Document zozm5n79KR21ZamrjkrQkJY30

FILE NAME: Sprayed Asbestos (SPRA) DATE: 1963 DOC#: SPRA018 DOCUMENT DESCRIPTION: Article from State Occupational Health Journal Construction Health Hazards VOL. 8. NO. 3 MICHIGAN DEPARTMENT OF HFALTH Albert F.. Heustis, M.D., Commissioner SPRING, 1%3 Construction Health Hazards Technological advancements along with new chemical products have created a new set of health hazard control problems in the construction industry. And these problems seem to be more severe in the construction field which does not have cither the site or personnel permanency of the manufacturing plant, Instead, the construction industry is characterized by mobility; pick-up work crews", foremen who have little or no knowledge of the inherent hazards in some of the materials being handled by their men; difficult working con ditions where weather is a significant ptoblcnv, and a prevailing attitude that the generally rugged workers in the construction industry arc not subject to health hazards. We have selected a group of topics lor consideration which wc consider timely, varied, and potential souiccs of health problems for construction workers. All of them have been dealt with at one lime or another by personnel of the Division of Occupational Health. Every year, either by re q u e st or through its own initiative the Division checks out and advises on many con struction jobs. * This is an extremely important function since more than 100,000 Michigan people work in construc tion and these workers daily lace hazards which can he detrimental to their health. These hazards can be injurious to health either through acute or long term exposure. The immediate asthma tic effects of a single toluene diiscyanate exposure or the pulmonary dif ficulties experienced by an asbestos insulation worker after 15 years on the job can both be serious health problems. Also, when considered in the light of lost time by workers which Figure 1 View of three workers on on osbestos spraying job. The worker at the floor level feeds the material. The worker at the upper left tamps the surface. Note that all three are exposed to excessive quantities of asbestos dust and that their respirators are not being worn. can mean severe economic loss to their families as well as to the em ployer, the problems become more important and more complicated. In this publication, we will deal with four rather divergent types of construction techniques which present varying degrees of hazards to work ers. They include: (1) application of epoxy-terrazzo floors and epoxy coat ings; (2) spraying of asbestos; (3) application of red lead paint; ami (4) pouring in place or application ol polyurethane foam. Epoxy-Terrctzzo Floors & Epoxy Coatings Principal health problems associated with the application of epoxy resin base m a te ria ls such as adhesives, paints, special surfacing mortars, and epoxy-terrazzo Hours are dermatitis from skin contact with the amines in the mix, excessive exposure to toxic solvents used in some of the resin systems, and, in general, nose, eye, and tin oat irritation caused by the amine catalyst and the solvents. Com pletely cured epoxy resins are not believed to present such hazards. Kpoxy resin materials can be so formulated (by literally tailoring the molecules) that a wide range of de sired properties can be obtained. Some adhesives can be made to present varying curing properties and unusual tensile strength. Surfacing compounds can be made impervious to almost all types of solvents. Paints can be made which are adaptable to conventional production spraying and baking oper ations in industry but which present unusual surface protection properties. And epfixy-terrazzo floors can be ap plied which are essentially non-shrink ing, are impervious to most solvents, present a wide range of colors, are considerably lighter than comparable concrete type terrazzo floors, and have excellent strength characteristics. While the relatively high cost of many epoxy products has limited their g e n e ra l application in the building trades, their exceptional properties have resulted in a ra pidly increased use in the building and construction industry for spe cialty applications. These include long-wearing paints with special finish effects on concrete block wall surfaces, epoxy te rra z z o 1loot's which have exceptional wear re sistant properties, and special sur face coating (paving application) on highways. The new International Bridge in Sault Ste. Marie has a thin layer of an epoxy water-re sistant coating material between a concrete base and the lop asphalt roadway surface. Purpose is to keep water from coming into contact with the concrete. Base m a te ria l in manufacturing epoxy resin is ethylene glycol which is reacted with various types of amines to form a liquid pre-polymer. A wide variety of particulate type fillers such as synthetic fibers, sand, metal powder, carbon black, and wood dust are used to effect certain properties and ap pearance and polymerization of the pre-polymer is brought about with the addition of diethylencdiaminc or other complex polyamines (catalysts). Rate of polymerization or curing can be varied by chemical formulation and the application of heat may or may not be required. During poly merization, various toxic amines are emitted and these can cause severe dermatitis or eye damage on contact or lung irritation if inhaled. Suscepti ble individuals can develop sensitivity to several of the amines used. In the epoxy-tcrrnzzo floor ap plication, marble chips are imbed ded to form a unique terrazzo surface. The substance has the ap pearance of conventional cement terrazzo but is applied to a tliick- ' WMn.' iX: - , feilrA SH*,'j j Fiqure 2. Materials used in application of epoxy-terrazzo floors and epoxy coatings be dangerous if allowed to come into contact with the skin. Please note the lack of protection at the resin mixing operation. You will notice that the workman in the center is smoking a cigarette. 2 ness of only 3/16 of on inch. This epoxy-terrazzo can be applied directly over dry concrete or wood, both of which have to he properly prepared to receive the su rfa c in g xylene concentration was reduced to about 40 parts per million where it remained until the next xylene ap plication. It appears that xylene or whatever solvent is used for easing the trowel material. ing and rolling job constitutes the Some ot the adhesive or primer greatest health hazard in application coats contain solvents such as xylene of epoxy-terrazzo flooring but that and toluene indicating the need for the solvent exposure can he reduced proper control. A mixture of marble to acceptable values with the use of chips and epoxy resin is then apphed appropriate ventilation. to the floor and troweled to a level of approximately 3/16 of an inch This s followed by application of a heavy layer of marble chips which is spread uniformly over the entire floor and set in place with a roller. Where the ventilation measures taken arc not satisfactory, the use of approved respiratory protective equipment is indicated. Il is also reasonable from the point of view of safety that the cleaning of all After several days of curing, the equipment witli a solvent should floor is then wet-ground with water in he done out-of-doors where pos a conventional manner. It has been reported to this Division that der matitis is a common ailment among epoxy-terrazzo floor applicators ap parently caused by the amine catalyst. But this has not been evident in the two studies conducted to date. Ar rangements were made with a local manufacturer of flooring material to conduct occupational health studies at two jobs which were scheduled since we were interested in both the amine concentrations which developed during application of the flooring ma terial'and the xylene concentrations which built up as a result of release from the primer coat and the trowel ing operations. Use of xylene is nec essary to ease troweling and surface rolling and to minimize adherence of the tools to the uncured resin mixture. sible. Tools and containers for mixing the epoxy resin floor compounds are usually cleaned with toluene, xylene, acetone, or mixtures of solvents com monly known as lacquer thinners. The flammability or cxplosibihly problem does not appear to he severe but since flammable materials are be ing handled, necessary measures to prevent a solvent buildup to explosive levels or to minimize the possibility of ignition of either liquid or an airvapor mixture should be taken. The need for ventilation during application of the flooring material has already been noted. There is also a need for good personal hy giene habits among workers to min- iivu'zc effect of skirt contncl. Warm water and mild soap should In one recent study of the appli be available so washups may he done cation of a conductive surface type as frequently as needed and workers terrazzo floor in a surgery suite, no should receive instruction on proper significant concentrations of amines work procedures as well as on the were found in the immediate work hazards of the materials they arc hand area (ranged from 0.1 to 0.2 parts ling. Solvents such as xylene and lolu- per million), perhaps because of the cne should not be used for cleaning the marginal type ventilation provided skin but rather special skin cleaners in the room. It did not appear that any of the workers had dermatitis and no reports of skin difficulties were made to us should be made available for this pur pose. Since there is a skin exposure problem, appropriate protective cloth ing including gloves should be worn. A combustible gas indicator was used to determine the concentration of xylene vapors in the breathing zone Suggested Work Control of the workers during various stages Procedures of iroweiing and rolling. It indicated vapor concentrations which reached a ' peak of approximately 600 parts per million when the solvent was first dis tributed With, n tong bristle brush (swishing in the air). In less than a minute, the solvent c o n c e n tra tio n dropped to about 400 parts per mil lion and about eight minutes later the All workers on the job should he properly instructed on the toxic nature of materials they arc to handle; the proper work procedures to minimize any hazard due to skin c o n ta c t or inhalation; and obviously, proper application tech niques to minimize exposure time. Appropriate ventilation should he provided wherever the work is being done to minimize the conccnlrations of amine or solvent which might develop. The rate of air flow should be sufficient lo keep contaminants at levels generally below the maximum threshold level. P ro te c tiv e w ork clothing should he worn on the job so that as much of the body surface as possible is protected. The work clothing, particularly the gloves should he impervious to the ma terials being handled. Personal hygiene is very im portant. Workers should he en couraged to wash up with soap and water frequently (or use waterless cleaners); should minimize the use of solvents for skin cleaning (use specially prepared cleaners); and should do all their work in a way as to minimize exposure to any of the materials handled. This calls for neatness on the job. A lthough the flammability problem is not severe, it is never theless present, since flammable materials particularly solvents are used and the air vapor concentra tions reached can he relatively high. Accordingly, smoking as well as other sources of ignition should he controlled on the job. l'ire ex tinguishing equipment should he handy. Respiratory protective equip ment such as chemical cartridge respirators may be required in cer tain areas where high solvent con centrations develop despite the use of ventilation. Such re s p ira to rs should he available on the job, should be kept in proper repair at all times, and workers should he trained to use such equipment. Spraying of Asbestos Asbestos is commonly applied to interior surfaces. It is used mainly on exposed steel beams and girders in buildings where fireproof construction is required as well as on ceiling and ceiling ap ro n s of auditoriums and meeting rooms. Because it leaves a finish which is somewhat soft, it is limited in use to areas which can he protected cither by additional cover ings o r i n d i r e c t ly through inaccessi bility. Asbestos coatings may be applied either manually or pneumatically. The 3 a finish coat mix. Analysis showed both materials were nearly 100 percent a sb e sto s w ith a small amount of filler as a non-fibrous nature. Findings of our dust study were discussed with representatives of the contractors, the building trades coun cil, and business agents of every trade on the job. Wc indicated that dust concentrations were excessive but that the problem could be corrected by segregating and ventilating the oper ation and/or by the use of approved respirators by everyone on the floor in which the fireproofing operation was being carried out. The follow-up visit revealed that the fireproofing contractors had pro Figure 4. Workmen loods asbestos for pneumotic feed to spray gun. He is not wearing respirator. information we present is primarily concerned with pneumatic application. The principal hazard in spraying as bestos is excessive contamination of the air with asbestos dust particles. Inhalation of excessive quantities of asbestos dust over a period of years on the job can result in serious lung difficulties. The hazards of asbestos spraying arc not only limited to the spray operators, but may affect anyone in or near the contaminated work area. is 5 million particles of dust per cubic foot of air. A series of representative work room air samples were collected. Sampling locations were from 15 to 30 feet from the spraying operation and the d u st concentrations were found to range from 14 to 59 million particles per cubic foot, considerably above the maximum allowable con centration level. Two samples of the spraying materials were lab tested. One was a base coat material and the other vided a large wall fan which was used when the spraying was done. Also, the floor on which the crew was working was sealed off by means of plastic curtains. No other workers were required to work on the floor while spraying was taking place and if one elected to, he was supposed to wear a Bureau of Mines-approved respirator. T hese Were on hand with each contractor providing them for his own men. In another study in which the interior of a dome was being sprayed, the crew was uninformed of the as bestos inhalation hazard, respirators were a v a ila b le but not necessarily worn, and the dust concentrations ex ceeded 10-million particles per cubic foot of air in the workroom. Because of inaccessibility no breathing zone Recently, tills Division studied a routine asbestos spraying oper ation in which the spraying equip ment consisted of a feeding hopper and a compressor connected with a flexible hose to a gun. Asbestos fibers from the hopper were fed into the flexible hose and propelled by a blower system to the spray gun where it was wetted with water (sometinies containing an adhesive). The armrnnt of asbestos fibers and water applied in the final mix were controlled with a valving system on both the spray gun and the hopper feed mechanism. Although employees doing the 1ire- proofing were provided with dust respirators, other tradesmen (electri cians, plumbers, carpenters) were not similarly protected. They complained and a study was conducted quickly. Present maximum allowable con centration for asbestos dust as recom mended by the American Conference of Governmental Industrial Hygienists Figure 5. Asbestos spraying operation is shown. 4 samples were collected at the elevated height where the spray operator was located hut it is assumed that the concentrations there were excessive. Since the spraying operation is such that the maximum threshold level will be exceeded in almost all instances where the work is done unless control measures arc applied, it is reasonable to expect that all asbestos spray con tractors will adequately control the operations so as to minimize the health hazard to their workers. Suggested Work Control Procedures Educate all workers as to the asbestos toxicity problem and proper work techniques. Provide adequate ventilation so that the dust concentrations de veloped in the general workroom do not exceed the maximum thresh old level. Wherever possible, segregate the asbestos spraying operations so adjacent areas in the work place are not contaminated with asbestos dust. ' Provide and make the wearing of Bureau of Mines-approved type respiratory protective equipment mandatory where the dust con centrations arc ex cessiv e. Such respirators should be provided by the contractor. All employees engaged in such xvork should be given pre-employ ment physical examinations before being hired and should be given periodic physical exams. These ex aminations should include chest x-rays. Vacuum cleaner type surface cleaning procedures should be used in place of manual sweep tech niques. Application of Red Lead Paint After several investigations, this Division has c o n firm e d that lead hazard problems on construction and highway work exist mainly as a result of lead-based paint coatings used on structural steel. Our attention was first directed to this problem as a result of reports indicating that paint crew employees on a highway bridge project had developed lead poisoning. Inquiries since directed to the highway departments in other states have not verified similar p ro b lem s in these locations. Observation on the job indicates a general lack of knowledge of the seriousness of this problem by most workers and .supervisory personnel. Eor example, on a routine highway bridge maintenance job involving sand blasting of the painted steel structural members, the workers were not wearing respirators. Air samples indicated lead concentra tions ranging from (5 to 110 milli grams per cubic meter and dust concentrations ranging from 117 to 285 millions of particles per cubic foot of air. Lead may enter the body through inhalation, swallowing, or absorption through the skin. The latter can be ruled out in construction work unless gasoline containing tetraethyl or tetramethvl lead is handled by employees in a careless manner allowing it to make direct contact with the skin. Inhalation is dangerous where wire brushing, sanding, or grinding is done, particularly with automatic tools, and where lead-based paints are applied with hot or cold air or airless spray methods. Swallowing is another serious mode of lead entry into the body and reflects personal hygiene habits which have been observed to be basically poor on outdoor construc tion projects. Lead contaminated work clothing, dirty hands, and activities such as smoking and eat ing on the job site can all result in swallowing hazardous amounts of lead. Our Division feels the problem is severe and the well-being of many workers is being endangered on an almost daily basis. On construction jobs, certain environmental control procedures should be implemented for the benefit of all employees including (hose of the subcontractors. A major contractor may be able to put through an adequate program for his own employees because of direct supervision. But the problem is more difficult with subcontractors. Possibly, effective control can be initiated as a contract stipulation. Another important consideration is the educational approach through meetings and in making adequate and carefully p re p a re d material available to work crews. The obvious answer to the lead paint problem is the use of a substi tute paint. While we have been suc cessful in this approach in several steel 5 fabricating shops where iron oxide pigmented paint is now used, even in these places, job orders arc received from time to time where the customer insists on lead type paint. Paint manufacturers maintain that there arc substitutes available which are at least as good as lead coatings. Apparently, they have not been suf ficiently diligent in proving it. The alternative is effective protection of the worker on the job. In the area of protective equip ment, respiratory protective devices such as the type approved by the Bureau of Mines for protection against lead dispersokl and organ ic vapors should be worn by all employees engaged in wire brush ing, grinding, automatic sanding, or any other type of operation which produces any appreciable quantities of lead dust. While working in en closed areas such as in bridge tow ers or in water tanks, workers should wear Bureau of M inesapproved air supply hoods. Super visors should see that respirators are in good working condition and see to it that the men wear them as part of the job requirements. Protective clothing is important since contaminated clothing is a source ofjjcad dust. A usual practice is to have lead workers in industry change clothing in locker rooms designed tor the purpose. On arrival, w orkers change into clean work clothes and belorc departing, arc encouraged to take showers ami change back into street clothing. The work clothing is then laundered. Outdoor construc tion workers, especially, wear the same work clothing for extended pe riods of time. This is a source of contamination. Personal hygiene is the most im portant single factor in preventing in gestion of lead and involves not only routine and deliberate washing of the hands and face but a personal con sciousness of the need for extreme care in handling hazardous materials. llot xvater, soap, and towels should be provided so that the men can keep reasonably clean. Washup procedures should be enforced particularly before the noon meals and before workers leave the job site. The use of waterless cleaners may be satisfactory as a substitute for soap and water in the event that they can not be supplied. The fact that smok- ing and placing the hands in or near the mouth also can result in ingestion of lead should be emphasized to the workers. In the care of the eyes and face, the use of face shields or safety glasses should he a mandatory re quirement on all jobs where flying debris is present in the atmosphere. This is especially important in wire brushing, grinding, and sanding. Effective supervision is another important factor. An occasional project engineer sometimes has little actual interest in the health and safety of his men, so it becomes important for the contractor to fol low up on all jobs to see that con ditions which could endanger health of the employees arc controlled. It's an excellent practice to sec that all employees arc given pre-employ ment physical examinations and that (hey be cheeked periodically when they are engaged in potentially haz ardous work. All employees who may possibly be exposed to lead should be tested for lead absorption in ac cordance with the program outlined in Volume 5. Issue I (Fall, 1959), Michigan's Occupational Health bul letin. The Division is prepared to collect and analyze urine and blood samples submitted for evaluation of lead absorption where new biological control programs are being instituted. Education of workers as well as supervisors is unquestionably neces sary. Suggested Work Control Procedures Educate employees as to the lead toxicity problem and in prop er work techniques. Good personal hygiene habits are particularly important. Water, soap, and towels should he pro vided and workers should at least wash their hands thoroughly be fore eating and before leaving their work stations. W a te rle ss h an d cleaners should he provided where water is unavailable. Bureau of Mines-approved respirators should be provided and their use made mandatory '1*0 excessive dust (grinding, chipping, wire brushing) and paint pigment (spray painting) are given off. Use of frequently cle a n e d work clothing should be encour aged. Workers should he given pre employment and periodic physical examinations. A biological testing program should be instituted where working with lead is a routine matter. A minimum program follows: Minimum Medical Program This is a recommended minimum lead control program. For case in interpretation of lead and blood levels, refer to Tabic 1. Incorporate a routine biological test program for all employees exposed to lead. . (a) Urine samples to be taken at least every three months and examined for lead content. In areas of excessive lead exposure (air con centrations above 0.15 M g/M ') urine samples should he obtained monthly from exposed workers. (b) Blood samples to be an alyzed for lead to be taken from all workers following urinary lead excretions greater than 0.15 mg Pb/1 urine. A second urine sample should be obtained at the same time for lead analysis. (c) Blood and urine samples to be repealed on a monthly schedule from all workers excreting lead in concentrations of 0.15 mg Pb/1 urine or with blood levels greater than 0.05 mg P b/100 grains whole blood. (d) Remove workers from lead exposure areas where blood lead concentrations reach a level of 0.08 mg P b/100 grams whole blood or above. Workers should not be re employed in lead areas until bio logical samples indicate reduced levels of lead in these body fluids (urine --equal to or less than 0.15 mg Pb/1 or urine. Blood equal to or less than 0.05 mg Pb/100 grams whole blood). Pouring In Place or Application of Polyurethane Foam The use of polyurethane resins in both foam products and other specialty items has grown remarkably in the past few years. The number of items made of polyurethane foam is almost endless and it enjoys particular popu larity in the construction industry basically as an insulating material. The chemical formulations used can he varied to produce poly urethane products of various chemi cal and physical properties and invariably involve a reaction of toluene diisocyanale with a p o l y ester or polycther type compound. During production of the foam, occupational health problems can de velop because of the common use of toluene diisocyanale, which is a highly toxic material. In high concentrations, TDi can be lethal and in small amounts, it is very irritating to the mucous membranes, p ro d u c in g an asthmatic type effect. Great care must be taken in its use and close engineering and medical supervision of the work men are desirable. Poured-in-place A- insulation (between partitions) and a spray application to surfaces of steel storage tanks, for example, are two important uses in the construc tion field. The foams are made by metering and mixing the correct amount of toluene diisocyanale and o th e r required ingredients (poly esters, polycthers). TABLE I. Urine ipnd rn.i/litpr 0.01 to 0.06 0.06 to 0.15 INTERPRETATION OF BIOLOGICAL LEAD SAMPLES Blond lend , m ,|/lQ 0 gm j:0 ; " \\ Non-occupational Normal lead absorption Rc-check: 4 to 8 weeks Occupational Normal lead absorption Re-check Occupational Hazardous lead absorption Re-check: 2 to 4 weeks Occupational Absorption compatible with lead intoxication Recommend Blood lead test, Hemoglobin and Erythrocyte count Routine urinalysis Physical examination Re-check: 1 to 4 weeks 0.02 to 0.04 0.04 to 0.07 0.07 to 0.08 0.08 Plus Non-occupational Normal leod absorption Occupational Normal lead absorption Re-check: 4 to 8 weeks Occupational Hazardous lead absorption Re-check: 4 to 8 weeks Occupational Absorption compatible with lead intoxication Recommend immediate recheck and remoxol from lead exposure area and physical examination ': .Y. : ; ' i .< ' ] , : f". ". j j.-.: : i f V.. 6 1>''i''ll'>J f-0/,115!lOlfiil 1f"S*'0* 11 SoPtCPNiK.'O'0HWO Figure 6. Personal a function of areas being sprayed, wind point protective devices as around the structure direction, and spray If (he material is to be sprayed on to a surface, which is typical of ihe outdoor application to storage tanks for insulation purposes, all of the chemicals used arc automatically metered through a special type spray gun unit. If the chemicals are to be poured between partitions or other cavities where it is to foam, gel, and cure it is simply a matter of metering and mixing the correct amount of materials and pouring Ihem into the mold. In either case, where the foam is the result of the carefully metered automatic spray system or a manual paper cup mixing operation on the job silc, a potential hazard exists. TDT, although generally used in amounts required for a complete chemical reaction, can he given off during the mixing, foaming, and curing procedures or can result from spillage. It can be irritating to the skin, eyes, and respiratory tract, cause eve injuries upon direct contact, and as noted above, can cause an asthmatic reaction in some people. Also, .susceptible individuals may become sensitized lo TDT. This contaminant can be controlled by providing vcnlilation and/or re spiratory protective equipment at the various so u rc es of contamination. Also, adequate facilities should be provided for decontamination of work areas in case of accidental spills of TDI. These should include adequate floor drainage, hoses, mops, and buck ets. A decontaminant consisting of aqueous 5% am m o n ia containing 10% isopropyl alcohol or a water solution of sodium carbonate should be kept on hand. An oil absorbent can be used since it is helpful in drying up spills. The contaminated absorbent then must be rem oved quickly to a ventilated location and/or treated with one of the decontamina ting solutions, Peterson, Copeland, and Iloylc, reporting on the potential health hazards of spraying polyurethane fomn out-of-doors' have indicated that hazardous concentrations of TDI can develop at varying dis tances downwind of the spray area dependent upon "distance from the gun, spray gun elevation, formula tion uses, temperature and humidity of the air, air pressure of the spray gun, rate of adduct (reaction prod uct of an excess of TDI with n polyol) used, configuration and size of the object being sprayed, wind velocity, and the use of tarpaulins lo reduce air turbulence." Based on their findings, there is no question but that the immediate spray crew at the spray point is in a vulnerable position because of the presence of excessive concentrations of TDt and should be provided with and made to wear air supply hoods and other protective clothing. It was also found that in outdoor spraying, the evolution of TDI vapor trom lhe foam surface, once applied, was an insignificant problem. The authors recommend that all persons within 150 feet downwind of the spray gun wear su ita b le eye protection. Figures 6 and 7 illustrate the recom mended precautions when spraying outdoors. Definitions of the terms used in the drawings arc as follows: excus HIOVIKJO weens *o rspitito* t0ui*l0 iib so m o ' sow q o j'fin Figure 7. The recommended prccouHons shown in this chart arc similiar to those in Figure 6, but in this case the sproy point is u p w in d of th e s tru c tu re b e in g sp ra y e d , 'Peterson, J. E., Copeland, R. A., Hoyle, H. R ; Health Hazards of Spraying Polyurethane Foam Out-of-doors, American Industrial Hy giene Association Journal Vol. 23, SepfemberOctober, 1962. 7 1. "Goggles re q u ir e d . This statement is intended to mean that the eyes should be completely pro tected from airborne material. Sucli protection can be achieved by wear ing a full-face gas mask, soft-frame louvered goggles, chemical workers' tight fitting rubber goggles, etc. Experience has shown that regular spectacles with or without sideshields are definitely not adequate eye protection. "In the area where goggles are required, some protection for the hair, clothing, and shoes is also recommended. The type of equip ment used is immaterial so long as it will protect against contact with sticky particles drifting in the air. Also, in this area, respiratory pro tection equivalent to or better than an organic vapor respirator should be immediately available to all per sonnel. Such respiratory protection should be worn at any time when the characteristic odor and/or ir ritation of TDI is noticed. 2. "Goggles and respirator re quired. In this area, both goggles and respirator should be worn at all times when spraying is being done. The word goggles lias the same meaning as above, and the goggles and respirator could, of course, mean a full-face gas mask, fhll-faee respirator, etc. Govcralls arc very desirable as are a hat (either soft or hard) and high rub bers. Hand protection (gloves of any type) is recommended. "Goggles and respirator should be the minimum protective equipment for all persons within 10 feet of the spray gun when the gun is not in use but is connected to the adduct supply line. Such conditions may well occur when the gun is being cleaned or inspected on the job, 3. "Air-supplied hood required. This recommendation is intended to apply lo all personnel within 10 feel of the spray gun, upwind, downwind, or laterally, while spray ing is being done. Along with the a ir-s u p p lie d hood, impervious gloves, lightly buttoned coveralls, and impervious foot covering arc also necessary." It should bo obvious that the pour ing of foam-in-place insulation indoors is also a matter requiring adequate control if the workers are to be pro tected. Suggested Work Control Procedures (Indoor) Educate the workers ns to the toxic nature of the materials being handled and inform them of the work procedures to he applied. Segregate the area with tar paulin or curtains of some type if spraying is done indoors or if the foam is poured in place or sprayed. Provide adequate ventilation control. In construction work, this is a rather loosely applied term and it is difficult to define here except to indicate that the air volumes exhausted to the outside from the work area should he such that in the general workroom area con centrations of TDI should not he in excels of the maximum threshold level of 0.02 parts per million. Where spraying is done, all personnel within 10 feel of the spray gun should wear air supplied hoods, impervious gloves, tightly buttoned coveralls, and impervious foot coverings. Chemical cartridge respirators arc suitable for work crews involved in the manual pour ing of resins, in the latter type operation it is important that the metering station he properly ven tilated and that all foam debris and waste paper cups and other con tainers he kept in a controlled location, since these can he sources of contamination. A considerable amount of develop ment work in the a p p lic a tio n of polyurethane foam to mine walls is presently being done. The foam lining is desirable for its insulating properties in sleep mines where air conditioning is applied (the rock slialum increases in temperature with depth) and may also serve to reduce resistance to air flow. Fitzpatrick2 and others in a recent paper described the results of their studies in a mine drift at a 4100 loot level where one to two inches of foam were applied using the spray gun tech nique. Methylene diphenyl diisoevanate (MDI) was used in place of tolu ene diisocyanate and the maximum vapor concentration was found to be 0.0b PPM. They reported that the particulates from the spray contained reacting MDI in the spray area and for 50 feet downwind and that with adequate icspiratory protection (sec information on spraying) .he airborne particulates containing MDI did not cause any obvious irritation to any of the men exposed. Summary It appears that much of the success in the control of health hazards in construction work is dependent on the requirements of governing agencies, the insistence of the client, the de termination of the contractors and subcontractors, the effectiveness of the supervisory personnel, and the attitude of (lie workers themselves. To the variables just listed, can be added the general character of the construction industry, factors such as rugged weather conditions, lack of sanitary facilities, te m p o ra ry work crews, pressure of schedules to be met, variation in operations (a plasterer may apply plaster one week and as bestos another), and the rough, chang ing nature of the site all impoitanl factors. Despite the foregoing, the prob lem of uncontrolled health ha/mds in construction work can he solved if there is a determination on the part of all involved to do so. Health and economic considerations leave no altcrnature hut successful con trol. Six general methods which tenil to minimize occupational health haz ards in construction include: ( I ) ade quate ventilation, natural or mechani cal, to dilute concentrations of gases, vapors, mists, dusts, and lmes to safe levels; (2) use of wet methods to allay dust: (3) personal hygiene, including frequent washing of the hands and body and frequent changes of clothes to minimize skin contact with chem ical agents', (4) personal protective devices, including respirators, gloves, clothing, hoots or shoes and eye guards: (5) education by keeping workers informed about the nature ot the potentially hazardous substances used and the physical agents en countered, including suitable protec tive measures lor each situation; and (6) substitution of non-toxic ol less toxic materials than are commonly used. js, "Scheel, Lester D., Worren, John W ., Laird, Frank J., Jr., Watson, Harold A , Harris, E. J., Beatty, Robert L., Fitzpatrick, M al colm, and Craft, Bob F.; A Survey of an Application ot Polyurethane Foam to Mine W alls Using Methylene Diphenyldiisocynatc (MDI I, paper presented at the American Industrial Hygiene Conference, 1963. VOL. K. NO. 3 SPRING, 1963 Puhi' ` -<! Quarterly by the Division of Occu pational Health, Mich igan Department o> Hcatth, Lansing 4 Michigan Bulk Rate U. S. Postage PAID Lansing, Michigan Permit No. 162