Monitoring of airborne artificial radioactivity with total beta counting

Both in Finland and in Bulgaria the national weather services started networks for airborne radioactivity monitoring in the late 1950s because of the intense testing of nuclear weapons. Soon the institutes in both countries adopted monitoring methods for airborne total beta activity because these methods are relatively simple and cost-efficient. A comparison of results from Finland and Bulgaria indicate that the temporal behaviour of airborne total beta activity is very similar in these countries. However, a few cases of different behaviour can be observed, e.g. in December 1966 owing to a leaking underground nuclear test in Semipalatinsk, former USSR.