ABSTRACT
Several studies published in the 1950s and 1960s noted the
particular role of the unattached radioactivity of radon decay
products (Knutson, 1988; Hopke, 1989). It was postulated that
upon inhalation, the high mobility (large diffusion coefficient) of
this radioactivity should cause significant diffusion in the lung
airways of such radioactivity and hence the main biological effect
of the radiation, to be in trachea. This was, in fact, confirmed
when medical researchers observed the localization of lung cancer
seen in miners in the respiratory systems of miners. Although
the effects of unattached fraction were documented long ago, they
are still not fully understood today, especially in connection with
the danger of radon in homes. To this day, a few instruments for
use in measuring this type of radiation have been developed for
commercial production.