Health Hazard Evaluation Report 2012-0065-3195 Page 1

Followback Evaluation of Lead and Noise 

Exposures at an Indoor Firing Range

Report No. 2012-0065-3195

November 2013

Jessica G. Ramsey, MS, CPE

R. Todd Niemeier, MS, CIH

Elena Page, MD, MPH

Lilia Chen, MS, CIH

JungHo Choi, MS, CIH

U.S. Department of Health and Human Services

Centers for Disease Control and Prevention

National Institute for Occupational Safety and Health
Page 2 Health Hazard Evaluation Report 2012-0065-3195

Contents

Highlights...............................................i

Abbreviations ..................................... iv

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

Methods ............................................... 1

Results .................................................. 2

Discussion ............................................ 8

Conclusions........................................ 11

Recommendations............................. 11

Appendix A ........................................ 15

Appendix B......................................... 20

References.......................................... 27

Acknowledgements........................... 33

The employer is required to post a copy of this report for 30 days at or near the 

workplace(s) of affected employees. The employer must take steps to ensure 

that the posted report is not altered, defaced, or covered by other material.

The cover photo is a close-up image of sorbent tubes, which are used by the HHE 

Program to measure airborne exposures. This photo is an artistic representation that may 

not be related to this Health Hazard Evaluation. Photo by NIOSH.
Health Hazard Evaluation Report 2012-0065-3195 Page i

We reevaluated lead 

exposures at an indoor firing 

range. Airborne exposures 

decreased after a new 

ventilation system was 

installed. We found lead on 

work surfaces and in vehicles. 

We measured high noise levels 

during firearms qualifications. 

Recommendations include 

eliminating dry sweeping, 

changing clothing before 

leaving the complex, and 

continuing the use of dual 

hearing protection.

Highlights of this Evaluation

The Health Hazard Evaluation Program received a request from an indoor firing range. The 

employer was concerned about lead and noise exposures during firearms qualification. This 

followback evaluation took place after the installation of a new ventilation system. 

What We Did

● We reevaluated the firing range in June 2012.

● We measured airflow in each bay of the firing range.

● We collected personal air samples for lead on instructors, shooters, and the hazardous 

materials technician.

● We collected area air samples for lead in the firing range, firearms cleaning area, 

classroom, lunchroom, and offices.

● We collected surface vacuum samples for lead. We 

sampled inside work and personal vehicles and from 

carpeted floors, rugs, and mats in the complex.

● We collected surface wipe samples for lead. We 

sampled in the firing range, firearms cleaning 

area, classroom, lunchroom, armory, offices, and 

in work and personal vehicles.

● We reviewed medical monitoring results of 

instructors and the hazardous materials technician.

What We Found

● Airflow along and downrange of the firing line 

met National Institute for Occupational Safety 

and Health recommendations.

● The firing range was still dry swept during cleaning.

● Instructors’ and shooters’ exposures to lead in the 

air were below occupational exposure limits.

● High levels of lead in the air were detected when cleaning behind the bullet trap.

● Low levels of lead were found in air from the firing range and firearms cleaning area.

● Surface wipe and vacuum samples detected lead throughout the complex and in work 

and personal vehicles.

What the Employer Can Do

● Do not dry sweep the firing range. Clean the floor with an explosion-proof vacuum 

cleaner that has high-efficiency particulate air filters.

● Remove carpet and rugs in the complex.

● Improve general housekeeping practices in the lunchroom, classroom, and offices.
Page ii Health Hazard Evaluation Report 2012-0065-3195

What the Employer Can Do (continued) 

● Provide instructors and the hazardous materials technician with lockers in an area that 

allows street clothes and shoes to be stored separately from lead-contaminated work 

clothes and shoes. Personal clothing should be left in a clean locker. 

● Provide disposable shoe covers and coveralls.

● Require instructors and shooters to use lead removal wipes and wash their hands and 

faces with lead removal soap before eating, drinking, or contact with others.

● Provide instructors and shooters annual training and educational materials about the 

health effects of exposure to lead (including the risks of take-home exposure) and noise.

What the Employees Can Do

● Do not eat, drink, chew gum, or use tobacco in the firearms cleaning area, classroom, or 

firing range.

● Continue to wear dual hearing protection while in the firing range. Dual hearing 

protection includes ear plugs and earmuffs.

● Wash your hands and face thoroughly with lead removal soap before eating, drinking, 

or contact with others. Use lead removal wipes to clean your hands.

● Wear shoe covers and coveralls in the range. Leave your range shoes at the range.

● Shower at the end of the work day and put on your clean personal clothes prior to 

leaving the complex.

● Wash clothes worn in the firing range at the firing complex.

● Report health concerns to your employer. If needed, seek medical care.
Health Hazard Evaluation Report 2012-0065-3195 Page iii

Mention of any company or product does not constitute endorsement by NIOSH. In 

addition, citations to websites external to NIOSH do not constitute NIOSH endorsement 

of the sponsoring organizations or their programs or products. Furthermore, NIOSH is not 

responsible for the content of these websites. All web addresses referenced in this document 

were accessible as of the publication date of this report.
Page iv Health Hazard Evaluation Report 2012-0065-3195

Abbreviations

cm2 Square centimeter

μg/dL Micrograms per deciliter

μg/m3 Micrograms per cubic meter

ACGIH® American Conference of Governmental Industrial Hygienists

BLL Blood lead level

CFR Code of Federal Regulations

dB Decibels

dBA Decibels, A-weighted

HEPA High-efficiency particulate air

HHE Health hazard evaluation

Hz Hertz

MDC Minimum detectable concentration

MQC Minimum quantifiable concentration

ND Not detected

NIOSH National Institute for Occupational Safety and Health

OEL Occupational exposure limit

OSHA Occupational Safety and Health Administration

PEL Permissible exposure limit

REL Recommended exposure limit

SLM Sound level meter

TLV® Threshold limit value

TWA Time-weighted average
Health Hazard Evaluation Report 2012-0065-3195 Page 1

Introduction 

The Health Hazard Evaluation (HHE) Program received a request from managers concerning 

lead and noise exposures at an indoor firing range in California. This report is a follow-up 

to our 2009 evaluation, in which investigators measured airborne lead exposures above 

occupational exposure limits (OELs) among instructors, shooters, and a hazardous materials 

technician and provided recommendations to reduce lead exposures at the range [NIOSH 

2011]. In response, the employer redesigned the range ventilation system, removed carpeting, 

added step-off cleaning pads at the firing range exit, mandated full facepiece powered air 

purifying respirator use by the hazardous materials technician, and improved cleaning 

procedures. We returned in June 2012 to reassess lead and noise exposures. 

Methods

Air Sampling for Lead 

We collected full-shift personal air samples over 2 days on instructors and a hazardous 

materials technician. We also collected task-based air samples on shooters during 

qualifications and firearms cleaning. Task-based samples were also collected on the 

hazardous materials technician during high-efficiency particulate air (HEPA) vacuum use, 

dry sweeping, and cleaning behind the bullet trap. We collected area air samples in the 

hazardous materials technician’s office, range office, armory, classroom, firearms cleaning 

area, lunchroom, and firing range. Samples were analyzed according to National Institute for 

Occupational Safety and Health (NIOSH) Method 7303 [NIOSH 2013].

Surface Sampling for Lead 

We collected and analyzed vacuum samples for lead on porous surfaces according to NIOSH 

Methods 9102 and 7303 [NIOSH 2013]. We took vacuum samples in the range and range 

complex, and in instructors’ and the hazardous materials technician’s personal and work 

vehicles. We used a 100 square centimeter (cm2) template when collecting vacuum samples 

on flat surfaces. 

We collected and analyzed wipe samples for lead on nonporous surfaces according to NIOSH 

Method 9102 [NIOSH 2013]. We took samples from the range office, armory, classroom, 

lunchroom, firing range, and personal and work vehicles. We also took samples of the 

hazardous materials technician’s respirator both inside the face mask and on the battery and 

motor. We used a 100 cm2 template to collect wipe samples on flat surfaces, and estimated 

100 cm2 of sample area on irregularly shaped or uneven surfaces.

We used commercially available dust wipes (SKC Inc., Full Disclosure® Instant Wipes) to 

qualitatively evaluate lead contamination on skin, clothing, and shoes. After the instructors, 

shooters, and hazardous materials technician left the firing range, we collected wipes on their 

hands, pants, and boots. Wipe samples were collected from the palm of each hand, one thigh, 
Page 2 Health Hazard Evaluation Report 2012-0065-3195

and the bottom of one boot. We estimated an area of 100 cm2 on these wipe samples. The 

visual limit of identification for the wipes was approximately 17–20 micrograms per sample.

Ventilation 

We reviewed the ventilation drawings and recent test and balance report, and visually 

inspected the ventilation systems for the entire firing range complex. We used a TSI 

VelociCalc® Plus Model 8386A to measure airflow at the firing line and at the bullet trap 

downrange when the range was empty. We took triplicate measurements in each lane along 

the firing line and at the bullet trap at approximately 3 feet and 5 feet. We averaged the 

measurements for each location, and compared them to the NIOSH recommended values. We 

were unable to evaluate airflow patterns in the range with a theatrical fog machine as planned 

because of a smoke sensor in the exhaust ventilation system.

Noise 

We collected 16 time-weighted average (TWA) personal noise exposure measurements over 

2 days on six shooters, six firing range instructors, and the hazardous materials technician. 

We measured personal noise exposures with Larson Davis SparkTM model 706RC or 705P 

integrating noise dosimeters. The dosimeters measured noise using three different settings 

to compare with the three noise exposure limits referenced in this report; the Occupational 

Safety and Health Administration (OSHA) permissible exposure limit (PEL), OSHA action 

level, and NIOSH recommended exposure limit (REL). Shooters and instructors wore noise 

dosimeters on day 1 of sampling. Instructors wore dosimeters on day 2 of sampling. We also 

measured area noise levels and took octave band measurements (noise levels in different 

frequencies) using two Larson Davis System 824 sound level meters (SLMs) and real-time 

frequency analyzers. We mounted the SLMs on tripods at a height of approximately 5 feet 

to represent the ear position of a standing shooter. We placed the tripods with SLMs in the 

middle of each group of shooters approximately 4–6 feet behind the student, where the 

instructors normally stood. Because of safety concerns and risk of interfering with shooters 

and instructors, we were not able to place SLMs closer during qualifications.

Medical Records Evaluation 

We reviewed blood lead levels (BLLs) from 2008–2013 for instructors and the hazardous 

materials technician. BLLs were initially collected by the employer as part of OSHA

mandated medical surveillance for lead, but the employer continued to offer testing to 

employees on a yearly basis as a service even when it was no longer required. 

Results 

Lead 

The instructors’ full-shift TWA lead exposure concentrations ranged from 0.15–3.8 

micrograms per cubic meter (μg/m3) over the sampling period (345–488 minutes). Instructors 

spent up to 4 hours in the range on any given day and the remainder of the time was spent 
Health Hazard Evaluation Report 2012-0065-3195 Page 3

in the classroom or office. Results of the air sampling for lead on individual instructors are 

presented in Appendix A, Table A1. 

The shooters’ task-based TWA lead concentrations ranged from 1.5–9.0 μg/m3 over the 

sampling periods (147–200 minutes). Shooters spent approximately 1 hour in the classroom 

and 3 hours in the range and firearms cleaning area. The remainder of the day was spent in 

defensive tactics training in another section of the complex. Air sampling for lead on shooters 

was done while they were in the range and when cleaning their firearms. These results are 

presented in Appendix A, Table A2.

Full-shift and task-based air sampling results for lead on the hazardous materials technician 

are presented in Table 1. The hazardous materials technician’s daily range cleaning activities 

included using a HEPA vacuum behind the firing line and dry sweeping down range. The 

lead concentrations for these tasks ranged from not detected (ND) (< 0.3 μg/m3)–7.3 μg/m3. 

The technician also used a HEPA vacuum behind the bullet trap approximately once a week. 

On June 5, 2012, the hazardous materials technician began cleaning the area behind the 

bullet trap but stopped so that qualifications could resume in the range. This task was usually 

completed in 1 day; however, in this case, the task was completed the following day. We used 

the same sample collection cassette for cleaning activities on June 5 (8 minutes) and June 6 

(37 minutes), to meet the minimum sample volume recommended in the NIOSH sampling 

and analytical method. The airborne lead concentration during the task of cleaning behind 

the bullet trap was 330 μg/m3. The technician’s full-shift exposure to airborne lead exceeded 

the OSHA action level of 30 μg/m3 on June 6, 2012. This exposure corresponded to the day 

that he spent 37 minutes cleaning behind the bullet trap. We did not collect any task-based 

samples for tasks outside the range, which included changing filters, completing paperwork, 

and occasionally travelling offsite.

Table 1. Concentrations of lead on personal air samples of the hazardous materials technician

Date Location Sample

time

(minutes)

Sample

concentration

(μg/m3)

6/5/2012 Full-shift 440 1.6

Task–HEPA vacuum front of range 27 ND*

Task–dry sweep downrange 61 7.3

6/6/2012 Full-shift 480 34†

Task–clean behind bullet trap 45 330‡

*Below the minimum detectable concentration (MDC) (0.3 μg/m3).

†A full-shift concentration was calculated assuming no exposure for 173 minutes while offsite 

performing a delivery. The concentration for the sample time of 307 minutes was 53 μg/m3. 

‡This sample also includes 8 minutes spent cleaning behind the range on 6/5/2012.

Results of the area air sampling for lead are in Appendix A, Table A3. The lead 

concentrations ranged from ND (< 0.09 μg/m3)–3.3 μg/m3. Most results were low or at a 

concentration between the MDC and the minimum quantifiable concentration (MQC).
Page 4 Health Hazard Evaluation Report 2012-0065-3195

Figure 1. Location of radial air diffusers in an indoor firing range. 

Photo by NIOSH.

The range of surface sampling results is shown in Table 2. These results showed the presence 

of lead on work surfaces outside the range, including work and personal vehicles. Surface 

vacuum sample results are presented in Appendix A, Table A4 and surface wipe sample 

results are presented in Appendix A, Table A5. 

Table 2. Summary of lead concentrations in surface vacuum and wipe samples 

Sample location Number of samples Sample concentration 

(μg/100 cm2

)

Range surfaces 27 ND*–96

Personal vehicles 14 ND*–21

Work vehicles 11 0.72–120

*Below the MDC (0.4 μg/100cm2

)

We did qualitative sampling for the presence of lead on hands, shoes, and pants for 5 

instructors, 5 shooters, and the hazardous materials technician. All of the samples taken 

on shoes and pants were above the limit of visual identification. All of the samples taken 

on shooters hands were above the limit of visual identification. All but one of the samples 

on instructor’s hands was above the limit of visual identification; the one instructor who 

tested negative had used lead removal wipes when leaving the range. The hazardous 

materials technician’s hands also tested negative, it was noted that he had washed his 

hands prior to sampling.

Ventilation

The new ventilation system was a push-pull ventilation system typically seen in indoor firing 

ranges. The system was computer controlled with several alarms and a pressure sensor to 

alert staff of system failures. Four separate ventilation systems served the range with one 

system serving each firing 

bay (eight firing lanes). Each 

system was designed to 

supply approximately 21,000 

cubic feet per minute of air 

and exhaust approximately 

24,000 cubic feet per minute 

of air. The ventilation systems 

were separate from the rest 

of the complex and were 

designed to allow air to travel 

from uprange to downrange, 

from contaminated to 

less contaminated areas. 

Supply air was delivered 

by perforated radial air 

diffusers mounted at ceiling 

height along the back wall 
Health Hazard Evaluation Report 2012-0065-3195 Page 5

of the range. The radial diffusers were approximately 16 feet behind the firing line, except 

near the entry door, the range officers’ desk, and the far end of the range where they were 

approximately 10 feet behind the firing line. Figure 1 is a picture of the radial air diffusers. 

Air was exhausted from the range at the bullet trap, which was about 75 feet from the 

firing line. Exhaust air passed through HEPA filters before delivery to the outdoor ambient 

environment. 

A summary of the ventilation flow rate measurements is provided in Figure 2. Appendix A, 

Tables A6–A9 provide the supply airflow measurement data for each of the lanes. Since our 

previous site visit in December 2009, bay 4 had been converted from a special weapons and 

tactics training bay to a traditional bay with eight qualification lanes.

Figure 2. A graph showing a summary of the ventilation flow rates for each bay of the firing range.

Noise

Full shift personal noise monitoring results for instructors and the hazardous materials 

technician are provided in Appendix A, Table A10. All instructors’ TWA noise exposures 

exceeded the NIOSH REL, OSHA action level, and OSHA PEL. Their full shift noise 

exposures ranged from 95–101 decibels, A-weighted (dBA), using OSHA criteria and from 

106–110 dBA using NIOSH criteria. The hazardous materials technician’s full shift noise 

exposure was below OELs. TWA noise monitoring results for shooters are provided in 

Appendix A, Table A11. Shooters wore noise dosimeters for 2.5–3 hours during qualification 

exercises and firearms cleaning. Their noise exposures during that time ranged from 103–107 

dBA using OSHA criteria and from 111–115 dBA using NIOSH criteria. Because of the high 
Page 6 Health Hazard Evaluation Report 2012-0065-3195

noise exposures during firearms qualifications, their full-shift noise exposure would also 

exceed the OELs even if they had no noise exposure during the remainder of the workday. 

We also sampled the area in the vault with a noise dosimeter because of employee concerns 

of the noise produced by the electrical box. The noise level collected next to this box during 

a 7-hour period was 60 dBA by the NIOSH criteria. SLMs were used to measure background 

levels of noise in the firing range before qualifications with the ventilation system on and 

no other activities taking place (78.6 dBA) and during the hazardous materials technician’s 

vacuuming activities (79.2 dBA).

One-third octave band noise frequency measurements collected when shooters were in the 

firing range for qualification are shown in Figure 3. Octave band measurements provide 

information about the frequency distribution of noise. These measurements showed that the 

highest sound pressure levels of 110 decibels (dB) occurred at 630 Hertz (Hz), and were 

greater than 100 dB across all the one-third octave bands from 12.5–31.5 Hz and between 

125–4,000 Hz. 

Figure 3. One-third octave band center frequency levels over a 500-second period of shooting.

Peak sound levels ranged from 149.6–154.4 dB during qualification. Shooters typically fired 

a series of shots in succession followed by several minutes without shooting at which time 

instructors provided additional guidance or training. An example of peak sound levels during 1 

minute of shooting rifles is shown in Figure 4. Four peaks greater than 150 dB and several peaks 

greater than 140 dB occurred during this time period.
Health Hazard Evaluation Report 2012-0065-3195 Page 7

Figure 4. Peak sound levels measured on June 6, 2012, during 1 minute of shooting rifles in the indoor 

firing range.

Medical Records Evaluation

We reviewed 52 BLLs from 15 instructors and the hazardous materials technician between 

2008–2013. Because instructors are detailed to this location for an average of 2 years, seven 

instructors only had BLLs prior to the installation of the new ventilation system, three had 

BLLs only after the installation, and five had BLLs before and after the installation. The 

technician had BLLs before and after the installation as well. Thirty-nine BLLs were taken 

before the installation of the new ventilation system. Fifteen of the 39 (38%) were below 

the limit of detection (< 3 micrograms per deciliter [μg/dL]). The remaining 24 ranged from 

3–12 μg/dL. The 13 BLLs after the installation of the new ventilation system included 7 

(54%) below the limit of detection; the remaining 6 ranged from 3–7 μg/dL.

Other Observations

The hazardous materials technician wore a Tyvek® suit with hood, gloves, and a full 

facepiece powered air purifying respirator during all cleaning activities that we monitored. 

The hazardous materials technician had received OSHA lead abatement training and had 

been fit tested on the respirator. We observed the hazardous materials technician’s use of 

personal protective equipment, including donning and doffing procedures. The hood of 

his Tyvek suit interfered with the sealing surface of the respirator facepiece during use; he 

handled contaminated items without gloves; and he cleaned his respirator with a wet towel. 

We provided recommendations to improve these practices and noted that he had modified his 

procedures the following day. 
Page 8 Health Hazard Evaluation Report 2012-0065-3195

Instructors and shooters did not regularly use lead removal wipes or wash their hands before 

eating, drinking, or smoking during breaks. Shooters and instructors also helped clean spent 

casings past the firing line, which potentially increases lead contamination of their shoes. 

Additionally, shooters may increase lead contamination of their clothing when using a prone 

shooting position with no protection between their clothing and the floor.

Instructors did not regularly wash their work clothing at the range. The washer and dryer 

were in the men’s locker room; therefore, female employees did not have access.

All instructors and most shooters wore double hearing protection, a combination of insert ear 

plugs and earmuffs. Most instructors wore the 3M PeltorTM OptimeTM 105 earmuffs with a 

noise reduction rating of 30 dB. Some instructors and shooters provided their own earmuffs. 

Formable foam insert earplugs (Howard Leight Laser Lite®) with a noise reduction rating of 

32 dB were placed in locations easily accessible to instructors and shooters, such as a counter 

in the hallway leading to the firing range and on the tower table in the firing range.

Discussion 

Lead

All instructors had full-shift airborne lead exposures less than 8% of the NIOSH REL

and OSHA PEL. The average airborne lead concentration for instructors was 1.9 μg/m3, 

compared to 10.3 μg/m3 in our previous evaluation [NIOSH 2011]. We found a twentyfold 

reduction in average airborne lead exposures for shooters during qualifications and firearms 

cleaning. The average airborne lead concentration for shooters was 5.0 μg/m3, compared to 

102 μg/m3 in the previous evaluation. We attribute these substantial reductions in instructors’ 

and shooters’ airborne lead exposures to installation of the new ventilation system because 

they spent approximately the same amount of time in the range performing qualifications as 

they did during the initial visit.

We more fully characterized the hazardous materials technician’s lead exposure during this 

evaluation by collecting task-based and full-shift personal air samples. The higher full-shift 

concentration (34 μg/m3), which was above the OSHA action level for lead, occurred on 

the day the technician cleaned behind the bullet trap for more than half an hour. However, 

these results were substantially lower than the 670 μg/m3 full-shift concentration that we 

measured earlier [NIOSH 2011]. Job tasks for the hazardous materials technician were 

basically the same with the exception of changing filters inside the firing range. The airborne 

lead concentration while HEPA vacuuming behind the bullet trap was more than 6 times 

greater than the NIOSH REL and OSHA PEL; the exposure during this task was the primary 

reason the hazardous materials technician’s full-shift exposure exceeded the OSHA action 

level for lead. It is unclear how the high lead exposure during cleaning behind the bullet trap 

was occurring. In a conversation with the firearms coordinator after the site visit, we learned 

that since the installation of the new ventilation system the hazardous materials technician 

no longer needed to clean behind the bullet trap. The range managers were considering 

permanently sealing the door to that area. 
Health Hazard Evaluation Report 2012-0065-3195 Page 9

The area airborne lead concentrations in administrative areas outside of the firing range were 

below the limit of detection (< 0.09 μg/m3). Area airborne lead concentrations in the range 

and where firearms were cleaned or stored were detectable but low, similar to the results 

during our initial evaluation [NIOSH 2011].

BLLs were similar before and after the installation of the ventilation system, despite 

large reductions in airborne lead concentrations. This finding suggests that ingestion or 

dermal absorption of lead is contributing to the BLLs, although other sources (including 

mobilization of bone lead or sources of exposure outside the workplace) could also be 

a factor. We detected lead in 92% of samples from surfaces around the complex. The 

concentrations varied substantially but were similar to those found in our initial evaluation. 

We observed shooters and instructors eating and drinking in the firearms cleaning area and 

the classroom. Additionally, we observed instructors using smokeless tobacco and chewing 

gum in the firing range. These activities increase the potential for lead ingestion. The floor 

of the hazardous materials technician’s office was carpeted, and several areas in the complex 

had rugs and mats. Carpets and rugs could accumulate lead and increase opportunities for 

contaminating shoes and clothing. The firing range contracted companies to clean offices and 

bathrooms, change out rugs, and wax floors; however, more frequent use of lead removal 

cleaner on commonly touched surfaces should reduce the amount of lead contamination. A 

yearly cleaning of the entire complex would help reduce the amount of lead that may have 

accumulated on static surfaces.

Occupational health and safety government agencies or national organizations have 

not established surface contamination limits for lead. However, OSHA specifies in its 

substance-specific standard for lead that all surfaces be maintained “as free as practicable of 

accumulations of lead” [29 CFR 1910.1025(h)(1)]. 

We found lead on the hands, pants, and shoes of most instructors, shooters, and the hazardous 

materials technician. This lead migrates outside of the range into the rest of the complex 

and into personal and work vehicles. We detected lead in all of the vehicles sampled. Lead 

in personal vehicles poses a potential exposure hazard to others who may ride in those 

vehicles. Lead in vehicles can also be tracked into the home where it can expose others. The 

best way to reduce the risk from take-home lead exposures is to prevent the spread of lead 

contamination to areas outside the range.

Ventilation

In 2009, NIOSH issued recommendations on occupational exposure to lead and noise in 

firing ranges [NIOSH 2009]. The new ventilation design in the range meets the NIOSH 

recommendations by providing a recommended minimum airflow of 50 feet per minute 

along the firing line and a recommended downrange minimum airflow of at least 30 feet per 

minute. NIOSH has also recommended an optimal airflow across firing lines in indoor firing 

ranges of 75 feet per minute [NIOSH 1975]. Although some of the ventilation measurements 

we collected at the firing line were above 75 feet per minute, all of our air sample results 

were less than 20% of the most conservative OELs. This finding suggests that the current 
Page 10 Health Hazard Evaluation Report 2012-0065-3195

ventilation design is controlling airborne lead exposures for instructors and shooters. Also, 

as recommended by NIOSH, the range was maintained under negative pressure relative to 

the adjacent firearms cleaning area. However, because of the fire suppression system we 

were unable to perform a smoke test in the range to determine if the air flow was distributed 

evenly, floor to ceiling and wall to wall. 

Noise

Repeated exposure to impulse noise can result in permanent noise-induced hearing loss 

[Patterson and Hamernik 1992; Pekkarinen et al. 1993; Chan et al. 2001]. Impulsive noise, 

such as that from 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. Also, measuring high intensity impulsive noise, such as gunfire 

noise, with dosimeters may underrepresent noise exposure and hearing loss risk [Kardous et 

al. 2003; Kardous and Willson 2004]. 

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

necessary [Berger 1983]. Proper insertion of hearing protection is critically important to 

ensure sufficient noise attenuation. NIOSH has found that poor insertion of formable hearing 

protection into the ear canals reduces the ability of the hearing protectors to attenuate noise 

exposure [NIOSH 2005].

Octave band analysis allows for determination of the dominant noise frequencies and can 

be useful for identifying potential engineering controls. One of the primary sources of noise 

generated during firearms use is the muzzle blast during firing, which generates high noise 

across the mid to high frequency range. The only effective method to substantially reduce 

shooters’ or instructors’ noise exposure from gunfire is using noise suppressors attached to 

the end of the gun barrel. 

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]. 

During our evaluation of medical records, we determined that audiometry and blood lead 

testing were done sporadically. The American Conference of Governmental Industrial 

Hygienists (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 2013]. 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 for a variety of ototoxicants including solvents and 
Health Hazard Evaluation Report 2012-0065-3195 Page 11

lead [U.S. Army 2009]. The highest projected 8-hour TWA personal air concentration for lead 

among instructors (3.8 μg/m3) did not exceed 50% of the NIOSH REL; however, reviewers 

of employees’ audiometric tests should consider possible additive, potentiating, or synergistic 

effects between noise exposure and lead when evaluating audiograms. 

Conclusions 

The installation of a new ventilation system at the indoor firing range improved the airflow 

along the firing line and downrange. This change resulted in large reductions in average 

airborne lead exposure for instructors and shooters. Instructor BLLs remained virtually 

unchanged from the time of the first site visit but were below 10 μg/dL. We found lead on 

surfaces in the complex; in work and personal vehicles; and on hands, clothes, and shoes 

of instructors. We also observed eating and drinking in the firearms cleaning area, and 

employees using smokeless tobacco in the firing range. These practices and the presence 

of lead on surfaces may be contributing to on-going lead exposure. We found very high 

airborne lead levels when the hazardous materials technician cleaned behind the bullet trap. 

Additionally, all instructors’ noise exposures exceeded OELs. 

Recommendations 

On the basis of our findings, we recommend the actions listed below. We encourage the firing 

range to use a labor-management health and safety committee or working group to discuss 

our recommendations and develop an action plan. Those involved in the work can best set 

priorities and assess the feasibility of our recommendations for the specific situation at the 

firing range. 

Our recommendations are based on an approach known as the hierarchy of controls 

(Appendix B). 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 

personal protective equipment may be needed. 

Elimination and Substitution

Eliminating or substituting hazardous processes or materials reduces hazards and protects 

employees more effectively than other approaches. Prevention through design, considering 

elimination or substitution when designing or developing a project, reduces the need for 

additional controls in the future.

1. Stop dry sweeping in the range.

2. Stop cleaning behind the bullet trap. The redesign of the ventilation system makes this 

cleaning unnecessary. 

3. Use nonlead bullets and nonlead primers as they become economically feasible.
Page 12 Health Hazard Evaluation Report 2012-0065-3195

Engineering Controls 

Engineering controls reduce employees’ exposures by removing the hazard from the process 

or by placing a barrier between the hazard and the employee. Engineering controls protect 

employees effectively without placing primary responsibility of implementation on the 

employee. 

1. Routinely test and balance the ventilation system to ensure that airflow is within the 

recommended ranges along the firing line (50–75 feet per minute) and downrange (35 

feet per minute).

2. Sample the air for lead if changes are made to the ventilation system or administrative 

practices that affect lead exposures change.

Administrative Controls

The term administrative controls refers to employer-dictated work practices and policies 

to reduce or prevent hazardous exposures. Their effectiveness depends on employer 

commitment and employee acceptance. Regular monitoring and reinforcement are necessary 

to ensure that policies and procedures are followed consistently.

1. Prohibit eating, drinking, gum chewing, or tobacco use in the range, firearms cleaning, 

and classroom areas. Post signs on the door to the range stating this policy.

2. Provide shooters a sheet of paper or other disposable material to place on the ground 

beneath them when they kneel or shoot from a prone position. 

3. Stop instructors and shooters from removing spent casings past the firing line. All 

casings past the fining line should be removed by the hazardous materials technician 

during cleaning. 

4. Prevent the transfer of lead from the range to other work areas and vehicles.

a. Provide instructors and the hazardous materials technician with lockers for 

storing street clothes and shoes separately from lead-contaminated work clothes 

and shoes. 

b. Provide coveralls for instructors to wear over their work uniform when they go 

into the range as an extra measure to prevent lead contamination on clothing. The 

coveralls should be removed and left at the entrance to the range before breaks 

or lunch. Provide a uniform for the hazardous materials technician to wear under 

the Tyvek suit. At the end of the day, the uniforms and coveralls should be left at 

work to be laundered. Anyone handling these dirty items should follow the same 

controls as those who work in the range.

c. Require instructors and the hazardous materials technician to leave shoes worn on the 

firing range at the complex. Additionally, all personnel should wear disposable shoe 

covers before entering the range and then discard them before leaving the complex.
Health Hazard Evaluation Report 2012-0065-3195 Page 13

d. Make sure all personnel entering the range thoroughly wash their hands and faces 

before breaks, lunch, and departing at the end of the day. We recommend the use 

of lead removal wipes at the range exit and lead removal soap in the restrooms. 

e. Instruct the instructors and hazardous materials technician to shower at the end of the 

work day and put on their clean personal clothes and shoes before leaving the complex.

5. Clean all personal and work vehicles using HEPA vacuums on porous surfaces and 

wet wiping on nonporous surfaces. The American Industrial Hygiene Association 

maintains a list of lead abatement consultants in California: https://webportal.aiha.org/

Custom/ConsultantsSearch.aspx.

6. Remove carpet in the simulation room adjacent to the range. Also remove carpeted and 

antifatigue mats because they may be accumulating lead.

7. Improve general housekeeping practices to remove lead from all surfaces. Use a HEPA 

vacuum on porous surfaces and wet wipe nonporous surfaces. Clean tables in the 

range after each qualification, and clean classroom tables daily. Sample surfaces that 

employees regularly contact using NIOSH Method 9100 [NMAM 2013] to ensure that 

the surfaces are “free as practicable of accumulations of lead” according to the OSHA

lead standard [29 CFR 1910.1025(h)(1)].

8. Provide educational materials and prevention information about the health effects of 

exposure to lead and noise to all personnel on an annual basis. Include information 

about the risks of take-home exposure.

9. Perform medical surveillance for lead on instructors and the hazardous materials 

technician according to the expert guidelines outlined in Appendix B. Reviewers of 

audiograms should consider the effects of ototoxins, such as lead, on hearing loss.

Personal Protective Equipment

Personal protective equipment is the least effective means for controlling hazardous 

exposures. Proper use of personal protective equipment requires a comprehensive program 

and a high level of employee involvement and commitment. The right personal protective 

equipment must be chosen for each hazard. Supporting programs such as training, changeout schedules, and medical assessment may be needed. Personal protective equipment should 

not be the sole method for controlling hazardous exposures. Rather, personal protective 

equipment should be used until effective engineering and administrative controls are in place.

1. Continue wearing dual hearing protection (ear plugs and earmuffs) during weapons 

firing. 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 

shooters and instructors how to properly wear hearing protection.

2. Use a chemical protective glove such as nitrile for skin protection when cleaning 

firearms. Instructors should provide specific guidance to shooters about proper and 

appropriate use of skin protection.
Page 14 Health Hazard Evaluation Report 2012-0065-3195

3. Ensure that the hazardous materials technician wears a respirator with the sealing 

surface positioned directly against the skin to ensure a good face-to-facepiece seal. 

4. Instruct the hazardous materials technician to wear chemical protective gloves and 

keep those gloves on until the contaminated Tyvek suit is discarded and the respirator 

removed. Use lead removal wipes to clean the respirator.
Health Hazard Evaluation Report 2012-0065-3195 Page 15

Appendix A: Tables

Table A1. Concentrations of lead on personal air samples of 

instructors

Date Instructor ID Sample time

(minutes)

Sample 

concentration

(μg/m3)

6/5/2012 1 483 1.4

2 478 1.6

3 488 1.2

4 488 1.3

5 437 0.87

6/6/2012 1 454 (0.15)*

3 452 3.8

4 369 3.8

6 365 3.5

7 345 0.93

*Concentrations below the MQC (0.44 μg/m3) are listed in the 

table in parentheses to acknowledge uncertainty surrounding 

concentrations below the MQC.

Table A2. Concentrations of lead on personal air samples of 

shooters

Date Shooter

location

Sample time

(minutes)

Sample 

concentration

(μg/m3)

6/5/2012 Lane 1 178 8.1

Lane 2 193 7.4

Lane 6 200 4.0

Lane 8 184 4.0

Lane 9 177 2.2

Lane 12 199 9.0

Lane 16 148 5.3

Lane 18 147 3.8

Lane 20 148 6.0

Lane 30 152 3.2

Lane 32 149 2.7

6/6/2012 Lane 2 161 1.5

Lane 5 159 5.9

Lane 6 159 7.5

Lane 8 161 4.3

Lane 9 193 7.5

Lane 15 158 3.4
Page 16 Health Hazard Evaluation Report 2012-0065-3195

Table A3. Concentrations of lead in area air samples 

Location Sample time

(minutes)

Sample concentration

(μg/m3)

Firing range 562 3.3

Range officer desk 575 1.3

Hazardous materials technician office 563 (0.29)*

Armory 530 (0.18)*

Firearms cleaning table 577 (0.13)*

Classroom 578 ND†

Lunchroom 562 ND†

Administration office 530 ND†

*Concentrations between the MDC (0.09 μg/m3) and MQC (0.33 μg/m3) are listed in the table in 

parentheses to acknowledge uncertainty surrounding concentrations below the MQC.

†Below the MDC (0.09 μg/m3)

Table A4. Concentrations of lead in surface vacuum samples 

Location Sample concentration

(μg/100cm2)

Mat between range and offices 22

Men’s bathroom rug 16

Instructor #8 vehicle – floor 14

Work vehicle Insight license #221649 – floor 14

Hazardous materials technician’s office carpeted floor 9.9

Instructor #6 vehicle – floor 7.9

Instructor #1 vehicle – seat 7.6

Hazardous materials technician’s personal vehicle – seat 6.3

Main entry rug 6.1

Instructor #5 vehicle – seat 5.8

Work vehicle Suburban license #221856 – floor 4.9

Work vehicle Insight license #221649 – seat 4.5

Instructor #6 vehicle – seat 3.3

Defensive tactics rug 3.1

Shooter vehicle – floor 2.6

Instructor #9 vehicle – floor 2.3

Work vehicle Suburban license #221856 – seat 1.2

Work vehicle F250 – seat 0.72

Instructor #9 vehicle – seat 0.68

Instructor #1 vehicle – floor 0.34
Health Hazard Evaluation Report 2012-0065-3195 Page 17

Table A5. Concentrations of lead in surface wipe samples 

Location Sample concentration 

(μg/100cm2)

Hazardous materials technician’s work vehicle – floor 120

Hazardous materials technician’s changing area 96

Armory/vault – top of cabinet 84

Work vehicle F350 – floor 74

Hazardous materials technician’s respirator mask – rubber seal and inside 40

Hazardous materials technician’s respirator – battery and motor 33

Hazardous materials technician’s personal vehicle – floor 21

Work vehicle F250 – floor 21

Floor outside range door 19

Gun cleaning table 16

Range officer station 13

Hazardous materials technician’s work vehicle – seat 13

Range – table 11

Hazardous materials technician’s office table 6.6

Classroom – near microwave 5.6

Women’s restroom – floor 4.6

Work vehicle Tahoe license #221876 – armrest 4.2

Defensive tactics – classroom desk 3.3

Men’s locker room – floor 2.8

Main entrance – floor 2.3

Supervisor’s cubicle – floor 2.0

Instructor #5 vehicle – floor 1.7

Work vehicle Tahoe license #6EUR826 – driver door handle 1.6

Secretary’s office – top of cabinet 1.3

Defensive tactics – mat 1.3

Supervisor’s cubicle – desk 1.2

Lunchroom – cubicle (0.95)*

Shooter vehicle – seat (0.46)*

Lunchroom – table ND†

Lunchroom – counter ND†

Supervisory border patrol agent’s desk ND†

Instructor #8 vehicle – seat ND†

*Concentrations between the MDC (0.4 μg/100cm2) and MQC (1.2 μg/100cm2) are listed in the table 

in parentheses to acknowledge uncertainty surrounding concentrations below the MQC.

†Below the MDC (0.4 μg/100cm2)
Page 18 Health Hazard Evaluation Report 2012-0065-3195

Table A6. Bay 1 ventilation flow rates (feet per minute) measured on June 7, 2012

Firing lane # Firing line, Target 1.5m Firing line, Target 25m Bullet trap

(~3 feet*) (~5 feet*) (~3 feet*) (~5 feet*) (~3 feet*) (~5 feet*)

1 80 64 101 61 37 52

2 51 96 58 82 45 40

3 79 60 81 60 40 46

4 96 89 70 70 50 50

5 85 100 80 85 46 52

6 77 64 76 75 53 55

7 94 105 78 108 45 50

8 85 81 74 85 46 59

Average 81 82 77 78 45 51

Total average 80 48

*Height at which the rate of airflow was measured

Table A7. Bay 2 ventilation flow rates (feet per minute) measured on June 7, 2012

Firing lane # Firing line, Target 1.5m Firing line, Target 25m Bullet trap

(~3 feet*) (~5 feet*) (~3 feet*) (~5 feet*) (~3 feet*) (~5 feet*)

9 74 61 51 68 31 36

10 66 94 71 78 35 37

11 34 85 55 44 38 37

12 69 54 72 53 29 44

13 75 59 84 62 34 30

14 83 85 91 84 30 43

15 121 134 102 117 32 42

16 106 94 85 121 65 72

Average 79 83 76 78 37 43

Total average 79 40

*Height at which the rate of airflow was measured

Table A8. Bay 3 ventilation flow rates (feet per minute) measured on June 7, 2012

Firing lane # Firing line, Target 1.5m Firing line, Target 25m Bullet trap

(~3 feet*) (~5 feet*) (~3 feet*) (~5 feet*) (~3 feet*) (~5 feet*)

17 60 93 76 78 47 32

18 68 80 90 95 37 50

19 43 60 74 50 54 43

20 47 27 40 36 31 37

21 40 32 49 49 32 44

22 67 88 81 80 55 37

23 87 87 94 101 44 49

24 65 96 76 74 54 48

Average 60 70 73 70 44 43

Total average 68 44

*Height at which the rate of airflow was measured
Health Hazard Evaluation Report 2012-0065-3195 Page 19

Table A9. Bay 4 ventilation flow rates (feet per minute) measured on June 7, 2012

Firing lane # Firing line, Target 1.5m Firing line, Target 25m Bullet trap

(~3 feet*) (~5 feet*) (~3 feet*) (~5 feet*) (~3 feet*) (~5 feet*)

25 80 114 102 97 65 42

26 79 69 66 89 41 50

27 92 73 98 89 38 38

28 95 76 71 83 39 50

29 53 68 49 55 42 43

30 44 88 54 59 46 53

31 84 83 77 111 58 60

32 79 91 61 69 46 55

Average 76 83 72 82 47 49

Total average 78 48

*Height at which the rate of airflow was measured

Table A10. Full-shift noise dosimetry results for instructors and the hazardous materials technician

Date Job title Duration 

(hours:minutes)

OSHA AL OSHA PEL NIOSH REL

TWA

8-hr*

(dBA)

Dose

(%)

TWA

8-hr*

(dBA)

Dose

(%)

TWA

8-hr*

(dBA)

Dose

(%)

Day 1 Instructor 8:07 101 485 101 474 110 30,189

Day 1 Instructor 8:06 101 435 100 421 109 25,793

Day 1 Instructor 8:08 100 412 100 403 109 26,294

Day 1 Instructor 7:15 100 410 100 398 109 22,417

Day 2 Instructor 7:32 100 405 100 396 109 24,283

Day 2 Instructor 7:01 99 331 98 323 108 21,181

Day 2 Instructor 7:35 99 335 99 324 108 19,671

Day 2 Instructor 6:12 99 334 99 327 108 17,806

Day 2 Instructor 6:07 95 205 95 199 106 11,848

Day 2 Technician 5:07 65 3.1 53 0.6 74 7.5

Occupational noise exposure limits 85 50 90 100 85 100

*Projected 8-hour TWA assuming that noise exposures beyond the measured duration were below 

80 dBA.

Table A11. Personal noise dosimetry results for shooters during time in the firing range

Job title Lane Duration

(hours:minutes)

OSHA AL

TWA (dBA)

OSHA PEL

TWA (dBA)

NIOSH REL

TWA (dBA)

Shooter 29 2:37 107 107 115

Shooter 27 2:29 107 107 114

Shooter 5 2:45 106 106 114

Shooter 22 2:30 106 106 114

Shooter 14 2:48 103 103 111

Shooter 10 2:40 104 103 112
Page 20 Health Hazard Evaluation Report 2012-0065-3195

Appendix B: Occupational Exposure Limits and 

Health Effects

NIOSH investigators refer to mandatory (legally enforceable) and recommended OELs for 

chemical, physical, and biological agents when evaluating workplace hazards. OELs have 

been developed by federal agencies and safety and health organizations to prevent 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 if their exposures are maintained below these levels. Some may have 

adverse health effects because of individual susceptibility, a pre-existing medical condition, 

or a hypersensitivity (allergy). In addition, some hazardous substances act in combination 

with other exposures, with the general environment, or with medications or personal habits of 

the employee to produce adverse health effects. Most OELs address airborne exposures, but 

some substances can be absorbed directly through the skin and mucous membranes.

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

a normal 8- to 10-hour workday. Some chemical substances and physical agents have 

recommended short-term exposure limit or ceiling values. Unless otherwise noted, the shortterm exposure limit is a 15-minute TWA exposure. It should not be exceeded at any time 

during a workday. The ceiling limit should not be exceeded at any time.

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; 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. 

These limits are 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 and the adequacy of methods to identify and control the hazard. NIOSH 

RELs are published in the NIOSH Pocket Guide to Chemical Hazards [NIOSH 2010]. 

NIOSH also recommends 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.

● Other OELs commonly used and cited in the United States include the threshold limit 

values (TLVs), which are recommended by ACGIH, a professional organization, 

and the workplace environmental exposure levels), which are recommended by the 

American Industrial Hygiene Association, another professional organization. The TLVs 

and workplace environmental exposure levels are developed by committee members 

of these associations from a review of the published, peer-reviewed literature. These 

OELs are not consensus standards. TLVs are considered voluntary exposure guidelines 
Health Hazard Evaluation Report 2012-0065-3195 Page 21

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

control of health hazards” [ACGIH 2013]. Workplace environmental exposure levels 

have been established for some chemicals “when no other legal or authoritative limits 

exist” [AIHA 2013].

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

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

Gesetzlichen Unfallversicherung (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/Gefahrstoffdatenbanken/GESTIS-InternationaleGrenzwerte-für-chemische-Substanzen-limit-values-for-chemical-agents/index-2.jsp, contains 

international limits for more than 1,500 hazardous substances and is updated periodically. 

OSHA requires an employer to furnish employees a place of employment free from 

recognized hazards that cause 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))]. This is 

true in the absence of a specific OEL. It also is important to keep in mind that OELs may not 

reflect current health-based information.

When multiple OELs exist for a substance or agent, NIOSH investigators generally 

encourage employers to use the lowest OEL when making risk assessment and risk 

management decisions. NIOSH investigators also encourage use of the hierarchy of controls 

approach to eliminate or minimize 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). Control banding, a qualitative risk assessment and risk 

management tool, is a complementary approach to protecting employee health. Control 

banding focuses on how broad categories of risk should be managed. Information on control 

banding is available at http://www.cdc.gov/niosh/topics/ctrlbanding/. This approach can be 

applied in situations where OELs have not been established or can be used to supplement 

existing OELs.

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 

Inorganic lead is a naturally occurring, soft metal that has been mined and used in industry 

since ancient times. It comes in many forms (e.g., lead acetate, lead chloride, lead chromate, 

lead nitrate, lead oxide, lead phosphate, and lead sulfate). Lead is considered toxic to all 

organ systems and serves no useful purpose in the body. 
Page 22 Health Hazard Evaluation Report 2012-0065-3195

Occupational exposure to inorganic lead occurs via inhalation of lead-containing dust and 

fume and ingestion of lead particles from contact with lead-contaminated surfaces. When 

careful attention to hygiene, particularly hand washing is not practiced, smoking cigarettes 

or eating may create another route of exposure among workers who handle lead and then 

transfer it to their mouth through hand contamination. In addition to the inhalation and 

ingestion routes of exposure, lead can be absorbed through the skin [Stauber et al. 1994; Sun 

et al. 2002; Filon et al. 2006]. Workplace settings with exposure to lead and lead compounds 

include smelting and refining, scrap metal recovery, automobile radiator repair, construction 

and demolition (including abrasive blasting), and firing ranges. Occupational exposures also 

occur among workers who apply or remove lead-based paint and among welders who burn or 

torch-cut metal structures. 

Blood Lead Levels

In most cases, an individual's BLL is a good indication of recent exposure to lead because 

the half-life of lead (the time interval it takes for the quantity in the body to be reduced 

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

2005; CDC 2013a]. Most lead in the body is stored in the bones, with a half-life of years 

to decades. Measuring bone lead, however, is primarily done only for research. 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 monitoring the BLL over time is more specific for evaluating chronic occupational 

lead exposure.

BLLs in adults in the United States have declined consistently over time. In the last 10 years 

alone, the geometric mean BLL went from 1.75 μg/dL to 1.23 μg/dL [CDC 2013b]. The 

NIOSH Adult Blood Lead Epidemiology and Surveillance System uses a surveillance case 

definition for an elevated BLL in adults of 10 μg/dL of blood or higher [CDC 2012a].

Occupational Exposure Limits

In the United States, employers in general industry are required by law to follow the OSHA 

lead standard (29 CFR 1910.1025). This standard was established in 1978 and has not yet been 

updated to reflect the current scientific knowledge regarding the health effects of lead exposure. 

Under this standard, the PEL for airborne exposure to lead is 50 μg/m3 of air for an 8-hour 

TWA. The standard requires lowering the PEL for shifts that exceed 8 hours, medical 

monitoring for employees exposed to airborne lead at or above the action level 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. 

In the United States, other guidelines for lead exposure, which are not legally enforceable, 

are often followed. Similar to the OSHA lead standard, these guidelines were set years ago 

and have not yet been updated to reflect current scientific knowledge. 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. 

The ACGIH designates lead as an animal carcinogen [ACGIH 2013].
Health Hazard Evaluation Report 2012-0065-3195 Page 23

Health Effects

The PEL, REL, and TLV were intended to prevent overt symptoms of lead poisoning, but 

were not set at levels that would protect workers from lead’s contributions to conditions such 

as hypertension, renal dysfunction, and reproductive and cognitive effects [Schwartz and 

Hu 2007; Schwartz and Stewart 2007; Brown-Williams et al. 2009; Institute of Medicine 

2012]. Generally, acute lead poisoning with symptoms has been documented in persons 

having BLLs above 70 μg/dL. These BLLs are rare today in the United States, largely as a 

result of workplace controls put in place to comply with current OELs. When present, acute 

lead poisoning can cause myriad adverse health effects including abdominal pain, hemolytic 

anemia, and neuropathy. It has, in very rare cases, progressed to encephalopathy and coma 

[Moline and Landrigan 2005]. 

People with chronic lead poisoning, which is more likely at current exposure levels, may not 

have symptoms or they may have nonspecific symptoms that may not be recognized as being 

associated with lead exposure. These symptoms include headache, joint and muscle aches, 

weakness, fatigue, irritability, depression, constipation, anorexia, and abdominal discomfort 

[Moline and Landrigan 2005]. 

The National Toxicology Program recently released a monograph on the health effects of 

low-level lead exposure [NTP 2012]. For adults, the NTP concluded the following about the 

evidence regarding health effects of lead (Table B1).

Table B1. Evidence regarding health effects of lead in adults

Health area NTP 

conclusion

Principal health effects Blood lead evidence

Neurological Sufficient Increased incidence of essential tremor Yes, < 10 μg/dL

Limited Psychiatric effects, decreased hearing, 

decreased cognitive function, increased 

incidence of amyotrophic lateral sclerosis

Yes, < 10 μg/dL

Limited Increased incidence of essential tremor Yes, < 5 μg/dL

Immune Inadequate Unclear

Cardiovascular Sufficient Increased blood pressure and increased risk 

of hypertension

Yes, < 10 μg/dL

Limited Increased cardiovascular-related mortality 

and electrocardiography abnormalities

Yes, < 10 μg/dL

Renal Sufficient Decreased glomerular filtration rate Yes, < 5 μg/dL

Reproductive Sufficient Women: reduced fetal growth Yes, < 5 μg/dL

Sufficient Men: adverse changes in sperm parameters 

and increased time to pregnancy

Yes, ≥ 15–20 μg/dL

Limited Women: increase in spontaneous abortion 

and preterm birth

Yes, < 10 μg/dL

Limited Men: decreased fertility Yes, ≥ 10 μg/dL

Limited Men: spontaneous abortion Yes, ≥ 31 μg/dL

Inadequate Women and Men: stillbirth, endocrine effects, 

birth defects

Unclear
Page 24 Health Hazard Evaluation Report 2012-0065-3195

Various organizations have assessed the relationship between lead exposure and cancer. 

According to the Agency for Toxic Substances and Disease Registry [ATSDR 2007] and 

the National Toxicology Program [NTP 2011], inorganic lead compounds are reasonably 

anticipated to cause cancer in humans. The International Agency for Research on Cancer 

classifies inorganic lead as probably carcinogenic to humans [WHO 2006]. According 

to the American Cancer Society [ACS 2011], some studies show a relationship between 

lead exposure and lung cancer, but these results might be affected by exposure to cigarette 

smoking and arsenic; some studies show a relationship between lead and stomach cancer, 

and these findings are less likely to be affected by the other exposures. The results of studies 

looking at other cancers, including brain, kidney, bladder, colon, and rectum, are mixed.

Medical Management 

To prevent acute and chronic health effects, a panel of experts published guidelines for 

the management of adult lead exposure [Kosnett et al. 2007]. The complete guidelines are 

available at http://www.cdph.ca.gov/programs/olppp/Documents/medmanagement.pdf. 

The panel recommended BLL testing for all lead-exposed employees, regardless of the 

airborne lead concentration. The panel’s recommendations are outlined in Table B2. These 

recommendations do not apply to pregnant women, who should avoid BLLs > 5 μg/dL. 

Removal from lead exposure should be considered if control measures over an extended 

period do not decrease BLLs to < 10 μg/dL or an employee has a medical condition that 

would increase the risk of adverse health effects from lead exposure. These guidelines are 

endorsed by the California Department of Public Health [CDPH 2009], the Council of State 

and Territorial Epidemiologists [CSTE 2009], and the American College of Occupational 

and Environmental Medicine [ACOEM 2010]; and have been adapted for use by the U.S. 

Department of Defense [DOD 2007]. 

Table B2. Health-based medical surveillance recommendations for lead-exposed employees

Category of exposure Recommendations

All lead exposed workers •	 Baseline or preplacement medical history and physical 

examination, baseline BLL, and serum creatinine

BLL < 10 μg/dL •	 BLL monthly for first 3 months placement, or upon change in task 

to higher exposure, then BLL every 6 months; if BLL increases ≥ 5 

μg/dL, evaluate exposure and protective measures, and increase 

monitoring if indicated

BLL 10–19 μg/dL •	 As above for BLL < 10 μg/dL, plus:

BLL every 3 months; evaluate exposure, engineering controls, and 

work practices; consider removal

•	 Revert to BLL every 6 months after 3 BLLs < 10 μg/dL

BLL ≥ 20 μg/dL •	 Remove from exposure if repeat BLL measured in 4 weeks 

remains ≥ 20 μg/dL, or if first BLL is ≥ 30 μg/dL

•	 Monthly BLL testing

•	 Consider return to work after 2 BLLs < 15 μg/dL a month apart, 

then monitor as above

Adapted from Kosnett et al. 2007
Health Hazard Evaluation Report 2012-0065-3195 Page 25

Take-home Contamination

Occupational exposures to lead can result in exposures to household members, including 

children, from take-home contamination. Take-home contamination occurs when lead dust is 

transferred from the workplace on employees’ skin, clothing, shoes, and other personal items 

to their vehicle and home [CDC 2009, 2012b]. 

The CDC considers a BLL in children of 5 μg/dL or higher as a reference level above which 

public health actions should be initiated, and states that no safe BLL in children has been 

identified [CDC 2013a].

The U.S. Congress passed the Workers’ Family Protection Act in 1992 (29 U.S.C. 671a). 

The Act required NIOSH to study take-home contamination from workplace chemicals and 

substances, including lead. NIOSH found that take-home exposure is a widespread problem 

[NIOSH 1995]. Workplace measures effective in preventing take-home exposures were (1) 

reducing exposure in the workplace, (2) changing clothes before going home and leaving 

soiled clothing at work for laundering, (3) storing street clothes in areas separate from work 

clothes, (4) showering before leaving work, and (5) prohibiting removal of toxic substances 

or contaminated items from the workplace. NIOSH noted that preventing take-home 

exposure is critical because decontaminating homes and vehicles is not always effective. 

Normal house cleaning and laundry methods are inadequate, and decontamination can expose 

the people doing the cleaning and laundry. 

Noise

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

It is caused by damage to the nerve cells of the inner ear and cannot be treated medically 

[Berger et al. 2003]. More than 22 million U.S. workers are estimated to be exposed to 

workplace noise levels above 85 dBA [Tak et al. 2009] and are at risk of noise-induced 

hearing loss [NIOSH 1998]. 

Although hearing ability commonly declines with age, exposure to excessive noise can 

increase the rate of hearing loss. In most cases, noise-induced hearing loss develops slowly 

from repeated exposure to noise over time, but the progression of hearing loss is typically 

the greatest during the first several years of noise exposure. Noise-induced hearing loss can 

also result from a single noise exposure or short duration noise exposures, depending on the 

intensity of the noise and the individual’s susceptibility [Berger et al. 2003]. Noise exposed 

workers can develop substantial hearing loss before it is clearly recognized. Even mild 

hearing losses can impair a person’s ability to understand speech and hear many important 

sounds. Some people with noise-induced hearing loss also develop “tinnitus.” Tinnitus is 

a condition in which a person perceives hearing sound in one or both ears, but no external 

sound is present. Persons with tinnitus often describe hearing ringing, hissing, buzzing, 

whistling, clicking, or chirping like crickets. Currently, no cure for tinnitus exists.

The preferred unit for reporting of noise measurements is the dBA. A-weighting is used 

because it approximates the “equal loudness perception characteristics of human hearing for 
Page 26 Health Hazard Evaluation Report 2012-0065-3195

pure tones relative to a reference of 40 dB at a frequency of 1,000 Hz” and is considered to 

provide a better estimation of hearing loss risk than using unweighted or other weighting 

measurements [Earshen 2003]. 

Employees exposed to noise should have baseline and yearly hearing tests to evaluate their 

hearing thresholds and determine whether their hearing has changed over time. Hearing 

testing should be done in a quiet location. In workplace hearing conservation programs, 

hearing thresholds must be measured at 500, 1000, 2000, 3000, 4000, and 6000 Hz. 

Additionally, NIOSH recommends that 8,000 Hz should also be tested [NIOSH 1998]. The 

OSHA hearing conservation standard requires analysis of changes from baseline hearing 

thresholds to determine if the changes are substantial enough to meet OSHA criteria for a 

standard threshold shift. OSHA defines a standard threshold shift as a change in hearing 

threshold relative to the baseline hearing test of an average of 10 dB or more at 2000, 

3000, and 4000 Hz in either ear [29 CFR 1910.95]. If a standard threshold shift occurs, the 

company must determine if the hearing loss also meets the requirements to be recorded on 

the OSHA 300 Log of Injury and Illness [29 CFR 1904.1]. In contrast to OSHA, NIOSH 

defines a significant threshold shift as an increase in the hearing threshold level of 15 dB or 

more, relative to the baseline audiogram, at any test frequency in either ear measured twice in 

succession [NIOSH 1998]. 

NIOSH has an REL for noise of 85 dBA, as an 8-hour TWA. For calculating exposure limits, 

NIOSH uses a 3-dB time/intensity trading relationship, or exchange rate. Exposure to impulsive 

noise should never exceed 140 dBA. For extended work shifts NIOSH adjusts the REL. When 

noise exposures exceed the REL, NIOSH recommends the use of hearing protection and 

implementation of a hearing loss prevention program [NIOSH 1998]. 

The OSHA noise standard specifies a PEL of 90 dBA and an action level of 85 dBA, both as 

8-hour TWAs. OSHA uses a less conservative 5-dB exchange rate for calculating the PEL 

and action level. Exposure to impulsive or impact noise must not exceed 140 dB peak noise 

level. OSHA does not adjust the PEL for extended work shifts. However, the action level 

is adjusted. OSHA requires implementation of a hearing conservation program when noise 

exposures exceed the action level [29 CFR 1910.95].
Health Hazard Evaluation Report 2012-0065-3195 Page 27

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Page 32 Health Hazard Evaluation Report 2012-0065-3195

Keywords: North American Industry Classification System 928110 (National Security), 

lead, noise, ventilation, indoor firing range, take home
Health Hazard Evaluation Report 2012-0065-3195 Page 33

The Health Hazard Evaluation Program investigates possible health hazards in the 

workplace under the authority of the Occupational Safety and Health Act of 1970 (29 

U.S.C. § 669(a)(6)). The Health Hazard Evaluation Program also provides, upon request, 

technical assistance to federal, state, and local agencies to investigate occupational health 

hazards and to prevent occupational disease or injury. Regulations guiding the Program 

can be found in Title 42, Code of Federal Regulations, Part 85; Requests for Health Hazard 

Evaluations (42 CFR Part 85).

Disclaimer

The recommendations in this report are made on the basis of the findings at the workplace 

evaluated and may not be applicable to other workplaces.

Mention of any company or product in this report does not constitute endorsement by the 

National Institute for Occupational Safety and Health (NIOSH).

Citations to Web sites external to NIOSH do not constitute NIOSH endorsement of the 

sponsoring organizations or their programs or products. NIOSH is not responsible for the 

content of these Web sites. All Web addresses referenced in this document were accessible 

as of the publication date.

Acknowledgments 

Analytical Support: Bureau Veritas North America

Desktop Publishers: Greg Hartle and Mary Winfree 

Editor: Ellen Galloway 

Logistics: Donnie Booher and Karl Feldmann

Availability of Report

Copies of this report have been sent to the employer, employees, and union at the complex 

The state and local health department and the OSHA Regional Office have also received a 

copy. This report is not copyrighted and may be freely reproduced. 

This report is available at http://www.cdc.gov/niosh/hhe/reports/pdfs/2012-0065-3195.pdf.

Recommended citation for this report:

NIOSH [2013]. Health hazard evaluation report: followback evaluation 

of lead and noise exposures at an indoor firing range. By Ramsey JG, 

Niemeier RN, Page E, Chen L, Choi J. 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 

Report No. 2012-0065-3195.
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