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警报:实时检测石棉

一旦接受了作为其坚韧,弹性,防火质量的“奇迹矿物”,石棉现在被看作是一个杀手。国际劳动组织(ILO)估计,10名万名工人,每年从石棉有关的疾病而死亡全世界。

Even in Europe, where asbestos use is banned, asbestos-related disease is still the leading cause of occupational death. This is because many workers, especially tradespeople such as plumbers, builders, electricians, etc.,  are frequently exposed to airborne asbestos fibres that are produced when the materials containing them (such as insulation, ceiling panels, floor tiles and textured wall coverings, etc.) are disturbed. There are millions of tonnes of asbestos products in existing buildings across the EU, and in the UK alone, any building built before the year 2000 can contain asbestos.

Traditional methods of airborne asbestos detection involve collecting particles from the suspect environment and then using microscopy or x-ray analysis to look for fibres. This process could take days, by which time inadvertent inhalation of asbestos could have been suffered by anyone entering the tested environment. Until now, there has been no quicker way of detecting the presence of airborne asbestos fibres. However, the Centre for 大气和气候物理学 (CACP), part of the School of Physics Astronomy and Mathematics, has developed a new technique which can analyse airborne particulates in real-time and determine whether or not fibres are present and whether those fibres are asbestos.

The Particle 仪器 研究 Group first proposed their detection method over a decade ago, but it was too expensive to implement in a device that could be used routinely by tradespeople and others. Then in 2009, they were invited to join a consortium of European Trade Associations in an EU project 'ALERT' that sought to find a solution to the asbestos problem. The PI Group were funded through the €1.78 million 3-year consortium project.

所得到的“警报”仪器可以在几分钟或者甚至秒(取决于纤维浓度),而不是天检测空气中的石棉。它已涉及商业,公共,国内建筑物中的石棉清除工作(到目前为止,涉及青石棉,铁石棉和温石棉形式)已经开展的野外地区广泛的测试。

由于FP7警报项目结束时,我们一直在努力与警觉科技有限公司开发原型到商业上可行的产品。第一部是由于在市场上在2019年下半年。

背景

石棉是主要由具有晶体结构,该结构中,当它被分解或压碎复杂铁,铝,镁和钠的硅酸盐的材料,形成了分割长度成越来越小的丝纤维,其中,有可能是数十亿纤维或纤维束在空中。

SEM image of Crocidolite fibres

Inhalation of such fibres gives rise to a number of conditions which have become a leading cause of work related deaths. In 1990, the US National Institute for Occupational Safety and Health (NIOSH) stated that there is "no evidence for a threshold or 'safe' level of asbestos exposure". In 2010 the World Health Organisation estimated that approximately 100,000 people die each year from asbestos-related lung cancer, mesothelioma and asbestosis resulting from occupational exposure.

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警报仪器

粒子仪器研究小组使用涉及激光光散射和磁性取向,以提供石棉纤维的存在空气中的悬浮粒子的快速评估两阶段分析而开发的技术。

Dual-beam Fibre detection module

The above figure shows a cut-away representation of the  instrument chamber which contains the core system components. Ambient air is drawn through the inlet. Airborne particles are constrained in the flow and pass through two laser beams, one above the other separated by 3mm. Between the two beams the particle passes through a horizontal magnetic field (not shown). When the particle is in either of the beams, forward scattered light is focused on to a pair of vertically oriented linear array detectors which record two segments of the scattering pattern enabling us to quantify the particle shape and, in the case of a fiber, its orientation. The scattering pattern from fibres is very distinctive and a simple analysis can distinguish them from non-fibres.

Asbestos possesses the property of paramagnetism which means that in the presence of a magnetic field a fibre will experience a torque causing it to align itself in the direction of the field lines. The scattering patterns can be analysed to provide a measure of the orientation of a fibre and thus a change in the orientation as the fibre moves from one beam to another. In an ideal situation non-asbestos fibres will pass through the two beams in a stable orientation since they are not affected by the field where as a change in orientation of asbestos fibres will occur. In practice all fibres change orientation to some degree but the distribution of orientation change is greater for asbestos and it is this difference which enables the instrument to detect the presence of asbestos in a population of fibres.

A working prototype has been used in various field trials with considerable success. Crocidolite can be detected with >99% confidence with as a few as 10 fibre measurements. Chrysotile, which is more common but less toxic, is less easy to distinguish but can be detected with as few as 30-40 fibre measurements.

Prototype ALERT detector operating during a field-trial

现在的工作正在进行,以仪器发展到生产的原型。

A demonstration model indicating how the production instrument may look

欲获得更多信息

  • 通过从磁重新排列的纤维的光散射实时检测空气中的石棉的。 克里斯托弗·斯托普福德,保罗小时。凯伊,理查德秒。格林纳威,埃德温·赫斯特,兹比格涅夫ulanowski和沃伦河斯坦利。 OPTICS EXPRESS,第一卷。 21,第9期,第11356-11367(2013)(DOI:10.1364 / oe.21.011356)