This paper presents the results of the first systematic indoor radon survey in Montenegro, in 10
municipalities of its coastal and central regions. In rural areas one home was randomly selected in each 5 x 5 km
square of a regular grid covering the territory of Montenegro, while in urban areas the basic grid was subdivided
into 0.5 x 0.5 km squares, and in each of them one building was selected and one dwelling within the building. In
each of these 434 homes, radon measurements were performed twice a year, using passive dosimeters placed in
the living room or bedroom on the ground floor or the first floor. The CR-39 nuclear track detectors were
exposed each time for about six months. The annual average radon concentrations in the surveyed homes are
found to be lognormally distributed (GM = 49.6 Bq m-3, GSD = 3.2) within the range 2-2,208 Bq m-3. Their
arithmetic mean is 105 Bq m-3 and median 41.4 Bq m-3. Radon concentrations above the action level of 400 Bq
m
-3 are detected in 5.6% of the surveyed homes. Most of these 24 homes are detached single-family houses, and
the majority are rural. Radon concentrations were generally higher in detached family houses than in apartment
buildings, in older than in newer houses, and higher in rural than in urban homes. As to the domestic radon
exposure, this survey indicates reinforced concrete as the most favorable and stones as the most unfavorable of
the building materials commonly used in Montenegro. The lowest average effective dose is in urban homes on
the Montenegrin Coast (0.80 mSv y-1), while the highest is in the rural area of the Niksic municipality (7.31 mSv
y
-1), which is abundant in bauxite deposits.