Document NGQv6X3a2Z9vKZZVr2xQ8kpQD

FILE NAME: Sprayed Asbestos (SPRA) DATE: 1972 DOC#: SPRA047 DOCUMENT DESCRIPTION: Medical Journal Article - Application of Sprayed Inorganic Fiber Containing Asbetos-Occupational Health Hazards Application of Sprayed Inorganic Fiber Containing Asbestos: Occupational Health Hazards WILLIAM B. REITZE,* WILLIAM J. NICHOLSON, DUNCAN A. HOLADAY, and IRVING J. SELIKOFF M * * . a r m * * * o f the City University o f N ew York, F ifth Avenue and 100th Street, New York, New York 10029 i Over 40,000 tons of inorganic f'brous insubtion w ntam g b i multistoried ^ by the construction industry as a serious contam- buildings. The application of this a ^ 5 concentrations may range from 30 f/cc ination of the working environment. As exoosures and health of the workmen to more than 100 f/cc. Some eai y -- n ^ f f ^ a p h s of the working areas. in this comparatwely new occupation are given w ^ p ^ ^ ^ found tQ bfJ 70 f/cc Nearby workers may beindirectlyexposed h ten feet from the spraymg and 46 f/cc seventy nve ie Control measures are disr cussed. Introduction O ccupational inhalation hazards associated with the of asbestos fibers have been well established, with important risk of asbesto- sis, bronchogenic carcinoma, mesothelioma (pleural and peritoneal), and possibly other neoplasms.1 Such hazards have been found^n factories manufacturing asbestos products, in mines and mills producing the fiber, ' and in the use of asbestos products for insulation work in the construction industry.7 Starting in 1966, we undertook an investiga tion of another commercial use of asbestos in which an occupation hazard seemed possible-- the spraying of mineral fiber insulation material for fireproofing and heat insulation. Sprayed inorganic fiber insulation was intro duced in 1932 with the Limpet process, by the J. W. Roberts Company of Great Britain. Mr. N. ' Present address: Johns-Manville Industries, Man- UThise w o rT was supported in part by Pubiic Health ervice G rant ES-00358 and by Health Researcn louncil, NYC Grant U-1272. L. Dolbey, Director of Research for this com pany, is usually acknowledged as the pioneer developer. British Railway coach makers used the sprayed product containing asbestos in their coaches to control condensation and noise; it also acted as a thermal insulating material. In 1935 the spray process was first used in the United States. Most of the material applied dur ing the late 1930's was used for decorative fin ishes in night clubs, restaurants, hotels, etc. When this material was found also to be use ful as a fireproofing agent, such use gradually increased, and in 1950 the National Gypsum Company obtained the Underwriters Laborator ies' approval of its brand of spray insulation for fireproofing. In early 1951 the Asbestospray Company also had an inorganic fiber blend tested and approved by the Underwriters Lab oratories. The first use of sprayed "mineral fiber" as a fireproofing agent in a large multi story building occurred in 1958 with the erec tion of the sixty-story Chase Manhattan Bank building in New York City. In 1970, well over half of all the large multistory buildings con- 178 American Industrial Hygiene Association Journal 179 struded in this country made use of sprayed "inorganic fiber" as a fireproofing agent. States for shipboard installations during World War II. Uses of Sprayed Inorganic Mineral Fiber Insulation Mineral fiber materials containing asbestos have four major insulation uses in the construc tion and shipyard industries: (1) fireproofing, (2) thermal insulation, (3) acoustical and decor ative purposes, and (4) condensation control. Fireproofing accounts for the largest amount of mineral fiber sprayed in the United States. Formerly, structural steel in multistory build ings had to be encased in concrete to prevent buckling in the event of fire. The use of sprayed mineral fiber provides adequate fire protection, reduces installation costs, and reduces the weight load upon structural steel components. The use of sprayed insulation in thermal applications permits powerhouse turbines to be encased in a uniform, continuous coating which greatly reduces convection heat losses. Other industrial uses include coating of vessels in chemical plants and refineries, and insulating electrostatic precipitators, boiler breechings, and stacks. Because the newly applied surface of sprayed mineral fiber can be shaped, the materi al not only provides good acoustical control but also can be used for decorative ceiling and wall coatings for large areas in public buildings, res taurants, and similar establishments. Sprayed products containing asbestos fiber are particularly useful in controlling condensa tion in indoor swimming pool areas, laundries, textile plants, and other industrial buildings where condensation may cause extensive corro sion of structural steel. The unique wicking action of the individual asbestos fibers serves to keep the inner mass of the insulation free of moisture. The use of sprayed mineral fiber in the ship building industry was at one time rather exten sive in Great Britain. However, because of prob lems encountered in removal during repair, its use has now been discontinued in Great Britain. Very small quantities were used in the United Inorganic Fiber Mixtures Used for Spray Application Although the composition of the various spray products will vary with the intended use and the individual manufacturer, certain general formulations are similar. Most are termed "min eral fiber" materials, although naturally occur ring mineral fibers are usually in a minority, and man-made inorganic fibers dominate. The material used for fireproofing in build ing construction usually is a blend of 5 to 30% asbestos fiber (chrysotile), mineral wool, clay binders (as bentonite), adhesives, synthetic resins, and other proprietary agents such as oils. Many of the materials used for thermal insula tion on turbines contain nearly 100% asbestos fiber (often amosite or amosite and crocidolite) plus the usual binders and adhesives. The mate rial used for acoustical and decorative purposes may contain a greater percentage of mineral wool and little or no asbestos fiber. Some mate rials are applied as a sprayed slurry (commonly known as cementitious spray) and will often contain vermiculite, gypsum, and shorter asbes tos fibers (see Table I). Because the cementi tious material has a much greater density and increased weight per unit area, the supporting structure must sometimes be designed accord ingly. The quantity of mineral fiber used for spray applications in the United States today is stead ily increasing. In 1968 an estimated 40,000 tons of material were used for fireproofing alone. This does not include the amounts used for industrial thermal insulation, acoustical con trol, and condensation control. A thirty-story building may use 200 tons, while the World Trade Center complex being built for the New York Port Authority will use 5000 tons on the twin 110-story towers (above the fortieth floor, only non-asbestos-containing spray materials were used). The sixty-story Chase Manhattan Bank Building is fireproofed with 1,500,000 square feet of sprayed mineral fiber. The Hoi- March, 1972 180 TABLE I Composition of Sprayed Mineral Fiber Products Depending on manufacturer, the p r o d u c tm a j^ c o n t^ Decorative and acoustical Manufactured silicate fiber (such as Rock Wool) Asbestos fiber Mineral binders Clays - bentonite Hydraulic setting binders Portland cement Oversprays Emulsion type sealers Latex Acrylic Resin Paint Thermal'' Amosite asbestos fiber Crocidolite asbestos fiber Chrysotile asbestos fiber Manufactured silicate fiber (such as Dust-arresting additives Wetting agents Oils Rock Wool) Hydraulic setting binders Portland cement Aluminum silicate extruded fibers ("ceramic") _______ _______ Fireproofing (cementicious) Chrysotile asbestos fiber Gypsum Portland cement Vermiculite _____ aContains 5 to 30% asbestos fiber, bContains nearly 100% asbestos fiber. New York City, there were six to eight build ings taller than thirty stories being sprayed on any given day. An estimated 2500 tons were used in Great Britain during 1968. Use as a fire proofing agent consumed most of Britain s spray insulation material. Figure 1. Mixing hoppers and pum ps used to con vey material to point of application. land-American ocean liner Rotterdam contains 400 000 square feet of sprayed mineral fiber used for fire protection, thermal insulation, and sound and condensation control. Most sprayed material is used in large cities. During 1970, in Figure 2. Applicator applying sprayed t o p i n g containing asbestos. Note Worker is wearing respiratory pro > fnr such intense exposure. American Industrial Hygiene Association Journal ------------- 1 Volume 3 ------------------------------ - ' Number 3 ' MARCH, 1972 ------------------- - 3 ------------------------------------------------ -------------------- --G D.-DiV<i=n--cenzo, Ph.u., r.J. ' ...................................... . . . . 125 ^35 ............................................................ H6 Exposure M Sol M. Michaelson Standards - ................... ,* ^ .......................................... 165 Omnidirectional HlSh-F.r,eney Sound l ~ t .. ....................................................................... ... Anthony J. Schneider .......................... Application ot Sprayed inorganic Elbe, Containing '*" ; ............................... ................. 1,8 Polonium-210 in Blood and Urine o t U-- Li. Novak, M.Ph. and D. Panov, M.D. Analytical Guides ................................ Mine Worh.rs i ........................................................ ^ 2 si 5^ ' s ^ l s f e E o i iy !S s - asss^ Scherberger. g o io - t ' ^ ea|,h The University . Avenue. Westmont, New Jersey 0 8 1 0 8 . The subscription f U s e 1 ,* he Business Office for Sd OO iwr copy pr ^ edK aU advertisements and to reius the Association. Library of Cong fflce ofsPecondaciass ;Q wjumj,er 57-jiy 1. 8 S1ack, Inc., Thorofare, New Jersey _____ ____________ C H A gnS'f. " A-3 American Industrial Hygiene Association Journal 181 Methods of Application There are two principal methods of applying sprayed mineral fiber. In the dry method, dry material is dumped from a paper shipping bag into a large hopper, where the material is agi tated and subsequently blown into a 2- or 4-inch hose (Figure 1). The hose conveys the dry material to a nozzle at the actual site of application (Figure 2). As the dry material leaves the nozzle, it passes through the focus of a ring of fine water jets. Mixing takes place at this focal point, which is usually 4 to 8 inches from the end of the nozzle. The operator is able to control the air, material, and water mix, with valves at the nozzle. The wet method differs in that the material is premixed with water in the hopper, and the resulting slurry is pumped to the nozzle and sprayed upon the surface to be coated. The nozzle used is similar to that used to apply plas ter. Exposure of Workmen Spraying of mineral fiber is done by men in several different trade unions in the United States, depending on its purpose and local juris dictional agreements. All material that is used for thermal insulation is applied by members of the International Association of Heat and Frost Insulators and Asbestos Workers (AFL-CIO). This is a very minor part of their work, overall. Material used for fireproofing is often applied by members of the Plasterers' Union. Acousti cal and decorative material may be handled by carpenters, or other craftsmen. In New York City, fewer than 1000 men in all would have regular or intermittent exposure to sprayed asbestos insulation. The application of sprayed mineral fiber compounds containing asbestos is potentially associated with health hazards for two groups of people and possibly for a third. The first group, workmen actually engaged in applying the material, is relatively small in numbers. This group, however, is the most heavily exposed. Air samples taken on site and counted by using a modification of the method described by TABLE II Spraying of Thermal Insulation Power House Turbine3 Man at Nozzel (1) Man at Nozzel (2) Man Charging . Hopper 68 67 22 1 85 45 5 < 31 100 10 24 32 6 Spraying of Fireproofing --Multistory Building Man at Nozzel (3) Man at Nozzel (4) 30 99.0 43 94.5 20 49 34 aAll counts in fibers per cubic centim eter. Fibers longer than 5 microns, visible by optical microscopy at 440x with phase microscopy. Our studies have dem onstrated th at many more fibers shorter than 5 mi crons, too small to see by optical microscopy, accom pany the optically visible fibers and may exceed them in num ber (although not in mass) by several orders of magnitude. These smaller and thinner fibers and fibrils are detected only by election microscopy and are not included in counts such as these. Ayer and Lynch,8 counting only fibers longer . than 5 microns visible by optical microscopy at [ 400x, indicated that the worker handling the ; nozzle was exposed to fiber levels ranging from i a low of 30 f/cc to over 100 f/cc. The worker ; emptying the bags into the hopper was found to be exposed to fiber levels ranging from 5 f/cc to 22 f/cc. The large spread in counts can be attributed to differences in asbestos content of material, work proficiency, and the ever-chang- ' ing conditions on construction sites (see Table II). These dust levels are much higher than ; those at asbestos work sites in other trades. There are no satisfactory data at present , concerning disease among these men with direct exposure to sprayed insulation dusts. Their work experience in general has been too short to have led, as yet, to clinically evident disease. Among other asbestos-exposed workmen, sig nificant disease usually does not become evi dent for twenty or more years following onset of exposure.10 No group of workmen engaged marcn, i y / t Figure 3. S y * r ,I b e fo re * ..!. due , . . P-- most unhappy fate for the men who have been working in the sprayed insulation industry Among other insulation workers, with much less asbestos exposure, observed for more than twenty years from onset of exposure approxi mately one in five deaths has been of lung can2 one in ten of gastrointestinal cancer, and 2 o s t one in ten of pleural or peritoneal meso thelioma. In addition, almost one ir.te n has been of asbestosis and cor pulmonale. And these disease experiences have been associated, it may be noted, with dust exposure levels much lower than at spraying sites-perhaps on tenth or one-twentieth as high! The fate of the sprayed insulation workmen will likely resemble these experiences altho u ^ the pattern of distribution of deaths by cau may be different. Jacob and Anspach have demonstrated that, where asbestos work ex posure is unusually excessive deaths of asbestosis and cor puhnonali and fcwer of lung cancer; the workmen die of pulmo ,,,y insufficiency before th e, can live long enough to develop and die of long cancer to spraying asbestos has been examined after Yo'rk City, we have examined a dozen men who have sprayed asbestos. Most to d worked only two or three years ^ trade- they were asymptomatic, and their chest roentgenograms exhibited few o, no abnorm.ltties Two men had had longer experience. One, a man of 41 with fifteen years of exposure du a span of twenty-one years, was also with , shmtness of breath, and his film was non apart from minimal lower lobe reticular fibrosis. The second man, the only one who had gone more than twenty yean: from "* j 'exposure, was severely short of breath, M e * tensive asbestosis on x-ray, and " f p". monale He had had four years of work exper ence starting in 1935 tw e n 'y -^ e y e m lle fo re his death in 1964 at the age of 65 (Figure i ) . If experience in other asbestos trades is a guide, and if there is a consistent exposu _wp mav predict a meS r "r ^ o u P , which may involve many men working in the building construction trades in the country, especially 'those, engag d in hieh-rise construction work, is much larg . Pine fitters welders, electricians, plumbers, car- penters^and others may be on the site during or shortly after mineral fibers ha been sprayed. On-site samples taken at vanou distances from the nozzle show fiber counts f nm 70 f/cc 10 feet from the nozzle to r ^ J a t . counts taken 301 minutes after completion of-spra)r stillrangedfrom 1 4 f/cc and 60 minutes after, from 0.25 to 0 . lb Bcc Again, these counts var, because of Chang- ps in on-site ventilation. We have few data to predict the magnitude of The disease hazard among workmen with indirect exposure. That there is a P nus risk may be inferred from the increasing reports of mesothelioma among men working i S a r d s in which asbestos spraying was assoc S with such risk of indirect occupational Asbestosis is also found among 191 American Industrial Hygiene Association Journal become lodged in the lung. Once in situ, the fi bers continue to exert their effect on contigu ous tissue; while the individual may be spared further exposure, his lung and other tissues are not. Construction tra d e s workmen employed in buildings in which spraying of asbestos fiber in sulation was done should be considered to have to ensure adequate compliance for the control of the spraying of asbestos mineral fiber insula tion. The New York City Council thereupon banned all spraying of asbestos in N. . - e ective February 25, 1972-Local Law 49, 1971, A ir Pollution Control Code, Section 1403.2-9.11(B); enacted August 25, 1971. been subject to asbestos exposure and risk, in formation is inadequate to predict the magni tude of this risk; it may be considerable. Such occupational hazards are intolerable, and it is evident that they will not be permit ted In addition to efforts by regulatory agen R f fIeUkoff! I.J., e t Asbestos and N eoPlasia` A m er' Workers. B n tJ!. In M bM ^h***08 ith e r. peritoneal Tu- Brit. J. Ind. Med. 21:20 cies mentioned before, construction unions, too have taken steps to protect their members. Work stoppages have occurred in New York Citv Westchester County, and elsewhere, with men in various trades refusing to work during spray operations. If administrative regulation is unavailable or ineffective, self-regulation by la bor and employers in the construction trades may be substituted. Our studies suggest that the occupational hazard associated with spraying of asbestos in 4.Merewether, E.R.A.: A Memorandum o^A shesl0- 5 M c N u ltr ^ C .f Asbestos Exposure in AuslraUa. * " f l t i o n a , Conference on nesbure 1969. Proceedings (H.A. Shapiro, e a .),p p 20120?3 , C apetown, O xford University ^ ( 1 9 7 0 ) . 6. McDonald, J.D .: Research on Asbestos. M and E.C. Ham mond: Asbes7 tos* Exposure and Neoplasia. / . A rn e , Med. Assoc. 188:22 (!9 6 4 ). Aver- M easurem ent of Dust ^ Exposures to the M bestos Textile Industry. Am. Ind. Hyg. Assoc. J ^ 7 : 4 3 p Ferrand; ^ 9. Nicholson, W .J., A..N. * York City. Second In- sulation can be minimized or eliminated by suitable industry procedures. Such controls as " / S " " " " D C~ ,, ,0 1,, noted, will be expensive for the sprayed fire proofing industry; the burden in the competa- XO.Selikoff, I.J-, J ^ urg> insulation Work- r " u l i U d b StMes. A nn. N. Y. Acad. Sci. tive market place may make the product and process uneconomical, to give way to other means of fireproofing and insulating. Shou this occur, it will simply mean that the health f s o Y s e C ^petow n" O xford University Press of workmen must be considered in weighing th cost of work done. On some scales, as this one, health will weigh heavily. The alternative to controls will be banning the spraying of asbestos materials. While, as a general rule, control of environmental hazards seems preferable, if control measures are nei ther feasible nor effective, or if they are ignored or disregarded, banning will be considered. ,4- r s - d ' yards. Ann. ^ cuAP'RH^ en(pjeton:( Effects of Asbes- (1968). H am m o n d : Asbestos Bodies 1 S m UN Y C Pop'ulatfonin Two Periods o f Time. /- m N.y .c . ^ in fe r e n c e on Pneumoconiosis, Jo- ternational C f di (H.A. Shapiro, ed.), ^ " "^9 l o t C a p e m Z Oxford University Press Note: Since this manuscript was submitted it was determined that the existence of he N Y C Department of Air Resources had failed 16 Selikoff, U .: Partnership for Prevention. Ind. Med. Surg.39(4,:21(1970). ^ . ^ ^ 3 1971 American Industrial Hygiene Association Journal 183 TABLE III Area or Stationary Samples Taken during Spray Operation Sample Distance from Nozzle Man (ft) Count (fibers/cc)a 1 15 17 2 35 10 3 75 46 4 10 71 5 10 70 6 20 37.6 7 20 66.0 Taken 30 m inutes after spray operation had ceased for the day1' 8 1.01 9 1.12 10 1.55 11 4.22 Taken 60 m inutes after spray operation had ceased for the day*5 12 0.55 13 0.51 14 0.28 15 0.76 16 0.26 j*See footnote, Table II. "Samples taken on same floor as operation. these men,14 and asbestos bodies are detected in their lungs more commonly than among other comparable blue collar workers.15 The problem of indirect occupational expo sure in the construction trades is of importance, if only because of the number of workmen involved: In the United States, more than 3,000,000 men are regularly employed in the building trades. While the incidence of asbestosassociated disease among those indirectly exposed may be lower than among the one-in-ahundred with direct exposure, the total disease experience can be considerably greater. Our air studies indicate (Table III) that very high asbes tos fiber levels are found in the work environ ments of building trades workmen not associ ated with spraying operations, but simply work ing in the same buildings. We may not know the incidence of mesothelioma and lung cancer among men so exposed for twenty or thirty years. In New York City, where spraying was under way in the 1960's, asbestos disease result ing from this practice, among steamfitters, elec tricians, carpenters, painters, masons, and other trades, will not become evident until the Figure 4. Waste from spray application adhering to building materials used by other trades. 1980's, and 1990's, and the twenty-first cen tury. Similarly, we will not be able to assess possi ble disease among the general public for an other twenty or thirty years. We have deter mined that contamination of the community's air occurs as a result of uncontrolled or inade quately controlled spraying operations. As ex- March, 1972 184 pected, such contamination is greatest in the vicinity of the construction site. Since most of the spraying is done before the building curtain walls are erected, some of the spray material may blow outside the site. The quantity that escapes depends on wind, height of building, skill of operator, material, and control measures used. Construction sites have been studied where grossly visible waste from a spray application covered the ground to a depth of 1 inch for a distance extending 100 feet from the site (Figure 4). Control of Occupational Asbestos Hazards Associated with Sprayed Insulation The two most important sources for work man exposure during spray operations are (1) material that becomes airborne during the spray operation (overspray), both that which re mains at the job site and that which blows into the surrounding air, and (2) material that re mains on the site because of poor house keeping. Until recently, few control measures were used during application of sprayed mineral fiber. During 1969 and 1970, extensive field in vestigations were undertaken by our laboratory to ascertain the possible asbestos hazard in this trade and to develop corrective measures. In this, we had considerable cooperation from the Department of Air Resources of the City of New York, and some segments of the sprayed insulation industry, including a number of man ufacturing and contracting firms associated with the Sprayed Mineral Fiber Manufacturers Association and the Contracting Plasterers As sociation of New York. The International Asso ciation of Heat and Frost Insulators and Asbes tos Workers, AFL-CIO, although its members did little such work (rather, Plasterers' Union members were engaged), also provided consider able help, since they had had much bitter ex perience with the problem in general.16 Simi larly, valuable assistance was provided by the Johns-Manville Corporation, in keeping with their general perspective of developing effective controls for such asbestos uses as might be asso ciated with hazard. In this investigation, work sites were studied in eleven cities in eight states. Practices were found to be very much the same throughout the country, as described above. It is our general conclusion that sprayed insulation practices can be controlled to a point at which the occupational hazards, both direct and indirect, can be minimized or eliminated, but that such controls will be expensive, tedi ous, and cumbersome. Our findings may be summarized by consid eration of the Sprayed Insulation Regulations promulgated by the City of New York in April, 1970. These regulations were largely based upon the results of our studies, supplemented by valuable additions derived from the experi ences of the Department of Air Resources (Dr. Robert Rickies, Commissioner) and its staff, including those of Harold Romer, P.E., who headed a special group assigned to this problem. These regulations were the first by a govern mental agency to seek to control hazards associ ated with sprayed insulation and have more recently been followed by administrative ac tions in other cities including Philadelphia, San Francisco, Boston, and Chicago. In the Matter of the ) _ . r u * \ Spraying of Asbestos- ) Pnntflininff Material ) .. , Commissioner s Order PURSUANT to the authority vested in me by the New York City Charter and the New York City Air Pollution Control Code, IT IS HEREBY ORDERED that when ever asbestos-containing material is sprayed, the following precautions shall be taken to prevent and control the emission of asbestoscontaining particulate matter into the ambi ent air. 1. Before the start of spraying operations all floor areas shall be shoveled clean. Before the application of asbestos-containing mate rial commences, the floor of the area shall be cleared of all objects, material and equip ment other than that employed in the appli cation of the asbestos-containing insulation or all objects, materials, etc., shall be cov ered with plastic or other approved tarpau- American Industrial Hygiene Association Journal lins in a manner that precludes the subse quent dispersal of asbestos particulates. 2. The entire floor, or the part of the floor to be insulated shall be enclosed with plastic or other approved tarpaulins in a manner which shall preclude the escape of asbestoscontaining material from the enclosure. All interior open areas, such as elevator shafts, stairwells, etc., shall be enclosed in a manner which shall prevent the escape of asbestoscontaining material from the working area. "Stack effect" of the shafts, stairwells, etc.' shall be considered satisfactory only if visi ble insulating material cannot escape from the enclosure. 3. Wet asbestos-containing material which has fallen to the floor shall be swept up con tinuously to prevent dispersal of dried ma terial. Under no condition shall this material be removed later than at the end of the working day. Swept-up material shall be placed in a heavy plastic bag strong enough to resist tearing or breaking under normal handling conditions and clearly marked as containing asbestos waste. The contents of the aforementioned plastic bags shall not be transferred to another container. The plastic bags shall be placed upon a vehicle for dis posal at an approved site. 4. All floors will be vacuumed shortly after drying. The vacuum cleaner shall contain a strong, single-service disposable inner bag of durable material which shall be removed, then be placed in a container of the type de scribed in paragraph 3, which shall thereafter be placed on a vehicle for removal and dis posal at an approved site. 5. The materials used to form the enclosure shall be thoroughly vacuumed upon comple tion of the application of the insulation in the area. The entire floor area, all ledges and surfaces including tarpaulins upon which waste insulation material may have fallen, shall then be vacuumed or revacuumed be fore removal of the enclosures. 185 6. Enclosures shall not be. dismantled until the area has been thoroughly vacuumed after completion of spraying and cleanup. 7. All areas used for opening bags containing asbestos insulating material and/or charging of hoppers shall be enclosed in such a man ner that asbestos-containing insulating mate rial shall not be permitted to escape from the immediate area in which such activity takes place. 8. Signs shall be posted outside enclosures warning persons of the hazards of entering the enclosure without appropriate mask and other apparel. 9. All persons involved in the spraying of asbestos at the site must be furnished with Bureau of Mines approved respirators for pneumoconiosis-producing dust or equip ment as required by N.Y. State Department of Labor and must be furnished with suit able coveralls which will be left at the site and thereby preclude the removal of asbes tos from the site. No person shall be permit ted in an area in which asbestos spraying or handling has taken place until final vacuum ing referred to in paragraph numbered `5' herein, unless such person is furnished with and wears a Bureau of Mines approved res pirator for penumoconiosis-producing dust and coveralls of the type described herein. Facilities shall be provided and procedures instituted and supervised that preclude the removal and dispersal of asbestos-containing material from the construction site on the clothing or other appurtenances of persons leaving the area. 10. Any plenum or other structures coated with asbestos-containing insulation which is intended for use in the circulation of air in the building must be thoroughly cleaned of all debris and waste insulation. All applied asbestos-containing insulation .within a plenum or duct must be coated with a seal ant which precludes exposure of the asbes tos-containing material to the circulating air. 186 March, 1972 11. A person shall be assigned the full-time responsibility to supervise the spraying and related operations to assure that no asbestos bearing material is released from the con struction site. 12. In case o f emission of asbestos from the construction site, immediate steps shall be taken to cause the cessation of such emis sions by either effective control measures or work stoppage at the source of the emis sions. There shall then be immediate and complete cleanup of all material that has es caped the construction site by measures that will insure that no further dispersal of any asbestos material into the atmosphere can occur. 13. Notice of intent to spray asbestos-con taining material on any premises shall be given to the director of Field Services, De partment of Air Resources, 134 Centre Street, New York, N.Y. (212-566-2735). Said notice shall be both oral, by telephone, and in writing and shall specify, at least two (2) days prior to said spraying, the floors on which the spraying will take place. It will be seen that these early regulations (they have since been strengthened) were di rected largely to the prevention of the environ mental hazard. In addition, we were able to identify a number of other approaches which were more specifically concerned with the oc cupational hazard. Reduction of Airborne Asbestos during Spray Operations Currently, consideration is being given with in the industry to several proposals aimed at reducing the amount of asbestos dust which might become airborne during spraying. An important approach includes elimination of asbestos from the material used and the addi tion of oils or wetting agents. Formulation changes have met with some success. Several manufacturers are now producing material which contains no asbestos. The disease poten tial of these substitute materials is largely un known, and New York City regulations require the same precautions during their application as with asbestos-containing materials. ' In Great Britain, the modification of spray equipment has received considerable attention A method of prewetting the fiber before con veying material to the nozzle has been devel oped. Although this prewetting process signifi cantly reduces fiber counts during applications the method does not yet lend itself to volume spraying as done in the United States. Progress has been made in developing effec tive means of enclosing areas during spray appli cation (Figures 5 to 10). Several contractors have custom-designed canvas or reinforced plas tic tarpaulins with various flaps and interlock ing closure devices. Wooden frames covered with reinforced plastic are in use. Not only must the perimeter be enclosed, but the stair wells and elevator shafts must be sealed to pre vent the stack effect from carrying dust and fiber to the outside atmosphere. Some rather unique ways have been developed for enclosing outside spandrels and columns prior to spray ing. Since the design of buildings may differ widely, methods for-enclosing must be individu ally tailored for a particular structure. To elimi nate the need for temporary enclosure of budd ings, some contractors are rescheduling the spray application to permit prior erection of curtain walls and glazing of the window open ings. Enclosure with canvas and plastic has mark edly improved since enactment of more strin gent regulations. Ambient air samples taken near spray job sites that have been enclosed by means of newer methods have shown that ex cellent containment is possible. Asbestos fiber emissions from properly enclosed spray opera tions were not detected with the light micro scope. Electron microscope examination of samples is currently under way to determine if the spray process adds significantly to the as bestos fiber background level in ambient air. In limited studies, it did not. Enclosure tarping, however, still has not solved the problem of wind erosion during the interval between com- American Industrial Hygiene Association Journal 187 Work Practices It is our conclusion that much can be done to reduce dust by the individual workman on the job, in his everyday handling o f the spray material. Methods of opening, emptying, and stacking bags, proper methods of using and ad justing the nozzle, and methods of personal protection are important. Attention to seeming ly small details by the worker are important, and these should be the object of training and education programs. The sprayed mineral fiber manufacturers association has prepared a book let outlining such improved work practices. Too Figure 5. Floor of building after spray application. Note piles of waste asbestos-containing materials and flapping tarpaulins, inadequately secured. Figure 7. Wind and weather damage to enclosure canvas. Figure 6. Multistory building inadequately en closed with canvas. Note openings where tarpaulins have not been secured. pletion of spray and erection of "skin" or cur tain wall. Architectural awareness of this prob lem may permit design of future multistory buildings to ensure erection of curtain walls be fore spray fireproofing is applied. Scheduling is no simple matter, however, and this may be very difficult. Figure 8. Enclosure of multistoried building with laced canvas and plastic tarpaulins. 188 Figure 9. Custom-fabricated tarpaulins for building enclosure. Note tongues and tie-downs to prevent ma terials from dropping along the side of the building. Figure 10. Where a long span exists between col umns, the tarpaulins must be securely fastened at the bottom to prevent flapping in the wind. March, 1972 the supervisor or foreman. His task, however, should also be lightened by the development of procedures which do not depend upon work man cooperation, skill, knowledge, training, or dedication to safety. Elimination of hazards should be built into the work procedure! Other wise, if anything can go wrong, it well may, and the price of failure is unacceptable. This is not to say that the on-site operations of the workman are not important; of course, they are. One area in which no planned pro gram, however effective in principle, can be suc cessful without workman cooperation and un derstanding is housekeeping. In our studies, we found that quantities of waste sprayed mineral fiber are still allowed to remain on the floors, ledges, and nearby equipment (Figures 11 to 13). Asbestos-containing waste is often tracked underfoot on a construction site for many months. In some cases, because of poor house keeping, waste fibrous material is allowed to re main in ventilating ducts and dropped ceilings to contribute to lifetime contamination of the structure. Experimental work is now under way to re design existing commercial vacuum cleaners to permit their use in construction cleanup. Wet pickup of large volumes of material and collec tion in disposable bags are two features which must be included in a redesigned unit (Figures much reliance should not be placed, however, on diligence and training of individual work men. We have found that work crews are incon stant, with inexperienced men often added as the volume of work increases. These men, at other times, do plastering, and spraying of in sulation may be only intermittent employment for them. Few contractors employ a constant work force, and apprenticeship programs have been scant and fragmentary, where they exist, in this country. Rather, education will have to be a constant, on-going affair and often the responsibility of Figure 11. Asbestos-containing waste allowed to re m ain in lim ited access areas and ventilating plenum of completed buildings. American Industrial Hygiene Association Journal 189 14 and 15). To reduce the number of men ex posed and to facilitate easy cleanup, several of the general contractors have begun a program of carefully planned work schedules. The men and material of other trades are kept off the floor until the spray and cleanup are completed (Figure 16). Respirator Protection Personal protection of the workers applying the spray material is an area that needs consid erable attention. We found that many men ap plying sprayed mineral fiber containing asbestos did not wear any personal respiratory protec tive device. A very few wore disposable respira tors, and a few wore more conventional types. Prior to 1970, all disposable respirators avail able on the market were totally unsuitable for this specific use. Progress being made in development of new respiratory protective devices is indeed encour aging. Many major manufacturers of such pro tective devices will probably have an effective disposable unit available sometime during 1971. It is hoped that a device of this type will have an overall efficiency great enough to adequately protect many men working in the general area of the spray operation although not near the spraying itself, nor within the spray enclosure. Figure 13. Uncovered pieces of equipment left on the floor dunng spray application collect debris from the spray operation. Figure 14. Waste material should be picked up and packaged in tightly closed containers. Figure 12. Poor housekeeping. Waste asbestos ( : spray material covering conduit box where other crafts j may work weeks or months later. Nevertheless, because of the high fiber counts, 100 f/cc, a conventional filter-type respirator will not provide adequate protection for the worker handling the spray nozzle or for other workers in the enclosure. In such areas, some type of supplied air respirator must be used. The chief fault of many of the available sup plied air units is their bulk. Here again, great progress is being made in the development of small belt-carried units (Figure 17). A quick look at the fiber counts in various areas at or near the spray operation points the need for mandatory effective respiratory protection. 190 March, 1972 be-few men have reached twenty years from onset of w ork-but of young men who have been regularly employed in spraying asbestoscontaining insulation materials it is possible that a majority will die of asbestos disease, in cluding lung cancer, pleural and peritoneal mes othelioma, and asbestosis. Our studies indicate Figure 15. Waste material being transported to des ignated landfill areas in covered trucks with packages secured to prevent the spread of material through streets and roads. Two steps are essential to speed the use of res piratory protection in the spray insulation trade: (1) a device more acceptable from a standpoint of worker comfort and (2) a massive educational program among these workers. Discussion Investigation of the sprayed mineral fiber in dustry indicates an important asbestos hazard exists for workmen employed in this trade. It is too early to tell how severe the death toll will Figure 17. Because the spray applicators are sub jected to high concentrations of asbestos fibers, some type of air filtration or supplied air respirator is neces sary. A prototype of the Burgess filtered air respirator. Figure 16. Enclosed areas should be appropriately marked to prevent other trades from entering the area being sprayed. that they have been exposed to asbestos dust levels otherwise seldom seen nowadays in the asbestos industry. An equally unacceptable hazard may exist for other construction workmen, exposed on construction sites to dusts derived from spray ing operations. While such indirect occupational exposure is intermittent, it is still at levels found in other trades to have high risk. Unfor tunately, intermittent high peak exposures may carry the potential of serious disease twenty, thirty or more years later. The inhaled fibers