Lebanon’s lung cancer rate is about 33 per 100,000 for men and 15.5 per 100,000 for women (Ministry of Public Health 2011), which is 1.3 times higher than the rate for men (26 per 100,000) and twice the rate for women (7 per 100,000) in the eastern Mediterranean region (GLOBOCAN 2012). These rates contribute to the high burden of non-communicable diseases in the country. Determining the chain of causality for such high cancer rates is a complex undertaking requiring long-term and expensive studies to examine the interplay between behavioral, social, and environmental factors. To explore concentrations of certain carcinogenic agents so as to confirm or exclude their possible contributions to these high cancer rates, space and time concentration surveys become necessary. Here, indoor and outdoor radon concentrations, a well-known carcinogen as classified by the International Agency for Research on Cancer (IARC 1988), are measured across Lebanon for the first time with the goal of establishing a baseline level and quantifying the causes of its variations.
Globally, radon is considered an important cause of lung cancer after smoking. A number of studies reviewed elsewhere (WHO 2009) have confirmed that even low concentrations of radon — as may be found indoors — contribute to lung cancer occurrence. The World Health Organization (WHO) estimates an increase in lung cancer of 16 percent per 100 Bq radon.
Other studies have also shown that lung cancer risk increases by some 25 fold when comparing smokers vs. nonsmokers exposed to elevated radon levels irrespective of sex (Kim et al. 2016; Peterson et al. 2013). These findings suggest that elevated radon levels may disproportionately impact the population of Lebanon, where smoking is quite prevalent. In fact, adult smoking has been estimated at 38.5 percent in Lebanon and is on the increase among youth (Saade et al. 2008; Shamseddine et al. 2014). Hence, this indoor-outdoor radon study is warranted given the cancer and smoking rates in the Lebanese population.
After conducting the national sampling campaign, exceedance probabilities for the 300 Bq recommended reference level for radon concentration set by the International Commission on Radiological Protection (ICRP) in dwellings (ICRP 2009) are computed. Prior indoor sampling of radon in Lebanon was conducted in 2010, but the study focused on only one town and three villages in southern Lebanon (Kobeissi et al. 2014). The study reported that radon levels ranged from 30 to 120 Bq . The goals of the aforementioned study were to explore differences in radon concentration between various locations within dwelling areas with a focus on (1) ventilation patterns across the season, and (2) the presence of granite countertops in kitchens. The specific objectives here are to explore connections between indoor and outdoor radon concentrations in relation to seasonal variations, geographic locations, and living habits in Lebanon. The work here also aims at establishing baseline values and variations of radon concentration instead of offering the final word on indoor radon hazard assessment. To address these specific objectives, four hypotheses are framed and tested that consider whether geographical region, proximity to fault lines, construction material of houses, and seasonality explain the space and time variations in indoor and outdoor radon concentrations. To place these results in a broader context, the measurements reported here are compared to regions that share either geologic or climatological characteristics of Lebanon.