TM

NIOSH HEALTH HAZARD EVALUATION REPORT 

HETA #2004-0014-2929 

Navajo Agricultural Products Industry 

Farmington, New Mexico 

February 2004 

This Health Hazard Evaluation (HHE) report and any recommendations made herein are for the specific facility evaluated and may not be universally

applicable. Any recommendations made are not to be considered as final statements of NIOSH policy or of any agency or individual involved.

Additional HHE reports are available at http://www.cdc.gov/niosh/hhe/reports

This Health Hazard Evaluation (HHE) report and any recommendations made herein are for the specific facility evaluated and may not be universally

applicable. Any recommendations made are not to be considered as final statements of NIOSH policy or of any agency or individual involved.

Additional HHE reports are available at http://www.cdc.gov/niosh/hhe/reports

applicable. Any recommendations made are not to be considered as final statements of NIOSH policy or of any agency or individual involved.

Additional HHE reports are available at http://www.cdc.gov/niosh/hhe/reports
ii 

DEPARTMENT OF HEALTH AND HUMAN SERVICES 

Centers for Disease Control and Prevention 

National Institute for Occupational Safety and Health
iii 

PREFACE

The Hazard Evaluation and Technical Assistance Branch (HETAB) of the National Institute for 

Occupational Safety and Health (NIOSH) conducts field investigations of possible health hazards in the 

workplace. These investigations are conducted under the authority of Section 20(a)(6) of the 

Occupational Safety and Health (OSHA) Act of 1970, 29 U.S.C. 669(a)(6) which authorizes the Secretary 

of Health and Human Services, following a written request from any employers or authorized 

representative of employees, to determine whether any substance normally found in the place of 

employment has potentially toxic effects in such concentrations as used or found. 

HETAB also provides, upon request, technical and consultative assistance to federal, state, and local 

agencies; labor; industry; and other groups or individuals to control occupational health hazards and to 

prevent related trauma and disease. Mention of company names or products does not constitute 

endorsement by NIOSH. 

ACKNOWLEDGMENTS AND AVAILABILITY OF REPORT

This report was prepared by Chandran Achutan, Ph.D., Randy L. Tubbs, Ph.D., and Daniel J. Habes, 

MSE, CPE, of HETAB, Division of Surveillance, Hazard Evaluations and Field Studies (DSHEFS). 

Desktop publishing was performed by Shawna Watts. Review and preparation for printing were 

performed by Penny Arthur. 

Copies of this report have been sent to employee and management representatives at NAPI. This report is 

not copyrighted and may be freely reproduced. The report may be viewed and printed from the following 

internet address: www.cdc.gov/niosh/hhe/hhesearch.html. Single copies of this report will be available 

for a period of three years from the date of this report. To expedite your request, include a self-addressed 

mailing label along with your written request to: 

NIOSH Publications Office 

4676 Columbia Parkway 

Cincinnati, Ohio 45226 

800-356-4674 

After this time, copies may be purchased from the National Technical Information Service (NTIS) at 5825 

Port Royal Road, Springfield, Virginia 22161. Information regarding the NTIS stock number may be 

obtained from the NIOSH Publications Office at the Cincinnati address. 

For the purpose of informing affected employees, copies of this report 

shall be posted by the employer in a prominent place accessible to the 

employees for a period of 30 calendar days.
iv 

Highlights of the NIOSH Health Hazard Evaluation

Characterization of noise exposures during agricultural operations at the 

Navajo Agricultural Products Industry

NIOSH received a management request from the Navajo Agricultural Products Industry (NAPI) to 

monitor employee noise during processing and packaging of potatoes (Fresh Pack area), making of alfalfa 

pellets, and working at the mechanic shop.

What NIOSH Did

 We took noise measurements on employees 

in Fresh Pack, alfalfa pellet operation, and 

mechanic shop. 

 We observed work practices in Fresh Pack 

and the alfalfa pellet operation. 

What NIOSH Found

 Employees in Fresh Pack are exposed to 

loud noise. 

 Noise is well managed in Fresh Pack. 

Employees are wearing ear protection 

properly and at all times. 

 Employees who stack boxes and sacks of 

potatoes have potential for low back injury. 

 The alfalfa pellet mill operator and 

mechanics are exposed to loud noise. 

 The alfalfa pellet mill operator and front 

loader are exposed to organic dust that may 

contain mold. 

What NAPI Managers Can Do

 Develop a hearing conservation program for 

the alfalfa pellet mill operator and mechanics. 

 Start a respiratory protection program at the 

pellet mill operation. 

 Reduce the time spent continuously stacking 

boxes and sacks to two hours. 

 Reduce the weight of potatoes in boxes and 

sacks in Fresh Pack. 

What the NAPI Employees Can Do 

 Continue to wear ear plugs in noisy 

environments. 

What To Do For More Information:

We encourage you to read the full report. If you 

would like a copy, either ask your health and 

safety representative to make you a copy or call 

1-513-841-4252 and ask for 

HETA Report #2004-0014-2929

iv 

Highlights of the HHE Report 

Health Hazard Evaluation Report 2004-0014-2929 

Navajo Agricultural Products Industry 

Farmington, New Mexico 

February 2004 

Chandran Achutan, Ph.D. 

Randy L. Tubbs, Ph.D. 

Daniel J. Habes, MSE, CPE 

SUMMARY

On October 1, 2003, the National Institute for Occupational Safety and Health (NIOSH) received a 

management request to conduct a health hazard evaluation (HHE) at Navajo Agricultural Products 

Industry (NAPI), in Farmington, New Mexico. The request was to evaluate noise exposures during 

potato processing and packaging (Fresh Pack area), corn storage and dispensing (Granary), and 

equipment maintenance and other mechanical tasks at the Mechanic Shop. During the course of the 

investigation, NIOSH was also requested to measure noise exposure during the manufacture of alfalfa 

pellets. During the NIOSH visit, the granary was not operating and was not monitored. Potential 

ergonomic hazards were identified during the packaging of potatoes in the Fresh Pack area. 

Between October 27 and 30, 2003, NIOSH investigators conducted a site visit at NAPI. Following a 

meeting on October 27, 2003, with NAPI’s safety officers, NIOSH investigators toured the facility. On 

October 28 and 29, 2003, NIOSH measured noise exposure to 18 employees in the Fresh Pack area, 

where potatoes are unloaded from a truck, washed, sorted, and packaged for shipment. On October 30, 

2003, NIOSH investigators measured noise exposure on two employees during the manufacture of alfalfa 

pellets, and on two mechanics from the mechanic shop. 

The noise exposure assessment revealed that, of the 22 employees monitored, 6 attained or exceeded the 

NIOSH Recommended Exposure Limit (REL). Four of these employees were from the Fresh Pack area, 

and one each from the alfalfa pellet-mill operation, and the mechanic shop. Two of the six (bagger and 

pellet mill operator) also exceeded the Occupational Safety and Health Administration (OSHA) Action 

Limit (AL). NAPI has a well-managed hearing conservation program for employees in the Fresh pack 

area. Employees were observed wearing foam ear plugs correctly and consistently. We observed 

ergonomic-related issues during the packaging of potatoes and potential exposure to mold during the 

manufacture of alfalfa pellets. 
v 

There is a potential for excessive noise exposure in the Fresh Pack area, the alfalfa-pellet 

manufacturing area, and the mechanic shop. Twenty-seven percent of the employees 

who were monitored for noise attained or exceeded the NIOSH REL. In addition, there is 

an ergonomic hazard during the packaging of potatoes in the Fresh Pack area and a 

potential for respiratory hazards during the manufacture of alfalfa pellets. 

Recommendations on these issues are included in this report. 

Keywords: SIC: 0723 (Crop Preparation Services for Market), 2048 (Prepared Feeds for Animals and 

Fowls) and 7538 (Automotive Repair/Mechanic), noise, potato packaging and processing, alfalfa pellets, 

mechanics, agriculture, ergonomics, mold 

TABLE OF CONTENTS

Preface.........................................................................................................................................................iii

Acknowledgments and Availability of Report.........................................................................................iii

Highlights of the NIOSH Health Hazard Evaluation .............................................................................iv

Summary.....................................................................................................................................................iv

Table of Contents ........................................................................................................................................1

Introduction.................................................................................................................................................1

Background .................................................................................................................................................1

Methods........................................................................................................................................................2

Evaluation Criteria .....................................................................................................................................3

Results ..........................................................................................................................................................4

Discussion ....................................................................................................................................................5

Conclusions..................................................................................................................................................7

Recommendations.......................................................................................................................................8

References....................................................................................................................................................8

Health Hazard Evaluation Report No. 2004-0014-2929 Page 1 

INTRODUCTION

On October 1, 2003, the National Institute for 

Occupational Safety and Health (NIOSH) 

received a management request to conduct a 

health hazard evaluation (HHE) at Navajo 

Agricultural Products Industry (NAPI), in 

Farmington, New Mexico. The request was to 

evaluate noise exposures during potato 

processing and packaging (Fresh Pack area), 

corn storage and dispensing (Granary), and 

equipment maintenance and other mechanical 

tasks at the Mechanic Shop. During the course 

of the investigation, NIOSH was also requested 

to measure noise exposure during the 

manufacture of alfalfa pellets. During the 

NIOSH visit there was no work at the granary, 

and this operation was not monitored. Potential 

ergonomic hazards were identified during the 

packaging of potatoes in the Fresh Pack area. 

Between October 27 and 30, 2003, NIOSH 

investigators conducted a site visit at NAPI. 

Following a meeting on October 27, 2003, with 

NAPI’s safety officers, NIOSH investigators 

toured the facility. On October 28 and 29, 2003, 

NIOSH measured noise exposure to 18 

employees in the Fresh Pack area, where 

potatoes are unloaded from a truck, washed, 

sorted, and packaged for shipment. On October 

30, 2003, NIOSH investigators measured noise 

exposure on two employees during the 

manufacture of alfalfa pellets, and on two 

mechanics from the mechanic shop. 

BACKGROUND

NAPI was established in 1970 as the Navajo 

Nation's farming and agri-business enterprise. 

Approximately 60,000 of the 110,000 acres of 

Navajo land are cultivated. Crops grown by 

NAPI include potatoes, onions, pumpkins, and 

corn. NAPI is a main processor of potatoes for 

the potato chip industry. 

Fresh Pack 

The potato processing plant is located in a 

rectangular “high-bay” area measuring 

approximately 200 feet by 60 feet. There are 28 

salaried employees in this area. Normal 

working hours are between 8:00 a.m. and 4:30 

p.m., Monday through Friday, with a lunch 

break between noon and 12:30 p.m. The major 

processes involved with potato processing and 

packaging are as follows: 

Unloading 

Potatoes are brought into the unloading area in 

trucks. They are then transferred into a storage 

bin, via a conveyor. Employees are positioned 

between the end of the truck and the beginning 

of the conveyor and along the conveyor to 

separate good potatoes from rotten potatoes, 

mud clods, and other debris. Unloading a truck 

takes approximately 30 minutes, and usually, 

four or five employees are involved with the 

process. During this survey, between four and 

eight truck loads of potatoes were unloaded each 

day. The potatoes are stored in a bin, from 

which they are sent to the washer. The washer is 

an automated process. When not unloading, 

employees assist with other tasks in the plant. 

Sorting 

Three sorting lines at this facility separate the 

potatoes by size and quality. The washed 

potatoes come off a conveyor to Sorting Line I. 

This sorting line is split into two lanes. Five 

metal bins are located between both lanes. 

Rotten potatoes are discarded in one of the bins, 

which are then transported outside the facility 

via a conveyor. In the remaining four bins, 

oversized or fused potatoes are placed for further 

processing. The rest of the potatoes are passed 

over a set of rollers that separates them by size. 

From there, the potatoes are sent to Sorting Line 

II. Potatoes are further sorted for size and 

quality, and sent for packaging. Potatoes 

discarded at Sorting Line II and the oversized 

and fused potatoes from Sorting Line I are 

further processed at Sorting Line III. At Sorting 

Line III, potatoes are discarded or sent for 

packaging. Two employees work in Sorting 

Line I, one on each lane. About four employees 

work in each of Sorting Lines II and III. 
Page 2 Health Hazard Evaluation Report No. 2004-0014-2929 

Packaging 

The packaging operation includes one or two 

employees who assemble cardboard boxes, one 

who weighs boxes, two to three employees who 

feed boxes to the boxing line, three who stack 

the 50 pound filled boxes on pallets, four who 

fill and weigh 100-pound bags, two to three who 

stack the 100-pound bags on pallets, and a 

forklift driver who removes the stacked pallets 

for storage and shipment.

Manufacture of Alfalfa 

Pellets 

The first step in the manufacture of alfalfa 

pellets is the grinding of raw alfalfa. The alfalfa 

used to manufacture pellets is sometimes moldy, 

and/or mixed with moldy hay. The grinder is 

about 20 feet high and 10 feet wide. The grinder 

stands vertically, part of it is on the main floor, 

but most of it is in a basement. Raw alfalfa is 

loaded a little at a time onto the grinder by a 

front loader, to prevent the grinder from 

clogging. The ground alfalfa is transported via a 

vacuum system to the pellet-mill, where under 

heat and pressure, it is compressed into pellets. 

The pellets are cylindrical in shape, and are cut 

into lengths of six to eight inches. The pellets 

are cooled, sieved, and transferred to storage 

bins via a vacuum system. The pellet-mill 

operation is carried out by two employees: a 

front-loader driver who loads the alfalfa onto the 

grinder and an operator who runs the pellet-mill 

machine. 

Mechanic Shop 

At the time of the survey, at least two mechanics 

were working in the mechanic shop. One person 

remained in the shop, while the other was in the 

field, on service calls. Tasks performed by both 

individuals included changing oil in trucks, 

repairing tires and wheelbarrows, and 

miscellaneous small projects. 

METHODS

Noise Sampling Strategy 

NIOSH investigators selected employees 

working in all parts of the Fresh Pack area, 

employees working in the alfalfa pellet-mill 

operation, and two employees from the 

mechanic shop. Eighteen employees were 

monitored in the Fresh Pack area over a two-day 

period: three unloaders, eight sorters, and seven 

in the packaging area. The front loader and the 

pellet-mill operator from the alfalfa pellet-mill 

operation and two mechanics from the mechanic 

shop were each sampled for one day. In 

addition, real-time, instantaneous noise 

monitoring was also conducted in various parts 

of the Fresh Pack area and the alfalfa pelletmaking operation. 

Noise Sampling 

Instrumentation 

Quest® Electronics Model Q-300 Noise 

Dosimeters were worn by the employees while 

they performed their daily activities. The noise 

dosimeters were attached to the wearer’s belt 

and a small remote microphone was fastened to 

the wearer’s shirt at a point midway between the 

ear and the outside of the employee’s shoulder. 

A windscreen provided by the manufacturer of 

the dosimeter was placed over the microphone 

during recordings. At the end of an inspection, 

the dosimeter was removed and paused to stop 

data collection. The information stored in the 

dosimeters was downloaded to a personal 

computer for interpretation with QuestSuite 

Professional computer software. The dosimeters 

were calibrated before and after the 

measurement periods according to the 

manufacturer’s instructions. Real time, 

instantaneous noise monitoring was done by a 

Quest Electronics Model 2400 Sound Level 

Meter (SLM). The instrument was set to 

measure noise levels between 70 and 140 

decibels, on an A-weighted slow-response scale 

[dB(A)]. The SLM was calibrated before and 

after the measurement periods according to the 

manufacturer’s instructions. 
Health Hazard Evaluation Report No. 2004-0014-2929 Page 3 

EVALUATION CRITERIA

As a guide to the evaluation of the hazards posed 

by workplace exposures, NIOSH field staff 

employ environmental evaluation criteria for the 

assessment of a number of chemical and 

physical agents. These criteria are intended to 

suggest levels of exposure to which most 

workers may be exposed up to 10 hours per day, 

40 hours per week for a working lifetime 

without experiencing adverse health effects. It 

is, however, important to note that not all 

workers will be protected from adverse health 

effects even though their exposures are 

maintained below these levels. A small 

percentage may experience adverse health 

effects because of individual susceptibility, a 

pre-existing medical condition, and/or a 

hypersensitivity (allergy). In addition, some 

hazardous substances may act in combination 

with other workplace exposures, the general 

environment, or with medications or personal 

habits of the worker to produce health effects 

even if the occupational exposures are controlled 

at the level set by the criterion. These 

combined effects are often not considered in the 

evaluation criteria. Finally, evaluation criteria 

may change over the years as new information 

on the toxic effects of an agent become 

available. 

The primary sources of environmental 

evaluation criteria for the workplace are: (1) 

NIOSH Recommended Exposure Limits 

(RELs),1

 (2) the American Conference of 

Governmental Industrial Hygienists’ (ACGIH®) 

Threshold Limit Values (TLVs®),2

 and (3) the 

U.S. Department of Labor, Occupational Safety 

and Health Administration (OSHA) Permissible 

Exposure Limits (PELs).3

 Employers are 

encouraged to follow the OSHA limits, the 

NIOSH RELs, the ACGIH TLVs, or whichever 

are the more protective criteria. 

OSHA requires an employer to furnish 

employees a place of employment that is free 

from recognized hazards that are causing or are 

likely to cause death or serious physical harm 

[Occupational Safety and Health Act of 1970, 

Public Law 91–596, sec. 5(a)(1)]. Thus, 

employers should understand that not all 

hazardous chemicals have specific OSHA 

exposure limits such as PELs and short-term 

exposure limits (STELs). An employer is still 

required by OSHA to protect their employees 

from hazards, even in the absence of a specific 

OSHA PEL. 

Noise-induced loss of hearing is an irreversible, 

sensorineural condition that progresses with 

exposure. Although hearing ability declines with 

age (presbycusis) in all populations, exposure to 

noise produces hearing loss greater than that 

resulting from the natural aging process. This 

noise-induced loss is caused by damage to nerve 

cells of the inner ear (cochlea) and, unlike some 

conductive hearing disorders, cannot be treated 

medically.4

 While loss of hearing may result 

from a single exposure to a very brief impulse 

noise or explosion, such traumatic losses are 

rare. In most cases, noise-induced hearing loss 

is insidious. Typically, it begins to develop at 

4000 or 6000 Hertz(Hz) (the hearing range is 20 

Hz to 20000 Hz) and spreads to lower and 

higher frequencies. Often, material impairment 

has occurred before the condition is clearly 

recognized. Such impairment is usually severe 

enough to permanently affect a person's ability 

to hear and understand speech under everyday 

conditions. Although the primary frequencies of 

human speech range from 200 Hz to 2000 Hz, 

research has shown that the consonant sounds, 

which enable people to distinguish words such 

as "fish" from "fist," have still higher frequency 

components.5

The A-weighted decibel [dB(A)] is the preferred 

unit for measuring sound levels to assess worker 

noise exposures. The dB(A) scale is weighted to 

approximate the sensory response of the human 

ear to sound frequencies near the threshold of 

hearing. The decibel unit is dimensionless, and 

represents the logarithmic relationship of the 

measured sound pressure level to an arbitrary 

reference sound pressure (20 micropascals, the 

normal threshold of human hearing at a 

frequency of 1000 Hz). Decibel units are used 

because of the very large range of sound 

pressure levels which are audible to the human 

ear. Because the dB(A) scale is logarithmic, 

increases of 3 dB(A), 10 dB(A), and 20 dB(A) 
Page 4 Health Hazard Evaluation Report No. 2004-0014-2929 

represent a doubling, tenfold increase, and 100-

fold increase of sound energy, respectively. It 

should be noted that noise exposures expressed 

in decibels cannot be averaged by taking the 

simple arithmetic mean. 

The OSHA standard for occupational exposure 

to noise (29 CFR 1910.95)6

 specifies a 

maximum PEL of 90 dB(A) for a duration of 

8 hours per day. The regulation, in calculating 

the PEL, uses a 5 dB time/intensity trading 

relationship, or exchange rate. This means that a 

person may be exposed to noise levels of 

95 dB(A) for no more than 4 hours, to 100 

dB(A) for 2 hours, etc. Conversely, up to 16 

hours exposure to 85 dB(A) is allowed by this 

exchange rate. The duration and sound level 

intensities can be combined in order to calculate 

a worker's daily noise dose according to the 

formula: 

Dose = 100 X (C1/T1 + C2/T2 + ... + Cn/Tn ), 

where Cn indicates the total time of exposure at a 

specific noise level and Tn indicates the 

reference duration for that level as given in 

Table G-16a of the OSHA noise regulation.6

 

During any 24-hour period, a worker is allowed 

up to 100% of his daily noise dose. Doses 

greater than 100% are in excess of the OSHA 

PEL. 

The OSHA regulation has an additional action 

level (AL) of 85 dB(A); an employer shall 

administer a continuing, effective hearing 

conservation program when the 8-hour timeweighted average (TWA) value exceeds the AL. 

The program must include monitoring, 

employee notification, observation, audiometric 

testing, hearing protectors, training, and record 

keeping. All of these requirements are included 

in 29 CFR 1910.95, paragraphs (c) through (o). 

Finally, the OSHA noise standard states that 

when workers are exposed to noise levels in 

excess of the OSHA PEL of 90 dB(A), feasible 

engineering or administrative controls shall be 

implemented to reduce the workers' exposure 

levels. 

NIOSH, in its Criteria for a Recommended 

Standard,7

 and the ACGIH,2 propose exposure 

criteria of 85 dB(A) as a TWA for 8 hours, 5 dB 

less than the OSHA standard. The criteria also 

use a more conservative 3 dB time/intensity 

trading relationship in calculating exposure 

limits. Thus, a worker can be exposed to 

85 dB(A) for 8 hours, but to no more than 

88 dB(A) for 4 hours or 91 dB(A) for 2 hours. 

Twelve hours exposures have to be 83 dB(A) or 

less according to the NIOSH REL. 

RESULTS

A total of 22 full-shift dosimeter samples were 

collected during the evaluation. The Quest 

dosimeters collect data so that one can directly 

compare the information with the three different 

noise criteria used in this survey, the OSHA PEL 

and AL, and the NIOSH REL. The OSHA 

criteria use a 90 dBA criterion and 5-dB 

exchange rate. The difference between the two is 

the threshold level employed, with a 90 dBA 

threshold for the PEL and an 80 dBA threshold 

for the AL. The threshold level is the lower 

limit of noise values included in the calculation 

of the criteria; values less than the threshold are 

ignored by the dosimeter. The NIOSH criterion 

differs from OSHA in that the criterion is 85 

dBA, the threshold is 80 dBA, and it uses a 3-dB 

exchange rate. Because of the different 8-hour 

criteria and exchange rates, the dose equations 

used to calculate the equivalent TWA values are 

different for the NIOSH and OSHA criteria. 

The OSHA dose equation is TWA = 16.61 x 

log10 [Dose/100] + 90, and the NIOSH equation 

is TWA = 10.00 x log10 [Dose/100] + 85. 

A summary of the personal dosimeter results is 

presented in Table 1. In addition, real-time, area 

measurements taken at various locations in the 

Fresh Pack and pellet-mill areas are provided in 

Table 2. The dosimeter also provides real-time 

exposure monitoring over the sampling period. 

Each data point represents the integrated average 

noise for a 1-minute period, using the NIOSH 

3-dB exchange rate. Typical graphs from the 

survey are shown in Figures 1-4. The graphs 

have a lower limit of 70 dBA which is the 

lowest noise value the dosimeters captured. 
Health Hazard Evaluation Report No. 2004-0014-2929 Page 5 

Fresh Pack 

In Fresh Pack, noise levels were below the 

OSHA PEL. The OSHA AL was exceeded 

once, and one reading (84 dBA) was close to the 

OSHA AL of 85 dBA. In four instances, the 

NIOSH REL was either attained or exceeded. In 

two instances, the percentage of daily dose 

exceeded 100%, as computed by the NIOSH 

formula, and in two additional instances, 

exceeded 90%. The percent dose was not 

exceeded by the OSHA computation based on 

the PEL criterion. Noise exposures in the 

packaging area were higher than those in the 

unloading and sorting areas. Among the 

packagers, the highest exposure (90 dBA) was 

during the packaging of potatoes in 100-pound 

sacks. 

As shown in Figure 1, exposures among the 

unloaders followed a “box-plot” pattern, 

whereby exposures increased sharply, stayed 

constant during the unloading process, and then 

dropped sharply at the conclusion of the tasks. 

Smaller peaks with a rapid response time may be 

attributable to other tasks performed by the 

unloader, such as making boxes, feeding boxes 

to the line, etc. Noise exposures to the sorters 

were uniform throughout the day. A typical 

noise profile is shown in Figure 2.

Manufacture of Alfalfa 

Pellets 

During the manufacture of alfalfa pellets, the 

noise exposure to the pellet mill operator 

exceeded the OSHA AL and the NIOSH REL, 

but was below the OSHA PEL of 90 dBA. The 

front loader’s exposure was below all exposure 

criteria, probably because he was up high in the 

vehicle and spent time away from the grinder. 

The front loader had a cab, but it was open at 

least part of the day. Figure 3 compares the 

noise exposures to both the pellet mill operator 

and the front loader. The pellet mill operator’s 

exposure was higher than that of the front 

loader, probably because he was right next to the 

mill most of the day. The noise levels by the 

grinder ranged from 86-105 dBA, as shown in 

Table 2. 

Mechanic Shop 

One of the mechanics in the mechanic shop 

(mechanic-1) exceeded the NIOSH REL, but 

was well below the OSHA PEL and REL. The 

second mechanic (mechanic-2) was below all 

recommended and regulatory values. Figure 4 

shows the profile of the mechanic who exceeded 

the NIOSH REL. The profile is useful to identify 

tasks that result in high noise exposure. 

DISCUSSION

Fresh Pack 

Employee noise exposures measured during this 

survey were below the OSHA PEL, but above 

the NIOSH REL. The hearing protection 

provided for exposed workers (formable 

earplugs) was adequate to reduce exposures 

measured during this survey to below the 

NIOSH REL, provided that it is used properly 

and consistently. We observed good compliance 

with the wearing of the earplugs during the twoday survey. 

Sound level measurements in various parts of 

the Fresh Pack area showed that noise levels 

were between 85 and 93 dBA. The highest 

noise level was recorded next to a machine 

guard in the sorting area. The machine guard 

was worn out, thus exposing the belts that are 

contained within the guard. 

The results obtained on this survey are 

comparable to a similar, smaller survey NIOSH 

conducted at this facility in August 1998.8

 

During the 1998 survey, production was not to 

capacity, and there were many equipment 

failures, which led to a less-than-typical work 

environment. Nevertheless, personal dosimeter 

samples collected on four individuals during the 

1998 survey exceeded the NIOSH REL and, in 

two instances, exceeded the OSHA AL. 

Sometime after the 1998 survey, NAPI instituted 

engineering modifications to the equipment to 

further reduce noise exposure. These 

modifications included rollers with ball bearings 

and the incorporation of elastic materials 

between roll structure and metal braces. 
Page 6 Health Hazard Evaluation Report No. 2004-0014-2929 

During the survey, we observed that some 

employees in the packaging area were involved 

in tasks that required heavy and repetitive lifting 

of boxes and sacks filled with potatoes. 

Repeated awkward and heavy lifting can lead to 

back injuries and other musculoskeletal 

problems. Though a comprehensive ergonomic 

evaluation was not done in this survey, we noted 

work practices and collected measurements that 

enabled us to conduct a limited ergonomic 

evaluation of the workplace. 

We observed employees in the packaging area 

lifting 50-pound boxes of potatoes and stacking 

them on pallets. The pallets were usually seven 

boxes (70 inches) tall. Each box had cut-out 

handles and measured 18 inches by 11.5 inches, 

with a height of 10 inches. In most cases, 

employees were lifting the boxes using the cutout handles. In some instances, especially when 

stacking the boxes high, the employees were 

holding the boxes vertically between the palms 

of their hands. We observed an employee 

stacking a maximum of nine boxes every 5 

minutes or 90 pounds per minute. The total 

number of 50-pound boxes stacked by four 

employees during a 5-minute time span was 30. 

Some employees were lifting 100-pound sacks 

and stacking them on pallets. Three employees 

stacked 31 bags, each weighing 100 pounds, 

during a 20-minute period. One of the three 

employees stacked 19 bags in 20 minutes. 

When broken down into 5-minute time periods, 

this employee stacked eight bags in one 5-

minute time period, or 160 pounds per minute. 

To assess the health impact from heavy and 

repetitious lifting, we used the NIOSH Lifting 

Equation (NLE). The NLE is a tool for 

assessing the physical demands of two–handed 

lifting tasks. The equation provides a 

Recommended Weight Limit (RWL) and a 

Lifting Index (LI) for a lifting task, given certain 

lifting conditions. The RWL is the maximum 

weight that can be handled safely by almost all 

healthy workers in similar circumstances. The 

LI is the ratio of the actual load lifted to the 

RWL. Lifting tasks with an LI <1.0 pose little 

risk of low back injury for the majority of 

workers. Tasks with an LI > 1.0 may place an 

increasing number of individuals at risk of low 

back pain or injury. Many researchers believe 

that tasks with an LI > 3.0 pose a risk of back 

injury for most workers.9

 NIOSH recommends 

that the LI not exceed 2.0 for any given task. 

Based on the assumptions that there is no 

twisting of the body during the lifts, the boxes 

and bags are held close to the body, and that the 

boxing and bagging of potatoes lasts more than 

2 hours a day, we calculated an LI of 2.9 for the 

boxing operation, and an LI of 4.7 for the 

bagging operation. Both of these operations, 

therefore, place the workers at an increased risk 

for low back pain or injury. 

Assuming that the boxes are stacked sevenboxes high, the LI during the stacking of 

50-pound boxes on pallets can be reduced by (1) 

limiting the number of continuous hours that a 

person stacks the boxes to less than 2 hours at a 

time and (2) reducing the weight of potatoes in 

each box. By simply limiting the continuous 

number of hours that a person stacks boxes to 

less than 2 hours per lifting session, the LI can 

be reduced to 2.2. (The positive effect of this 

control measure would be maintained provided 

the worker is allowed to recover by resting or 

performing some non-lifting task for about 45 or 

more minutes before lifting boxes again.) By 

reducing the weight of the potatoes in each box 

from 50 to 40 pounds, the LI can be reduced to 

2.3. By reducing the number of hours, and the 

weight of potatoes in each box, the LI can be 

further reduced to 1.8. Similarly, if the weight 

of the 100-pound potato sacks is reduced to 50 

pounds, and the continuous work hours is 

limited to less than 2 hours at a time, the LI can 

be reduced to 1.8. It is assumed that the average 

height of the stacked sacks is 42 inches. 

The unloading process can be dusty, though the 

dust levels are not likely to exceed any exposure 

criteria. Nevertheless, respirators are provided 

to employees who may wish to wear them. We 

noticed that employees wearing respirators were 

not doing so correctly. In one instance, an 

employee stuffed the top set of the respirator’s 

bands inside the respirator. The same employee 

was also noticed beating a respirator on a pole to 

remove dust. 
Health Hazard Evaluation Report No. 2004-0014-2929 Page 7 

The forklift in the Fresh Pack area that is used to 

lift pallets stacked with boxes and sacks is not 

equipped with a back-up alarm. Backing up a 

forklift when the rear view is obstructed may 

result in injuries or fatalities. Back-up alarms 

are specified in the OSHA Construction Safety 

and Health requirements, which is covered by 29 

CFR Part 1926.601(b)(4). OSHA has no 

requirements for back-up alarms in the general 

industry standards, 29 CFR Part 1910, which 

covers operations similar to NAPI, but injuries 

and fatalities that may occur as a result of 

operating forklifts without back-up alarms can 

be cited under the general duty clause 

[Occupational Safety and Health Act of 1970, 

Public Law 91-596, sec. 5(a) (1)]. 

Manufacture of Alfalfa 

Pellets 

Of the two employees sampled during the 

manufacture of alfalfa pellets, the noise 

exposure to the front loader was below all 

exposure criteria. Thus, this employee is not 

required to be part of a hearing conservation 

program. The noise exposure to the pellet mill 

operator exceeded the OSHA AL and the 

NIOSH REL, and was close (88 dBA) to the 

OSHA PEL. Any employee who runs the pellet 

mill should be included in a hearing 

conservation program. The operator controls the 

machine operation from a control booth, which 

can afford adequate noise protection. The noise 

level on a platform outside the booth was 100 

dBA, but it dropped to 80 dBA with the door 

partially closed. The door could not be 

completely closed because there was an electric 

cord that was blocking the opening. It would be 

prudent to run the wire through the wall, via a 

conduit, thus shutting the door completely. We 

also observed that the pellet mill operator spends 

a great deal of time outside the control booth. 

The process by which raw alfalfa is loaded onto 

the grinder generates a thick cloud of dust. 

Since some of the alfalfa is moldy, the dust may 

contain microorganisms, which if inhaled, could 

be detrimental to the health of the employees in 

the area.10,11

Mechanic Shop 

Of the two mechanics who were monitored, the 

one who stayed in the shop exceeded the NIOSH 

REL. His major activity during the day of 

monitoring was repairing a large tire from a 

tractor. The noise exposure occurred during the 

pounding of the metal rim of the tire. This 

repair job took approximately two hours. The 

second mechanic was in the field on service 

calls. His largest exposure to noise occurred 

when intermittently stepping on the gas pedal of 

a stationary tractor. Other tasks done by this 

mechanic included servicing a truck (changing 

oil and air filters) and changing a door handle on 

a tractor. The sampling duration on this 

mechanic was only 5-1/2 hours, because he had 

to leave work early on the day of sampling. The 

mechanics informed us that their busiest times 

were in spring and in summer, just prior to and 

during the planting and harvesting season. 

CONCLUSIONS

The noise exposure assessment revealed that of 

the 22 employees who were monitored, 6 

attained or exceeded the NIOSH REL. Four of 

these employees were from the Fresh Pack area, 

and one each from the alfalfa pellet mill 

operation and the mechanic shop. Two of the 

six (bagger and pellet mill operator) also 

exceeded the OSHA AL. None of the 

employees exceeded the OSHA PEL. 

Overall, the noise exposures at NAPI are well 

managed. Employees who work in areas with 

exposure to loud noise are provided foam 

earplugs that reduce their noise exposure to an 

acceptable level. We observed that employees 

were wearing their earplugs properly. NAPI has 

a hearing conservation program for employees 

in the Fresh Pack area; employees are sent to 

occupational medicine physicians for annual 

hearing examinations. Also, NAPI has made 

engineering changes in the potato processing 

equipment. 

We identified a hazard from lifting and stacking 

heavy boxes and sacks of potatoes that puts 

employees at risk of musculoskeletal injuries. 
Page 8 Health Hazard Evaluation Report No. 2004-0014-2929 

We also identified the potential for exposure to 

microorganisms from inhaling dust during the 

alfalfa manufacturing process. 

RECOMMENDATIONS

We are making the following recommendations 

to make the workplace safer for all employees: 

Fresh Pack 

Both human speech and machine sounds contain 

high and low frequencies that can be distorted 

by conventional Hearing Protection Devices 

(HPD). To minimize this distortion, and to 

improve communication, we recommend the use 

of HPD that are linear and more moderate in 

attenuation. Examples of this include Natural 

Sound TechnologyTM or NSTTM, developed by 

Bilsom (www.bacou-dalloz.com), and the UltraTech or Musician series HPD, by AEARO 

(www.aearo.com). These devices are available 

from most vendors who sell safety supplies. 

Grainger [(505) 327-9953], and Strategic Supply 

[(505) 326-3333], located in Farmington, New 

Mexico, are two distributors for AEARO 

products. Additionally, a maintenance program 

for noise controls need to be implemented, to 

assure that they continue to function as 

designed. 

To prevent musculoskeletal injuries, we 

recommend reducing the weight of potatoes in 

the sacks and boxes to a weight not exceeding 

40 pounds for the boxes and 50 pounds for the 

sacks. We also recommend reducing to 2 hours 

the maximum amount of time that an employee 

is continuously stacking boxes and sacks on 

pallets. 

We recommend installing a back-up alarm on 

the forklift that is approximately 10 dB above 

the ambient noise, and fixing the machine guard. 

Manufacture of Alfalfa 

Pellets 

Enroll pellet mill operators in a hearing 

conservation program. We also recommend that 

the operator limits the amount of time spent 

outside the control booth and continues to wear 

ear protection when outside the control booth. 

The door on the control booth should be closed 

tightly when the operator is inside the booth. 

The electric cord that is currently blocking the 

door needs to be routed outside the booth 

through a conduit in the wall. 

A written respiratory program based on OSHA’s 

Respiratory Protection Standard (29 CFR 

1910.134) that outlines the appropriate respirator 

based on the hazard, and employee training on 

how to wear a respirator and store it safely, 

should be developed and managed by a qualified 

program administrator. 

Mechanic Shop 

Employees involved with service call activities 

and employees in the mechanic shop who are 

potentially subjected to high noise levels must 

be included in a hearing conservation program. 

Alternatively, a task analysis can be carried out 

to determine which activities require HPD.12

REFERENCES

 1. NIOSH [1992]. Recommendations for 

occupational safety and health: compendium of 

policy documents and statements. Cincinnati, 

OH: U.S. Department of Health and Human 

Services, Public Health Service, Centers for 

Disease Control and Prevention, National 

Institute for Occupational Safety and Health, 

DHHS (NIOSH) Publication No. 92-100. 

 2. ACGIH [2003]. 2003 TLVs® and BEIs®: 

threshold limit values for chemical substances 

and physical agents. Cincinnati, OH: American 

Conference of Governmental Industrial 

Hygienists. 

 3. CFR [1997]. 29 CFR 1910.1000. Code of 

Federal Regulations. Washington, DC: U.S. 

Government Printing Office, Office of the 

Federal Register. 

 4 Ward WD, Royster LH, Royster JD 

[2000]. Anatomy & physiology of the ear: 
Health Hazard Evaluation Report No. 2004-0014-2929 Page 9 

normal and damaged hearing. Chapter 4. In: 

Berger EH, Royster LH, Royster JD, Driscoll 

DP, & Layne M, eds. The noise manual. 5th ed. 

Fairfax, VA: American Industrial Hygiene 

Association, pp 101–122. 

 5 Suter AH [1978]. The ability of mildly 

hearing–impaired individuals to discriminate 

speech in noise. Washington, DC: U.S. 

Environmental Protection Agency, Joint 

EPA/USAF study, EPA 550/9–78–100, AMRL–

TR–78–4. 

 6 Code of Federal Regulations [1992]. 

OSHA. 29 CFR 1910.95. Washington, DC: 

U.S. Government Printing Office, Federal 

Register. 

 7 NIOSH [1998]. Criteria for a 

recommended standard: occupational noise 

exposure (revised criteria 1998). Cincinnati, 

OH: U.S. Department of Health and Human 

Services, Centers for Disease Control and 

Prevention, National Institute for Occupational 

Safety and Health, DHHS (NIOSH) Publication 

No. 98-126. 

 8 McCammon J [1998]. Health hazard 

evaluation report: Navajo Agricultural Products 

Industry, Farmington, N.M. Denver, CO: US 

Department of Health and Human Services, 

Public Health Service, Centers for Disease 

Control and Prevention, National Institute for 

Occupational Safety and Health, HETA 98-

0315. 

 9 Waters TR, Putz–Anderson V, Garg A 

[1994]. Applications manual for the revised 

NIOSH lifting equation. U.S. Department of 

Health and Human Services, Public Health 

Service, Centers for Disease Control and 

Prevention, National Institute for Occupational 

Safety and Health, Publication 94–110. 

 10 Merchant JA [1987]. Agricultural 

exposures to organic dusts. Occupational 

Medicine. 2(2): 409-425. 

 11 Kirkhorn SR, Garry VF [2000]. 

Agricultural lung diseases. Environmental 

Health Perspectives. 108 Supplement 4: 705-

712.

 12 Tubbs RL [2002]. Health hazard 

evaluation report: Marion County Board of 

Education, Fairmont, West Virginia. US 

Department of Health and Human Services, 

Public Health Service, Centers for Disease 

Control and Prevention, National Institute for 

Occupational Safety and Health, HETA 2002-

0222. 
Page 10 Health Hazard Evaluation Report No. 2004-0014-2929 

Table 1 

Personal Noise Dosimeter Results 

Navajo Agricultural Products Industry 

Farmington, New Mexico 

October 27-30, 2003 

Date Department Duration 

(hh:mm) 

Job location Dose (Percent) Lavg (dBA) 

 OSHA 

AL 

OSHA 

PEL 

NIOSH/ 

ACGIH 

OSHA 

AL 

OSHA 

PEL 

NIOSH/ 

ACGIH 

10/28/03 Fresh Pack 07:03 

06:52 

07:19 

07:15 

07:10 

07:21 

07:01 

07:02 

07:01 

07:04 

Unloader-1 

Unloader-2 

Sorter-1 

Sorter-2 

Sorter-3 

Box maker 

Bagger-1 

Bagger-2 

Pallet stacking 

Plastic bag 

packing 

16.8 

18.5 

38.8 

36.7 

43.3 

29.5 

76.5 

39.4 

34.6 

30.3 

0.7 

0.5 

0.1 

0.6 

0.1 

0.8 

43.2 

2.6 

2.2 

0.6 

40.1 

36.6 

80.4 

76.5 

94.6 

57.6 

281.4 

93.3 

88.2 

61.8 

77.1 

77.8 

83.2 

82.8 

84.0 

81.2 

88.1 

83.3 

82.3 

81.4 

53.9 

52.4 

41.0 

53.1 

42.5 

54.8 

83.9 

63.7 

62.5 

52.9 

81.0 

80.6 

84.1 

83.8 

84.8 

82.6 

89.5 

84.7 

84.5 

82.9 

10/29/03 Fresh Pack 08:06 

08:05 

08:13 

08:12 

08:23 

08:08 

07:55 

08:02 

Sorter-4 

Sorter-5 

Sorter-6 

Boxer 

Box loader-1 

Box loader-2 

Box loader-3 

Forklift driver 

29.8 

34.9 

37.3 

25.1 

28.9 

32.3 

23.7 

15.4 

0.2 

0.2 

0.2 

6.9 

0.6 

3.9 

1.6 

2.8 

60.4 

70.9 

80.7 

358.9 

55.0 

74.1 

64.9 

47.9 

81.3 

82.4 

82.9 

80.0 

81.0 

81.9 

79.6 

76.5 

45.3 

45.0 

43.9 

70.7 

53.4 

66.6 

60.3 

64.2 

82.8 

83.5 

84.1 

90.5 

82.4 

83.7 

83.1 

81.8 

10/30/03 Pellet Shop 06:07 

06:12 

Operator 

Front loader 

100.8 

20.4 

73.9 

2.3 

458.6 

47.2 

90.1 

78.5 

87.8 

62.8 

91.6 

81.8 

10/30/03 Mechanic 

Shop 

07:06 

05:26 

Mechanic-1 

Mechanic-2 

18.2 

2.4 

15.1 

0.7 

253.1 

12.2 

77.7 

63.1 

76.4 

53.7 

89.0 

75.9 

The various dose percentages are the amounts of noise accumulated during a work day, with 100% 

representing the maximum allowable daily dose. Lavg refers to the average noise levels measured. 

OSHA: Occupational Safety and Health Administration 

NIOSH: National Institute for Occupational Safety and Health 

ACGIH: American Conference of Governmental Industrial Hygienists 

AL: Action Limit 

PEL: Permissible Exposure Limit 

dBA: Decibels on an A-weighted scale 
Health Hazard Evaluation Report No. 2004-0014-2929 Page 11 

Table 2 

Area Noise Levels in Fresh Pack and Alfalfa Pellet-Making Operation 

Navajo Agricultural Products Industry 

Farmington, New Mexico 

October 27-30, 2003 

Department Location Noise Level [dB(A)] 

 

Fresh Pack Sorting Line-I 

Sorting Line-II 

Sorting Line-III 

91 

86 

87 

 

Alfalfa Pellets Edge of grinder turret opening 

Stairway to grinder 

Downstairs 

Output end 

Platform next to control booth 

Control booth door open 

Control booth door closed with electric cord 

blocking seal 

86 

91 

105 

94 

100 

87 

80 

dBA: Decibels on an A-weighted scale 
Page 12 Health Hazard Evaluation Report No. 2004-0014-2929 

Figure 1 

Typical noise exposures for unloaders, and baggers in the Fresh Pack area 

65

70

75

80

85

90

95

100

105

8:24 9:36 10:48 12:00 13:12 14:24

Time

Lavg (dBA)

Bagger

Unloader

Figure 2 

Typical noise exposures for sorters in the Fresh Pack area 

65

70

75

80

85

90

8:09 9:21 10:33 11:45 12:57 14:09 15:21

Time

Lavg (dBA)
Health Hazard Evaluation Report No. 2004-0014-2929 Page 13 

Figure 3 

Profile of noise exposure to the front loader and pellet-mill operator 

during the manufacture of alfalfa pellets 

65

70

75

80

85

90

95

100

105

8:58 10:10 11:22 12:34 13:46 14:58

Time

Lavg (dBA)

Front Loader

Pellet Mill Operator

Figure 4 

Profile of noise exposures to a mechanic at the Mechanic Shop 

65

70

75

80

85

90

95

100

105

110

115

8:11 9:23 10:35 11:47 12:59 14:11

Time

Lavg (dBA)
DEPARTMENT OF HEALTH AND HUMAN SERVICES 

Centers for Disease Control and Prevention 

National Institute for Occupational Safety and Health 

4676 Columbia Parkway 

Cincinnati, OH 45226-1998 

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