1. بنام خدا عباس بهرامی عضو هیات علمی گروه بهداشت حرفه ای دانشکده بهداشت دانشگاه علوم پزشکی کاشان Bahrami_a@kaums.ac.ir

3. با سلام

4. 1- شیوۀ تجزیه ای میکروسکوپی آزبست را شرح دهد. 2- وسایل مورد نیاز نمونه برداری و آنالیز را نام ببرد. 3- 3- مفهوم Bias را شرح دهد. انتظار میرود دانشجو در پایان جلسه بتواند:

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

6. 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

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

8. FILTER HOLDER

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

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

11. WALTON BECKETT- GRATICULE

14. TEST SLIDE

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

16. 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)