Noise and Lead 

Exposures at an 

Outdoor Firing Range 

─ California

Lilia Chen, MS, CIH

Scott E. Brueck, MS, CIH

Health Hazard Evaluation Report

HETA 2011-0069-3140

September 2011

DEPARTMENT OF HEALTH AND HUMAN SERVICES

Centers for Disease Control and Prevention

Workplace

Safety and Health

 National Institute for Occupational 

Safety and Health
The employer shall post a copy of this report 

for a period of 30 calendar days at or near 

the workplace(s) of affected employees. The 

employer shall take steps to insure that the 

posted determinations are not altered, defaced, 

or covered by other material during such 

period. [37 FR 23640, November 7, 1972, as 

amended at 45 FR 2653, January 14, 1980].
Health Hazard Evaluation Report 2011-0069-3140 Page i

Appendix A

Report Abbreviations.......................................................................ii

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

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

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

Assessment.........................................................................2

Results and Discussion .......................................................3

Conclusions.......................................................................12

Recommendations.............................................................12

References ........................................................................14

Contents

Acknowledgments and Availability of Report.....................25

Occupational Exposure Limits and Health Effects.............18

Methods.............................................................................23

Acknowledgments

Appendix B
Page ii Health Hazard Evaluation Report 2011-0069-3140

μg/100 cm2 Micrograms per 100 square centimeters

μg/dL Micrograms per deciliter

μg/m3 Micrograms per cubic meter

AIHA American Industrial Hygiene Association

ACGIH® American Conference of Governmental Industrial Hygienists

AL Action level

BLL Blood lead level

CFR Code of Federal Regulations

dB Decibel

dBA Decibel, A-scale

dBC Decibel, C-scale

Hz Hertz

m3 Cubic meter

mg/m3 Milligrams per cubic meter

MDC Minimum detectable concentration

MQC Minimum quantifiable concentration

min Minute

MSDS Material safety data sheet

NAICS North American Industry Classification System

NIHL Noise-induced hearing loss

NIOSH National Institute for Occupational Safety and Health

NRR Noise reduction rating

OEL Occupational exposure limit

OSHA Occupational Safety and Health Administration

PBZ Personal breathing zone

PEL Permissible exposure limit

PPE Personal protective equipment

REL Recommended exposure limit

SLM Sound level meter

TLV® Threshold limit value

TWA Time-weighted average

WEELTM Workplace environmental exposure level

Abbreviations
Health Hazard Evaluation Report 2011-0069-3140 Page iii

The National Institute for 

Occupational Safety and 

Health (NIOSH) received 

a technical assistance 

request from a federal 

government agency in 

California. Although 

no health symptoms 

or hearing loss were 

reported, the requestor 

was concerned about 

exposures to noise and 

lead among firing range 

instructors at an outdoor 

firing range.

Highlights of the

NIOSH Health

Hazard Evaluation

What NIOSH Did

● We evaluated noise and lead exposures in April 2011.

● We took personal measurements for noise and lead.

● We took surface wipe samples and hand wipe samples for 

lead.

● We measured sound levels at different frequencies during live 

fire training.

What NIOSH Found

● Employee exposures to noise were above the NIOSH 

recommended exposure limit.

● Peak noise levels were above 160 decibels during gunfire.

● Employee exposure to lead did not exceed occupational 

exposure limits.

● We found lead on surfaces.

● Students appeared to have good hand washing practices.

What Managers Can Do

● Establish a hearing conservation program that includes 

annual audiograms for instructors.

● Require instructors and students to wear dual hearing 

protection during weapon fire, and provide training to 

ensure proper use. Dual hearing protection includes ear 

plugs and earmuffs.

● Consider supplying non-lead bullets and primers for classes.

● Require students and instructors to wash hands before 

eating, drinking, or using tobacco products.

● Notify employees and students that picnic tables have lead 

on them. Tell employees about the potential for getting lead 

from the table into their food or from their hands into their 

mouth. Managers should share this information with the 

firing range owner.

What Employees Can Do

● Wear dual hearing protection during weapon fire. Dual 

hearing protection includes ear plugs and earmuffs.

● Continue to use good hygiene practices. Wash your hands 

before eating, drinking, or using tobacco products.
Page iv Health Hazard Evaluation Report 2011-0069-3140

Personal noise 

measurements taken 

during a basic firearms 

course at an outdoor 

firing range exceeded the 

NIOSH REL. Personal lead 

air measurements did not 

exceed applicable OELs, 

but lead was found in air 

samples and on a picnic 

table where employees ate 

lunch. Employees should 

wear double hearing 

protection and participate 

in a hearing conservation 

program.

Summary

Keywords: NAICS 922190 (Other Justice, Public Order, and 

Safety Activities), firearms, lead, noise, impulse noise, impulsive 

noise, hearing loss, shotguns, rifles, outdoor firing range, ototoxins, 

ototoxicity

On February 25, 2011, NIOSH received a technical assistance 

request from a federal government agency to assess exposures to 

noise and lead of firing range instructors at an outdoor firing 

range in California. On April 11–12, 2011, NIOSH investigators 

evaluated employee exposures to noise and lead during a 3-day 

basic firearms course.

Eight students and five instructors contributed 14 personal noise 

dosimetry measurements over 2 days. During live fire training, we 

measured sound levels and octave band noise frequency levels with 

a type 1 SLM. We took 16 PBZ air samples and six surface wipe 

samples for lead. We also used a colorimetric wipe test to test for 

lead on hands.

Noise monitoring results indicated that all participants’ TWA noise 

exposures exceeded the NIOSH REL, some exceeded the OSHA 

AL, but none exceeded the OSHA PEL. However, noise dosimeter 

microphones and electronic circuitry do not adequately capture 

peak noise levels above the maximum range of the instrument, 

therefore, personal TWA noise measurements from gunfire 

noise using dosimeters should be interpreted cautiously. These 

measurements can underrepresent noise exposure and hearing loss 

risk from gunfire noise. Sound level meter measurements revealed 

that peak noise levels during gunfire were greater than 160 dB.

None of the lead PBZ air sampling results exceeded applicable 

OELs. Results varied from Day 1 to Day 2, which was likely due 

to the meteorological conditions. Under different meteorological 

conditions and employee proximity to the gun smoke source, 

exposures may be higher. Lead was found on the outdoor 

picnic table surface where we observed employees eating lunch. 

Employees appeared to have good hand hygiene as no lead was 

found on the hand wipes after washing.

Because of the high noise levels in firing ranges, double hearing 

protection is necessary. The noise levels generated by the firearms 

warrant a hearing conservation program, which should meet the 

requirements of the OSHA hearing conservation standard [29 CFR 

1910.95]. Firing range instructors should have yearly audiometric 

evaluations to measure hearing levels and identify hearing loss. 

Reviewers of audiograms should be aware of potentiating and 

synergistic effects of ototoxins such as lead and solvents. To reduce 

lead exposures, use of non-lead bullets and non-lead primers 

should be considered as it becomes economically feasible. Good 

personal hygiene should continue to be encouraged to reduce the 

potential for lead ingestion.
Health Hazard Evaluation Report 2011-0069-3140 Page 1

Introduction

Figure 1. Firearms used for training 

(from left to right: 12-gauge shotgun, 

.30-06 rifle, and .45-70 rifle).

On February 25, 2011, NIOSH received a technical assistance 

request from a federal government agency to assess exposures 

to noise and lead among firing range instructors at an outdoor 

firing range in California. No employees had reported hearing 

loss or health concerns to management. On April 11–12, 2011, 

NIOSH investigators evaluated employee exposures to noise and 

lead during a 3-day basic firearms training course.

Firing range instructors teach 1- to 3-day basic and refresher 

firearm courses to other federal government employees who 

carry a firearm for their job. They instruct courses approximately 

five times a year at a rented public outdoor firing range that 

is closed to the public on the days the course is taught. The 

basic firearms course we evaluated included classroom and 

field practice components, with about 6 hours per day of field 

practice. Students completed qualifying exams on the last day 

of the course. The class had three to five instructors and eight 

students. Three instructors were always present on the firing 

range with the eight students. Most of the class was taught at a 

straight lane outdoor range where students fired at paper targets, 

with earth backing behind the targets. Students spread out 

approximately 4 feet apart in a line about 15 yards away from the 

targets. During live fire exercises, instructors stood about 2–3 

feet behind students. Students used shotguns (12 gauge) and two 

types of rifles (.30-06 or .45-70) (Figure 1). Students did not use 

revolvers (.44 caliber) in this course, but in some other courses 

revolvers are also used. During the qualifying exams, students 

used parts of the skeet range and clay courses. The instructors 

selected ammunition for the course. Shotguns used rifled lead 

slugs. Rifles used bullets with partial or full copper metal jacket 

over lead. All the primers contained lead. The number of rounds 

fired in a typical training day varied depending on the class size 

and experience. Towards the end of the course, the instructors 

taught students how to clean the firearms.

The instructors brought all equipment, ammunition, PPE, and 

teaching materials to the firing range. They did not store any of 

their property at the range. All instructors and students wore 

safety glasses and earmuffs. During our evaluation, students wore 

3M (St. Paul, Minnesota) Peltor® TacticalTM 6-S with an NRR 

of 19 dB, and instructors wore Peltor® PowerCom PlusTM with 

an NRR of 25 dB during live fire. The agency had no blood 

lead monitoring program and no hearing conservation program 

although a draft hearing conservation program written by the 

agency safety specialist had been submitted to management. We 

obtained MSDSs for the chemicals used for cleaning the firearms.
Page 2 Health Hazard Evaluation Report 2011-0069-3140

Assessment

Figure 2. Sound level meter at firing 

line during firearm training exercises.

We held an opening meeting on April 11, 2011, with employer 

and employee representatives. On April 11 and 12, 2011, we 

interviewed several instructors; observed classroom and field 

activities; measured outdoor temperature, wind direction, and 

velocity; and sampled for noise and lead.

Eight students and five instructors contributed 14 personal noise 

dosimetry measurements over 2 days. Students and instructors 

wore integrating noise dosimeters on Day 1 of sampling. However, 

only instructors wore dosimeters on Day 2 of sampling. We 

measured area noise levels and performed octave band frequency 

spectrum analysis (measurement of noise levels in different 

frequencies) with two SLM and real-time frequency analyzers. The 

SLMs were mounted on tripods at a height of approximately 5 feet 

to represent the ear position of a standing shooter. We placed the 

tripods with SLMs on each end of the firing line approximately 4 

to 6 feet from the student (Figure 2). Because of safety concerns 

and risk of interfering with students and instructors, we were 

not able to place SLMs closer during live fire training sessions. 

However, during some of the qualifying exams, we handheld the 

SLMs approximately 1 to 2 feet from the instructor’s ear.

We took 16 personal breathing zone air samples and six surface 

wipe samples for lead. Surfaces tested included areas that people 

frequently touched, such as the trigger and forend of the firearm, 

doorknobs, and restroom water faucet handles. We also used a 

colorimetric wipe test to test for lead on hands.

More information on OELs and health effects for noise and lead 

can be found in Appendix A. More information on sampling 

methodology for noise and lead can be found in Appendix B.
Health Hazard Evaluation Report 2011-0069-3140 Page 3

Results and Discussion

Table 1. Personal noise dosimetry results*

Job title Duration OSHA AL OSHA PEL NIOSH REL

(h:mm) TWA†

TWA 

8-hr‡ Dose§ TWA†

TWA 

8-hr‡ Dose§ TWA†

TWA 

8-hr‡ Dose§

(dBA) (dBA) (%) (dBA) (dBA) (%) (dBA) (dBA) (%)

Student 5:00 89 85 50 89 85 50 100 97 1598

Student 4:54 87 84 44 87 84 44 99 96 1269

Student 4:59 88 84 44 87 84 44 98 96 1269

Student 5:04 86 82 33 86 82 33 97 95 1007

Student 4:52 86 83 38 86 82 33 98 95 1007

Student 4:57 84 80 25 84 80 25 95 93 634

Instructor 4:59 89 85 50 88 84 44 98 96 1269

Instructor 4:53 89 86 57 88 85 50 96 94 799

Instructor 4:55 82 78 19 82 78 19 93 91 400

Instructor 5:37 88 85 50 87 85 50 97 96 1269

Instructor 4:59 86 83 38 86 83 38 97 95 1007

Instructor 5:42 84 82 33 84 81 29 95 94 799

Instructor 6:30 83 82 33 82 80 25 95 94 799

Instructor 6:34 78 75 13 78 74 11 90 88 200

Exposure Limits 85 50 90 100 85 100

 * Exposures at or exceeding exposure limits are highlighted in bold and italicized font.

 † TWA noise exposures for the duration of the noise monitoring period

 ‡ Projected 8-hour TWA assuming that noise exposures beyond the measured duration were below 80 dBA

 § Dose is based on TWA 8-hour noise exposure.

Noise 

Results from the personal dosimetry measurements are provided 

in Table 1. Results indicated that all participants’ TWA noise 

exposures exceeded the NIOSH REL, some exceeded the 

OSHA AL, but none exceeded the OSHA PEL. Noise dosimeter 

microphones and electronic circuitry do not adequately capture 

peak noise levels above the maximum range of the instrument and 

“clip” noise levels at approximately 145 dB. Previous research on 

the use of dosimeters for gunfire measurements concluded that 

these electroacoustic limitations produce errors in calculating 

TWA noise levels from impulsive noise environments [Kardous et 

al. 2003; Kardous and Willson 2004]. Therefore, personal TWA 

noise measurements from gunfire noise collected with dosimeters 

should be interpreted cautiously and considered to underrepresent 

noise exposure and hearing loss risk from gunfire noise.
Page 4 Health Hazard Evaluation Report 2011-0069-3140

Results and Discussion (continued) One-third octave band noise frequency measurements collected 

when students were shooting .45-70 rifles are shown in Figure 

3. These measurements showed that the highest sound pressure 

levels (125 dB) occurred at 500 Hz, and were greater than 110 dB 

across all the one-third octave bands from 125 Hz to 20,000 Hz. 

Measurements taken during shooting of the 12-gauge shotgun and 

the .30-06 rifle had similar results. Octave band measurements 

provide information about the frequency distribution of noise. 

Because the energy from noise is usually widely distributed over 

many frequencies, the frequency range is broken into a smaller 

range of frequencies (called bandwidths), the most common being 

the octave band (defined as a frequency band where the upper 

band frequency is twice the lower band-edge frequency).

Figure 3. One-third octave band noise frequency levels of four rifles (.45-70) being fired over a 90-second period 

during a basic firearms training course.

Octave band analysis allows for determination of the dominant 

noise frequencies and can be useful for identifying potential 

engineering controls. For example, if low frequency noise is 

dominant (i.e., the highest octave-band sound levels occur 

in frequencies of 500 Hz or less), noise is likely generated by 

vibration, and noise controls that reduce or isolate the vibration 

from tools or equipment might decrease noise levels. If high 

frequency noise is dominant (i.e., the highest octave band 

sound levels occur in frequencies of 2,000 Hz or greater), noise 

enclosures, barriers, or sound absorption systems are typically the 

most effective approach [Driscoll and Royster 2003]. One of the 
Health Hazard Evaluation Report 2011-0069-3140 Page 5

Results and Discussion (continued) primary sources of noise generated during gunfire is the muzzle 

blast during firing, which generates high noise across the mid to 

high frequency range. The only potentially effective noise control 

method to reduce students’ or instructors’ noise exposure from 

gunfire is through the use of noise suppressors that can be attached 

to the end of the gun barrel. However, some states do not permit 

civilians to use suppressors on firearms.

Peak sound levels ranged from 154.6 dB to 163.1 dB during 

shooting exercises. Peak levels for the 12-gauge shotgun and .30-

06 rifles were slightly higher than for the .45-70 rifle (Table 2). 

During training exercises, students typically fire a series of shots 

in succession followed by several minutes without shooting for 

instruction. An example of peak sound levels during 1 minute of 

shooting a .30-06 rifle is shown in Figure 4. Eight peaks greater 

than 160 dB and several others greater than 150 dB can be seen 

during this time period.

Table 2. Peak sound level range for firearms

Firearm Peak Sound Level Range (dB) Ammunition Weight (Grains)

12-Gauge Shotgun 154.6 – 162.7 438

.45-70 Rifle 155.2 – 159.9 350

.30-06 Rifle 158.7 – 163.1 173

Figure 4. Peak sound levels during one minute of shooting .30-06 rifles in a training exercise.
Page 6 Health Hazard Evaluation Report 2011-0069-3140

Results and Discussion (continued) Research has shown that repeated exposure to impulse noise 

can result in permanent NIHL [Patterson and Hamernik 1992; 

Pekkarinen et al. 1993; Chan et al. 2001]. Noise produced by 

impulsive noise, such as gunfire, has sufficient intensity to 

permanently damage unprotected ears in a very short period 

of time; damage can occur in minutes rather than the days or 

years typical of industrial noise exposure. The OSHA PEL and 

NIOSH REL state that exposure to impulse noise should not 

exceed 140 dB. However, peak impulse is not the sole factor in 

hearing damage. Other factors such as duration of the impulse and 

frequency of exposure also have an effect on hearing loss.

Because of the high noise levels in firing ranges, double hearing 

protection is necessary to protect hearing. Research has reported 

that double hearing protection can provide the additional noise 

reduction needed in high noise level environments [Berger 1983]. 

However, proper insertion of hearing protection is critically 

important to ensure proper noise attenuation. NIOSH has 

previously identified poor insertion of formable hearing protection 

into the ear canals [NIOSH 2005].

To estimate hearing protector attenuation NIOSH recommends 

using subject fit data based on the American National Standards 

Institute’s standard S12.6-1997 [ANSI 1997]. However, if no 

subject fit data are available, NIOSH recommends adjusting 

the hearing protectors’ ratings by subtracting 25% from the 

manufacturer’s labeled NRR for earmuffs and subtracting 50% 

from the manufacturer’s labeled NRR for formable earplugs. An 

additional 5 to 10 dB of attenuation can be added for use of dual 

hearing protection [NIOSH 1998]. Figure 5 shows the range of 

estimated noise attenuation that could be achieved for properly 

fitted and worn ear plugs and earmuffs, using NIOSH noise 

attenuation calculations for unweighted or dBC noise exposure 

levels. For dBA noise exposure levels, an additional 7 dB should be 

subtracted from the derated NRR.

On the basis of hearing protection worn by instructors and 

students during the training class (instructors: Peltor® PowerCon 

PlusTM with an NRR of 25 dB; students: Peltor® TacticalTM 

6-S with an NRR of 19 dB), the estimated hearing protector 

attenuation using the NIOSH hearing protector derating formula 

is 19 dB for instructors and 14 dB for students. If instructors 

and students wore earmuffs with an NRR of 33 dB along with 

properly inserted ear plugs, their estimated attenuation for dual 
Health Hazard Evaluation Report 2011-0069-3140 Page 7

Results and Discussion (continued) protection using the NIOSH hearing protector derating formula 

would increase to 30–35 dB. In tests of hearing protection using an 

acoustic mannequin, NIOSH found that in some instances double 

hearing protection actually provided more peak noise attenuation 

than the NIOSH hearing protector derating formula calculates 

[NIOSH 2003, 2005].

Figure 5. Range of estimated noise attenuation (dB) for combination of properly fitted and worn insert type ear 

plugs and earmuffs, based on NIOSH noise attenuation calculations for unweighted or dBC noise levels.

In 2002, NIOSH proposed a simplified formula to reduce the risk 

of exposure to impulse noise in terms of the number of gunshot 

impulses to which a person can be exposed per day [NIOSH 2002]:

N = 10((140 – PI )/10)

where N is the number of gunshot exposures permitted, and 

PI is the peak impulse level in dB under hearing protection. PI 

is determined by subtracting the noise attenuation for hearing 

protection from the peak noise exposure level for a gunfire 

impulse.

Figure 6 shows the number of gunshot exposures permitted on the 

basis of peak noise levels under hearing protection. For example, if 

the peak noise level under hearing protection is 120 dB, applying 

this formula yields N=100 gunshots. The NIOSH proposed 

formula is a conservative estimate and does not take into account 

the duration of the impulse, its spectral content, or its energy.
Page 8 Health Hazard Evaluation Report 2011-0069-3140

Results and Discussion (continued)

Figure 6. Number of gunshot exposures permitted using NIOSH recommendations [NIOSH 2002], based on peak 

sound levels (dB) under hearing protection.

Lead

We collected 16 PBZ area air samples on students and instructors 

for lead. None of our results exceeded applicable OELs. These 

results are listed in Table 3. Results from Day 1 were very low with 

only one quantifiable PBZ air sample. Results from Day 2 were 

higher than Day 1, with the highest lead exposure found on an 

instructor at 15 μg/m3

. The concentration differences between Day 

1 and Day 2 were most likely due to the meteorological conditions. 

On Day 1, the wind moved gun smoke down the course and away 

from the employees. On Day 2, the wind was mild and moved 

gun smoke up the course towards the employees. On Day 2, it is 

possible that students’ exposures would have been even higher 

than the instructors’ because of their closer proximity to the smoke 

sources. Past studies looking at lead exposure to outdoor firearm 

instructors found that despite “natural ventilation” at outdoor 

firing ranges, PBZ levels exceeded OSHA, NIOSH, and ACGIH 

*Peak sound level under hearing protection is calculated by subtracting the estimated noise attenuation for hearing protection 

from the peak noise exposure level for a gunfire impulse.
Health Hazard Evaluation Report 2011-0069-3140 Page 9

Results and Discussion (continued) OELs of 50 μg/m3

 as an 8-hour TWA [Goldberg et al. 1991; 

Tripathi et al. 1991; Mancuso et al. 2008]. Studies have also shown 

that jacketed or non-lead bullets can reduce lead concentrations 

[NIOSH 1986; Tripathi et al. 1991; NIOSH 1995] in air and on 

surfaces. Although we did not find air lead levels that exceeded the 

OELs, it is possible that airborne lead levels could be higher during 

certain meteorological conditions, and care should be taken to 

minimize lead exposures.

Table 3. PBZ air sampling results for lead*

Day Type Sampling Time Sample Volume

8-hr TWA*

Concentration

(min) (m3) (μg/m3)

1 Student 307 0.61 1.02

1 Student 302 0.59 [0.82]

1 Student 300 0.59 [0.75]

1 Student 306 0.60 [0.70]

1 Student 303 0.60 [0.57]

1 Student 307 0.61 [0.51]

1 Student 267 0.53 [0.44]

1 Student 304 0.60 [0.49]

1 Instructor 305 0.60 ND

1 Instructor 300 0.59 ND

2 Instructor 370 0.72 15 

2 Instructor 364 0.70 4.3 

2 Instructor 313 0.61 1.5

2 Instructor 359 0.70 1.2

2 Instructor 315 0.62 [0.66]

2 Instructor 297 0.58 ND

MDC† 0.32

MQC† 1.3

NIOSH REL (8-hr TWA) 50

OSHA PEL (8-hr TWA) 50

ACGIH TLV (8-hr TWA) 50

Values in brackets indicate levels between the MDC and MQC.

*Concentrations were calculated to reflect an 8-hour TWA by assuming no lead exposure beyond the measured 

duration.

†Based on an air volume of 0.62 m3

.
Page 10 Health Hazard Evaluation Report 2011-0069-3140

Results and Discussion (continued) The highest levels of surface contamination for lead were found on 

the firearms, which was expected (Table 4). Lead levels were much 

lower on surfaces where frequent contact occurs, such as door and 

sink handles. Lead was found on the outdoor picnic table surface 

where we observed employees eating lunch, so care should be taken 

to prevent lead from transferring from the table surface to food or 

hands to mouth.

Table 4. Lead surface wipe sampling results

Location Concentration (μg/100 cm2)

Rifle forend* 1.0

Shotgun stock* 0.68

Rifle stock* 0.10

Picnic table 0.08

Men’s restroom sink handles* 0.03

Door handle into classroom* 0.02

* Approximated 100 cm2

 surface area

All students showed a positive result for lead on their hands 

immediately after returning from the range after live firearms 

practice. After hand washing, no positive result was observed on 

the hand wipes (Figure 7). We also asked one instructor to use 

the wipes after returning from the range and washing hands. The 

instructor’s hand wipe results showed a negative result. Aside 

from an occasional demonstration, the instructors did not usually 

handle firearms. These results indicate that students had good 

hand hygiene.

Figure 7. The left wipe, taken from a student who had just returned from 

the shooting range and had not yet washed hands, is positive for lead. 

The right wipe, taken after the student had washed hands, is negative 

for lead.
Health Hazard Evaluation Report 2011-0069-3140 Page 11

Results and Discussion (continued) Ototoxins

Ototoxins are chemicals that can cause hearing damage when 

absorbed into the body. Studies have shown that exposure to 

some chemicals, such as lead and some solvents, can cause 

hearing loss [Sliwinska-Kowalska et al. 2004; Hwang et al. 

2009]. The mechanism of loss is not well understood, but it is 

hypothesized that ototoxins entering the blood stream damage 

inner ear structures, causing nerve damage and/or oxidative 

stress [Henderson et al 2006; Johnson and Morata 2010]. Some 

chemicals may not cause hearing loss alone, but can exacerbate 

hearing loss caused by noise (potentiation). Some chemicals may 

cause a synergistic effect, where the combined effect of the two 

exposures is greater than either alone. It is difficult to distinguish 

whether hearing loss is caused by ototoxicants or excessive noise, as 

both losses appear similar on pure tone audiograms and have many 

other similar characteristics (e.g., bilateral loss, loss starting in the 

high frequencies).

Solvents are used to clean firearms after use. Although none of 

the ingredients listed on the MSDS that were given to us had been 

observed as ototoxicants, users should be aware that moderate 

exposures (below or around the OEL) to solvents such as toluene 

[Morata et al. 1993; Chang et al. 2006], xylene, and mixtures of 

solvents [Sliwinska-Kowalska et al. 2004; Fuente et al. 2009] have 

been shown to be associated with hearing loss [Sliwinska-Kowalska 

et al. 2007].

The ACGIH states that, “In settings where there may be exposures 

to noise and to carbon monoxide, lead, manganese styrene, 

toluene, or xylene, periodic audiograms are advised and should be 

carefully reviewed” [ACGIH 2011]. The U.S. Army recommends 

annual audiometric monitoring when workers are exposed to air 

concentrations that are at or exceed 50% of the most stringent 

OEL criteria for a variety of ototoxicants including solvents and 

lead [U.S. Army 2009]. The highest lead PBZ air concentration 

(15 mg/m3

) did not exceed 50% of the NIOSH REL, but because 

meteorological factors may cause variations in worker exposure, it is 

possible that exposure on a different day could be higher. We were 

also told that some instructors shot recreationally, which would 

contribute to their overall lead and noise exposures. Reviewers of 

employees’ audiometric tests should be aware of possible additive, 

potentiating, or synergistic effects between noise exposure, solvents, 

and lead when evaluating audiograms.
Page 12 Health Hazard Evaluation Report 2011-0069-3140

Recommendations

Conclusions

Personal noise measurements taken during a basic firearms 

course exceeded the NIOSH REL, some exceeded the OSHA 

AL, but none exceeded the OSHA PEL. Peak sound levels 

exceeded 160 dB. Because of the high noise levels in shooting 

ranges, the use of double hearing protection is necessary. 

The noise levels generated by the firearms warrant a hearing 

conservation program, and firing range instructors should have 

yearly audiometric evaluations. Personal lead air measurements 

did not exceed applicable OELs, but lead was observed in 

the air and on some surfaces. Meteorological conditions 

and employee proximity to the gun smoke may greatly affect 

exposures. Reviewers of audiograms should be aware of 

potentiating and synergistic effects of ototoxins. To reduce lead 

exposures, use of non-lead bullets and non-lead primers as they 

become economically feasible should be considered. Good 

personal hygiene should be encouraged to reduce lead ingestion 

potential.

On the basis of our findings, we recommend the actions listed below 

to create a more healthful workplace. Our recommendations are 

based on the hierarchy of controls approach (refer to Appendix A: 

Occupational Exposure Limits and Health Effects). This approach 

groups actions by their likely effectiveness in reducing or removing 

hazards. In most cases, the preferred approach is to eliminate 

hazardous materials or processes and install engineering controls 

to reduce exposure or shield employees. Until such controls are in 

place, or if they are not effective or feasible, administrative measures 

and/or personal protective equipment may be needed. PPE is the 

least effective means for controlling employee exposures. Proper use 

of PPE requires a comprehensive program, and calls for a high level 

of employee involvement and commitment to be effective.

1. The noise levels generated by the firearms warrant a hearing 

conservation program. At a minimum, the program should 

meet the requirements of the OSHA hearing conservation 

standard [29 CFR 1910.95]. Another source for designing 

an effective hearing loss prevention program is the NIOSH 

occupational noise criteria document [NIOSH 1998].

2. Firing range instructors should have yearly audiometric 

evaluations to measure hearing levels and identify 

hearing loss. Reviewers of audiograms should be aware of 

potentiating and synergistic effects of ototoxins, such as lead 

and solvents, on hearing loss.
Health Hazard Evaluation Report 2011-0069-3140 Page 13

Recommendations

(continued) 3. Instructors and students should wear dual hearing 

protection (ear plugs and earmuffs) during weapons fire. 

For maximum protection, select earmuffs and ear plugs 

that provide a high level of noise attenuation. Because of 

the critical importance of proper use and fit, train students 

and instructors how to properly wear hearing protection. 

Encourage the use of dual hearing protection during 

recreational shooting.

4. Consider using non-lead bullets and non-lead primers as 

they become economically feasible.

5. Employees should follow safe work practices identified by 

the firing range and employer. They should continue good 

personal hygiene practices including hand washing before 

eating, drinking, smoking, and leaving the range.

6. Assume that picnic tables are contaminated with lead, and 

take precautions to prevent transfer of lead from surface 

to food or hands to mouth (e.g., cover the table with a 

disposable tablecloth before eating). This information 

should be shared with the range owner.
Page 14 Health Hazard Evaluation Report 2011-0069-3140

References

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both singly and in combination. Am Ind Hyg Assoc J 44(5):321–

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workers exposed to toluene and noise. Environ Health Perspect

114(8):1283–1286.

Driscoll DP, Royster LH [2003]. Noise control engineering. In: 

Berger EH, Royster LH, Royster JD, Driscoll DP, Layne M. eds, The 

noise manual, 5th ed. Akron, OH: American Industrial Hygiene 

Association, pp. 279–378; [Reference: Table 9.5, pp. 298–300].

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Rabinowitz PM [2009]. Peripheral and central auditory dysfunction 

induced by occupational exposure to organic solvents. J Occup 

Environ Med 51(10):1202–1211.

Goldberg RL, Hicks AM, O’Leary LM, London S [1991]. Lead 

exposures at uncovered outdoor firing ranges. J Occup Med 

33(6):718–719.

Henderson D, Bielefeld EC, Harris KC, Hu BH [2006]. The role of 

oxidative stress in noise-induced hearing loss. Ear Hear 27(1):1–19.

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association between low levels of lead in blood and occupational 

noise-induced hearing loss in steel workers. Sci Total Environ 

408(1):43–49.
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documentation of health risks from chemicals. Kjell Torén, ed. 

Gothenburg, Sweden. pp. 14–19.

Kardous CA, Willson RD, Hayden CS, Szlapa P, Murphy WJ, 

Reeves ER [2003]. Noise exposure assessment and abatement 

strategies at an indoor firing range. App Occ Environ Hyg 

18(8):629–636.

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in impulse noise environments. J Occup Environ Hyg 1(7):456–

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Mancuso JD, McCoy J, Pelka B, Kahn PJ, Gaydos JC [2008]. The 

challenge of controlling lead and silica exposures from firing ranges 

in a special operations force. Military Med 173(2):182–186.

Morata TC, Dunn DE, Kretschmer LW, Lemasters GK, Keith RW 

[1993]. Effects of occupational exposure to organic solvents and 

noise on hearing. Scand J Work Environ Health 19(4):245–254.

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81(6):753–755.

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occupationalototoxinfactsheet-chppm.pdf]. Date accessed: July 2011.
Page 18 Health Hazard Evaluation Report 2011-0069-3140

Appendix A: Occupational Exposure Limits and Health Effects

In evaluating the hazards posed by workplace exposures, NIOSH investigators use both mandatory (legally 

enforceable) and recommended OELs for chemical, physical, and biological agents as a guide for making 

recommendations. OELs have been developed by federal agencies and safety and health organizations to 

prevent the occurrence of adverse health effects from workplace exposures. Generally, OELs suggest levels 

of exposure that most employees may be exposed to for up to 10 hours per day, 40 hours per week, for a 

working lifetime, without experiencing adverse health effects. However, not all employees will be protected 

from adverse health effects even if their exposures are maintained below these levels. A small percentage 

may experience adverse health effects because of individual susceptibility, a preexisting 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 

employee to produce adverse health effects even if the occupational exposures are controlled at the level set 

by the exposure limit. Also, some substances can be absorbed by direct contact with the skin and mucous 

membranes in addition to being inhaled, which contributes to the individual’s overall exposure.

Most OELs are expressed as a TWA exposure. A TWA refers to the average exposure during a normal 

8- to 10-hour workday. In the United States, OELs have been established by federal agencies, professional 

organizations, state and local governments, and other entities. Some OELs are legally enforceable limits, 

while others are recommendations. The U.S. Department of Labor OSHA PELs (29 CFR 1910 [general 

industry]; 29 CFR 1926 [construction industry]; and 29 CFR 1917 [maritime industry]) are legal limits 

enforceable in workplaces covered under the Occupational Safety and Health Act of 1970. NIOSH RELs 

are recommendations based on a critical review of the scientific and technical information available 

on a given hazard and the adequacy of methods to identify and control the hazard. NIOSH RELs can 

be found in the NIOSH Pocket Guide to Chemical Hazards [NIOSH 2010]. NIOSH also recommends 

different types of risk management practices (e.g., engineering controls, safe work practices, employee 

education/training, personal protective equipment, and exposure and medical monitoring) to minimize 

the risk of exposure and adverse health effects from these hazards. Other OELs that are commonly used 

and cited in the United States include the TLVs recommended by ACGIH, a professional organization, 

and the WEELs recommended by the AIHA, another professional organization. The TLVs and WEELs 

are developed by committee members of these associations from a review of the published, peer-reviewed 

literature. They are not consensus standards. ACGIH TLVs are considered voluntary exposure guidelines 

for use by industrial hygienists and others trained in this discipline “to assist in the control of health 

hazards” [ACGIH 2011]. WEELs have been established for some chemicals “when no other legal or 

authoritative limits exist” [AIHA 2011].

Outside the United States, OELs have been established by various agencies and organizations and 

include both legal and recommended limits. The Institut für Arbeitsschutz der Deutschen Gesetzlichen 

Unfallversicherung (IFA, Institute for Occupational Safety and Health of the German Social Accident 

Insurance) maintains a database of international OELs from European Union member states, Canada 

(Québec), Japan, Switzerland, and the United States. The database, available at http://www.dguv.de/ifa/

en/gestis/limit_values/index.jsp, contains international limits for over 1,500 hazardous substances and is 

updated periodically.

NIOSH investigators encourage the use of the traditional hierarchy of controls approach to eliminate or 

minimize identified workplace hazards. This includes, in order of preference, the use of (1) substitution 

or elimination of the hazardous agent, (2) engineering controls (e.g., local exhaust ventilation, process 

enclosure, dilution ventilation), (3) administrative controls (e.g., limiting time of exposure, employee 

training, work practice changes, medical surveillance), and (4) personal protective equipment (e.g., 

respiratory protection, gloves, eye protection, hearing protection).
Health Hazard Evaluation Report 2011-0069-3140 Page 19

Appendix A: Occupational Exposure Limits and Health Effects (continued)

Below we provide the OELs and surface contamination limits for the compounds we measured, as well as a 

discussion of the potential health effects from exposure to these compounds.

Lead

Lead is ubiquitous in U.S. urban environments due to the widespread use of lead compounds in industry, 

gasoline, and paints during the past century. Exposure to lead occurs via inhalation of dust and fume and 

via ingestion through contact with lead-contaminated hands, food, cigarettes, and clothing. Absorbed lead 

accumulates in the body in the soft tissues and bones. Lead is stored in bones for decades, and may cause 

health effects long after exposure as it is slowly released in the body. 

Symptoms of chronic lead poisoning include headache, joint and muscle aches, weakness, fatigue, 

irritability, depression, constipation, anorexia, and abdominal discomfort [Moline and Landrigan 2005]. 

Overexposure to lead may also result in kidney damage, anemia, high blood pressure, infertility and 

reduced sex drive in both sexes, and impotence. In most cases, an individual’s BLL is a good indication of 

recent exposure to lead, with a half-life (the time interval it takes for the quantity in the body to be reduced 

by half its initial value) of 1–2 months [Lauwerys and Hoet 2001; Moline and Landrigan 2005; NCEH 

2005]. Elevated zinc protoporphyrin levels have also been used as an indicator of chronic lead intoxication, 

however, other factors, such as iron deficiency, can cause an elevated zinc protoporphyrin level, so the BLL 

is a more specific test for evaluating occupational lead exposure.

Under the OSHA general industry lead standard (29 CFR 1910.1025), the PEL for airborne exposure to 

lead is 50 μg/m3

 for an 8-hour TWA. The standard requires lowering the PEL for shifts exceeding 8 hours, 

medical monitoring for employees exposed to airborne lead at or above the AL of 30 μg/m3

 (8-hour TWA), 

medical removal of employees whose average BLL is 50 μg/dL or greater, and economic protection for 

medically removed workers. Medically removed workers cannot return to jobs involving lead exposure until 

their BLL is below 40 μg/dL. NIOSH has an REL for lead of 50 μg/m3

 averaged over an 8-hour work shift 

[NIOSH 2010]. ACGIH has a TLV for lead of 50 μg/m3

 (8-hour TWA), with worker BLLs to be controlled 

to or below 30 μg/dL, and designation of lead as an animal carcinogen [ACGIH 2011].

The NIOSH REL is consistent with the OSHA PEL, which is intended to maintain worker BLLs below 40 

μg/dL. This is also intended to prevent overt symptoms of lead poisoning, but is not sufficient to protect 

workers from more subtle adverse health effects like hypertension, renal dysfunction, and reproductive and 

cognitive effects [Schwartz and Stewart 2007; Schwartz and Hu 2007; Brown-Williams et al. 2009]. Adverse 

effects on the adult reproductive, cardiovascular, and hematologic systems, and on the development of 

children of exposed workers, can occur at BLLs as low as 10 μg/dL [Sussell 1998]. Recommendations from 

the March 2007 edition of Environmental Health Perspectives’ Mini-Monograph on adult lead exposure 

and from the Association of Occupational and Environmental Clinics include advising workers and 

shooters that BLLs should be kept below 10 μg/dL [CSTE 2009]. 

In homes with a family member occupationally exposed to lead, care must be taken to prevent “take 

home” of lead, that is, lead carried into the home on clothing, skin, hair, and in vehicles. High BLLs in 

resident children and elevated concentrations of lead in the house dust have been found in the homes of 

workers employed in industries associated with high lead exposure [Grandjean and Bach 1986]. Particular 

effort should be made to ensure that children of persons who work in areas of high lead exposure receive a 

BLL test. The current CDC screening guidelines for children use 10 μg/dL as a “level of concern” in order 

to intervene and prevent long-term cognitive deficits [CDC 2005]. 
Page 20 Health Hazard Evaluation Report 2011-0069-3140

Appendix A: Occupational Exposure Limits and Health Effects (continued)

Lead-contaminated surface dust represents a potential source of lead exposure, particularly for young 

children. This may occur either by direct hand-to-mouth contact, or indirectly from hand-to-mouth 

contact with contaminated clothing, cigarettes, or food. Previous studies have found a significant 

correlation between resident children’s BLLs and house dust lead levels [Farfel and Chisholm 1990]. In 

the workplace, generally there is little or no correlation between surface lead levels and employee exposures 

because ingestion exposures are highly dependent on personal hygiene practices and available facilities 

for maintaining personal hygiene. No current federal standard provides a permissible limit for lead 

contamination of surfaces in occupational settings. 

Noise 

Noise-induced hearing loss is an irreversible, sensorineural condition that progresses with exposure. 

Although hearing ability declines with age (presbycusis), noise exposure produces more hearing loss than 

that resulting from aging alone. This NIHL is caused by damage to nerve cells of the inner ear (cochlea) 

and, unlike some conductive hearing disorders, cannot be treated medically [Berger et al. 2003]. In most 

cases, NIHL develops slowly and usually occurs before it is noticed. Hearing loss is often severe enough to 

permanently affect a person’s ability to hear and understand speech. For example, people with hearing loss 

may not be able to distinguish words such as “fish” from “fist.” [Suter 1978].

The dBA is the preferred unit for measuring sound levels to assess employee noise exposures. The dBA 

noise scale is weighted to approximate the sensory response of human ears to sound frequencies near 

the hearing threshold. Because the dBA scale is logarithmic, increases of 3 dBA, 10 dBA, and 20 dBA 

represent a doubling, tenfold increase, and hundredfold increase of sound energy, respectively. Noise 

exposures expressed in dBA cannot be averaged by taking the arithmetic mean.

The OSHA noise standard [29 CFR 1910.95] specifies a PEL of 90 dBA as an 8-hour TWA. The OSHA 

PEL is calculated using a 5 dB exchange rate. This means that a person may be exposed to noise levels of 95 

dBA for no more than 4 hours, 100 dBA for 2 hours, 105 dBA for 1 hour, etc. An employee’s daily noise 

dose, on the basis of duration and intensity of noise exposure, can be calculated 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. Doses greater than 100% 

exceed the OSHA PEL.

When noise exposures exceed the PEL of 90 dBA, OSHA requires that employees wear hearing protection 

and that an employer implement feasible engineering or administrative controls to reduce noise exposures. 

The OSHA noise standard also requires an employer to implement a hearing conservation program 

when 8-hour TWA noise exposures exceed the AL 85 dBA. The program must include noise monitoring, 

employee notification, observation, audiometric testing, hearing protectors, training, and record keeping.

NIOSH [NIOSH 1998] and ACGIH [ACGIH 2011] recommend an exposure limit of 85 dBA as an 8-hour 

TWA. A more conservative 3 dB exchange rate is used in calculating these exposure limits. Using NIOSH 

criteria, an employee can be exposed to 85 dBA for 8 hours, but to no more than 88 dBA for 4 hours, 91 

dBA for 2 hours, 94 dBA for 1 hour, etc. According to the NIOSH REL, 12-hour exposures must be 83.2 

dBA or less.
Health Hazard Evaluation Report 2011-0069-3140 Page 21

Appendix A: Occupational Exposure Limits and Health Effects (continued)

Audiometric evaluations of employees’ hearing thresholds must be conducted in quiet locations, preferably 

in a sound-attenuating booth, by presenting pure tones of varying frequencies at threshold levels (i.e., the 

level of a sound that the person can just barely hear). Zero dB hearing level represents the hearing level of 

an average, young individual with good hearing. OSHA requires hearing thresholds to be measured at test 

frequencies of 500, 1,000, 2,000, 3,000, 4,000, and 6,000 Hz. Individual employee’s annual audiograms 

are compared to their baseline audiogram to determine if a standard threshold shift has occurred. OSHA 

states that a standard threshold shift has occurred if the average threshold values at 2,000, 3,000, and 

4,000 Hz have increased by 10 dB or more in either ear when comparing the annual audiogram to the 

baseline audiogram [29 CFR 1910.95]. The NIOSH-recommended hearing threshold shift criterion is a 

15-dB shift at any frequency in either ear from 500–6,000 Hz measured twice in succession [NIOSH 1998]. 

Both of these hearing threshold shift criteria require at least two audiometric tests.

The audiogram profile is a plot of the hearing test frequencies (x-axis) versus the hearing threshold levels 

(y-axis). For many employees, the audiogram profile tends to slope downward toward the high frequencies 

with an improvement at the audiogram’s highest frequencies, forming a “notch” [Suter 2002]. A notch in 

the audiogram of an employee with otherwise normal hearing may indicate the early onset of hearing loss. 

The notch from occupational noise can occur between 3,000 and 6,000 Hz [ACOM 1989; Osguthorpe 

and Klein 2001]. However, it is generally accepted that a notch at 4,000 Hz indicates occupational hearing 

loss [Prince et al. 1997]. An individual may have notches at different frequencies in one or both ears [Suter 

2002]. For this evaluation, a notch is defined as the frequency where the hearing level is preceded by an 

improvement of at least 10 dB and followed by an improvement of at least 5 dB.

References 

ACOM [1989]. Occupational noise-induced hearing loss. ACOM Noise and Hearing Conservation 

Committee. J Occup Med 31(12):996.

ACGIH [2011]. 2011 TLVs® and BEIs®: threshold limit values for chemical substances and physical 

agents and biological exposure indices. Cincinnati, OH: American Conference of Governmental Industrial 

Hygienists.

AIHA [2011]. AIHA 2011 Emergency response planning guidelines (ERPG) & workplace environmental 

exposure levels (WEEL) handbook. Fairfax, VA: American Industrial Hygiene Association.

Berger EH, Royster LH, Royster JD, Driscoll DP, Layne M, eds. [2003]. The noise manual. 5th rev. ed. 

Fairfax, VA: American Industrial Hygiene Association.

Brown-Williams H, Lichterman J, Kosnett M [2009]. Indecent exposure: lead puts workers and families at 

risk. Health Research in Action, University of California, Berkeley. Perspectives 4(1)1–9.

CDC [2005]. Preventing Lead Poisoning in Young Children. Atlanta: CDC; 2005. [http://www.cdc.gov/

nceh/lead/publications/prevleadpoisoning.pdf]. Date accessed: September 2011.

CFR. Code of Federal Regulations. Washington, DC: U.S. Government Printing Office, Office of the 

Federal Register.

CSTE [2009]. Public health reporting and national notification for elevated blood lead levels. CSTE 

position statement 09-OH-02. Atlanta: CSTE 2009 [http://www.cste.org/ps2009/09-OH-02.pdf]. Date 

accessed: September 2011.
Page 22 Health Hazard Evaluation Report 2011-0069-3140

Appendix A: Occupational Exposure Limits and Health Effects (continued)

Farfel MR, Chisholm JJ [1990]. Health and environmental outcomes of traditional and modified practices 

for abatement of residential lead–based paint. Am J Pub Health 80(10):1240–1245.

Grandjean P, Bach E [1986]. Indirect exposures: the significance of bystanders at work and at home. Am 

Ind Hyg Assoc J 47(12):819–824.

Lauwerys RR, Hoet P [2001]. Chapter 2. Biological monitoring of exposure to inorganic and organometallic 

substances. In: Industrial chemical exposure: guidelines for biological monitoring. 3rd ed. Boca Raton, FL: 

CRC Press, LLC, pp. 21–180. 

Moline JM, Landrigan PJ [2005]. Lead. Chapter 39.8. In: Textbook of clinical occupational and 

environmental medicine, Rosenstock L, Cullen MR, Brodkin CA, and Redlich CA, eds., 2nd ed. 

Philadelphia, PA: Elsevier Saunders, pp. 967–979.

NCEH [2005]. Third national report on human exposure to environmental chemicals. Atlanta, GA: U.S. 

Department of Health and Human Services, Centers for Disease Control and Prevention. National Center 

for Environmental Health Publication number 05–0570.

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.

NIOSH [2010]. NIOSH pocket guide to chemical hazards. 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. 2010-168c. [http://www.cdc.gov/niosh/npg/]. Date accessed: 

September 2011.

Osguthorpe JD, Klein AJ [2001]. Occupational hearing conservation. Clin Audiol 24(2):403–414.

Prince M, Stayner L, Smith R, Gilbert S [1997]. A re-examination of risk estimates from the NIOSH 

Occupational Noise and Hearing Survey (ONHS). J Acous Soc Am 101(2):950–963.

Schwartz BS, Hu H [2007]. Adult lead exposure: time for change. Environ Health Perspect 115(3):451–454. 

Schwartz BS, Stewart WF [2007]. Lead and cognitive function in adults: A question and answers approach 

to a review of the evidence for cause, treatment, and prevention. Int Rev Psychiatry 19(6):671–692.

Sussell A [1998]. Protecting workers exposed to lead-based paint hazards: a report to congress. 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. 98–112.

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.

Suter AH [2002]. Hearing conservation manual. 4th ed. Milwaukee, WI: Council for Accreditation in 

Occupational Hearing Conservation.
Health Hazard Evaluation Report 2011-0069-3140 Page 23

Appendix B: Methods

Noise Dosimetry

Noise dosimeters (Larson Davis, Provo, Utah, SparkTM models 706RC or 705P) 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 outside of the shoulder. A windscreen provided by the dosimeter manufacturer was placed 

over the microphone to reduce or eliminate artifact noise, which can occur if objects bump against an 

unprotected microphone. The dosimeters were set up to collect data using different settings to allow 

comparison of noise measurement results with the three different noise exposure limits referenced in 

this health hazard evaluation, the OSHA PEL and AL and the NIOSH REL (Table B1). During noise 

dosimetry measurements, noise levels below the threshold level are not integrated by the dosimeter for 

accumulation of dose and calculation of TWA noise level.

The dosimeters averaged noise levels every second. At the end of the sampling period, the dosimeter was 

removed and paused to stop data collection. The noise measurement information stored in the dosimeters 

was downloaded to a computer for interpretation with Larson Davis Blaze® software. The dosimeters were 

calibrated before and after the measurement periods according to the manufacturer’s instructions.

Table B1. Dosimeter settings

Parameters OSHA AL OSHA PEL NIOSH REL

Response Slow Slow Slow

Exchange rate 5 5 3

Criterion level 90 90 85

Threshold 80 90 80

Upper limit 115 115 115

Area noise levels and octave band noise frequency analysis (measurement of noise in different frequencies) 

were measured with System 824 SLM and real-time frequency analyzers (Larson-Davis, Provo, Utah). The 

SLMs were equipped with 0.25-inch random incidence Type 1 microphones; the instruments measured 

noise levels between 16 and 170 dBA. Sound level and octave band frequency spectrum measurements 

were collected at a sample rate of 51,200 times per second and averaged eight times per second. The SLMs 

were calibrated before and after the measurement periods according to the manufacturer’s instructions. 

SLMs were either handheld or mounted on a tripod at a height of approximately 5 feet.

Lead in Air

Air samples for lead were collected on 37-millimeter diameter, 0.8-micron pore-size mixed cellulose ester 

filters using SKC Air Check® 2000 air sampling pumps (SKC Inc., Eighty Four, Pennsylvania) calibrated 

at a flow rate of 2 liters per minute. The inlet port of the sampling pump was connected to the sampling 

media with Tygon® tubing. For PBZ samples, the sampling media were attached to the employee’s lapel 
Page 24 Health Hazard Evaluation Report 2011-0069-3140

Appendix B: Methods (continued)

within the breathing zone, roughly defined as an area in front of the shoulders with a radius of 6 to 9 

inches. Samples were analyzed by inductively coupled plasma according to NIOSH Method 7303 [NIOSH 

2011].

Lead on Surfaces 

We collected six surface wipe samples for lead. Surface samples were collected with premoistened 

Palintest® dust wipes (Palintest USA, Erlanger, Kentucky). The collection procedure was as follows: (1) 

identify the area to be sampled, (2) put on a pair of disposable nitrile gloves, (3) place the wipe flat on 

surface as defined by the 10 centimeter by 10 centimeter disposable template and wipe surface using three 

to four horizontal S-strokes, side-to-side so that entire surface is covered, (4) wipe the area with three to 

four vertical S-strokes, (5) wipe the area with three to four diagonal S-strokes, and (6) place the wipe in a 

sterile container. A new template and a pair of disposable gloves were used for each wipe sample. The wipe 

samples were digested and analyzed by inductively coupled argon plasma according to NIOSH Method 

9102 [NIOSH 2011].

Lead on Hands 

Hand wipe samples were collected and analyzed with a commercially available dust wipe (Full Disclosure® 

Instant Wipes, SKC Inc., Eighty Four, Pennsylvania) conforming to the American Society for Testing and 

Materials Standard E 1792 (Specifications for Wipe Sampling Materials for Lead in Surface Wipes). After 

collection, each wipe was sprayed with a 5% leaching solution of acetic acid to solubilize lead and lead 

compounds into lead ions. The wipe was then sprayed with a chilled solution of sodium rhodizonate, a 

chemical that reacts colorimetrically to the presence of lead by changing from yellow to red. The visual 

limit of identification for the method is approximately 17–20 micrograms per sample.

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Supplement 2003–154. http://www.cdc.gov/niosh/nmam/. Date accessed: September 2011.
Health Hazard Evaluation Report 2011-0069-3140 Page 25

Acknowledgments and

Availability of Report

The Hazard Evaluations 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 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 employer 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 any company or product does not constitute 

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This report was prepared by Lilia Chen and Scott E. Brueck of 

HETAB, Division of Surveillance, Hazard Evaluations and Field 

Studies. Health communication assistance was provided by Stefanie 

Evans. Editorial assistance was provided by Ellen Galloway. Desktop 

publishing was performed by Robin Smith and Greg Hartle.

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Below is a recommended citation for this report:

NIOSH [2011]. Health hazard evaluation report: evaluating noise and lead 

exposures at an outdoor firing range – California. By Chen L, Brueck SE. 

Cincinnati, OH: U.S. Department of Health and Human Services, Centers for 

Disease Control and Prevention, National Institute for Occupational Safety and 

Health, NIOSH HETA No. 2011-0069-3140.

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