ABSTRACT

Globally, exposure to high levels of radon gas is a known health risk. Granite commonly contains high concentrations of uranium and subsequently high exhalation of radon gas. In the Saldanha Bay area of South Africa, granites dominate the underlying geology as well as the surface characteristics of the area. This implies that elevated levels of radon gas may exist in houses in the area. However, a survey of indoor radon concentrations in the town of Vredenburg in the Saldanha Bay area recorded average indoor radon concentrations well below those recommended as threshold levels by international bodies. The average radon concentrations are also significantly below those recorded in Paarl, a town about 100 km south-east of Vredenburg with a similar underlying geology, but different climatological characteristics.

Indoor radon concentrations were measured in 34 homes in Vredenburg, and 62 houses in the west side of Paarl, on or near the granite outcrops. Electret ion chambers (E-PERM^TM) from Rad-Elec Inc were used to measure indoor radon in the randomly selected houses in each area. For both surveys, the electrets were deployed for periods of between 5 and 20 days. The Paarl survey was conducted between October 2003 and March 2004, while houses in Vredenburg were surveyed during January and February 2019.

In this article, researchers develop a theory to explain the lower than predicted indoor radon concentrations, as well as the difference in results obtained from the Vredenburg and Paarl surveys. They attribute these anomalies to the mitigating effect of the prevailing climatological conditions of the Saldanha Bay area and the generally mild climate experienced at both sites. The research postulates that these conditions can significantly reduce the health hazard associated with elevated indoor radon levels.

摘要

在全球范围内，接触高浓度氡气是一种已知的健康风险。花岗岩通常含有高浓度的铀，随后会释放出大量的氡气。在南非的萨尔达尼亚湾地区，花岗岩主导着该地区的下伏地质和地表特征。这意味着该地区的房屋中可能存在较高水平的氡气。然而，对 Saldanha 湾地区 Vredenburg 镇室内氡浓度的调查记录的平均室内氡浓度远低于国际机构推荐的阈值水平。平均氡浓度也明显低于帕尔镇的记录，该镇位于弗里登堡东南约 100 公里处，具有相似的潜在地质，但气候特征不同。

室内氡浓度在 Vredenburg 的 34 个家庭和 Paarl 西侧的 62 个家庭中，在花岗岩露头上或附近进行了测量。Rad-Elec Inc 的驻极体离子室 (E-PERM ^TM ) 用于测量每个区域随机选择的房屋中的室内氡。对于这两项调查，驻极体的部署时间为 5 到 20 天。Paarl 调查是在 2003 年 10 月至 2004 年 3 月期间进行的，而 Vredenburg 的房屋则是在 2019 年 1 月和 2 月期间进行了调查。

在本文中，研究人员开发了一种理论来解释低于预测的室内氡浓度，以及 Vredenburg 和 Paarl 调查结果的差异。他们将这些异常现象归因于萨尔达尼亚湾地区普遍的气候条件和两个地点普遍温和的气候的缓解作用。研究假设这些条件可以显着减少与升高的室内氡水平相关的健康危害。