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

خدا بنامعباسبهرامی

حرفه بهداشت گروه علمی هیات عضوایبهداشت دانشکده

کاشان پزشکی علوم دانشگاه

[email protected]

سالم با

1. دهد- شرح را آازبست میکروسکوپی ای تجزیه شیوۀ2. ببرد- نام را آانالیز و برداری نمونه نیاز مورد وسایل3 -.Biasمفهوم- 3 دهد شرح را

: بتواند جلسه پایان در دانشجو میرود انتظار

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

ActinoliteActinolite

AmositeAmosite

ChrysotileChrysotile

CrocidoliteCrocidolite

AnthophylliteAnthophyllite

TremoliteTremolite

ANALYTHICAL METHOD (WHO)ANALYTHICAL METHOD (WHO)

Principle of the methodPrinciple of the method::

Sampling of a known air volumeSampling of a known air volume

Filters are “cleared” (rended transparent)Filters are “cleared” (rended transparent)

Fibres in a measured area of the filters are Fibres in a measured area of the filters are counted using a phase-contrast optical microscopycounted using a phase-contrast optical microscopy

MATERIALMATERIAL

SamplingSampling

Sampling pumpSampling pumpFilter holderFilter holderFilterFilter

CountingCounting

MicroscopeMicroscopeGraticuleGraticuleStage micrometerStage micrometerTest slideTest slide

FILTER HOLDERFILTER HOLDER

Esters of cellulose

Cellulose nitrate

Base plug

Base xxx

Back-up padsMembrane filter

Cowl

End cap

End cap plug

COUNTING FIBRESCOUNTING FIBRES

The fibres counted must have the The fibres counted must have the following propertiesfollowing properties::

L>5L>5μμmmD<3 D<3 μμmm

L/D>3L/D>3

WALTON BECKETT- GRATICULEWALTON BECKETT- GRATICULE

TEST SLIDETEST SLIDE

COUNTINGCOUNTING

Counting fields are choosen at random. Counting fields are choosen at random. The counting finishesThe counting finishes::

- -100100 fields countedfields counted--100100 fibres countedfibres counted - -A minimum of 20 fields must be countedA minimum of 20 fields must be counted

CALCULATIONCALCULATION

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)