This paper presents the results of a survey of indoor radon
concentrations in the dwellings of 10 Municipalities in the Skopje: the
capital and the largest city of the Republic of Macedonia. The indoor
radon concentrations were measured during the four successive seasons
from December 2008 to December 2009 using integrating passive alpha
track-etch detectors with an exposure period of three months. The annual
mean indoor radon concentration in each measuring site was estimated as
an arithmetic mean from the four individual measurements.
The measurements were completed for 124 dwellings, of which 112
dwellings revealed indoor radon concentrations lower than 200 Bq m−3,
and 3 showed radon concentrations in excess of 400 Bq m−3. The annual
mean indoor radon concentrations were found to be log-normally
distributed, ranging from 18 to 502 Bq m−3. The geometric mean value of
the indoor radon concentration in Skopje region was estimated to be
83*/1.94 Bq m−3. The results of analysis of variance showed statistically
significant differences in annual mean indoor radon concentrations
among the different municipalities (p=0.021).
The influence of the factors linked to building characteristics in relation to
the annual mean of indoor radon concentration was also a subject to
examination. The factors which allow differentiation into subgroups
(significance level p<0.05) were: the floor level (p<0.0001), presence of
basement (p<0.0001), and type of heating (p=0.004). Seasonal
dependence of indoor radon concentration was observed. The minimum
indoor radon concentrations were found in the summer season whereas
maximum levels were observed in the winter season (p< 0.0001)..