Document 0qk0J2VObQpb6pkMY9vMMY9nx

FILE NAME: Visible Dust (VDT) DATE: 1937 June DOC#: VDT005 DOCUMENT DESCRIPTION: Article from Trade Journal UKj < c- I C.UU-11 J J ' O J l-nwllM., , nuliJV J ^ Q sM a*a& !!*& Z \ Tm Ewplotul' xaun Evcwouim c Mawum. 1 -Av_I - / i u ( f<lt ) OCCUPAT'ITOA RNJAAL! nDiISEF AASCTE7 HT AAZ7 AA RR Dn CS f ANTHRAX Anthrax il i asutafieaa dacsae, common *o msn and n a t domestic assiseJ, and tratuiartted by the akin or hide, bau, wool, or bristles o infected airimlis to a a s . With human ieisgt. it app ean ia two la m e; firat, o s the skin s a i second, sitttgeBtl; within the body. The disease is found in eattl, rfsag>, goats, bores, as p ip , especially those besa foreign aanntriea, It s e y oeeai in carpet railla, leather indottrie* esd tan neries, among brash maker*, pWtezere, foil t&ake n , rag pickers, mxvss, tuskers, veteriesriiBs, fanners, bulehen, longshoremen, freight b u d le n , and vcoufonally is persona oouide of any indue try. It airy aSss he found. ia noBneetioa with the preparation o f akin i s In? suostifaeitmag. Th iraicetina fot the akin eocen, S B great a n y esaet on the espesad paru erf the body, aoeh u the face, throat, reeds, test, hands, ana fore a m . The gens fedges in a cot or break i s the skia and is robbed fa by the worker's dirty hands or the rubbing of clothing. It is partiealaxly difficolt and stufabsa 4a correct and reqoiret caspatest mediatl aemie. The fis t step in the esstrol o f the infectob k ts use only H oes, and class from non-iafoeted area*. Disinfection, hy satis factory methods, Mould be made of the h id and sidos that has entered the oonntry and are knows to he from anthem: infeeted eonnsrics. The tssoal srass of ea epidemic si' anthrax, is shai every year or so in the large kalh er tan ning em rra there are one or two caaes which may be f a ls i Immediately, after tbit there is consid erable investigation and the greatest of medical precautions are taken for a short time. After a period is wind: the fitment precautions are ob served, the tees dies down and the industry re. rorcs to its setnasl operations and no Hosier- is taken noli! there is soother outbreak. Dae to the comparative rarity of anthrax It is difficult la maintain abnervaoess of, ell the safety precaalions. Seine of the methods for the prevention of the infection front ub res are as follows: 1; Remove *1 visible factory dost by measu of mechanics! exhaust at the point of origin. 2. Dispose of Lhe dost collected fay fanraing. 3. Make provision for i fcret id kit with iterilized dreatinga, fasadagea, cotton, end a S.% solution of iodiae- 4. Post a notice &i to anthrax and ita preveslian. 5. Provide overalls lor all worker exposed to the baaird. 6. Have lunch room seprele from workroom. 7. Provide adequate washing facilities, hot wa ter, leap, etc. 8. Hare employees keep work e] from street clothre. 9. Provide good, neutral ventilation with ranlight wherever possible. 10. Instruct the workmen to prevent contact of fasies with the bare akin. IW ASBE5TO5IS A patnitiai ubesteua haiartl ia fo he looked for wherever aabestoa dust i i created, Among the possible sonwe* a n the m ijh n gan l milling of aabestoa, and the weaving, n w h ia in g sad the m ixisg of asbtslsa saa ss iM o t camjxrerade, In dustries which have this expontre are lsuraktiira, brake lilting and gaska manufacturing. One of the most common operations where as bestos it mod ia is the manofaenun o f patch mate, rial for roofs. The practice is to damp the asheatsa into a patty chaser with asphalt and the two materials are mated together. There are a Bomber of sn ail plants that da this type of work without t s f particular attempt to control the dart While it la true that lower workers are exposed to aabestoei* than ailiooiia, it is a definitely im portant mtpatisssl jRasaae braird and should he eosetdered aa sack, la the opm ios o f certain authorities ii to established that sebfistsisB may rase disability and death, and that arav well _de- pattiele* being larger, (be damage ia to the bron chioles rather tbs to the alveoli, the latter being too small to admit spy large proportion of the jjMtielea. The fibre* of hcalAtis is ehareeterised hy the formation, of so-called "Asbestos Bodies", a pbesomeaon quite different from toy found ia asiioesis. The symptoms e l sshertosii are generaliy sissiW tn those of ailieosis, particu larly aa regards a grsdsally mcreaaiag dypiots fsbortne of hrestiT}. Prolonged espasare to tv hextos dost esnsed s palmoniry fibrosis e l a type different from till cotit and denjonatxaile n Xray films. Cases of definite heart enlargement are freqogatiy ~KaSl*aiS 'prediipoiiuon to 'toherenlosu does not ip p eir o he eaosed hy espoasire to asbestos doit. It ia not hriieved ifast sahestoaiia may add to the mor tality of pctBBoaia, and sente noD-mbemtfst polmocary infeetiens. The eanecnirstiorj of dost in aabestoa fabricating plant* depend primarily o s tbe grade of best; m ill fiber gives rise 1 a higher concentration than erode fiber. Operation arranged io decreasing concentration e l dust are preparing, carding, weaving, spinning, twisting and warping. The comrol is rather difficult hm CU000011 D CT-27-2004 15=35 P*fr : 1 LAWRENCE flPDEKSHU T h i Em floisu' Gsgut CNcm uxiH C, VLnuiJ. 'l-l y ik J \2dZ>tt [ )*<u i, 557 U u im p o h a u ihat all atw cn>^!grn h* mined phweicailf, iaeludiag X-rav acatninaDa the cheat- r H l,nnnich aa ejrpoiiire ts thii dual will esnoe eniargemenl al thc k u r t it u &1q apartsstt that B ta witk w$*h ie j r t j shottld B&t be fsootd Sa atbestai dass. Some of ikc naelhodi uaed la mluimue Ute bas. ard t a aiheataus i n u iollewa: 1. Remove U viaihle faetory dtt hy tnest of weehaniasl eihaost &t the point of origin, 2. losprsv the geaer-s] plant Ventilation by fam in th roof m aidewall. 3. Phyaicol exastizutioe of aecr eraployttea uni periedicaily la t tba d ie n employee*. Tkii raeomtaendasiea ahonJd be diocassssS witk the Q a i Department. BENZOL Benzol it t vaiatile, infiggim tele, alnxxt colorleu liquid wtk a strong wwtish tmelL II cvaporatea very eaaily and auk et,a very good tohrem (or gota, ress rad ftu . Itt vapors sre heavier tb&n tir. l i ic dso called beasene, bet it tatui boi be sairtsk.es fa r benrine, w kiik issaes team petroleum nsd le saasb ices L ar^lsL B ^ s a l coaiee from seal tar. Benzol it seed in iadniuiea in tke nunaXaetra of robber afflaste, lacquer*, vazniahm and fiate*, ptin le euad ru sio b retteteli, in tke chemical TMdatiry, in dlMsmg of printer* roller*, engraving p it tea. a t i n the manufacture of robber goads, arti<3*1 Icari?, sanitary tin a n a , oil cloth e sc linoleum . Ales, at tu n a it may bs pretest is connection wish the manufacture of airplane, rubber reclaiming, phtujogriph record tnoirufay luring. imitation either and pyroxylin manufac turing, including inch lubsuncea viacoloid. 6bcrloid, and celluloid. It si tued aery orienaively in tke BiaBufaetnre of dyea sad is the tarring poim 'for * good many of the dyes and esplori!. While much has been done to elim inile the use of benaol sa t solvent or to control it sa asany indo lirici, the nee of benzol u a raw m itene] is the manufacture of nitrehenscDc, aniline and the other various dye intermediate will probably in crease rather than deersatse, There can be so anit oti tute recommended for its use to eoaaeenon with the manufacture of dye intermediates. Poisoning muaily ocean by the breathing of benaol fumea. When these are drawn into the braga, beaxat U dissolved is the blood ind car ried through the body. Acuta paiaoning occun whets large amounts are breathed in a abort rime. The Derma eystes is poisoned m d the hreithin# apparatus paralysed. Smaller asnaoats breathed orer a period of time eauie chronic peiaoarag which weaken* and tbina the blood. Thii type of poisoning ti more common in industries, Benaol is also a shin irritane L may be sbiorbed through the kin and tbe mon common instance In industry ia where she material ia spilled os the clothe* arid no attempt ii made ts remove i t The control of the benaol hazard depend* upon the prevention of inhalation or akin absorption of the material. The fallowisg practices should be pm in operation wherever passible: L Don's lo t b& uol T ldi b often tke simplest Beam of control. It it passible many times to find tbit another solvent may be used and tke heard completely eliminated. Tke dye and explosives istdasBrira are, of course, tke, eseepaoiu to, this general role. Tokteas is sue malarial tb it might he used u a askaieete, It it poiassoaa, bat much Ices t s< than boaoL S igh boiling petroleum frac tion* aim provide a non-isfiammable, non, tesric subsistst lo t heaaoL In orekiag to cltmtoEs the hazard from benzol this recsmmendarioa ohoold always he given etsse- * risl coaridcretioia, and it will he found that fea a mijcrity of easss a nritable rchstisnie eon he fesnd. % Bessove benui] fume at point of engirt by exkatut venrilatusn. 3. Seep fight ea v es sb jeerpUckst m u in in j igW fll 4 Be M low a rtld ^ Heated whh aoy sastpaund eoBUiaisg haasal to dry in trosh* sestBi ealcas tke vapor* are removed. S. Maks drying chambers for materials treated with benaol mixture as gas tight as po*si< hie, and have rise sir pressure intide the ehsgahgra lightly leas than that ostoide. 4 Spray objects with a paiut mixture contain ing hetrol only when they are in properly eoastxscled and ventilated booth. 7. Inspect euefaBy pipe lines rad other appa ratus aentiinmg beasol to detect rad pre vent leata. g, Provide positive preortare helmets for worknuta whs repair leak*, enter beaaol tasks or use any mixture containing benso] in a w sfised pace. Supply rubber gloves to worker* in contset with liquid besuol. 3<L hi a m n p tg Kih.vugi ventilatiou reBjeEsher that beaaol fumes ere heavier than ait. 11 Tret the eottcentroiien of betuol fume la the air af work-room. Benaol abouid not be allowed to exceed one hundred parts per mOlioa of six. I t Provide medical anptrriaion for worker* with benaol Thia should be diocnased with he Qrim BcpaFtmen!. 13. T retafer worker* to other departm ents if benaol affect them . 14. Have a complete physical examination made of each employee, including a blood examination, before thi* employee works with heuaoL r.m CUOOOOl UL | " 7 --2 0 0 4 /nw 1, 1937] LHW KtNLt PlHUfcKSHU The Employjrs" Gaour Eweiwasssut hUsum . ?13 910 0250 $ ftg S esb d a n ssnl*iaig free silica aed m te (while m i ) a ltb o afb a s inorjanie doti ahoidd t e = sidered m aea-hassdeus UBt definitely provsd Asb&mttds is a (Uatasc, io. sobe isggwcu s sa te ' to te te ishai&sins of asbestos S i r s , lis liases! fsiforta indade the ais f c vsloptasas a i s stersstsrjste type o brate iS te a a s tasase i, Beesoss asbestos dasi ossaku o f fibres, t e ses p a se a ste as deeply inte the ieags &s aeji tilica i a l , a s, isiatas al kiliisg the ssigraisg sslls (phagocyte*) it lodges ia te all <A bSss bsaM&idhD (o r pasaagies) proteeag fchrooa tiente whiea t s i i te aasetykt these pas sages. Infection, sas& m feaxalgak, are a s s IreqaiBaS as *rA a fa sia , eM m ifesae aa*y m aati tfa M i w r i, a T S ^ S a ic ta tem " J U f A ' iETS& "v S E f m r ^1 S c Im e y m p ie s riS a ssaip of ya, slthoB fh esposase a l a very le yeese te a p re s s s defeat aymptomt Tfcs prarteiaB o astaslsiis m sa te s r a s g E a te i thsau^h f e a .esAr^eosi m. sfeSeraaa sj ypra s g sa a so - essussQta rajd'dag she intelaaiBB o esd, asid ira re (deritej asi sgosi^dy, s tita ai ene* f lie s, these duela preda s l e e ilhsas fibrosas su ibas licxtgR., B^s@|t$Bed by pigmstPa- t i e s -- U eek as red r**p*eriv*ly -- das u>' the calor s tfee E>0tnaee^ t e either eas deas te htlty resale. Fra*a a practical stsrsdpsist, does te te.rd eei mine usually esataiaa free tilica ead may prudaes aatferace silicosis. Most tetaseis* otes ara n&rodssed with frac silica asid c m pro duce dasbiliry, is geaemOv eew iered th at she development o tkess (arma s pBeHmscsaiosk is baaed sb tese factors: ( \) The anacestrates o dual in the air: 2I The p p e p sfo s o the frac silica a t satestns (aa ike, eass assy t e j ia sisa dnat; (3) The Isagth s a d continuity s apaasrg- These stay sLss t e uirieA ssaffiptjBlty, hot. frons aa esg tsecri | tassdpost tfec Srat t li a s s a a e d fseora ara the priisdpai s t t Thi, lharizfera, Eaeass vlfri A e higher she pro portion of free oiBea (piarte) or ssheatao in site dust o eUc air teat is breasted, th e lower sbosld be the ito'i&i eaeenS-ilion of dotL Ob the ether te n d . iS s te silica or aabcstoa content a( *te dust ta low, it ia telEetncd that higher iota) concent' lions of dg can t e breathed without physical im pairm ent However, sher is ets tipper limit ol dustiaesn, irrespective o{ the nature the dust, te y a e d which eertaiE types a? long conditions may develop if thia dusty at? ii brentheil This bm it is at pruwai considered la be 50,000,000 pS''ticlca of dsjat per euhie foot f sir. fin n Silioos ia one a! the sta rt ofeuiadnai elements ia aacurc. Free dlUsc is silicon dinside (S > 0 .) so o ife re a m w d fro pfayioiagkay is e n ilicates w hich ua metal caita of th e h y p sth e cal cOm m u a d d {Le. 6 a SiO*. Ca A I. IL 0 , ) . It sees? eith er aa a principal eoaatitneBt or os a s im purity sn a s i a m , ro e h , eiaya, aasds, cad s lh e r iBoiag^is snljsSa^eas e i tedunteel im psrtasee -- the highe? the pestsstage of dlifts the greater the heglth hueinL Q oasjs, QoiJfmTE, Fwkt, CsrEir, T b t o u , DMTOtMcaiotis, Easts, Sa m , a sa Sajwtowe, (S) qiq the 33638 eaeumsn lottsu of oHIea, varying asly i a cfptallsJie farm 6,ad camiee i oatare. rssaashle otsadard o penaigsahle dastisseaa s r sb S dosts is as follows*. W ha " " a&aseisled * * " psrBUei tat suit! fmi 9t sir with no gsaarte --- SO * low " -- y j " 30% " -- IS " 180% " -- S tte e a sEapdg ase p m g ly msMsmj, bgm% hesed E espasissss pas c%ks. aed ieal esidsaeg. As b s t s is a SbrOffle^mhaereJ widely ssed ia indtutry, C m T s s m e ( S ,, Mfs, S)*, 0,1 M its m ast oat! fflsra, CSsate a m ise a a l T ism s- fite, & Ssr^sitse aa JiwhephyBkg ase i b a Issao as Aabsslm, aitfamag^ of teaser ia dttstrlsl `Tb~ handling of aehestos gea.ers.te! a dart eemponod of t e e te m a s parti- de white when iahsled over a period of time, may cara* eteeitosie, G aartns dost esselbIsb ahont $0% free silica and is aae af the wam% oBeatesh ija the canaetion o iilioosiB. The freqtasoey of eilicscia, tahercal&- is, hiTjBCiiites, zmeTjmzeSz ta d o th er respirator? ailm enu la shaortaelly high asaeag workers espoead is grnsite uzt. Mambs, awb Lnres?iS!ffi are saposed priacipally of calcsoia eajhoaaig sh ie b ii physioUogicaUy inert. Dalaao silses ii p re ssst ie eseessiv ssaoaata, this glass s i rocks may he considered relatively sea-fcKSsionfi, CmsJ MoaSf Seism eorhoaate of oieil orgis may bo iaduded in tei> gm ap. S/Ufcsraivs, * reec aasiatissg m ainly o p enid e s of quarts aasd cem eated wilh r.ihc, ia need to grindieg wheeU and io huSldiisg metefsL I u high silica cornea! renders it a definite oceopa- u a su l diseas hazard. Mtca a m S s.ts.a rt (W hite Mical sre pan. aihle ofender cause! of iheeou. W hrever poasible, th nat of tend e o n u iu isg Becdis-Ukc ccyatok of semcile should he avoided. P .0 4 CUOOOOZ9 '-j'w 1 C Psgf 10] 13- JD - hukci'wC n n o atD n u T u t Em l c t z s G*out> EKCiweeitwc Ma ku a <*-> ? i a kiccdk/ f / 1, ) ! ' Gttoum. P lastm or P aws ar* prioejpeily Calcium asdiate and do not proem a senoiu h&sard. C***0*urfBUM (Silicas carbide, Si C) Alinsl'm, A iflir rt, CnicwtJOM (Oxides of Aiastfaasi) are widely aaed as srti&ei) briiwea, eapeeiaDy fa gnadiag wheels. Ac inroaugjtisa revealed so tniuuai LisisJ-d la brtatbiBg ihe eW>. of these: mbulasrcea. Com. as Casbgk dtun , ia sSss ihoejjoc s i isee eBiet m ar produce i mild fihwiij with disaster*sioB of the lungs, bat ere not disabling. Cement D ust u/miDy eoatajias bram 1% to c!.5.7e or more ires silica. The ireqaauEy ai res piratory ailment* ajsooj werter* expoacd to ee> meal dtut (daitine* making {ran 2S to 3 mil lion particle* per cubic {not of air) la about twice that of workers La sos-dsaty sack.) T u x (Saapjtoise) ia used i s bot i e powders, as * Siler ia paper manniaetitrisg, is elate pencils, etc. Talc usually eantsiai imparities s p e tia llj tremelite, Talc dust eortiafaaag 40% oc more tremolite may induce a Hoe S ax bilateral fihrobia of the fataga which ii desaoaitrabls in the 3Ursy. Is the hmes&s of I s *ttiea it eanssi ha anid to he diw&Bgg. Su its dost reacts in a rasasc? ifauXar to faagfairemoliie life, G IS K U f&tfi tbur enstMsfag eohr 1Q% issmelk e with e * af I n aKes has y w a l a Mgfe feeqtsraey of paeassaEaasalsaia sad b ataloais. Occawic ThiX3$ fWoad, for, textika, feather, etc.), er not pnenatosoeoBsatii producing hot stay exhibit irritating or tol i t properties, depend- & lag eo the nature a t the substance, DOST C O N T I OL Is industrial hygiene work, the following are the chief factors io determining the dust hazard. J_ The nature of the dual .- (a) Ita saatpoaiifan (b) Its particle rite properties 3, The eascestration a! dost is the air 3. The degree of exposers of the worker* to dotty air 4. Xu physiological settee, whether it i* fa) Physiologically inert (b) Capable o( producing as allergic reac tion (bay feer) (e) Toxic-- (lead, etc.) (d) Capable of producing paeumoDocomotie D otti are solid particles generated by the Otrhanicaj dIsIntegracron of eolid organic or in&rrasic idten tit, A doit eland may be composed of billies* of oirdcletLof Tirria ij iq and shapes, each stiuhle pam de fteeo^aruej1''by n u iT .ta i"tile pafticlea v S S t c a a ly M d e x thiTl&iroiaiBt> tfie dnit ii geseratej ihe larger particlu~ic51e^ ont with a velocity depeadiag, stassg other things, aa se, The imslfar particles settle out mare slowly and may be caned throughout the plant fay air canasta. In a material of ailara* properties, the average particle se is the same as the Lee at she fadfaideal partida, m d a chemical acalytii by weight can be applied aaaeriekOy. I s an indnttrUl ms cloud, however, there ia a wide ariatioB in the aixes e l the fadiridutl particles, O ta Urge particle of quersz will weigh more than one hen tired, email particles of feld spar. A shc&eal analysis reported by weight will show the prosaice of asna 0% q u m s, by num ber, less than 1%. Itr occupational issase work we ace fatcrenad is the tmniher o f particles of quartz leas than 10 m icro in size per eehie foot b! air, sines the !re> qnency at nspirmtnry diaeasw 1 eetrelated Is tromeriisa! oh! cettats. Bsoaass of the diScalty fa distfagaiihing free silica ferns Bombtied afliea, chemical asslytii tatut hs setOBpasfad h f pfawpaphic: andytii ia which miaeasds are identified fay their optical properties!. Scat particles ia hs air may esaiahs a p*iti-re or Begasin eleetWrtStitk charge. The awreeaon berwcea particles of opposite electrical properties eases! them, apon tamest, to cling together, a presem k a w a ai fleosdatiea. Flocstlation sdnasa ike ecttEsg raa ai a dost eka. In feS ssg with titix problem, a dust cloud Bit be sriioaliaed aa a nupenuon of non-naiiorm particles of eomtantly aryfag size, percent oosnposifioK, at Irregular eoaeeslratioB xud oapredietthle hchiTior. The first step la as! cuotrol v a r i is to deterstine the eoBcsatsrasoa of dost is the sir. inrot*- fag the caHetties o deat from the air aad its qruasutieB by Ishorslorv mesas -- making doit coasts. Dust coast* are reatonahiy acenrote approm atiosi of the camber of particle* ef dost eon* U icsd ia a giren toSu b s e l air. The iaisrasatioft, wfatn obtafaed, merely aignifies that st that per(jealay fesstani snd leeitios, lb* sampling dertes used coQecisd the determined amount of d ost A ample takes shortly tfierwards coder different weather eonditioiu, or in a lightly different locaties wiD *ary oostidershly. An faamsniest safflpifag Btaall rolemes of air will prodoee a greslel perceauje of erroi tfasn wj as instrument i*mplinr l&roe Tolnmea at air. Te fetain a representative picture of candisinos, it i* aeceuary to average the reanlt of a somber of large rolme ample takes i s the ame spot ewer s long period of time, erapfayisg as nctroGumt of faow a efficiency sgafaal A partb-U lire* el the given dost. DPfaen dost ic the air-is visible we know the r . (cid CU00030 U C1- 7 -2 0 0 4 l b : J b /a .' 1, 193? ] LHWWbNLt (IHLfcKbHU T m i EwPLOTtu' G to u p Enctveemnc Manu a i. yiy 02ba [ Page u he*A irrirta. whcg not v itih k , dust coa s ti ebaniti b e empToyed, -- -- lh e earliest practical instrument for sampling dotty ti r was tbc Konimeter (dtm meter) W oped by engineer in the South A ln ess mines. A m esitired volerne of sir is drawn by a amali hand piston through an orifice and impinged at high velocity upon a circular glass plate which is tun- ally coated with a film of gelatin. T he doit is the air itieka sn the plate m a apot roughly circo lar, and can be counted directly through the at tached snaeroK opb W hile this instrument it of low efficiency and can sample only very m u ll volumes of air, it can take 30 samples on one plate, is compact, and obviate* th e necessity of laboratory renting. I t w u need saccearfuHy in South A frica as a comparative instrument, and aided m aterially in South Airican dost control work. The O rn a i meter was first used to sample at mospheric desta. A hand piston draws the d u ty air through a take lined with wet blotting paper which s e r r a to hum idify the incoming sir. The sir passes through a slit orifice, and expanding, is chilled, causing the m oisture in the air to east the dust particles w ith water. U se coated par ticles are impinged on a amali cover glass, oppo site the orifice, in the form of a ribbon. The p a rtirie* in this ribbon ana counted udder a mivrroscope, usually employing oil immersion methods. The Owens je t m eter is vert efficient for extremely fine dusts. For industrial dusts it is about 40% efficient, h u t its compactness sud simplicity render it invaluable, lik e the kouim eter it t a k a small 'grab" samples and unless used properly may give misleading results. The principal disadvantage of the Owens instram eni is that a new cover must he inserted for each sam ple, and in changing, exposes the clean slip to contamination from dost in the air. A variation of the Owens meter will be brought out shortly in which m soy sample may he taken without chang ing the glass plate. Bausch akb Lcvrs Dust Counts* -- This is an ingenious improvement on the Owen* Jet Meter that has jest recently been p at on the mar k e t It const the particles by the dark field technique which give much higher results th in the impinger. The chief objection si the present is that tt gives shnormally high results is the pres ence of smoke which constitutes little hazard. It will, doubtless be improved or modified is the near future. The standard method of dust sampling in American (G- S. Public H ealth Service Tech nique) employs the Grcenberg-Smilh impinger ap paratus. This method is invaluable because it was used t establish correlation between dust conditions sad the frequency of respiratory di seases. . Dusty air is drawn, at o tta n i rate, through a glass tube sad impinged against a fist pitie im mersed in water. Tbe force of the impingement coats the dust particles with water and they re main impended in the liquid. The cleao air passes out through a baffled tube. Suction it sup plied by an electric ruction pump or by a earspressed air ejector. A known volume of the dusty water is plaeed under the microscope and the panicles ootmied. The *vintages of the im pinge; apparatus are that it sample large volume of air, ess he left running for h o s n w ithout attention, and is the standard method for this country. Its disadvantages are th at it is bulky and hard to transport, it fragile and expensive, and dusts so collected cannot be measured directly. There are two instruments claim ed to he 100% efficient, the d e a r ie precipitator which u ti lizes an electric field to deposit the dust particles on a celluloid cylinder; and Green's thermal preeipiiator. utilizing heat waves tor the aarne p u r pose. Of these instruments, one is useful in tbe laboratory only and the other ia anil in the early stages of development. Several short-cut methods of sampling and comparative quantitation are available for routine plant operation, There are four general methods of dust con trol arranged below in order of th eir effectiveness. L Substitution of Process 2. Isolation of Proeeta 3. Removal, dilution, o r suppression of dust i t its source A Respiratory Protection In many plants, materials containing silica are used in dusty operations lo r which son-silieioua materials may he rabatituted. F or example, in find blasting, the use of metal abrasive instead of ailiciout sand will reduce the duct hazard con siderably. Flint, used in packing kilns, may he replaced by another leas hazardous m a te ria l Sometimes a dusty operation o r a defective or dusty machine may be replaced by anothe; with consequent increase in efficiency and decrease in dust dispersion. If snbslitntion is not feasible it may be possi ble to isolate the process either by use of a sepa rate building, a sealed enclosure, or by carrying on the operation st night when fewer workers will be exposed. For example, the shaking out of large castings in a foundry may be done at night by a few well protected men, thus preventing all other workers from inhaling the dost during the day. The most practical method of dust control is that of {15 suppression, (2) dilation, or (3) re moval at the point of generation. It is possible to produce dust w ithout diapersice it and a noa-dual producing operation may disperse accumulated dust from cither operations without producing any of itself. T be aetajJ mefhanie&I force that generates the duet is no! nffideot to project the tiny particle* very far into the air. It U the vibration and air motion inci- H. 0b CU0OOO31