The levels of radon gas recorded in Israeli homes rose steadily over the past two decades.
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According to the Environmental Protection Ministry, the concentrations of the naturally occurring radioactive gas are below the maximum acceptable levels, but some experts believe the increase in the levels that have been found is cause to reduce the permissible threshold for radon in building materials in order to reduce exposure to the gas.
Exposure to radon is known to cause lung cancer: The U.S. Environmental Protection Agency lists radon as the second leading cause of lung cancer and the No. 1 cause of lung cancer among nonsmokers. In Israel, it escapes from the soil naturally and is found in building materials produced from rock in some areas in Israel.
The data on the increase in radon levels were presented at the annual conference of the advocacy organization Environment and Health Fund, held last week in Jerusalem. The authors of the report, scientists from Ben Gurion University of the Negev and the Soreq Nuclear Research Center, found that radon levels in new buildings were significantly higher than in older buildings, and that concentrations in single-story homes were higher than that in apartment buildings.
A study conducted by Reut Spitzer of the Department of Environmental Quality Sciences at Hadassah Academic College in Jerusalem found that the average concentration of radon measured in residential buildings rose 21 between 1998 and 2012. In mamadim, the reinforced security rooms required in all new buildings, the concentration of radon was one-third higher than in ordinary rooms.
In a presentation at the conference, Moshe Shirav-Schwartz, a former researcher at the Geological Survey of Israel, and Gustavo Haquin of the Soreq Nuclear Research Center argued that one of the causes for the increase in radon concentrations was the use of a new method for using raw materials from a layer of rock that was not used in the past. These materials contains higher concentrations of uranium, which decays into radon.
At issue is a process for producing Portland cement (used to make concrete) that was introduced by Nesher Israel Cement Enterprises. The researchers concluded that the company’s new formulation of Portland cement increases the risk of radon exposure. They call for amending standards for building materials to reduce the concentration of radon.
The Environmental Protection Ministry said in response: “This is a moderate increase in the concentrations of radon in Israeli buildings, which is a far cry from the threshold determined by the Environmental Protection Ministry based on the recommendations of the International Commission on Radiological Protection, which ruled that the maximum concentration permitted in residential buildings will be 200 becquerel (a radiation measurement unit) per cubic meter.
“The reasons for the increase are a lower rate of air replacement in the new buildings due to the improved sealing today with the advanced construction methods. The sealing includes a more widespread use of concrete for building apartments compared to previous years, in which construction was based on blocks. The density of the concrete is greater than that of the blocks, and as a result the concentration of radon is higher.
“Another reason is the use of new raw materials for producing the concrete: sand from the Rotem region instead of sea sand, and dolomite limestone instead of limestone, leads to a larger amount of radon. The solution for the increase in radon concentration is to increase the ventilation in the rooms. The ministry is also working to carry out measurements of the concentration of radioactive materials in various construction products, which are being conducted in the ministry’s laboratory for environmental radiation. There is monitoring of measurement reports with irregular results for concentrations of radon, as well as repeat inspections.”
Nesher said in response: “Radon concentrations are affected mainly by the area and the land on which the house is built, and by causes related to the lack of ventilation, such as improved sealing that reduces natural ventilation. In recent decades there has been no change in the composition of the Portland cement and it accounts for about one-tenth of the components of the concrete. An attempt to present and explain the increase in the concentration of radon, if it exists, requires a well grounded scientific study.”