بنام خدا عباس بهرامی عضو هیات علمی گروه بهداشت حرفه ای دانشکده بهداشت دانشگاه علوم پزشکی کاشان

با سلام

1- شیوۀ تجزیه ای میکروسکوپی آزبست را شرح دهد. 2- وسایل مورد نیاز نمونه برداری و آنالیز را نام ببرد مفهوم Bias را شرح دهد. انتظار میرود دانشجو در پایان جلسه بتواند:

For the purposes of the Directives “Asbestos” includes the following: For the purposes of the Directives “Asbestos” includes the following: ActinoliteAmositeChrysotileCrocidoliteAnthophylliteTremolite

ANALYTHICAL METHOD (WHO) Principle of the method: Sampling of a known air volume Filters are “cleared” (rended transparent) Fibres in a measured area of the filters are counted using a phase-contrast optical microscopy

MATERIAL Sampling  Sampling pump  Filter holder  Filter Counting  Microscope  Graticule  Stage micrometer  Test slide

FILTER HOLDER

Esters of cellulose Cellulose nitrate Base plug Base xxx Back-up pads Membrane filter Cowl End cap End cap plug

COUNTING FIBRES The fibres counted must have the following properties: L>5μm D<3 μm L/D>3

WALTON BECKETT- GRATICULE

TEST SLIDE

COUNTING Counting fields are choosen at random. The counting finishes: fields counted -100 fibres counted - A minimum of 20 fields must be counted

CALCULATION c = concentration (fibres. ml-I) D = diameter of the exposed filter area (mm) N = total number of fibres counted d = diameter of the gRaticule (pm) n = number of graticule areas examined v = volume of air sampled (litres)