Occupational Health Study of Heavy Equipment Operators. January 1966 == sS =a State of California ° Department—of Public-Health-> Bureau of Occupational hel ''''\OCCUPATIONAL HEALTH STUDY OF HEAVY EQUIPMENT OPERATORS a This study conducted bys: California State Department of Public Health Bureau of Occupational Health and United States Public Health Service Division of Occupational Health Fred Ottoboni, Ch.E., M.P.H. Thomas H. Milby, M.D. California State Department of Public Health™ Bureau of Occupational Health , 2151 Berkeley Way Berkeley, California 94704 January 1966 OOb6S1L '' / b6004556S J La CTP RGTY Va]. ah ORLY (Of AR ''RCa445 C75 02 PUBL OCCUPATIONAL HEALTH STUDY OF HEAVY HQUIPMENT OPERATORS SUMMARY During the summer of 1965, at the request of the California State Conference of Operating Engineers, an extensive field study was undertaken to assess the impact of noise, dust, and heat on the health of heavy equipment operators. One-hundred and ten men at 16 construction sites located in California participated in these medical and environmental studies. High equipment noise levels and significant noise-induced hearing loss among operators were major findings. Operator dust exposures were found to be in excess of safe limits in a number of jobs. Push=-Cat operators, as a group, were exposed to consistently high dust concentrations. Noise and dust control measures in the form of mufflers, enclosed cabs, and other equipment design changes were recommended. Attention was called to the need for equipment seating standards. ''''INTRODUCTION During the summer of 1965, the California State Department of Public Health, with the assistance of the United States Public Health Service, com= pleted an extensive field study to evaluate the effects of heat, noise, and dust on the health of heavy equipment operators. This work grew from a heat stress study that was completed in the summer of 1964132 at the request of the Operating Engineers Local Union No. 3. The findings of this study, along with a growing concern on the part of the Engineers’ Union for the health and safety of their men operating heavy equipment of ever-increasing size and speed, led to a formal request by the California State Conference of Operating Engineers for a more comprehensive study during 1965. In view of the large number of men regularly employed in the heavy construction industry, it is disturbing to note the lack of information in the occupational health literature concerning the effects of working conditions upon the health of these individuals. Studies done in California during 19617 call attention to the dust and noise problems of above-ground construction workers and suggest the possibility of adverse health effects arising from the constant jolting experienced by heavy equipment operators. The 1964 heat stress work! = discussed problems of operator dehydration and high equipment surface temperatures. California occupational disease statistics* show con- struction workers suffer an overall occupational disease rate of nearly twice that of the average for all California workers. Beyond this, the details of working conditions as they affect the health of approximately 30,000 heavy equipment operators in California have remained unexplored. STUDY METHODS The 1965 study began on August 10th and ended October 19th. It covered 16 construction sites located in the Sacramento Valley, the San ''''Joaquin Valley, the Los Angeles Basin, and the Southern California Desert selected so as to be representative of earth moving projects in California. Of necessity, the study was limited to the more common types of equipment which included: dozers, front-end loaders, large rubber tired earth moving equip- ment and road graders. No attempt was made to change the pattern or rate of work being performed; in fact, the individual operators and construction con= tractors were asked to carry on normally. The study group was comprised of 6 to 12 operators from each work site visited and totaled 110 men. Participation by the operators, although voluntary, was virtually 100%. In order to assess the impact of the work environment on certain of the operator's physiological functions, each participant was examined before starting his work shift in the morning and again at the end of his work shift in the evening. The following procedures were carried out on each participat- ing operators an examination of the ear canals and a hearing test (northern area only); respiratory function test (southern area only); determination of body weight, pulse rate, and oral temperature; and an analysis of the urine for albumin, sugar, and blood. Pertinent medical and occupational information was recorded and complete daily water balance studies were planned. During the same day, the noise levels and dust concentrations to which these men were exposed were measured. Systematic readings of air temperature, humidity, air motion and machine surface temperatures were planned but were not undertaken because of the unseasonably cool weather conditions prevailing during the study period. In addition, throughout the course of the entire study, equip- ment seat design was noted in relation to operator safety, comfort, and operating efficiency. Noise analyses were obtained adjacent to the operators in the only way possible; by riding with the operator. Two types of noise#measuring ''''instruments were used, a General Radio 1558 Octave-Band Noise Analyzer which was read directly, and a high-fidelity portable tape recorder which was later replayed in the laboratory through a B & K Statistical Distribution Analyzer and Graphic Level Recorder. The two methods differ slightly in that the direct method shows a single noise value for each octave band while the tape method shows a range 5 decibels in height for each octave band. This differ- ence in instrument read-out accounts for the differences in the symbols used on the graphs in this report which present equipment noise levels. Forty-five dust samples were collected with midget impingers driven by small battery operated pumps. These were strapped to the operator in order to approximate breathing zone conditions. Dust counts were obtained using the standard light-field method. Free silica determinations were made by X-ray diffraction analyses of soil samples. An additional 29 dust samples were collected on membrane filter units which were designed to collect only the respirable, fraction of air=-borne dust. These units were mounted near the operator on individual pieces of construction equipment for 4-hour sampling periods. The material collected by the filters was subsequently analyzed for total silica. It should be pointed out that this method is new and, unlike the midget impinger method, has not received official recognition as a method for estimating silicosis hazard. RESULTS Heat No new information was obtained with respect to the effects of solar and equipment heat on the health of equipment operators. Air temperatures and humidities during the entire study period were essentially inside the comfort range. Equipment surface temperatures, while often warm to the touch, did not '' © ''present heat stress problems. However, these hot surfaces may become important when combined with the heat load contributed by the hot California summers. Noise Every piece of equipment studied, with the single exception of the Caterpillar 657 Tandem Scraper with an air-conditioned cab, was found to expose the operator to excessive noise levels (Figures 1-10). The bold curved line drawn in Figures 1-10 specifies the limiting octave band sound levels for a 5-8 hour daily noise exposure as defined by the Noise Control Safety Orders, Department of Industrial Relations, State of California. According to this regulation, noise control or hearing conservation measures must be taken should any of the occupational noise levels in specified octave bands equal or exceed the permissible limits for daily exposure times of 5 hours or longer. For daily exposures of less than 5 hours, the regulation indicates that the cited limits may be raised by 3 decibels for each halving of the exposure time. The limits indicated in this regulation can be considered as liberal when compared with other criteria aimed at safeguarding hearing against noise-induced damage?’®, The latter criteria contain limiting values that are 5 to 10 decibels more stringent than those specified in the California regulation for comparable exposure conditions. The noisiest piece of equipment encountered was the Allis-Chalmers - 562 Twin Bowl Scraper with overall noise readings as high as lee decibels. The Caterpillar D-9 Tractor, a widely used piece of equipment, also ranked high with an overall noise level of 112-114 decibels. The widespread practice of failing to install mufflers on engine exhaust stacks of construction equipment appeared to be a major reason for the high noise levels found. The effect of this practice is not limited to the operator of the unmuffled machine. Figure 2 shows a D-8 operator with a very ''''high noise exposure when pushing a TS-14 Scraper equipped with a straight exhaust on the rear engine. The noise exposure of D-8 operator, working alone pulling a sheepsfoot, is shown in the same figure for comparison. The effect of an air-conditioned cab in controlling scraper operator noise exposure is illustrated in Figure 8. For comparison, noise levels on a scraper without a cab are also shown. Although the two machines are not of the same model number, they are similar enough to demonstrate the noise protection afforded by a tight cab. Audiometric Examination On-site hearing tests were performed on 66 heavy equipment operators using a closed automobile as a test booth. Fifty-three men were tested both at the beginning and at the end of a work shift. Tests were repeated on two successive days on seven men. This demonstrated that test-retest reliability was adequate. Analysis of test results led to the following conclusions: 1. Hearing levels for the heavy equipment operators showed systematic and statistically significant changes in the direction of poorer hearing with increasing age and for higher frequencies (Figure 11)*. These changes persist even after correction for aging by comparison with groups of non=-noise-exposed males of like ages (Figure 12). When reading graphs of hearing levels it is important to realize that as the curves move downward in the direction of higher decibel hearing levels, they reflect changes in the direction of poorer hearing. For example, a test subject who has a 50 decibel hearing level at 2,000 cycles per second is much more “hard of hearing" at that frequency than a test subject who has a 10 decibel hearing level at that frequency. It should also be pointed out that the frequencies 500, 1,000, 2,000, and 4,000 cycles per second are chosen because they indicate hearing levels for speech and, therefore, Significant losses at these levels may be expected to interfere noticeably with voice communication. ''''Bo Comparison of hearing levels measured before and after work on the same 55 men revealed statistically significant short-term hearing losses (termed temporary threshold shifts, or TTS) in all age groups and for most frequencies (Figure 13). These shifts are considered the result of noise exposure and are generally thought to be fore- runners of permanent hearing loss if excessive noise exposures are allowed to continue. Average TTS as great as 12.5 decibels were measured. Moreover, as others have nobed”, size of TTS tended to vary inversely with hearing level. (The less the hearing loss, the more the TTS.) Hearing levels in the study group demonstrated systematic and statistically significant changes toward poorer hearing, particularly at the higher frequencies with increasing exposure when years of work experience is used as an index (Figure 14). These changes: are Similar to those found in groups classed by age, because age and work experience tend to be related. Dust. . The results of the dust studies are shown in Tables I and II. Depending upon wind conditions, dampness of the ground, soil conditions, and type of equipment used, the dust counts from the impinger samples ranged from very low levels to well above the limits set by the California General Indus- 12 try Safety Orders’. These Orders list maximum allowable dust concentrations which are based on the free silica content of the dust as follows: Free Silica Content MPPCF* Less than 5% , 50 5=25% 20 25-50% 10 More than 50% 2 *MPPCF - Millions of particles per cubic foot of air. '' ''In this study, soil samples ranged from 15 to 49% free silica and maximum acceptable dust concentrations were either 10 or 20 MPPCF*. With the exception of one sample taken from an unusually wet job, operators of Push=-Cats were exposed to consistently high dust levels, regard- less of soil or weather conditions. Grader operators, on the other hand, received very low dust exposures. The highest dust concentrations encountered were in two dozer operators sampled at a brush clearing project. The counts, at 72 and 288 million particles per cubic foot of air, were well beyond the limits set by the California General Industry Safety orders“, The results of the membrane filter samples (Table II) generally support the above findings. The safe limit set for this method is 0.2 mg of respirable silica per cubic meter of air. The average exposure of Push-Cat operators exceeded this value. Standing out as a new and potentially serious dust hazard is the high speed earth tamper, as illustrated by the FWD Wagner Compactor. A single dust sample taken on the only piece of equipment of this type found during the study appears significant at 38 million particles per cubic foot of air, when considered in relation to soil conditions and other air samples taken in the immediate work area (Table I). The fill involved was very damp and had a low dust potential as shown by the very low counts obtained from a dozer-sheepsfoot combination and a rubber tired scraper working the same fill. Visual obser- vation of the FWD Wagner Compactor in action leads to an obvious conclusion: the compacting wheels spin off a great deal of loose dirt because of their high rotational velocity and are, in effect, efficient dust generators. Traveling belt loaders must be commented upon even though only one was observed and only one dust sample taken. This sample, froma D-8 operator pushing the loader, was nearly 5 times the safe limit (Table I). '' ''Also deserving attention are the front-end loader operators, as all three of the dust samples collected on these machines were above the safe limit (Table I). Machine Seating Arrangements The quality, state of repair, and location of seats encountered on heavy equipment varied widely; some operators sat on exposed seat springs while others rode with reasonable comfort. Shock absorbing mountings appeared to be a standard factory installation on the large rubber tired vehicles. In practice, however, many of these shock absorbers were badly maintained and of little walue to the operator. On one spread seat shock absorbers had been eliminated in favor of solid mounting. Seats were often found to be mounted directly over, or adjacent to, hot machine components creating an unnecessary heat load on the operator. Seat covering materials were of smooth, impervious plastic materials which, While durable, restricted the operator’s ability to evaporate sweat Body Temperatures, Weight Changes and Pulse Rates These determinations were included to evaluate heat stress, but did not yield useful results because no excessively hot weather was encountered. Urinalyses A rapid screening test for urinary albumin, blood, and sugar was included among the survey procedures, because previous conversations with heavy equipment operators had suggested that bloody urine was sometimes passed after a particularly arduous day’s work. However, among the 80 men tested, blood was found in only one urine specimen. Likewise, only one operator had a significant quantity of sugar in his urine and one operator had significant urinary albumin present. Each of these three men was advised to consult his personal physician, ''''- 10 - Pulmonary Function Two tests of lung function were included in the survey of operating engineers working in the southern part of the State. One test reflected lung volume and the other measured the ease with which air is moved in and out of the lungs. No significant abnormalities were discowered among the operators tested. DISCUSSION The uniformly high equipment noise levels and the operator hearing losses demonstrated during the course of this study are cause for considerable concern, These findings clearly imply that unless effective remedial measures are undertaken, the vast majority of heavy equipment operators of the future will be victims of significant, noise-induced hearing loss; a condition which cannot be cured but which can be completely prevented through protection of the ears from excessive noise levels. In reviewing methods of prevention of noise-induced hearing loss in the construction industry, three approaches must be considered: (1) the use of personal protective devices such as earplugs or muffs, (2) control of noise at its source through improved equipment design,and (3) provision of a sound-~ attenuating cab. From a practical point of view, the use of earplugs is not feasible in the heavy construction industry because heat, dust, dirt, and the lack of washing and fitting facilities on construction projects combine to make the continuous use of earplugs exceedingly uncomfortable and, therefore, of limited effectiveness. The use of muffs is also impractical as they would not stay in place under the jolting and bouncing experienced by the heavy equipment operator. ''''a TE me Prevention of noise-induced hearing loss in the industry must, therefore, be based either on noise source control or operator enclosure. Responsibility for this action rests with the equipment manufacturer because the typical construction contractor lacks the specialized knowledge and facilities available to undertake such a complex task. Observations during this study indicate that the "straight" exhaust stack is the prime noise source. Installation of effective mufflers on all heavy equipment should be mandatory. In cases where operator noise exposures are not controlled to a safe level by exhaust mufflers, further design changes will be necessary. Operator enclosure in a sound-tight cab shows promise as evidenced by the noise control provided by the air-conditioned cab encountered during this study. Special attention must be directed toward the noise encountered by the Push-Cat operator when working with rear-engined scrapers. Data obtained during this study indicated that the noise levels reaching this operator from some scraper engines are in themselves in the hazardous range. Noise suppres- sion on the Cat alone will not solve the problem; similar measures must. be taken with the rear scraper engine. An alternative is to enclose the Push-Cat operator in a sound=-tight cab. Long-term exposure to high concentrations of silica-containing airborne dust may cause a chronic, disabling lung disease termed silicosis. Prevention of this disease is based on dust control, thus the General Industry Safety Orders! list maximum acceptable concentrations of dust which are con- sidered to be safe, even if inhaled daily over a working lifetime. These acceptable concentrations take into consideration the size of the dust parti- cles, the silica content of the dust, and specify the sampling method to be ''''=» 12 = used. As defined by these standards, Push-Cat operators, as a group, showed a consistently high dust exposure regardless of soil, moisture and wind conditions, Of nine impinger samples representing dust exposure to full-time Push=-Cat operators, only one was low enough to be considered safe, and this low count was from a job that was unusually wet. Visual observation was not always dependable in predicting dustiness. Jobs that were obviously very dusty showed high counts. On the other hand, six of the eight high counts collected on Push-Cats were from jobs that were visually not extremely dusty» Of additional interest is the fact that the application of water to a cut, while partially effective, did not reduce dust levels to acceptable concentrations. The most likely reason for this is that the passing spray from a water wagon can only wet the surface dust but does not penetrate to the depth of the scraper cut. In view of these findings, the application of special dust control measures to protect Push-Cat operators is recommended. These measures may take various forms. For intermittent, temporary exposures, an ordinary dust respirator might be acceptable. For the large, typical Push-Cat operations, however, the only alternative apparent at present is a cab supplied with filtered air. These are currently in use on equipment in California to protect heavy equipment operators in certain dusty open pit mining operations, and have proved to be dependable and inexpensive in relation to total equipment costs’. The benefit derived from such a cab may become increasingly apparent when used for the combined purpose of noise, dust, and temperature control. Dust measurements among scraper operators were high in some samples, but generally reflected a problem associated with individual jobs rather than ''''the scraper operator group as a whole. Scraper operator exposures were a combination of the dust encountered in the cut and on the haul roads and fill. Thus, in most instances, relatively clean air on the haul roads and fill had the effect of lowering the total measured dust. It is reasonable to assume that in many instances, dust suppression through the use of water on the fill and haul roads had the effect of holding the scraper operator's exposure with- in safe limits regardless of dust levels in the cut area. For this reason, the diligent use of water, on fills and haul roads, is recommended. The addi- tion of small amounts of detergent to enhance the wetting power has been very successful in the control of other dusty processes and should be considered as a method of increasing the effectiveness of water wagons’ >, Because only a few dust samples were obtained on front-end loaders, high speed compactors, and belt loaders, general statements regarding the need for dust control are not possible. Heavy equipment seat design and maintenance, while extremely important from the occupational health point of view, is too complex to be covered by this study. Mention should be made here, however, of the relation- ship between seat, seat belt, and roll=-bar. Review of on-the-job deaths resulting from crushing injury sustained by operators thrown out of or caught under toppling heavy equipment makes obvious the need for seat belts and roll- vars?®, Unfortunately, however, the seat in which the man is to be firmly fastened by the seat belt has received comparatively little attention. It is our opinion that seat standards are badly needed and steps should be taken toward their preparation. Because of the mild temperatures prevalent during the study, no additional information regarding heat stress was developed. However, mention ''''~ 14 = should be made of the problem of voluntary dehydration encountered during the preliminary study completed during the summer of 1964. At that time, it was found that virtually all operators failed to drink sufficient amounts of water during the day to keep pace with water loss through sweating. Recent reports have shown that drinking adequate amounts of water considerably improves the overall performance of men working in heat, Moreover, a decrease in body weight of 3 to 5% may be expected to hamper working efficiency and is suffi- cient to limit physical performances”, Voluntary dehydration should, therefore, be eliminated if men are to operate efficiently and continuously. Operators should be encouraged to drink as often as possible, preferably about every hour. Supplying adequate amounts of water is not enough; the temper- ature of the water is most important and can be a critical factor in determining the amount of water voluntarily taken by men exposed to heat and exercise. Warm or tepid water is disliked and will not be drunk in sufficient quantities to prevent voluntary dehydration. The same holds true for iced water, and when either is taken in large quantities, the result frequently is gastric distress and vomiting!, The preference among soldiers and working men for drinking water is a temperature between 50 and 68°F. This temperature can easily be maintained when canvas water bags are employed. Because the convenience and availability of the water supply will also influence the amount taken in, water should be made readily available at all times during the working day. In review, a maxim of industrial health seems to remain true in this study: Whenever jobs become specialized and machines grow in speed and effi- ciency, the risk of intensifying a particular industrial health problem increases. This has been the case with the noise problem and the Push-Cat '' ''= 15 = dust problem described in this report. It also may describe the current chain of events with front-end loaders, fast compactors, belt loaders, and other construction machinery. While more studies are recommended and undoubtedly will be carried out, these studies most often are undertaken after the equipment is designed and in widespread use. The application of controls after such a time lag results in unnecessary operator exposure and in difficult, expensive, and sometimes impossible demands upon the construction contractor. A good share of responsibility for health hazard control resides with the equipment manufacturer during the design and field testing stages. Equipment can be built to operate quietly (note the automobile). Machinery likely to be an unusual dust generator normally leaves the factory accompanied by the filters and maintenance manuals mecessary to protect its moving parts against dust damage. The health of the operator of that machine deserves Similar attention. RECOMMENDATIONS 1. Control operator exposure to equipment noise by installation of mufflers or other equipment design changes. Personal protective devices are not an adequate solution. 2. Provide environmental control against dust for Push-Cat operators in the form of air-conditioned sala 3. Protection against dust for opérators of high speed compactors, front-end loaders, and belt loaders may be necessary. Additional studies are required. ''boniGe ashe a ee ee ey, Thapar he ane I gees A eile are ! ited bo eS lg ee a — id ''= 16° « Control the dust exposure of scraper operators by more diligent application of water to haul roads and fill areas. Addition of detergent to enhance the wetting power of water should be considered. Set standards for equipment seat design and maintenance. This may be accomplished by a working group composed of represent- atives from the California State Department of Public Health, the California State Department of Industrial Relations, equip- ment manufacturers, construction contractors and the Operating Engineers’ Unions. 322° ''''TABLE I RESULTS OF IMPINGER DUST SAMPLES Silica Safe Sample in soil limit result Description of Description of samplel % MPPCF MPPCF jobsite 1. Upwind air -~ -< Canal cut. Weather cool, light 2. TSS-40 scraper 4g 10 wind, Water applied to cut and 3. D=-9 Push-Cat - 49 10 haul road. Dust barely visible 4, D-9 Ripper-Cat 49 10 in cut and moderate along haul 5. Grader, Cut and road. haul road kg 10 6. Grader, finishing slope 4g 10 7. D-9 Ripper-Cat -(wet soil) 4g 10 8. TS-14 scraper kg 10 1. Tandem coupled D-9 Borrow pit. Weather cool, ripper and pusher 29 10 light wind. Soil damp from 2. Cat 660 scraper 29 10 previous rain. Water applied 3. Upwind air = == to cut and haul road. Dust seldom visible. 1. D-7 dozer L5 20 Brush clearing job. Weather 2o D=7 dozer ‘15 20 warm, visibly very dusty. 1. Cat DW-20 scraper 15 20 Shallow cut. Weather cool, 2. Tandem coupled D-9 light wind. Water applied to pusher and ripper 15 20 cut and haul road. Dust barely visible. 1. WABCO B~70 scraper 38 10 Highway grade. Weather warm, 2. WABCO B~70 scraper 38 10 light wind. Water applied to 3. Cat 660 scraper 38 10 cut and haul road. Heavy 4, Front-end loader 38 10 visible dust near belt loader. 5. Cat D-8 pushing belt loader 38 10 1. D-9 Push=Cat 27 10 Canal cut. Weather cool, light 2. Euclid TS=14 wind, Water applied to cut, scraper 27 10 fill and haul roads. Visible 3. D-9 Push-Cat 2? 10 dust clouds around equipment. 1. John Deere 5010 Subdivision construction. scraper 10 20 Weather foggy with light wind. 2o D-9 Push-Cat 10 20 Soil damp, water applied to 3. Cat 641 scraper 10 20 fill. Little visible dust. ''''TABLE I (CONT. ) RESULTS OF IMPINGER DUST SAMPLES Free Dust& Silica Safe Sample Description of in soil limit result Description of sample 1 % MPPCF MPPCF jobsite 4, FWD-Wagner Subdivision construction. compactor 10 20 38.2 Weather foggy with light wind. 5. D=-8 towing Soil damp, water applied to sheepsfoot 10 20 4,9 fill. Little visible dust. 1. HD-21 pusher 34 10 13 Subdivision construction. 2. D-9 pusher a4 10 16.1 Weather foggy with light wind. 3. AC-562 tandem Water applied to haul roads and > scraper 34 LO 17.9 fill. Moderate visible dust. 4, AC=562 yoked to sheepsfoot 34 10 10.8 5. Upwind air “= -- 103 1. D-8 pusher 26 10 302 Canal cut. Weather clear, 2. Euclid TS-14 light wind. Area heavily pre- _ scraper = 26 LO 2.5 wetted. No visible dust. 3. Euclid TS=-14 scraper 26 10 0.8 4, D=8 dozer 26 10 0.8 1. D-9 pusher 19 20 46 Canal cut. Weather clear, 2. D-9 pusher 19 20 2262 light wind. Soil dry. Heavy 30 Cat DWe2l scraper 19 20 4,0 dust in cut. 4, Cat DW-21 scraper 19 20 S51 1. Front-end loader Miscellaneous = Weather clear, working broken light wind, dry soil. Heavy asphalt pavement 32 10 10.3 visible dust on sample 2. 2. Front-end loader Others, mild visible dust. working loose dry dirt 32 LO 61.6 3. Front-end loader working crushedrock 39 10 24.0 4, Power shovel work- ing borrow area 23 20 16.8 J eamples obtained at operator's breathing zone. “safe limit from California General Industry Safety Orders. MPPCF = millions of dust particles per cubic foot of air. ''''TABLE II RESULTS OF MEMBRANE FILTER DUST SAMPLES Number of Total Respirable Silica (mg/M>)* samples Sample group taken Minimum Maximum Average Safe limit Scrapers 13 0.01 0.72 0.17 Ove Graders 5 0.01 0.1 0.04 0.2 Dozers 4 0.0L 0.19 0.13 Ose Dozers clearing brush 3 0.04 0.29 0.15 0.2 Push-Cats 4 0.06 0.61 0.31 Owe *Concentration of respirable silica in milligrams per cubic meter of air. '' 7 ey woe Sere “r i * x » ae ee ge | ee a th = ''Figure 1 EQUIPMENT NOISE LEVELS IN COMPARISON TO CALIFORNIA NOISE CONTROL SAFETY ORDERS 120 A Oo e 110 o e e © Oo 0 R u A Oo o A A z 100 © a CALIFORNIA NOISE LIMIT N o oO c = So A ov 90 a - e WW & oJ ¢ o “d — 80 A > oe o re o e © © 70b vu > w WW Oo ° 60 + 50 | | | i l | | | 37.5 75 150 300 600 1200 2400 4800 75 150 300 600 1200 2400 4800 9600 Octave pass bands in cycles per second Allis Chalmers-562 Twin Bowl Scrapers Moving Loaded Up A Long Flat Grade 4 Straight Exhaust Stack and No Windshield @ Very Short Straight Exhaust Stack and No Windshield Oo Straight Exhaust Stack With Windshield Note: Data obtained adjacent to operator with direct reading sound analyzer. ''''Octave band level in db re 0.0002 microbar Figure 2 EQUIPMENT NOISE LEVELS IN COMPARISON TO CALIFORNIA NOISE CONTROL SAFETY ORDERS 120 - 110L . CALIFORNIA iam: . NOISE LIMIT ° e -— e 90 | a 80 + 70 b 60 F 50 \ l l l | l L l 37.5 75 150 300 600 1200 2400 4800 75 150 300 600 1200 2400 4800 9600 Octave pass bands in cycles per second e Caterpillar D-8 Pushing Euclid TS-14 Scraper s Similar Caterpillar D-8 Towing Sheepsfoot Note: Data obtained adjacent to operator with direct reading noise analyzer. '' ''Octave band level in db re 0.0002 microbar Figure 3 EQUIPMENT NOISE LEVELS IN COMPARISON TO CALIFORNIA NOISE CONTROL SAFETY ORDERS 120 110 e A CALIFORNIA e 100 z NOISE LIMIT ‘ a e i o : e oO e 90 F ‘ oO e A oO 80 © a a 70 A 60 fF 50 L \ l L l l l 37.5 75 150 300 600 1200 2400 4800 75 150 300 600 1200 2400 4800 9600 Octave pass bands in cycles per second a Euclid Crawler Dozer A Michigan Front-End Loader With Euclid Engine ® Euclid TS-14 Scraper Note: Data obtained adjacent to operator with direct reading noise analyzer. ''''Octave band level in db re 0.0002 microbar Figure 4 EQUIPMENT NOISE LEVELS IN COMPARISON TO CALIFORNIA NOISE CONTROL SAFETY ORDERS 120 110 CALIFORNIA NOISE LIMIT a 100 IL Ace * A @ oA o 90 Ae 80 70 60 [- 56 l l l l l l l l 37.45 ves) 150 300 600 1200 2400 4800 75 150 300 600 1200 2400 4800 9600 Octave pass bands in cycles per second Caterpillar D-9 Dozers O Pushing Scrapers Without Rear-end Engines 4 Pushing AC-562 Double Bowl Scrapers e Pushing AC-562 Double Bowl Scraper and Being Pushed by a Second D-9 Dozer Note: Data obtained adjacent to operator with direct reading noise analyzer. ''ie ''Octave band level in db re 0.0002 microbar Figure 5 EQUIPMENT NOISE LEVELS IN COMPARISON TO CALIFORNIA NOISE CONTROL SAFETY ORDERS 120 110 100 CALIFORNIA — oO NOISE LIMIT a a A 90f- o A . A 80 , e . 70 60 50 | | ! it l | | 37.5 75 150 300 600 1200 2400 4800 75 150 300 600 1200 2400 4900 9600 Octave pass bands on cycles per second 0 Allis Chalmers HD-21 Dozer Working Alone A Allis Chalmers HD-21 Dozer Pushing AC-562 Twin Bowl Scrapers @ FWD-Wagner WC-17 Compactor Note: Data obtained adjacent to operator with direct-reading noise analyzer. ''''Octave band level in db re 0.0002 microbar Figure 6 EQUIPMENT NOISE LEVELS IN COMPARISON TO CALIFORNIA NOISE CONTROL SAFETY ORDERS 120 110 NOISE LIME? 100 90 i 80 + 70 60 - 50 ] l l l l l \ l 37.5 75 150 300 600 1200 2400 4800 75 150 300 600 1200 2400 4800 9600 Octave pass bands in cycles per second | Caterpillar D-9 Dozer NX Caterpillar D-9 Tandem Coupled Dozers Note: Data obtained adjacent to operator with tape recorder and subsequently analyzed. ''''Octave band level in db re 0.0002 microbar 120 110 100 90 80 70 60 50 Figure 7 EQUIPMENT NOISE LEVELS INCOMPARISON TO CALIFORNIA NOISE CONTROL SAFETY ORDERS CALIFORNIA NOISE LIMIT + i | ! | | | | I | 37.5 75 150 300 600 1200 2400 4800 75 150 300 600 1200 2400 4800 9600 Octave pass bands in cycles per second | Caterpillar D-8 Dozer X Caterpillar D-8 Dozer With Iron Canopy Note: Data obtained adjacent to operator with tape recorder and subsequently analyzed, '' ''Octave band level in db re 0.0002 microbar Figure 8 EQUIPMENT NOISE LEVELS IN COMPARISON TO CALIFORNIA NOISE CONTROL SAFETY ORDERS 120 110 F i CALIFORNIA 100 NOISE LIMIT ‘ i] | M MX Xl =< 80 7O- 60 50 1 | | | | | 1 | 375 75 150 300 600 1200 2400 4800 75 150 300 600 1200 2400 4800 9600 Octave pass bands in cycles per second Caterpillar 657 Tandem Scraper With Air Conditioned Cab | Caterpillar 660 Scraper Note: Data obtained adjacent to operator with tape recorder and subsequently analyzed. '' ''Figure 9 EQUIPMENT NOISE LEVELS IN COMPARISON TO CALIFORNIA NOISE CONTROL SAFETY ORDERS 120 110 | | CALIFORNIA X NOISE LIMIT 100 er _ Octave band level in db re 0.0002 microbar 80 70+ 60 + 50 | | | | | l | | 37.5 75 150 300 600 1200 2400 4800 75 150 300 600 1200 2400 4800 9600 Octave pass bands in cycles per second | LeTourneau-Westinghouse B-70 Self-Loading Scraper Euclid TSS-40 Tandem Scraper Euclid TS-14 Tandem Scraper WN EX Note: Data obtained adjacent to operator with tape recorder and subsequently analyzed. ''=—=s8 = i ia So QQ Ee = et SS Sa a a Liat a TL - ae ' E ''Octave band level in db re 0.0002 microbar Figure 10 EQUIPMENT NOISE LEVELS IN COMPARISON TO CALIFORNIA NOISE CONTROL SAFETY ORDERS 120 110 - % yy CALIFORNIA 100 UL} NOISE LIMIT 90 b i YW Yj UU 80 F- 70 [- 60 F- 50 l l l 1 l l l 1 37.5 75 150 300 600 1200 2400 4800 TS 150 300 600 1200 2400 4800 9600 Octave pass bands in cycles per second | | Michigan Dozer (rubber tires) NX Caterpillar No. 16 Road Grader V/ Yj LeTourneau Power-Packer G Note: Data obtained adjacent to operator with tape recorder and subsequently analyzed. ''''Average hearing levels in decibels (ASA 1951) -10 10 20 30 40 50 60 Figure 11 AVERAGE HEARING LEVELS OF HEAVY EQUIPMENT OPERATORS BY AGE AND FREQUENCY —— Average age: Ow==——O 23.0 years @m————@ 30.1 years (32 ears) Cnt] 39.2 years (42 ears) Mm —— 50.6 years (42 ears) | | | ! 500 1000 2000 4000 Frequency in cycles per second ''''Average hearing levels in decibels (ASA 1951) Average hearing levels in decibels (ASA 1951) Figure 12 AVERAGE HEARING LEVELS BY AGE GROUPS FOR HEAVY EQUIPMENT OPERATORS -10 10 20 30 40 50 60 -10 10 20 30 50 AND NON-NOISE EXPOSED POPULATION ” -10 Age 16-25 Years 50 Lk Age 26—35 Years | | 1 60 l | | I 500 1000 2000 4000 500 1000 2000 4000 -10 10 F 20 F 30 - 40 + Age 36-45 Years Age 46-55 Years 50 - ! | | | 60 | i] | j 500 1000 2000 4000 500 1000 2000 4000 Frequency in cycles per second Frequency in cycles per second o-——-o Non=noise exposed o——e Equipment operators ''''Figure 13 TEMPORARY THRESHOLD SHIFTS AT THE END OF A SINGLE WORK DAY FOR HEAVY EQUIPMENT OPERATORS BY AGE AND FREQUENCY. (Data based on pre- and post-exposure tests on 53 men (106 ears)). or a eq @ 2D od °o o ro A Sr ol we) oH od a a 7 10r- ° a n £ x x 1000 cps ease o————o 2000 cps f e——_e 4000 cps a 8 20 N | ! i 20-25 26-35 36-45 46-58 Age groups in years Figure 14 AVERAGE HEARING LEVELS OF HEAVY EQUIPMENT OPERATORS BY LENGTH OF WORK EXPERIENCE AND FREQUENCY -10 LO 30r Work experience: e——e 1-9 yrs (44 ears) a——-» 10-19 yrs (54 ears) Average hearing levels in decibels (ASA 1951) 40 o—o 20-34 yrs (28 ears) 50 [- 60 I 1 l l 500 1000 2000 4000 Frequency in cycles per second ''''10. il. 12. 13. 14, REFERENCES Ottoboni, F.3; and Milby, T. H.: How heat affects operators. Western Construction. July, 1965. Henschel, A.; Ottoboni, F.; Fisher, G.; Carlow, T.3; Milby, T.3; and Brandford, P.: Heat stress on heavy equipment operators. A preliminary survey. U. S. Department of Health, Education, and Welfare. Public Health Service, Division of Occupational Health. September, 1964. Burns, C.3; Ottoboni, F.3; and Mitchell, H. W.: Health hazards and heavy construction. Am. Indust. Hyg. Assoc. Jo 232273, 1962. Berkov, B.: Occupational Health in California. Bureau of Occupational Health. California State Department of Public Health. 1965. Cohen, Ae: Damage risk criteria for noise exposure aspects of acceptability and validity. Am. Indust. Hyg. Assoc. J. 24:227, 1963. Glorig, A.; Ward, W. D.; and Nixon, J. C.: Damage risk criteria and noise-induced hearing loss. Arch. Otolaryngol. 743413, 1961. Riley, E. Co; Sterner, J. Ho; Fassett, D. W.; and Sutton, Wo. Le: Ten years’ experience with industrial audiometry. Am. Indust. Hyg. Assoc. J. 223151, 1961. Nixon, J. C.3 and Glorig, A.: Noise-induced temporary threshold shifts vs. hearing level in four industrial samples. J. Auditory Res. 22125, 1962. Schuknecht, G. Go: Ventilating units provide more safety. Engr. and Mining J. 157392, 1956. Unpublished data. Bureau of Occupational Health. California State Department of Public Health. Strydom, N. Bo; Van Graan, C. H.§ and Holdsworth, L. Does The water requirements of humans. J. Occup. Med. 73581, 1965. State of California, Department of Industrial Relations. Division of Industrial Safety. General Industry Safety Orders. 1963. Berger, L. Bo: Some considerations on dust control in coal mining. A.M.A. Arch. Industrial Health 152499, 1957. Henschel, A. Fos Water balance - a problem in occupational health. Occup. Health Rev. 17:11, 1965. ''''ACKNOWLEDGMENTS The California State Department of Public Health gratefully acknowledges the invaluable assistance provided by the United States Public Health Service, Division of Occupational Health, in carrying out this study. Appreciation is also due to the International Union of Operating Engineers and its two local Unions, No. 3 and No. 12, for their active participation in planning and coordinating the field work. Acknowledgment must also be given to the individual construction contractors and their supervisory staffs for their cooperation. Finally, the Department is especially indebted to the individual equipment operators involved who were, to a man, friendly and cooperative under conditions which were sometimes difficult. FO:THMs AMT (RT915665C) '' > ''''''