室内氡污染控制与治理关键技术研究

Radon is one of important indoor pollutants, and it is the second largest cause of lung cancer. Radon pollution from building materials has seriously affected indoor air quality and the safe use of building materials, and it has become a prominent problem in our country. The radon control limits of current national standard do not apply to light porous wall materials, resulting in radon concentration in considerable number of new housing exceed the limit annually. This not only affects the public health, but also increases the difficulty and cost of governance for radon pollution. Therefore, it is in urgent need to carry out research on the radon pollution problems caused by new building energy-saving materials - light porous wall materials, which are commonly used in China. This study is to find out the relationship between the radium content and radon exhalation rate of lightweight building materials, law of the radon migration and precipitation, influencing factors and the control method by the sample test, simulated room experiments and field-proven methods, and to establish forecast model between radon exhalation rate of building materials and indoor radon entry rate by multiple nonlinear regression analysis. The results would provide a theoretical basis for indoor radon pollution control and curbing appearance of high radon buildings from the building source, and would also provide case studies and technical guidance for revising radon control standards and governing the buildings of which indoor radon exceed the limits.

室内氡是室内重要污染物，是引起肺癌的第二大因素。在我国，来自建筑材料氡的污染已成为影响室内空气质量和建材安全使用的突出问题。由于现行国标中氡的控制限值不适用于轻质混凝土建筑材料，导致每年有相当数量新建房屋氡浓度超标。这不仅影响到公众的健康，而且增加了治理的难度和成本。因此，急需对我国普遍使用的新型建筑节能材料--轻质多孔混凝土墙体材料氡污染问题开展研究。本课题拟通过样品测试、模拟房实验和现场验证研究轻质建筑材料镭含量与氡析出率的关系、氡的运移和析出规律、影响因素和控制方法。通过多元非线性回归分析建立建材氡析出率和室内氡进入率的预测模型。研究结果对从建筑源头上控制室内氡的污染，遏制氡超标建筑出现提供理论依据，亦对我国建材氡控制标准修订和超标建筑的治理提供案例分析和技术指导。

我国建筑材料氡的污染已成为影响室内空气质量和建材安全使用的突出问题。本课题建立和完善加气混凝土砌块氡射气系数、孔隙度、扩散长度、表面氡析出率测量方法及测量装置，轻质多孔混凝土建筑材料氡运移和析出规律和影响因素的研究，建筑材料氡控制指标与限值的研究与验证，建材降氡技术的研究以及超标建筑降氡技术的研究，取得的主要研究结果如下：.1.创建了密闭腔体加活性炭盒来测量建材氡析出率的方法及装置，建材氡射气系数快速测量方法及装置，测量孔隙率的气体置换法，建材氡扩散长度测量方法及装置，参加了累积氡探测的国际比对，保证结果的可靠性和可比性。.2.加气混凝土砌块样品氡析出率与226Ra含量具有较显著性正相关，R2=0.4349。经模拟房、毛坯房和现有住宅验证，室内氡浓度与加气混凝土墙体材料中226Ra含量亦有显著性正相关，R2=0.5789。扩散系数和扩散长度随密度等级增加而降低，具有较显著性负相关，也就是说等级密度越低，材料的孔隙度越高，越有利于氡的扩散。砌块表面氡析出率随含水率（从2％～66％范围）的增加呈增长趋势，砌块表面氡析出率与外界温度呈正相关。 .3.为排除工艺和原材料的影响，委托加工了6种以粉煤灰为主要原料，密度等级（B03-B08）的加气混凝土砌块，分析结果显示，无论是砌块、粉状样品还是加工样品的密度等级与干密度和孔隙度均有显著性相关。射气系数随等级密度增高而降低，即材料的密度越高，孔隙度越低，氡的析出能力也就越低。.4.对深圳模拟房加气混凝土砌块表面氡析出率与氡浓度的关系进行了探讨和预测，选择广州、合肥加气混凝土为主要墙体材料的新建毛坯住宅进行了氡析出率现场测量与房屋氡浓度的预测验证。结果表明，广州测试房间计算与测量氡浓度的偏差≤20%；合肥测试房间计算与测量氡浓度偏差≤30%。通过模型计算，确定130 Bq/kg作为加气混凝土砌块镭含量限值， 20 Bqm-2h-1作为加气混凝土裸露墙面氡析出率的限值。.5.对镭含量较高的煤矸石烧结砌块、煤矸石烧结多孔砖和掺渣烧结多孔砖的研究发现，加工工艺可以抑制氡的析出。通过通风换气、密封屏蔽、土壤减压和净化器四种方法验证了其降氡效果，并进行了比较。.本研究结果为目前在我国广泛应用的轻质混凝土材料氡的控制及建材标准提供了理论依据和实验数据。亦对我国从源头上控制室内氡的污染，遏制高氡建筑物和超标建筑的治理提供案例分析和技术指导。