winter.Precipitation is a major factor affecting the concentrations of

7

Be

212

Pb and

214

Pb

the monthly mean values reach minimum in August

when precipitation is the biggest of all the months.Artificial radionuclides

such as

137

Cs

have not been found.