“…This property is called proportional effect, and is typical for log-normal fields. Antonic et al, 2007 Indoor ME, town LN; GSD: summer 2.98, winter 3.27, all 3.00 Bertolo and Verdi, 2001 Soil gas IT Approximately LN regional; better in geologically homogeneous region Bertolo et al, 2006 Indoor IT, Triveneto LN Celik et al, 2008 Indoor TR, Kars province Approximately LN Chen et al, 2006 Indoor Canada Nation wide GSD ¼ 3.5 assumed Chen et al, 2008 Indoor Canada, Winnipeg LN; basement GSD 2.00, bedroom 2.17 Christofides and Christodoulides, 1993 Indoor CY Very roughly LN; not so if a background is subtracted. Cohen, 1985 Indoor USA, Pittsburgh Upper and lower tail deviate from LN, equally for basement, 1. and 2. floor; GSD ¼ 2.…”