Introduction
Guilan is one of the provinces in North of Iran, with population of 2,480,874 and a total area of 14,042
square kilometers. This study assesses the outdoor natural gamma dose rates in the air of 49 cities in Guilan
and calculates corresponding average annual effective dose.
Materials and Methods
A total of 260 different sample points measurements were carried out. The results include both terrestrial and
cosmic ray components of gamma radiation level.
Results
The outdoor gamma dose rates range from 65 to 127 nSv h-1 with the mean of 94 ± 24 nSv h-1.
Conclusion
The average outdoor gamma dose rate for Guilan determined in this study is significantly higher in
comparison with values reported by UNSCEAR 2000 from different countries with the mean of 59 nSv
although in comparison with many provinces of Iran, it is lower.