Heavy constrodion equi ment noise study using dosimetry 

and time-motion studies-R 

Eillmorth spencera)andPeter ~walchd'~ 

'noise faduced hearing loss continues to afflict workers in many occuptional 

scZtings despite longstanding recognition of the problems and well-lnzown 

methods of prevention and regulations. The foczls of this research was to 

deternine the noise exposures of heavy constrnctionequipment operators whiIe 

docnrnenting the workers' task, (i.e. hauling, moving, and/or pushing 

mnstmctionmaterial).Time-motion strrdies wereperformed at the construction 

sitesandwere used to correlatethe noise dodagewith thework performed by the 

equipment operators. The cwnniative dose for'each operator was then plotted 

withreferences to work tasks.Thiswas done to identify the tasksthat caused the 

greatest noise exposure. Three constrrrction sites were studied for this research. 

Thetypes of constructioneqnipment studied included asphalt pavers, backhoes, 

bulldozers, compaction equipment, excavators, haul trucks, telehandkrs, and 

wheeled loaders. The results indicate that the majority of operators were overexposed to hamrdons noise. 

13,036%. In the constructionind~stry,heavy construction equipment i8 a major contn'butm to .high noise 

The National Institute for Occupational Safety and levels at most job sites. In a paper by Alice H. suter4 

Health 0estimates that in 1995 about 754,000 wer 100 studies and reports pertaining to ~onstruction 

US. construction workers are exposed to potentially noise are cited.Theuse of time-motionstudies of work 

hazardous noise Imls above 85 ~BCA)'.Sound levels tasks along with the operator's daily dose are not being assodated with heavy construction equipment range used in most of these references with only one study ftom 80 to 120 dB(A) mdpowa tools commonly used identified as directly using we-minute sound levels by Jn constructionproduce sound levelsup to 115 ~B(A)~. work-task The current study was performedto identify The buI1dozer opemtms consistentiy had zhe higher the wera11.A-weightedsound levels of heavy constmccontinuous noise exposures ranging hn~ a NIOSH tion equipment a@ the ~sultatltoccupational noise 

RlX (Recommended Exposure ~imit)~ dosq of 844% apsm of the operators during normal operation, in 

to 25,836%. This dose equates to an OSHA PEL carrelation to mk-tasks. Dosimeters wm used to 

~dssi'bleExpome Lirhit) doseB of 139% to meam the noise levels and caIcu1ate the opewtm's 1,397%.Technologically achievable engineeringnoise daily noise dose over an 8-how shift (dose8) using controts can seduce the total sozznd level seaclung the NIOSH criteria, Wide Range (for Zd, and OSHA 

bdldozm operator by as much as 3 dB(A). This cdd crikria The NIOSH WL (Recommended Exporn potentidly reduce the REL Dose, of the operator by Limit) is 85 dea%eIs, A-weighted, as an 8-br 

time-weighted wmge (85 &(A) as an 8-hr TWA) 

'I 	 Thohdings and conclusionsinthis paper ak those ofthe with a 3-dB exchange rate. The NOSH recommendaa~thorsand do not necasmlly reprelrentthe views of the tion further states that: Txposms at or &be this 

NationaI Institute: of Z)cmpatimal Safetj and Health level are hazatdo~s."~Therefore the data will be 

(NIOSH).Also, referencetospecificbrand names doesnot presented wing fie NIOSH REL criteria and.the corm- imply endorsement by h eNTOSH. 	 spaitding work-task. 3uter4 also recommends that a National Institute of Occupational Safety and Health, 

Pittsbargh Research Laboratory, 626 CochmsMill Road, noise control database be develaped,which was started 

Pitlshrgh PA 15236;ernail: espence@dc.gw. with this &dy. The correiation of dosimeter and 

b' 	 National Ifistihlte of OccupationaT Safety md Health, he-motion studks can be used to Iden@ mdprioziPittsburgh Researchlaboratory, 626 Cochm Mil1Road, 2ize noise control efforts, including .maintai&ng 

Pittsburgh PA 15236; mail: pkovalchik@cdc.gov. designed noise cuntroIq retrofitting engheerhg noise 
Table 1--Internal dosimeter settings5. 

Designation 'Parameters Settings Designation 

Dose Weighting A 

Measurement 1 Threshold Level 80 dB NIOSH 

Exchange Rate 3 dB Recommended 

Exposure Level 

Criterion Level 85 dB 

Response Slow 

Upper Limit 140 dB 

Dose Weighting A 

Measurement 2 Threshold Level 40 dB Wide Range 

(LCq) 

Exchange Rate 3 dB 

Criterion Level 85 dB 

Response Slow 

Upper Liinit 140 dB 

Dose Weighting A 

Measurement 3 Threshold Level 90 dB OSHA 

Exchange Rate 5 dB Permissible 

Exposure Level 

(PEL) 

Criterion Level 90 dB 

Response Slow 

Upper Limit 140 dB 

Dose Weighting A 

Measurement 4 Threshold Level 80 dB OSHA 

Exchange Rate 5 dB Action Level 

Criterion Level 85 dB 

Response Slow 

Upper Limit 140 dB 

controls, administrative noise controls, and the use of 

personal protection equipment. Some recommendations on noise control treatments, estimated costs, and 

quieted noise levels, will also be discussed in this paper 

1. 	General Instrument and Measurement 

Information 

The noise measurements were obtained using 

Larson-Davis SparkTM 705+ dosimeters because they 

are capable of measuring and recording dose with four 

separate noise criteria and sampling at a 1 -second interval over 13 hours5. The dosimeters were programmed 

as shown in Table 1. The noise measurements using the 

OSHA settings (shown in Table 1) were used primarily 

for informational purposes (i.e., a reference for the 

operators who must comply with the OSHA regulations, refer to Table 2). The areas where noise controls 

were most needed were determined by examining the 

percentage of workers exceeding 100% dose based on 

the NIOSH REL. A Personal Digital Assistant (PDA) 

with subject observation software or a watch combined 

with handwritten notes were utilized to conduct task 

observations on the equipment operators. These observations were used to define their activities, behaviors, 

and machine functions occurring during their work 

shift. 

1.2 	 Data Collection 

The machine type, manufacturer, model, and serial 

number and the engine manufacturer, model number, 

power rating, and rated speed were documented via 

handwritten notes on data sheets. In addition, the 

condition of the machine, existence of engineering 

noise controls, and modifications to the machine were 

also noted. When practical, digital pictures were taken 

of each side of the machine, the engine compartment, 

and the operator station. Further, close-up pictures 

were taken of installed engineering noise controls and 

observed damage such as broken windows or missing 

door seals were noted. The dosimeters were calibrated 

prior to and after each measurement. The dosimeter 

microphone was clipped to the midpoint of the worker's 

shoulder with the diaphragm pointing up6 and the time 

that the dosimeter microphone was first placed on the 

worker and the time of removal were documented. 

1.3 	 Data Analysis Plan 

The dosimetry results were examined with the aid of 

task observations to determine the tasks, behaviors, and 

machine operations that resulted in the highest noise 

exposures. Documenting worker activities enabled the 

researchers to correlate sound levels at the operator ear 

during work-tasks under field conditions. Sufficient 

data were collected to document and determine where 

noise control development was necessary by identifying the machines whose operators were over-exposed to 

noise in excess of 85 dB A-weighted sound levels at the 

operator's position. The dosimetry results were 

downloaded into a searchable database. The task observations were imported into an Excel dosimetry macro 

to facilitate determination of the significant contributors to the workers noise dose. 

2 RESULTS 

Table 2 shows the range of time-weighted average 

noise doses and the length of time the operator was 

monitored. The range in the operator's dose for a 

specific machine can be attributed to factors including 

but not limited to: hours worked, the monitoring of 

different operators, the operators' degree of expertise, 

the condition of the terrain, the presence of or the 

proximity of noisy equipment, and quantity of 
Table 2-Citation values of tonal targets in the experiments with three speakers. 

Noise Monitor 

Machine NIOSH REL Exposure Time 

(Number Sampled) Dose8(%) Range OSHA PEL Dose8 (%) Range Level dB(A) (minutes) 

Dozers Bulldozer (1 0) 844-25,836 139-1,397 92-1 09 362-63 0 

Older and No Cabs 6,557-25,836 523-1,397 102-109 362-630 

Newer with Cabs 1,245 -2,45 8 191-356 95-99 420-630 

Newest and No Cab 844 139 92 575 

Saws Hand Saw (2) 4,094-9,194 173-301 94 -98 74-1 64 

Road Saw (2) 1,242-2,090 108-265 90.5-97 155-415 

Trucks Haul Truck (6) 28-492 24-1 65 80-92 479-630 

Trucks with AC 28 -55 24-35 80-82 479-630 

Trucks without AC 174-492 104-1 65 90-92 479-630 

Others 	 Road Grader (1) 3,023 252 97 630 

Tele-Handler (1) 472 64 8 7 463 

Asphalt Paver (3) 150-160 17-76 7 8-8 8 328-550 

Front End Loader (4) 18-200 2-1 7 76-78 500-539 

Excavator (4) 7-1 55 0-1 6 75-78 480-630 

Plate Tamper (3) 62-146 7-23 76-80 508-5 10 

Multi-Machine (1 7) 3 1-3,084 2-392 76-1 00 70-630 

construction work done. For bulldozers, the age, size, should do their own noise survey to determine their 

and work-cycle were all factors affecting the operator's workers' noise exposure to base their Hearing Loss 

dose. The bulldozer operators were consistently Prevention program3 on. If an individual daily noise 

overexposed to noise based on both the NIOSH REL dose is unusually high, that operator or job position 

and OSHA PEL criteria. Again, some of the wide should be observed and more noise control methods 

ranges of TWA doses* can be attributed to hours applied3. 

worked, a ten-hour shift will have a much higher doses Figures 1-7 show selected samples of the curnulathan an eight-hour shift under the same noise ( tive dose for operators of various types of equipment. 

>85 dB(A)) conditions. While the data from Table 2 Note that the ordinate (y-axis) is different for each 

can be used as a reference, every construction site figure due to the large range of values. The higher noise 

Caterpillar Bulldozer D9G ldle and Pushing Trailer Pan Scraper 

-

ldle 

Dose =Fh l min 

ldle 


Dose = F ?l min 


LA=% dB 


Dose = 66% l mln 

1020 AM 1021 AM 1022 AM 10:23 AM 10:24 AM 1025 AM 

Time of Day 

Fig. I-5-minute work-cycle of a Caterpillar D9G Bulldozer Operatol: 
Caterpillar Bulldozer D8H ldle and PullingTrailer Pan Scraper 

8:00 AM 8:05 AM 830 AM 8:15 AM 820 AM 8:25 AM 8:30 AM 

Time of Day 

Fig. 2-30-minute work-cycle of a Caterpillar D8H Bulldozer Operator. 

doses came primarily from the largest bulldozers and D9G Bulldozers were built from the late 1960's to 

(shown in Figs. 1 and 2). These included the Caterpillar early 19703, but appeared to be in good condition 

Bulldozer D8Hs and D9G which only had Roll-Over despite their age. The newer Caterpillar D8N Bulldozand Falling-Object Protection Systerns (ROPSIFOPS) ers had cabs with ROPS protection (cumulative dose is 

and stack exhausts without mufflers. The exhaust shown in Fig. 3). It was observed that the cabs had little 

stacks on these machines ended at approximately the or no sound absorbing material inside. The seals 

height of the ROPSIFOPS. This appears to be a signifi- around the cab doors were in poor condition. The 

cant source of the operators' noise exposure. The operators were observed to operate the Caterpillar 

A-weighted equivalent continuous sound levels (L,,) D8Ns Bulldozers with a combination of doors andlor 

measured with the dosimeters ranged from 104 to windows open, thereby greatly reducing the ability of 

108 dB for the bulldozers. The older Caterpillar D8H the cab to protect the operators from hazardous noise. 

Caterpillar Bulldozer D8N ldle and Pushing Dirt 

I ! 

3 

, 

/ PushingDirt 

Idle Dose am 1min 

Dose=3% f min L,=99 dB 

I 

i 

! 

I 

1 ,

I 

I ! 

i 

I I

! 1,600 

3:05 PM 3:lO PM 3:15 PM 3:20 PM 3:25 PM 3:30 PM 

Time of Day 

Fig. 3-30-minute work-cycle of a Caterpillar D8N Bulldozer Operator. 
Caterpillar Bulldozer DGMXL Pushing Dirt 

1 PushingDirt 

Dose=Z%frnin L,=96dB I I i 

ldle / 

Dose = 1% l min 

LAw92dB 1 

Off Bulldozer i 

I

I 

Dose=2% 1 mln 

920 AM 9:25 AM 

Time of Day 

Fig. 4-15-minute work-cycle of a Caterpillar D6MXZ,Bulldozer Operator: 

The air conditioning units on the Caterpillar D8Ns recorded when the grading was done uphill (Fig. 5). In 

Bulldozers were not functional. If the units worked, this case the engine noise appears to be the significant 

perhaps the workers would use the air conditioning and source of the operator's noise exposure, since the 

keep the cab doors and windows closed. The newest exhaust muffler was in good condition and the exhaust 

bulldozer studied was a Caterpillar D6MXL having is directed away from the cab. 

noise controls consisting of acoustic foam on the The gas powered hand saws used 6" abrasive 

ceiling of the ROPSIFOPS, an exhaust muffler, and an circular-disk blades to cut relief-joints in a concrete 

enclosed engine compartment. Even with no cab, the road and re-bar from broken concrete slabs. The saw 

Caterpillar D6MXL Bulldozer had the lowest opera- operator was exposed to noise from the cutting operator's dose of all the bulldozers (Fig. 4). tion and the exhaust of the engine. The road saws had 

The road grader had a cab, but no insulation on the 26" toothed circular blades that were used to cut a 

walls, floor, or ceiling and the doors were left open concrete road into approximately 6' by 6' slabs so they 

during operation. The highest sustained dose was could be easily removed. The road saw operators were 

Caterpillar Road Grader ldle and Grading 

, 

, 

I I 1 I 

! 

3 

/ Grading Downhill 

I Dose =6?h l min 

I 

I 

I 

/ Grading Uphill I 

1 Idle 

I 

200 

7:30 AM 7:35 AM 7:40 AM 7:45 AM 7:50 AM 

Time of Day 

Fig. 5-30-minute work-cycle of a Caterpillar Road Grader Operator: 
Hand Saw Cutting Relief Joints in Concrete Road 

3,500 

1,000 

8:15 AM 8:20 Ah4 8:25 AM 8:30 AM 836 AM 8:40 AM 8:46 AM 

Time of Day 

Fig. 6-30-minute work-cycle of a Hand Saw Operator. 

not as close to the cutting operation as were the hand Several operators used multiple machines during the 

saw operators. Because the road saws were automated observed time. Those operators were grouped in the 

and had good mufflers, the operators were exposed to multi-machine category, which consisted of several 

less noise than the hand saw operators (Fig. '7). different machines including backhoes, soil compacAll of the haul trucks were similar in size, but the tors, front-end loaders, andlor excavators, that were 

operators of the newer trucks with air-conditioning had operated as the need arose. The noise dose for the 

lower noise exposures than the operators of the older operators of these machines was included in Table 2 to 

non-air-conditioned trucks, even though the new trucks show the high variability of noise doses at construction 

were operated with the driver-side window open. Note sites. 

that in Table 2 the operators of the non-air-conditioned Table 3 lists the observed work-task that subjected 

trucks were over-exposed and exceed the NIOSH REL the operator to the greatest noise exposure during a 

as well as the OSHA PEL. work-shifi. Using one bulldozer operator's cumulative 

Road Saw Cutting Concrete Road 

1,400 I Moving 

Dose = 08 IMin LA= 91 d 0 i

I 

- Dose= 16% l min 

... ... ,........... .. 

0 

9:30AM 1090 AM 10:3o AM il:m AM 11:aAM 

Time of Day 

12:00 PM 12:30 PM I:a PM I:30 PM 

Fig. 7-Cumulative NIOSH Noise Dose of a Road Saw Operator, rzmning from 9.50 AM until 1:20 PM. 
Table 3-Tasks that cause the greatest noise exposure. 

Graph 

Machine Observed Task Example 

Bulldozer D9G Pushing Trailer Pan Scraper 1 

Bulldozer D8H Scraping top-soil into Pan 2 

Bulldozer -D8N Pushing soil uphill 3 

Bulldozer D6MXL Pushing soil uphill 4 

Road Grader Grading haulage road uphill 5 

Hand Saw Initial cut into concrete 6 

Road Saw Initial cut into concrete 7 

NIOSH noise dose and the bulldozer's approximately 

2-minute idle/push work-cycle as an example from Fig. 

1, the following details the operator's noise exposure. 

For this example, a 5-minute period (10:20 - 10:25) is 

used at a time when all of the bulldozer operators were 

worlung together in a small job site and the operator 

had the highest and most sustained noise levels 

compared with the other operators. The Caterpillar 

D8Hs Bulldozers were used to pull a Trailer-Pan 

Scraper (Scraper) and the Caterpillar D9G Bulldozer 

operator (shown in Figs. 1 and 2) helps the Scraper cut 

into the soil by pushing the Scraper. This work-cycle 

was done continuously, all day, in a confined area with 

a short uphill trip to the dumpsite where a Caterpillar 

D8N Bulldozer was working-all contributing to the 

high noise exposure. Even at idle the Caterpillar D9G 

Bulldozer operator was exposed to an A-weighted 

sound level (LA) of 96 dB shown in the 1-minute from 

10:20 to 10:21. Staying at idle for a full shift would 

result in a REL Dose, of 1270%. The highest noise 

exposure of 109 dB(A) was recorded when the 

bulldozer pushed the Scraper, resulting in the operator's 

daily noise doses of 25,835% (NIOSH REL). At the 

higher noise level both earplugs and earmuffs should 

be worn, but NIOSH cautions that even double protection is inadequate when TWA exposures exceed 

105 ~B(A).' The newer Caterpillar D8N Bulldozer 

(Fig. 3) pushed and compacted fill unloaded from the 

Scraper to level a ramp and would pause occasionally 

during the unloading. This bulldozer operator was 

exposed to an A-weighted sound level (LA) of 

99 dB(A) during the push-dirt work-cycle. Even at low 

idle the operator was exposed to an A-weighted sound 

level (LA) of 97 dB(A). The newest bulldozer studied 

was a Caterpillar D6=, even with no cab, this 

bulldozer had the lowest operator's daily dose at 844% 

(refer to Table 2). In Fig. 4 at low idle, the operator was 

exposed to an A-weighted sound level (LA) of 

92 dB(A). More significantly when pushing dirt, the 

operator was only exposed to an A-weighted sound 

level (LA) of 95 &(A). This is up to 14 dB less than 

the operator of other bulldozers. This can be attributed 

to the engineering noise controls consisting of an 

enclosed engine compartment, acoustic foam on the 

ceiling of the ROPS/FOPS, an exhaust muffler and the 

exhaust directed away from the operator. The different 

sizes of the engines and horsepower ratings of the 

bulldozers are also a factor, but this comparison can be 

endorsed as an administrative noise control for selecting the "right-size" machine for the job. Using the 

largest bulldozer available for common work-tasks can 

over-expose the operator and the other workers at the 

construction site to noise, when a small more efficient 

and most likely quieter bulldozer could do the job. 

The road grader had a cab, but no insulation on the 

walls, floor, or ceiling and the doors were left open 

during operation decreasing the ability for the cab to 

provide noise attenuation. In Fig. 5 at low idle, the 

operator was exposed to an A-weighted sound level 

(LA) of 91 dB(A). The highest sustained dose was 

recorded when the grading was done uphill; the operator was exposed to an A-weighted sound level (LA) of 

104 dB(A). The engine noise appears to be the significant source of the operator's noise exposure, since this 

operation is done under heavy engine load, and the 

muffled exhaust is directed away from the cab. For this 

work-task NIOSH recommends that when a worker's 

time-weighted noise exposure exceeds 100 &(A), 

both earplugs and earmuffs should be worn3. 

The hand saw operator was exposed to noise from 

the cutting operation, the exhaust noise and the noise of 

the engine. The highest recorded sound level (L,,) of 

114 dB(A) was when the saw first cuts into the 

concrete at 8:37 (Fig. 6). The operator referred to this 

task as a "cut-in" and in his opinion this was the loudest 

part of the job and as the data reflects the operator has 

accurately recognized this work-task as the loudest part 

of the job. The road saw operators were not as close to 

the cutting operation as were the hand saw operators. 

This takes advantage of the noise control principle of 

adding distance from the noise source to reduce the 

sound level reaching the operator. Because the road 

saws were automated and had good mufflers, the operators were exposed to less noise than the hand saw 

operators (Fig. 7 and Table 2). But the operator was 

exposed to a similar cut-in noise as the hand saw operator, a sound level (L,,) of 107 dB(A), because he had to 

bend over close to the saw blade to insure an accurate 

start to the cutting. After the cutting cycle was started 

he could stand and be farther away from the cutting, but 

still exposed to an A-weighted sound level (LA) of 

104 dB(A). Again, at these high noise level both 

earplugs and earmuffs should be worn, but NIOSH 

cautions that even double protection is inadequate 
3 

when TWA exposures exceed 105 ~B(A)~. 

To provide guidance to equipment operators, miners, 

and equipment manufacturers on technologically and 

administratively achievable engineering and administrative noise controls the Mine Safety and Health 

Administration (MSHA) has issued a Program Information Bulletin (PIB) (~04- 1 817. Ths PIB, titled: 

"Technologically Achievable, Administratively Achievable, and Promising Noise Controls," presents technologically or administratively achievable controls or a 

combination of controls which achieves at least a 

3 dB(A) reduction in a miner's noise exposure. This 

could potentially reduce the REL Dose8 of the most 

over-exposed worker, the Caterpillar D9G Bulldozer 

operator by 13,036%. In this PIB MSHA considers the 

following engineering noise controls, or a combination 

of these controls, to be technologically achievable in 

reducing the noise exposure of miners operating 

surface mobile equipment (e.g ., bulldozers, front-end 

loaders, trucks, graders, scrapers); 1) Environmental 

cabs (primarily on equipment manufactured since the 

mid 1970s) that include appropriately selected, 

correctly installed, and properly maintained acoustical 

materials, 2) Exhaust mufflers, and 3) Redirection of 

the exhaust away from the operator. Material and labor 

cost for the noise control installation will vary from 

machine to machine, and from region to region. While 

these costs are not fully calculable for this paper they 

are according to the PIB economically achievable. For 

some examples of administrative controls the PIB 

considers the following to be applicable: 1) Adjust 

work schedules, 2) Share work tasks and/or rotate 

workers, 3) Lhit duration of work shifts, and 4) Limit 

the duration of noisy tasks. 

CONCLUSION 

This study documents the extent of noise 

over-exposure of bulldozer, hand saw, road grader, and 

road saw operators using both NIOSH REL and OSHA 

PEL criteria and provides some recommendation to 

decrease those exposure levels. The data from this 

study and a series of other studies were used to 

populate a data base recommended by suter4. The 

higher operators' noise doses came primarily from the 

largest bulldozers (Caterpillar D8Hs and D9G built 

from the late 1960's to early 1970's) which only had 

ROPS/FOPS and stack exhausts. The newer bulldozers 

(Caterpillar D8N) having cabs, but no interior sound 

absorbing material, with ROPSIFOPS protection 

provided considerably lower operators' noise dose than 

the older bulldozers (Caterpillar D8Hs and D9G). The 

newest bulldozer (Caterpillar DGMXL) even without a 

cab had the lowest recorded operator's dose of all the 

bulldozers. With proper application of noise controls 

the bulldozer operators' noise dose could be reduced. 

Newer equipment with mufflers as opposed to straightstack exhausts and cabs with interior sound absorbing 

material have lower in-cab noise levels particularly 

when doors and windows of the cab are closed. 

The road grader had a cab without sound absorbing 

material. Improvements and modifications such as . sound absorbing material to the grader cab would lower 

the noise levels if the doors and windows were kept 

closed. The operators of all machines with cabs would 

be more motivated to keep the windows and doors 

closed if air conditioning was available and/or working 

efficiently. Management and site supervisors must be 

made aware that the noise controls, engineered into the 

cabs (e.g., door and window seals, barrier and sound 

absorbing panels) are all compromised by non-working 

air conditioners. Maintaining the air conditioning is 

just as important as the barrier and sound absorbing 

panels for preventing the noise from reaching the 

operators of heavy equipment. 

The hand saw operators where only monitored for 1 

to less than 3 hours and still had the third highest noise 

dose. Monitoring for a full shift of work would likely 

have resulted in a much higher dose. To reduce noise 

levels on the gas-powered saws would involve a more 

comprehensive engineering control effort involving not 

only the manufacturer of the saws but also the 

manufacturer of the saw blades, since the noise from 

cut-in radiated mostly from the blade. Re-engineering 

of the engine placement, redirection of the exhaust and 

ergonomic hand controls (placing the hands and head 

further from the saw), for the hand saws are suggested 

engineering control considerations. A potential quick 

fix for the hand saws observed during this study would 

be a redirected and more efficient exhaust muffler. 

Hand saw blades have benefited from vibration and 

sound damping but the same controls have not been 

fully implemented into large road saw blades. Promotion of these controls can be accomplished through 

co-operative research programs with major saw blade 

manufactures. 

This paper has discussed four methods of reducing 

noise over-exposure of construction workers based on 

the principals of noise control8. Figure 8 shows those 

principles of noise control, and the dependence on 

compliance with maintenance and behavioral factors. 

When a machine has a designed noise control in place, 

such as a cab, the operator must be encouraged to keep 

the doors and windows shut to have the control work. A 

well operating air conditioner, available on most 

machines today, not only encourages the operator to 

maintain the noise control integrity of the fully 

enclosed cab, but promotes operator comfort and therefore higher job proficiency4. Maintenance must also be 
Fig. 8-Methods to decrease worker noise exposure. 

scheduled on the air conditioning and door and window 

seals and latches of the cab, to ensure the effectiveness 

of this sound absorberlbarrier. To retrofit an engineering noise control can involve expense, time and 

commitment from the safety engineer and/or construction site manager, and could involve increased maintenance on the machine. Management and workers must 

be supportive of administrative controls since compliance is dependent on human behavior. When personal 

protection equipment is needed, appropriate training 

and monitoring can increase the fit and proper use of 

the hearing protection33g. A variety of HPDs with 

appropriate attenuation and comfort should be available. An effective Hearing Loss Prevention Program, 

especially with the daily doses shown in this study, 

must be established at construction sites with noise 

problems and include most if not all of these methods 

to be effective. 

Another consideration for management, safety 

engineers and construction site managers is that a 

worker overexposed to noise is often more prone to 

fatigue and is less job proficient4. Studies of noisy 

companies that have implemented hearing loss prevention .programs show reductions in accident rates, 

illnesses, and lost time1'. 

While all the construction sites studied provided 

their workers with earplugs, none checked on the 

workers use, or made hearing protection mandatory. At 

the start of the day most equipment operators were 

observed wearing earplugs, but as the day wore on less 

operators were seen with hearing protection and by the 

end of the day very few had earplugs still inserted. 

Workers and management must recognize the crucial 

importance of wearing hearing protectors correctly. 

Intermittent wear will dramatically reduce their effective protection'0. For example, a hearing protector that 

could optimally provide 30 dB of attenuation for an 

8-hr exposure would effectively provide only 15 dB if 

the worker removed the device for a cumulative 

30-minutes during an 8-hour day. Although those who 

select hearing protectors should consider the noise in 

which they will be worn, they must also consider the 

workers who will be wearing them, the need for 

compatibility with other safety equipment, and 

workplace conditions such as temperature, humidity, 

and atmospheric pressureg. In addition, a variety of 

styles should be provided so that workers may select a 

hearing protector on the basis of comfort, ease of use 

and handling, and impact on communication. 

Additional details on how to select appropriate hearing 

protection can be found in the NIOSH criteria 

document-The best hearing protector is the one that 

the worker will wear3. 

4 REFERENCES 

1. 	 D. Hattis, "Occupational Noise Sources and exposures in Construction Industries," Eltlnz. Ecol. Risk Asses., 4, 141 7-144 1, 

(1 998). 

2. 	 N. Seixas, "Noise and Hearing Damage in Construction Apprentices," University of Wushington Final Report, (2004). 

3. 	 National Institute for Occupational Safety and Health (NIOSH), 

"Criteria for a Recommended Standard: Occupational Noise 

Exposure," DHHS NIOSH Publication No. 98- 126, Washington, D.C.: Department of Health and Human Services/National 

Institute for Occupational Safety and Health, (1998). 

4. 	 A. H. Suter, "Construction Noise: Exposure, Effects and the Potential for Remediation: A Review and Analysis," Am. Ind. Hyg. 

Assoc. J, 63, 768-789, (2002). 

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