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20世纪,越来越多的证据使人们意识到,吸入含石棉的灰尘会使从事与石棉有关的几种职业(如石棉采矿、造船和石棉产品组装)的工人患上几种严重的呼吸道疾病(石棉沉着病,肺癌和mesotheliuma)。为此已经制定了若干规定,以控制工人们在特殊的制造、采矿和其他工作地点与石棉尘埃的接触。比较间接的是控制和管理“天然产生的石棉”(NOA),这一问题近年来也引起了管理机构、健康机构和居民团体的注意。NOA包括在自然状态下原地找到的被描述为石棉的矿物,例如在基岩或土壤中的这种矿物。NOA之所以引起关注,是因为如果含石棉的岩石受到自然侵蚀或人类活动(例如修路、城市开挖、农业、采矿、压碎和碾磨)的影响,就有可能暴露并变成空中尘埃的微小纤维。天然石棉矿床的规模差异很大,从薄的四散的细脉一直到大的矿体。它们的地理分布与地质条件直接有关。石棉产出的地质背景是含镁丰富的主岩,这些岩石受到低压低温的变质作用蚀变而成。已知的容矿主岩包括变质的和已被交代的超基性岩(尤其是蛇纹岩)、一些基性火成岩、变质白云岩和变质的铁建造。石棉形状的角闪石在几种热液蚀变型的碱性火成侵入体中也能作为副矿物存在。石棉形成于可预见和可鉴别的地质环境。这种认识是一种信息,而这种信息使公众健康机构可以执行有情报根据的屏蔽和管理规划。第一步是在区域的或国家规模的尺度上确定和描述已知的(报道过的)石棉矿床。第二步是对容纳已知石棉矿的单位进行填图,以划定可能的其他石棉矿化的范围。这种地质研究使有关机构对遇到石棉的可能性做出规划,而尽量节省在不太可能遇到石棉矿的地区的管理费用。对石棉地质条件的认识可以事先应用于岩石和土壤的挖掘项目,而不管挖掘的规模有多大。这种对石棉管理的科学探索能有助于缓解对挖掘所发现的自然石棉矿床的连续不断地做出反应。因此,通过对很可能含有石棉矿床的地区做填图,规划者可开发出一些控制尘埃的程序,这些程序适用于工人和附近居民最容易暴露于空气携带的石棉的地区。
In the 20th century, a growing body of evidence led to the realization that inhalation of asbestos-containing dust could cause several serious respiratory diseases for workers engaged in several asbestos-related occupations, such as asbestos mining, shipbuilding and asbestos product assembly (Asbestosis, lung cancer and mesotheliuma). To that end, a number of provisions have been put in place to control the exposure of workers to asbestos dust at special manufacturing, mining and other duty stations. The more indirect control and management of “naturally occurring asbestos” (NOA) has also drawn the attention of regulatory agencies, health agencies and residential groups in recent years. The NOA includes minerals described as asbestos found in nature in situ, such as in bedrock or soil. The NOA draws attention because rock asbestos may be exposed and turned into dust in the air if it is subject to natural erosion or human activities such as road construction, urban excavation, agriculture, mining, crushing and milling Of tiny fibers. Natural asbestos deposits vary widely in size, from thin, thin veins to large ore bodies. Their geographical distribution is directly related to geological conditions. The geological background of asbestos output is a host of magnesium-rich rocks that have been altered by the metamorphism of low-pressure, low-temperature. Well-known host rocks include metamorphic and metasomatic rocks (especially serpentinite), some basic igneous rocks, metamorphic dolomites and metamorphic iron. Asbestos-shaped amphiboles also exist as accessory minerals in several hydrothermal altered alkaline intrusions. Asbestos is formed in a predictable and identifiable geological environment. This perception is a message that enables public health agencies to implement blockade and management plans based on intelligence. The first step is to identify and describe known (reported) asbestos deposits on a regional or country scale. The second step is to map the units that hold the known asbestos to delineate the possible range of other asbestos mineralization. Such geological studies have led agencies concerned to plan for the possibility of encountering asbestos and to try to save on administrative costs in areas less likely to encounter asbestos mines. Knowledge of asbestos geological conditions can be applied to rock and soil excavation in advance, regardless of the size of the excavation. This scientific exploration of asbestos management can help to mitigate the continual reaction to the excavation of the natural asbestos deposits found. Therefore, by mapping the areas likely to contain asbestos deposits, planners can develop programs to control dust that are suitable for workers and nearby inhabitants most likely to be exposed to airborne asbestos.