Radon progeny in ground level air shows one maximum in midwinter and one in late summer. A significant minimum in April-May seems to be due to lack of local exhalation and is possibly connected with a high ground water level. The mean ThB concentration shows a spring maximum and then decreases as RaC inceases toward autumn. In Helsinki city the RaF/RaC ratio is systematically higher than outside town.
No takes yet. Share an insight, caveat, or question.
Rolf Mattsson (1970) studied this question.
Synapse has enriched 2 closely related papers on similar clinical questions. Consider them for comparative context: