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FILE NAME: Sprayed Asbestos (SPRA) DATE: 1962 DOC#: SPRA017 DOCUMENT DESCRIPTION: Medical Journal Article - Some Health Hazards Associated with the Building Trades Some HeaBIi Hazards Associated with the Building Trades MILTON SHF.INBAUM AVx York State Department of Labor, Division of Industrial Hrpiene 30 Centre Street. New York 13, New York '' ' Technological advancement in building con-.trucnon has produced some new modes of exposures to some traditional hazards, and Las introduced several new types 01 hzzards; deluded are those from the use of various dustv,materials in new p r a s e s , from new chemical products and sn'vents as they are used in construction and from fuel exhaust. Recommendations are gnen for controlling hazards in th pneumatic application of sanded plaster and concreti grinding; in the vs of epoxv and polyurethanes; in paint soraying; and in the operation of engines for materialsrantlmg equipment and heaters for construction jobs. . iV'-ocuclon OGETHER with the utilization of many -T- new materials for construction, industry -..r.hiaa5; iR ^cent years made increased use of -.'-new methods of applying conventional ma- y'-jterials in construction. Incidental to this if there has been an increase in the potential M,,health hazards associated with various occu- /iyiaf'ons in the building trades. Several of the u. procedures and materials of construc- i- j.Iion and the hazards which may attend them I be examined in this paper. _ .V t^no'jmaHe Appltcafion of Plaster ' performed of all plastering operations. Bast coats are usually one-half inch thick and con sist of a mixture of about 20% gvpsurr plaster, 65% sand, and 15% water \v iti trace amount cf additives. For pneumatic appplication, this plaster.! mixed in a small ribbon mixer usually lo cated outdoors. Mixing these materials form: a tnick slurry having the consistency of heavy cream. The plaster is automatically fed intc a reciprocatirg piston pump which forces the mixture through a two-inch diameter rubbei hose to a spray nozzle. It may be applied tc JIT. The combination of high labor costs and any type of lath or to unprepared tile, bloc! f.-'he a.vailabilitv of substitute materials such as or concrete surfaces. The sprav nozzle con ^^prefabricated gypsum cement, cement and sists of a short Yenturi section terminatins yi^-ood chip, or cement and paper panels has at a removable perforated cap. Compmssec $ Hf^uised a considerable reduction in the use air between 16 and 22 pounds pressure ^ conventional gypsum plaster on lath. In forces tiie plaster through a - three-eighth- attempt to recover the market, the piaster- inch perforation in the cap. The distance industry has developed and inuoduced between the spray gun and the surface beint -.ion an increasing scale a pneumatic method sprayed may van- from a minimum .cf sb applying plasters. This method consists of incites to a maximum of four feet. ' ^pum ping either plaster slurries or fluffs to 3 lh e point of application and spraying them the receiving surface. This method climdwnates the need for hod carriers and reduces viv^oweiins:. A plastering crew consists of five or sb men. One is at the mixer; a second operate; tne spray gun: and the third man acts as sprayer's helper. The latter assists in moving the hose, preparing the area to be sprayed ypsem Plaster Base Coat The application of scratch or sancicc ' plaster base coats is the most extensis e!v and in e'eanirtg up after spraving. Tht remaining T" c.- follow three *o five minute: behind tire r -aver, 'eveling and trenvelin m anu ally. r ' \ Inis p a p rr v n p rn e m rd .it th f A n r i c a n Industrial i-torn- Confertncs i- W ash-wlnn, D. C V av W i .4. ~ -- The spray operation is very rapid. Th walls, ceiling; end closets of a 9 bv 12 foe 353 A i :->.-0o ' ' Ty* * a Jl' i & . j n .' ' l'f >` A / U; t September-October, 1962 T able I Measurement of Average Particle Size Device Used 1 Size in Micron** tkZ Cascade Impactor Group 1 2s..r0. 8.0 20.0 k aged percent of increase then fell into three 4I groups which differed only in the velocity i oi air flowing mrougn ine appai a.ius at me i time the samples were secured. The dry state particle size determinations were made by similar calculations based on the sum of all counts in each size range. Table I shows the Group 2 2.5 100.0 V jf", 4.5 9.0 42;o Parent material samples were obtained at 25.0 4-5 pnc.h sampling location and were analyzed Group 3 M icroscope graticule 2.75 w- for free silica by wet chemical methods in 6.0 11.0 261 accordance with the procedures outlined^by 30.0 99.8 aV . . . , < v.V 1 2.0 48..00 l\-\ 18.0 j 32.0 : Table II indicates the physical characteristics of the dust found at the breathing zone nf the operator during plaster spraying oper- ations. The samples obtained with the cas- room can be completed in less than half an cade impactor contained the dust with .its hour. However, the operation is extremely water content whereas the impinger samples dirty because of the considerable quantities were dry'. It was also found that the dust of underspray, rebound and drippings. Air concentration tends to diminish inversely movement within the area affects the oper- with the distance from the spray operator, ation and steps must be taken to close all Sampling at a distance of six feet showed exterior openings prior to spraying. the average count was about 10 M PPCr. Environmental Conditions In the course of an extended study of spray plastering operations, the Division of Industrial Hygiene collected ever seventyfive^-air samples using midget impingers and cascade impactor slides. Impinger samples were used to determine dust counts, dry state particle sire, and airborne free silica concentrations. Phase microscopy methods described by Crossman*1 and the author2 were used for airborne free silica concentra tion determinations. Dry state particle size determinations were made at the same time by measuring particles with a calibrated mraticule containing circles of various sizes. Samples were secured on cascade impacmr slides in accordance with the methods out lined by Littman.3 The number of dust par ticles in standard areas of each stage of each slide was counted. Counts in each stage were then converted to percentages of totals for each sample. The separate percentages of the totals of the several samples were averaged and converted to percents showing increase over the respective reference sizes, T h e aver- T able II , Physical Characteristics of Dust C reate by " Sanded Gypsum Plaster Spraying(a) P u at counts t F -ee silica concentration!b Mean particle site, dry state M ean particle size, w et state 2S-75 m ppri 61% 1.5 microns 6.4 m icrors t) As ind icated In breathins: zone sampUn;:. c) T h e tre e silien concentrations found m toe air samples w us l close agreem ent v-ith those found in th e parent rnamnai. In the course of pneumatic application of gypsum plaster, the spray operator may^ be exposed to a variety ol health hazards, first, there is always the possibility he might In hale dust containing silica. Second, he is ex posed to a constant barrage of wet alkaline gvpsum particles a n d . droplets that may cover the exposed skin area and enter the eyes. Thus, the dermatitis problem normally present in plastering Is extended because the face and neck as well as the hands are^ex posed. Irritations of the eye are also l-'Ciy for the same reason. In addition the spray operator may be required to work on narrow wooden scaffolds or ladders, or at best on cemi-finished floors, and the likelihood ot ,-dustrial Hygiene Journal # (alls and tripping is increased bv the presence rbereon of considerable quantities of wet which serves to accelerate and further sepa rate the asbestos fluff. Compressed air at plaster and construction debris. about 100 to 120 pounds pressure is fed into the Venturi immediately in front of the Protective Devices taper. The need for using protective devices The stirrer and accompanying dumping other than hand creams is limited to the operations are usually located near the spray spray operator since the concentration of dust ing operation within the building. Asbestos:n the atmosphere diminishes inversely with cement may be applied either before or distance, and because all members of the after the structure is closed in. The distance rrew other than the spray gun operator are between the spray gun and surface may vary ell behind the spray nozzle in terms of time from 6 to 24 inches. Surfaces may be pre and distance. The only practical means o.f viously treated with water d r a water-latex Drotecting the spray operator is by means of emulsion or mav be dry. Wetting the surface suppiied-air respirator. A supply of air is improves adhesion. Sometimes a latex emul readily available in the compressed air hose sion may be added directly to the asbestos feeding the spray gun. Experience has shown for the same purpose. that a nozzle respirator coupled to a full face The plastering crew normally consists of shield to protect the face and eyes is prac three men: a mixer, a spray operator, and a tical and adequate. helper. Occasionally one or two additional men may be assigned to the crew to level and Asbestos-Rockwool Cement Asbestos and asbestos-rockwool cement or fiberglass mixtures may be applied as interior finishes on solid surfaces to achieve a high fire-resistive rating and to deaden sound. Thev are most commonly used on exposed neel beams and girders in buildings which 5-eproof construction is required, as well as on ceilings and ceiling aprons of auditoriums and meeting rooms. Because these finishes are soft and friable they are limited to use hi areas where they may be protected by either their inaccessibility or additional coverings. : Asbestos cements may be applied either manually or pneumatically. The machine used for the pneumatic application of these finishes consist of a finger" stirrer which functions to fluff and to break up the asbestos strands of the raw tnatcrial, a paddle wheel fan, a length of three-inch diameter flexible hose and a nozzle. Because of mechanical filiations the hose is relatively short, not weeding 50 feet in length. The nozzle con- bts of two parts. The first is an outer annular section that is fed water at 80 to 100 pounds per square inch pressure and capped with a perforated ring. Its function is to create a fog to wet the asbestos. The second, or inner section, is essentiallv a Venturi tube smooth by hand. The general working con-' ditions are the same as experienced in spray- . irtg sanded gypsum plaster, except that the use of scaffolds and working over large areas are the rule rather than the exception. The Division's studies of this operation, al though not completed, have shown the presence of extremely dusty conditions. The average dust count in the breathing zone of the operator is about 200 mppef. Con-, siderable dustiness was noted at distances of 50 feet from the operation as well as in the area about the mixers. It was impossible to- , secure dust samples in areas where asbestos cements containing admixtures of latex emul sion were being sprayed since the adhesive " formed a gel in the impingr tubes. Besides a' high percentage of asbestos, the airborne dust may contain mineral wool, clay, fiber glass' and cement, a mixture which is potentially harmful to the lungs and irritating to the skin. The hazards produced by the pneu matic application of asbestos cement plaster are not limited to the spray operator, but may affect anyone working within 50 feet. - Recommended procedures for health pro tection tentatively call for use of airline res pirators by the spray operators, approved, dust respirators for the mixer tenders and helpers and the exclusion of all other persons 'immum,''mmw w m iw 356 ' - September-October, 196? from the general area in which asbestos is being mixed or sprayed. actual grinding. The first type, used for overhead and vertical surfaces, consists of a large wheel mounted on the ends of extended Expanded Aggregates Gypsum mixed with expanded aggregate, counterbalanced arms. It is driven by an electric motor through a belt and pulley ar rangement. The entire assembly is mounted cement and additives may be applied instead ' on wheels for portability. The arms and of various other combinations of materials to grinding head move through a vertical plane produce highly fire-resistive finishes. Because and may be independently controlled. Ceil this mixture is relatively light as compared ings can be ground by setting the arm.and to concrete, it is sometimes used in its place head position and by moving the carriage-. to reduce weight. However, expanded ag Vertical surfaces are worked accordingly by gregate plaster is not used widely because it is very expensive and does not improve^ the structural integrity of the building, More over, it is relativelv soft and friable, and does not have the good accoustical properties of asbestos plasters. Plasters made ^vith ex panded aggregates may be app'ied in a man ner similar to that used for sanded gypsum plaster. If they are applied pneumatically they must be leveled and troweled for a a reverse arrangement. i Another machine in common use consists of a fixed wheel mounted below a motor and set on wheels. I t Is used to grind and to polish floors. This machine may be used for wet as well as dry grinding. The -last type of machine is essentially a hand-held port able face-grinder. It is used in areas that cannot be ground with either of the iarg'-t machines. fine finish. _ Perlite and vermiculite are the most com monly, used expanded aggregates containing practically no free silica. Operations at which expanded aggregates are being applied pneu matically have not yet been studied by the Division and consequently no data >s avai.- Repairs which require repointing on s`one and brick buildings are related to ^cement grinding insofar as the portable grinder r used for the removal of the old grout. The edge of the wheel is used instead of the fac" and whatever is said of concrete grir.din: may be applicable to repointing operations able. as well. Concrete Grinding Concrete surfaces are usually smoothed, prior to the erection of the exterior wal.s; Concrete is poured as a semi-fluid material however, special work may be done after t..` ' into molds or forms constructed of wood or exterior has been completed. Floor grindtr" steel. After pouring, it is vibrated to fill ad and terrazzo finishing is usually done after the voids and spaces within the form. The both interior partitions and exterior wab joints at which the sections meet are not have been completed. The operation is qui" necessarilv flush, smooth, or tight. The sec rapid, and normally only one man is requm tions themselves"'"contain irregularities ana at a location. On large jobs, however, a'1 surface imperfections. Thus, after the con ditional personnel may be assigned to po^ crete sets and the forms have been removed able hand grinding to help shorten the tote the surface is rippled and ridged and contains numerous spines and bumps. If the concrete surface is to remain exposed these imper fections may spoil the appearance o. the finished construction or may pose a hazard to the occupants of the building. It is there fore necessaiy to remove them, and grinding is the process best suited for the work. ^ There are three main types of machines for grinding concrete, each of which uses high-speed carborundum wheel to do ` " work time. The Division's experience with concrc" grinding operations show that the dust cr* centrations may very widely depending 1 the phvsical conditions of enclosure, o.i'u tion o /w ind, and other factory It is lik-1 that the concentrations of dust in the wo ing area will be well above the MAC uny the process involves wetting. If the winc^ 'blowing toward the operator's back and y ,rial Hygiene Journal ` 357 .ance between the wheel and the operator at lean 6 feet, the dust concentration in the eathins zone may remain within tolerable .els. However, when the conditions are r. so favorable, the potential hazard to the ' rator may be considerable since the . zee hazards inherent in the use of epoxy resins. Measures to protect the health and safety of workers should be taken accordingly. The crew is usually small, with one man mixing and up to five men carrying, pouring, and troweling. ;ca content of the mortars and concrete Epoxy resins may be used in paints where- grinds ranges from 30 to 80 per cent. cver hard, durable surfaces are required, as in food processing plants and lavatories. roxy Resins Such paints are supplied either in rsady-to- Epoxv resins have gained widespread use use mixtures- containing the prepolymer, a relatively short period of time in many ;verse industries. Inherent limitations and Lch costs have limited their use by the buildi-t trades as agents for producing very hard or surfaces and as components of imperme- ` !e paints. Epoxy resins are manufactured by reacting hylene glycol with various complex amines - form a liquid prepolymer which may un;t certain circumstances be mixed with lers such as sand or talc. To form the \vmer. diethlenediamine or other complex catalyst, and colors suspended in solvents; or more commonly, in two containers, one hold ing the resin and the other the remaining materials, all of which are mixed immediately before use. The solvents normally constitute 50 to 60 per cent of the paint, which is usuallv applied by spraying. Polymerization is very rapid and the coat is set within an hour after spraving. The hazards involved are due principally to the solvents and may be con trolled in a manner indentical to that used in spray painting with other materials. ;'.amines are added as catalysts. Polymertion mav be rapid or slow and may or may ; require heat and curing. During polyrization various toxic amines are given I which may cause severe dermatosis on mtact with the skin or lung irritation if ihalecL , For use as a pavement over clean, dry oncrete or wood epoxy prepolymer is suptied with a mixture cf sand. The hardenfcr, r catalyst, is supplied in a separate container o be mixed on the job in small batches vhich must be poured immediately after mixing. After some polymerization has taken ,'iace, the mixture stiffens and can be spread o nroper depth and smoothed by troweling. The pavement usually becomes hard over night. The tools and containers for mixing and vorking epoxy resin mortars are usually leaned with toluol, acetone, or mixtures of solvents sold as lacquer thinners. Since the plastic is not soluble after it is fully polymerzed, the utensils must be cleaned prior to full set. The trowels and hand tools required >'or smoothing are cleaned frequently b) viping with solvent satutated rags. The use of solvents adds to the significant Spray Painting The pneumatic application of paint is not new. It has been used as a labor-saving technique for more than twenty years in the construction industry. Some recently de veloped paints such as those containing epoXy resins and the so-called speckled paints must be sprayed, while others such as synthetic enamels may be applied by either brush; roller, or by spraying. ' ` Conventional paints usually contain pe troleum naphtha; however, the newer types have a mixture cf solvents as a part or as the total constituent of their vehicle. Toluol, xylol, methyl ethyl ketone, isobutyl ketone, . benzol-and similar solvents may be used in-.-, various percentages which may exceed 60% of the total weight of the paint. These solevents evaporate far more rapidly and are anywhere from 3 to 30 times more toxic than naphtha. . . In .the construction industry the spray operator does not have the protection of a spray booth, and may frequently work in confined areas for relatively long periods of time. He may be provided with a cartridge type respirator for protection; nowever, 358 cartridge filter's rapidly clog with paint solids, and filter absorbents become saturated with the solvents in such atmospheres. The res pirator is then inoperative. Protection may better be secured by an airline respirator as suggested for use with plaster sprayess. Since organic thinners used in paints are highly flammable, and because the electrical power supplies, sparking devices, and other sources of ignition used in work areas are usually not enclosed, a considerable fire and explosion hazard is added to the inhalation .hazard present when using paints. - A recently developed airless spray gun is claimed to reduce substantially (if not to eliminate altogether) the hazards attendant to spray painting. This gun uses heat to re duce the viscosity of. the paint. Air pressure is applied directly onto the paint to cause the required flow. The paint is atomized by the nozzle and the sovents evaporate very quick ly. Since the solvent concentration in the paint is unchanged the hazards associated with the operation of an airless spray gun September-October, 1S87 are identical to any other spray paintim where no heat is involved. Conclusions , The construction industry faces numcroutraditional health hazards along with sonv new ones that have emerged. Plastcr-sprav. ing, concrete grinding, the use of epoz, resins, and paint spraying have been in cluded in this discussion. Respirators affor a means of protecting the worker but the'' use is practical and effective only for rein. tively short exposures. Further work re mains to be done in devising adequate con trol of hazards during extended exposures. References - 1. C r o s s m a n , G .: D eterm ination of F ree Silica, h r t>* pension Staining Microscopical Methods, Amer. t n ! Hyg. Assoc. Quart. 12: 117 (Septem ber 1951). 2. Shejnraum, M .: Experiences w ith Phase M tcrtr.ropv A m e r . Ind. Hyg. Astoc. J. 21: 518 (D ecem ber 3. Lippman, M. A Compact Cascade Im prctor for Survey Sampling-. Am er. Ind. Hyg. J. 22: 3+8 (C c tn ly 1%1). t t 4. TALvrrre, N . A .: D eterm ination of Q uartz in P r^ e rc e of Silicates Usint? Phosphoric Acid, Analviir* C hem . 22: 623 (April 1931). W HO Fellowships Available . The World Health Organization will provide to United States health workers in 1963, at the request of the Government of the United States, a limited number of short-term fellowships for the "improvement and expan sion of health services'' in the United States. All applications will be screened by a Selection Committee established' by the Surgeon General of the U. S. Public Health Service. Applications will be considered in public health and related fields. Ap plicants must be engaged in full-time public health or educational work. In making selection, the Committee will consider the ability of the individual, the field_of study proposed and the contribution which foreign study will make on his return. Officers and employees of the United States Government are not eligible. These fellowships will cover per diem and transportation and, except in very unusual circumstances, will be limited to short-term travel, i.e., two to four months. Employers of successful applicants will be expected to endorse applications and to continue salary during the fellowship. Fellowships will be awarded up to the total of the funds available but successful applicants could probably not start their fellowships before May 1, 1963. The deadline for the receipt of applications is January 1, 1963. Further information and application forms may be obtained from Howard M. Kline, Ph.D., Secretary, World Health O ganization Fellowship Selection Committee, U. S. Public Health Service. Washington 25, D.C.