Document jyxn1vXqGGGme09zj99mqyK0R

' SutA-fUiiihaU. Ufi Voi.>No.t*Ocub, 1*10 UOC V . COMPARISON OP SEVBRAlj ASBESTOS-DUST MEASURING METHODS FOR THE DETERMINATION OP MASS AND PARTICLE CONCENTRATIONS by Eo SUuoca. M. Sc.* institute of Occupational Health, Helsinki 1. Introduction Measuring methods __ - . , . ; . i ' . For the determination of die concentration of mineral dura 41. Particle counting methods liable to cause poeumoeoniosii, many methods have been developed In the different oountrlei. At to the meuurement principle Involved, the corresponding Irauuinenu can be Olvldril IlllO two itiutipil 1. Imuumenu lor the datemiliutlon of Uia particle Humbert . 3. Instruments (or the determination of the maw concentration. This classification is valid for both quartz- and asbestos- - Wltb the lmplnger method, dust-laden els 1s led through an Ipiptngor-gai washing bottis containing 10 cm* ethyl alcohol. Alf. Is drawn In by a baiiery-powered pump (MIA I'onwial Sampler) ai a rate of about 2.5 1/min- The aampllng period is ( or 10 min- Evaluation of the dust sample is performed under the microscope in the bright field at a magnification of 300 x. Upon counting of the asbestos dun, fqc,whtch we used sn eye containing dura. At the beginning of the twenties, the so* called Implsiger device for dust measurement was developed piece graticule (Whipple), the partief <f were classified at follows: u in the U.S. A., which, In the yean 133? -1931, was elabor ated Into the Midget lmplnger Method /l/. As Is known, this . method ts based on the collection of the dust panicles in a < a) particle* smaller than Su, | b) panicles larger than 5u, c) needles longer than Su, suitable absorption liquid and oo the microscopic counting of these particles In the sedimentation clumber, in Finland, occu* pstlonal hygiene hat started to develop according to the Amer* lean pattern only in the fifties. We thus applied the Midget d) needles longer than 10u. , - Needles are defined ar particles the length of which Is at lean 3 to 4 times their width. i With the membrane filter method for determination of the lmplnger Method for dust measure menu, especially as this method was already associated with recommended MAK values. Due tolacklng undemanding of the noxiouiness of asbestos dust, only s few durt meaturemeots were carried out io the Finnish particle number, the air, drawn In by a pump (MSA Personal ' Sampler), is led through t membrane filter (MllUpore filter, type AAWP 03? in the Aerosol Field Monitor). Air throughput Is shout 0.5 to 1.0 t/mln, sampling time 5 to 10 min. The asbestos industry during the fifties. Spurred oo by the many dlag- samples are prepared according to the methods of the U. S. nosed asbestotls cases, extensive dust measurements were lnltia Public Health Service /2/, a piece of the filter on the usdonly In tbcjiixtlej. As, however, the Midget lmplnger suffers ' specimen canto being made transparent with the aid of a mix from a oumbei of disadvantages (short sampling time, difficult 1 ture of dimethyl phtbslste and diethyl oxalste.v The particle particle counting, broad scattering of the reaulu, nooteparitioo concentration and particle size distribution Is for the time being , of the smallest particles, etc.}, we have begun, five years ago, to determined In the main according to the shove-mentioned perform simultaneously wltb the impinges measurements abo method of the U.S.Public Health Service. Tbe dust panicles gravimetric meatuiemeus, usU% act electrostatic pteclpUstor and membrane fillers, to determine the mass concentration of the dun. The idea was to develop a simple method for the monitoring art divided Into the following four groups: a) particles (grains), total concentration (P/cm*), ' ; b) needles, total concentration (needlo/cm*), of dust eooceouatioos tn the asbestos industry, whi cb could be applied on the spot, in the course of time, the electrostatic pre* c) needles, length exceeding Su (needles > Su/cm'), d) needles, length exceeding 10u (needles > lOu/cm*). dpUator method wsi dropped, as both methods 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 brane filter. During thclaii l`/t y**n w< have carried out psr iclc counting on the membrane filter under the phase contsast T<icfo<copc, in addition to the conventional particle conccncra- jo determination wuh the Midget Impinget Method. In the fol lowing we Intend to report oo our experience, during the last five Phaco NPL *0/0.6S and eyepiece PeriplsnCF 10 XM). Count ing ts canted but at s total megnifl cation of 500 x. The griticule used with the eyepiece it either of the Porton or of the Patterson type- years, with mear jremenu of asbestos dusi In an anthophyllite as* ' bestos factory snJ in several asbestos cement planu using also other asbestos types(chxytotUe, amoslte, aocldollte and some anthophyllite), at well as in a asbestos textile factory. . 2.2. Detetmination of the man concentration j We use membrane (then (Mimpose filter, type AAWP031 * Address of the author: Helsinki 29, Hssrtmanlnkani 1, Finland. iq the Aerosol Field Monitor) together with s pump and a gat I 8000 0376 U w , SCF-FA-6480 PROnnrcn t>v rnn