Radioactivity in the atmosphere.

Plots of activity concentrations of ⁷Be and ¹³⁷Cs in the ground level air around Grindsjön (In Sweden at 59°5′6,56″ N 17°52′11,20″ E) follows.

Reference:
C. Söderström, R. Arntsing, P. Jansson, K. Lindh and K. Wilhelmsen. "History of the sampling station at Grindsjön with Quarterly report on measurements of radionuclides in ground level air in Sweden. Fourth quarter 2003." Scientific report no FOI-R--1262--SE from the Swedish Defence Research Agency (FOI). ISSN 1650-1942. June 2004.