Document e7v1jkoDgeBVLa5rEE0x8y9ee

. ' . feetA-fteisikaU. Ueft VoL>No.t*Oewb, WO UDC MlSU.i.OM.m.lM:erT.BU > i : .' ., COMPARISON OP SEVERAL' ASBESTOS-DUST MEASURING . . * METHODS FOR THE DETERMINATION OF MASS AND ' ' \ PARTICLE CONCENTRATIONS ; 1.. & r RXI1IMT FH-228 t by t*ro SUUDCfi, M. Sc.* -. Institute of Occupational Health, Helsinki ;` 1. Introduction * !. "' 1 Measuring method!. : __ -i ; ' " r ' ` : ' ''...... '"fi. " 1 . i I . -r . v. For the determination of die concentration of mineral dura 11. Particle counting mothodr liable to cawe poeumoeonloab, many method! have been ; i -. . developed In the different oountrlei. Ai to the meaiuremeat With the Implnger method, dutt'laden air la led through an principle Involved, tlio corresponding Irauuinenu cm be ' Iptplngor-gas washing bottla containing 10 cm* ethyl alcohol. divided lmo two groupst . Air. U drawn In by a bauerypowered pump (MIA I'onwtal 1. Instruments lor the datemilnatlon of Uia particle numberi Sampler) at a rate of about s*.6 1/mio- The sampling period b . 2. tmi/umenu (or the determination of the maw S ot 10 min- Evaluation of the dun tamplc b performed under concentration. - the microscope in the bright field at a magnification of 300ir. . Thli cUulflcation b valid for both quarts* and asbestos- - . Upon counting of the asbestos dun, fqt.which we uted an eye* oomalning dura. At the beginning of the twentlu, the ao* called Implnger device for dun meaiuremeat wai developed In the U.S. A., which, In the yean 103? - 1931, waelabor ated Into the Midget Implnger Method /If. At b known, thb . method b bated on the collection of the dun panicles In a piece gtiileule (Whipple), the parties were classified ai follows: u < a) particle* smaller than Su, I b) panicles larger than 5u, ! c) needles longer than Su, suitable absorption liquid and on the microscopic counting of . these particles in the sedimentation chamber, in Finland, occu - d) needles longer than 10,,. , Heedlet are defined at particles the length of which b at pational hygiene hst started to develop according to the Amer* lean pattern only in the fifties. We thus applied the Midget least 3 to 4 times their width. | With the membrane filter method for determination of tbe Implnger Method for dun meaturemenu, especially as this .. particle numbet, tbe air, drawn In by a pump (MSA Personal ' method was already associated with recommended MAK values. Samples), b led through a membsane lilies (Mlllipote filter, Due tolacklng undemanding of the noxiousness of asbestoi dun, type AAWP 03? In the Aerosol Field Monitor). Air throughput only a few durt measurements were carried out in the Finnish . b about 0.5 to 1.0 1/min, sampling time S to 10 mist. The asbesux Industry during the fifties. Spurred on by the many diag templet ate prepared according to the method! of the 1). S. ' nosed aibestosis cases, extensive dust measurements were lnltia Public Health Service /2/, a piece of the filter oo tbe tedonly In thejiixties. As, however, the Midget Implnger suffers ' specimen carries being made transparent with tbe aid of a mix* trom a oumbei of disadvantages (short sampling time, difficult ' Use of dimethyl phtbalate and diethyl oxalate-v The particle particle counting, broad scattering of tbe results, nonteparatloo coocent/etioo andparticle size distribution is for tbe time being . of the smallest particles, etc.}, we have begun, five years ago, to determined In tbe main according to the above-mentioned perform simultaneously wltb the implnger measurements abo method of tbe U.S.Public Health Service. Tbe dust panicles gravimetric measurements, us trig an electrostatic precipitator ate divided lmo the following (out gtoupr. and membrane filters, to determine tbe mass concentration ofthe a) panicles (grains), total concentration (P/cm*), dust. Tbe idea was to develop a simple method for the monitorlog * | b) needles, total concentration (needlet/cm*), of dust concentrations in tbe asbestos industry, whi cb could be c) needles, length exceeding Su (needles * Su/cm*), applied on the spot- In the course of time, tbe electrostatic pre - d) needles, length exceeding 10u (needles > lOu/cm1). dpltator method wat dropped, at both method! yielded complete . Counting Is effected with the aid of the phase contrast ly comparable results, while it was much simpler to use the mem method (microscope Letts, type Ortholux, with objective brine filter. During the tin I'/t y*n we have entiled out par - Phaco NPL 40/0.6S and eyepiece PeriplanCF 10 XM). Count- iclc counting on the membrane filter under the phase contrast 1 log is carried but at a total megnifl cation of $00 x. The TUcsoscopc, in addition to the conventional particle concentre- . graticule used with the eyepiece U either of the Porion or of jo determination wuh the Midget Impingei Method. In the fol lowing we Intend to report oo our experience, during the last five the Patterson type- yean, with mciuicrnenu ofasbestos dust In ananthopbyllite as ' bestot factory anJ in several'asbestos cement plants using also other asbestos types(chsysotUe, amosite, aocldollte and some ' 2.2. Detetmination oi the mats concentration anthopbyllltc), at well at in a asbestos textile factory. j We use membrane filters (MUlipose filter, type AAWP031 * Address of the author: Helsinki 29, Haanmahlnkstu 1, Finland. It} tbe Aeroeol Field Monitor) together wltb a pump and a gas 4 i ' . I SCF-FA-6480 8000 t">376 El m i PROnnrcn t>v rnnn