Table 4.

Lung cancer incidence rates in Finland from 1955 to 2019 in radon-exposed municipalities with their corresponding hospital districts.

Hospital districts	University hospitals	IRR	95% CI
Reference (low)	Others	1.00	Reference
Lapland hospital district	Oulu University Hospital district	1.18	1.14-1.23
North Karelia hospital district	Kuopio University Hospital district	1.17	1.13-1.22
Northern Ostrobothnia	Oulu University Hospital district	1.13	1.08-1.17

Low-risk hospital districts (reference): Central Finland hospital district, Kanta-Häme hospital district, Kymenlaakso hospital district, Northern Savo hospital district, Päijät-Häme hospital district, Satakunta hospital district, South Karelia hospital district, Southern Savo hospital district, The Tampere region hospital district, Uusimaa not including the Helsinki hospital region.

High-risk hospital districts: Lapland hospital district, North Karelia hospital district, and Northern Ostrobothnia hospital district.