Assess the annual effective dose and contribute to risk of lung cancer caused by internal radon 222 in 22 regions of Tehran, Iran using geographic information system.

Radon gas is one of the most influential sources of indoor exposure. All its physical properties together make it a significant risk factor for lung cancer in the population. The research aims are outlined as (1) to measure the radon concentration in Tehran city and compare results with the international standards (2) to determine spatial distribution of radon gas concentration using Geographical Information System (GIS) software and (3) to estimate the annual effective dose and potential risk of lung cancer by radon-222 in Tehran city. In this study, 800 Alpha Track detectors were installed in houses in 22 regions of Tehran city and retrieved after 3 months. The measurements were repeated for spring and summer and autumn seasons. The annual effective dose and risk of lung cancer were assessed using standard equations. Data were analyzed using SPSS 20. Result showed the minimum and maximum radon concentration were observed in and Ghalee-kobra (0.13 Bq.m) and Charbagh-ponak district (661.11 Bq.m) respectively. There was no observed relationship between radon concentration and houses' model, cracking condition and constructionn materials. Expectedly, the storehouses and basements had significantly higher ( = 0.016) radon concentration than occupied rooms. The min and max of the estimated annual effective dose were 0.65 and 2.03 mSv, respectively. Result showed that around 5% of the sampling sites had higher level of radon than the maximum allowed by EPA. A rough estimation of the expected radon-attributed lung cancer incidences yielded approximately 5958 cases in the total population of Tehran every year. In view of the growing trend in cancer incidences, appropriate measures addressing radon should be undertaken in areas of increased exposure to this noble gas.