NIOSH HEALTH HAZARD EVALUATION REPORT 

HETA #2000-0191-2960 

Immigration and Naturalization Service (INS) 

National Firearms Unit (NFU) 

Altoona, Pennsylvania 

May 2005 

DEPARTMENT OF HEALTH AND HUMAN SERVICES 

Centers for Disease Control and Prevention 

National Institute for Occupational Safety and Health

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

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

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

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

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

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

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

PREFACE

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

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

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

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

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

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

potentially toxic effects in such concentrations as used or found. 

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

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

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

endorsement by NIOSH. 

ACKNOWLEDGMENTS AND AVAILABILITY OF REPORT

This report was prepared by Joshua Harney, Bradley King, and Randy Tubbs of HETAB, Division of 

Surveillance, Hazard Evaluations and Field Studies (DSHEFS), and Keith Crouch, Charles Hayden, 

Chucri Kardous, Amir Khan, Leroy Mickelson, and Robert Willson of the Engineering and Physical 

Hazards Branch (EPHB), Division of Applied Research and Technology (DART). Field assistance was 

provided by Melissa Finley. Analytical support was provided by Ardith Grote and DataChem 

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

were performed by Ellen Galloway. 

Copies of this report have been sent to employee and management representatives at INS NFU and the 

OSHA Regional Office. This report is not copyrighted and may be freely reproduced. The report may be 

viewed and printed from the following internet address: http://www.cdc.gov/niosh/hhe. Single copies of 

this report will be available for a period of three years from the date of this report. To expedite your 

request, include a self-addressed mailing label along with your written request to: 

NIOSH Publications Office 

4676 Columbia Parkway 

Cincinnati, Ohio 45226 

800-356-4674 

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

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

obtained from the NIOSH Publications Office at the Cincinnati address. 

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

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

employees for a period of 30 calendar days.
iii 

 Highlights of Health Hazard Evaluation 

Evaluation of Lead and Noise Exposures at an Indoor Firing Range

The National Institute for Occupational Safety and Health (NIOSH) received a management request for a health 

hazard evaluation (HHE) at the US Immigration and Naturalization Service (INS) National Firearms Unit (NFU) in 

Altoona, Pennsylvania. The request cited management concerns about officers’ potential exposure to noise and lead 

in an indoor firing range at the facility. The request resulted in several site visits over the course of more than 2 

years to conduct lead and noise exposure assessments during training and qualification rounds. 

What NIOSH Did

 April 5, 2000: Performed an industrial hygiene 

inspection and qualitative smoke testing for air 

flow patterns. 

 April 19–20, 2000: Assessed lead and noise 

exposures during firearms qualification 

exercises, and captured the firearm-specific 

sound frequency signatures made by weapons 

commonly used by the INS. 

 March 15, 2001: Identified the acoustical 

environmental parameters, conducted 

preliminary noise measurements, and provided 

noise abatement recommendations. 

 June 6, 2001: Conducted a more complete 

assessment of the worst-case noise environment 

during a typical training. 

 March 26, 2002: Performed sampling for 

airborne lead during qualification rounds after 

the removal of a roll-top door on one wall of the 

range. 

 September 25, 2002: Conducted additional lead 

and noise assessment after ventilation 

improvements had been implemented.

What NIOSH Found

 During these surveys, NIOSH investigators 

found excessive levels of lead and noise 

exposures. An inadequate ventilation system 

and certain design characteristics of the range 

were found to be contributing factors to the lead 

exposure. 

What INS NFU Managers Can Do

 Investigate the feasibility of using a completely 

lead-free practice round. 

 Install new diffusers on lanes near the end of the 

firing range shown to be areas of higher lead and 

carbon monoxide exposure. New diffusers 

installed at a lower height equal to diffusers in 

the other lanes will improve laminar airflow 

across the firing line. 

 Train employees in the proper use of hearing 

protection. Observations of earplugs that barely 

entered the ear canal and of earmuffs placed on 

officers’ legs or heads when not in use show that 

the users of these devices need to be instructed 

on proper use. 

What INS NFU Employees Can Do 

 Wash their face and hands thoroughly upon 

leaving the range and before eating, drinking, or 

smoking. 

 Use double hearing protection during 

qualification rounds to reduce noise exposure in 

the firing range to a safer level. 

Highlights of the NIOSH Health Hazard Evaluation

What To Do For More Information:

We encourage you to read the full report. If you 

would like a copy, either ask your health and 

safety representative to make you a copy or call 

1-513-841-4252 and ask for 

HETA Report #2000-0191-2960
iv 

Health Hazard Evaluation Report 2000-0191-2960

Immigration and Naturalization Service 

National Firearms Unit 

Altoona, Pennsylvania 

May 2005 

Joshua Harney, Bradley King, Randy Tubbs of HETAB/DSHEFS; Keith Crouch, 

Charles Hayden, Chucri Kardous, Amir Khan, Leroy Mickelsen, Robert Willson of 

EPHB/DART 

SUMMARY

On March 17, 2000, the National Institute for Occupational Safety and Health (NIOSH) received a 

management request for a health hazard evaluation (HHE) at the US Immigration and Naturalization 

Service (INS) National Firearms Unit (NFU) in Altoona, Pennsylvania. The request resulted in several 

site visits over the course of more than 2 years to conduct lead and noise exposure assessments during 

training and qualification rounds at the facility. During these surveys, NIOSH investigators sampled for 

lead and noise and found excessive levels of both. An inadequate ventilation system and certain design 

characteristics of the range were found to be contributing factors to the lead exposure. Recommendations 

were made for ventilation and design improvements, and for noise exposure reduction. 

Over several site visits conducted at the facility, NIOSH investigators concluded that 

health hazards existed at the times of the evaluations. The facility has since taken several 

steps to mitigate these hazards, including implementing of many of the recommendations 

proposed by the NIOSH investigators. Recommendations in the final interim letter have 

not yet been implemented due to lack of funding. However, NFU management has 

expressed a desire to continue working with NIOSH investigators before implementing 

any new controls should funding become available. The contents of this document 

present no new information; rather, it is a compilation of the letters and reports already 

sent individually to INS NFU management over the course of the investigation. 

Keywords: Firing ranges, lead, noise, shooting ranges, HVAC, ventilation, carbon monoxide (Police 

Protection). Sic: 9221, NAICS: 922120
Table of Contents 

Preface..........................................................................................................................................................ii

Acknowledgments and Availability of Report..........................................................................................ii

Highlights of Health Hazard Evaluation .................................................................................................iii

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

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

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

Evaluation Criteria .....................................................................................................................................1

Lead..........................................................................................................................................................2

Carbon Monoxide ...................................................................................................................................3

Ventilation ...............................................................................................................................................3

Noise .........................................................................................................................................................4

Methods and Results: Lead, Carbon Monoxide, and Ventilation ..........................................................5

April 2000 ................................................................................................................................................5

March 2002..............................................................................................................................................7

September 2002 .......................................................................................................................................8

Methods and Results: Noise .......................................................................................................................9

April 2000 ................................................................................................................................................9

March 2001............................................................................................................................................11

June 2001 ...............................................................................................................................................12

September 2002 .....................................................................................................................................13

Discussion and Conclusions .....................................................................................................................14

Lead........................................................................................................................................................14

Ventilation .............................................................................................................................................15

Noise .......................................................................................................................................................17

Recommendations.....................................................................................................................................19

Lead........................................................................................................................................................19

Ventilation .............................................................................................................................................19

Noise .......................................................................................................................................................20

Reference ...................................................................................................................................................23
Health Hazard Evaluation Report No. 2000-0191-2960 Page 1 

INTRODUCTION

In March 2000, the National Institute for 

Occupational Safety and Health (NIOSH) 

received a request for a health hazard evaluation 

(HHE) from the Eastern Region office of the US 

Department of Justice, Immigration and 

Naturalization Service (INS). The request cited 

management concerns about officers’ potential 

exposure to noise and airborne lead in an indoor 

firing range at the National Firearms Unit (NFU) 

in Altoona, Pennsylvania. 

NIOSH investigators visited the INS NFU on 

April 5, 2000, to conduct an opening conference, 

industrial hygiene inspection, and qualitative 

smoke testing. On April 19 and 20, 2000, 

NIOSH investigators returned to the NFU to 

assess lead and noise exposures during firearms 

qualification exercises, and to capture the 

firearm-specific sound frequency signatures 

made by weapons commonly used at the INS. 

This frequency analysis of the noise made while 

discharging a firearm was done to determine the 

attenuation characteristics needed for noise 

control and hearing protection devices (HPDs). 

On March 15, 2001, NIOSH investigators 

conducted a site visit to identify the acoustical 

environmental parameters, conduct preliminary 

noise measurements, and provide noise 

abatement recommendations. The NIOSH 

investigators returned to the facility on June 6, 

2001, to conduct a more complete assessment of 

the worst-case noise environment during a 

typical training or simulated session with 

numerous agents. Interim letters conveyed 

the results of these evaluations. An interim 

letter (July 5, 2001) detailed specific 

recommendations for reducing the lead 

exposures to the lowest technically feasible 

levels by improving the performance of the 

ventilation system of the main indoor firing 

range. In March 2002, a site visit was conducted 

after portions of the recommendations had been 

implemented, specifically removing a roll-top 

door on one wall of the range. This was 

followed by a site visit in September 2002 to 

conduct additional lead and noise assessment 

after ventilation improvements had been 

implemented. The results from the September 

2002 site visit prompted recommendations for a 

last round of improvements. However, due to 

lack of funding, the INS NFU was unable to 

implement these recommendations. 

BACKGROUND

The NFU is comprised of three main buildings. 

The first houses the INS agents’ offices, the 

armory from which all weapons are issued to the 

field, and various workshops where gunsmiths 

repair and test the weapons. The second building 

houses a small indoor firing range in which 

ballistics testing is completed for each lot of 

ammunition purchased by the NFU. The third 

building (and focus of this HHE) is the new 

training facility that houses a training classroom 

and the 20-lane indoor firing range. Its 

construction was completed in the fall of 1999. 

This larger range is ventilated by two rooftop 

heating, ventilation, and air conditioning 

(HVAC) units, while the adjacent classroom and 

storage rooms are served by separate general 

ventilation units. The bullet trap is directly 

exhausted by a dust collection unit (DCU) 

located outside the building. 

Housekeeping activities downrange from the 

firing line (sweeping, mopping, bullet trap waste 

collection, DCU filter replacement) are done by 

a hazardous waste disposal contractor, except for 

shooters collecting spent shell casings. 

Housekeeping activities uprange of the firing 

line are performed by onsite personnel. Shooters 

collect the empty shell casings after each 

shooting exercise using a floor squeegee, a hand 

broom, and a dustpan to deposit the casings into 

5-gallon buckets. The uprange floor is mopped 

weekly by housekeeping personnel. 

EVALUATION CRITERIA

As a guide to the evaluation of the hazards posed 

by workplace exposures, NIOSH field staff 

employ environmental evaluation criteria for the 

assessment of a number of chemical and 

physical agents. These criteria are intended to 

suggest levels of exposure to which most 

workers may be exposed up to 10 hours per day, 
Page 2 Health Hazard Evaluation Report No. 2000-0191-2960

40 hours per week for a working lifetime 

without experiencing adverse health effects. It 

is, however, important to note that not all 

workers will be protected from adverse health 

effects even though their exposures are 

maintained below these levels. A small 

percentage may experience adverse health 

effects because of individual susceptibility, a 

pre-existing medical condition, and/or a 

hypersensitivity (allergy). In addition, some 

hazardous substances may act in combination 

with other workplace exposures, the general 

environment, or with medications or personal 

habits of the worker to produce health effects 

even if the occupational exposures are controlled 

at the level set by the criterion. These combined 

effects are often not considered in the evaluation 

criteria. Also, some substances are absorbed by 

direct contact with the skin and mucous 

membranes, and thus potentially increases the 

overall exposure. Finally, evaluation criteria 

may change over the years as new information 

on the toxic effects of an agent become 

available. 

The primary sources of environmental 

evaluation criteria for the workplace are: (1) 

NIOSH recommended exposure limits (RELs),1

(2) the American Conference of Governmental 

Industrial Hygienists’ (ACGIH®) Threshold 

Limit Values (TLVs®),2

 and (3) the U.S. 

Department of Labor, Occupational Safety and 

Health Administration (OSHA) permissible 

exposure limits (PELs).3

 Employers are 

encouraged to follow the OSHA limits, the 

NIOSH RELs, the ACGIH TLVs, or whichever 

are the more protective criteria. 

OSHA requires an employer to furnish 

employees a place of employment that is free 

from recognized hazards that are causing or are 

likely to cause death or serious physical harm 

[Occupational Safety and Health Act of 1970, 

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

employers should understand that not all 

hazardous chemicals have specific OSHA 

exposure limits such as PELs and short-term 

exposure limits (STELs). An employer is still 

required by OSHA to protect their employees 

from hazards, even in the absence of a specific 

OSHA PEL. 

A time-weighted average (TWA) exposure 

refers to the average airborne concentration of a 

substance during a normal 8- to 10-hour 

workday. Some substances have recommended 

STEL or ceiling values which are intended to 

supplement the TWA where there are 

recognized toxic effects from higher exposures 

over the short-term. 

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 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 lead exposure include weakness, 

excessive tiredness, irritability, constipation, 

anorexia, abdominal discomfort (colic), fine 

tremors, and "wrist drop."4,5,6 Overexposure to lead 

may also result in kidney damage, anemia, high 

blood pressure, infertility and reduced sex drive in 

both sexes, and impotence. An individual's blood 

lead level (BLL) is a good indication of recent 

exposure to, and current absorption of lead.7

 The 

frequency and severity of symptoms associated 

with lead exposure generally increase with the 

BLL. The overall geometric mean BLL for the U.S. 

adult population (ages 20–74 years) declined 

significantly between 1976 and 1991, from 13.1 to 

3.0 micrograms per deciliter of blood (μg/dL). This 

decline is most likely due primarily to the reduction 

of lead in gasoline. More than 90% of adults now 

have a BLL of <10 μg/dL, and more than 98% 

have a BLL <15 μg/dL.8

Under the OSHA general industry lead standard 

(29 CFR 1910.1025), the PEL for airborne 

exposure to lead is 50 micrograms per cubic meter 

(μg/m3

) (8-hour TWA).9 The standard requires 

lowering the PEL for shifts exceeding 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 
Health Hazard Evaluation Report No. 2000-0191-2960 Page 3 

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 a 8-hour work 

shift. 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.2

The occupational exposure criteria are not 

protective for all the known health effects of lead. 

For example, studies have found neurological 

symptoms in workers with BLLs of 40 to 

60 μg/dL, and decreased fertility in men with 

BLLs as low as 40 μg/dL. BLLs are associated 

with increased blood pressure, even at levels less 

than 10 μg/dL. Fetal exposure to lead is associated 

with reduced gestational age, low birth weight, and 

early mental development with maternal BLLs as 

low as 10 to 15 μg/dL.10 Men and women who are 

planning on having children should limit their 

exposure to lead. 

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.11 Particular 

effort should be made to ensure that children of 

persons who work in areas of high lead exposure 

receive a BLL test. 

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-tomouth contact with contaminated clothing, 

cigarettes, or food. Previous studies have found a 

significant correlation between resident children’s 

BLLs and house dust lead levels.12 No current 

federal standard provides a permissible limit for 

lead contamination of surfaces in occupational 

settings. The Environmental Protection Agency 

(EPA) currently recommends meeting the 

following clearance levels for surface lead loading 

after residential lead abatement or interim control 

activities: floors, 40 micrograms per square foot 

(μg/ft2

); interior window sills, 250 μg/ft2; window 

troughs, 400 μg/ft2

.

13 These levels have been 

established as achievable through lead abatement 

and interim control activities, they are not based on 

projected health effects associated with specific 

surface dust levels. 

Carbon Monoxide 

Carbon monoxide (CO) is a colorless, odorless, 

tasteless gas produced by incomplete burning of 

carbon-containing materials. The initial symptoms 

of CO poisoning may include headache, dizziness, 

drowsiness, and nausea. These initial symptoms 

may advance to vomiting, loss of consciousness, 

and collapse if prolonged or high exposures are 

encountered. Coma or death may occur if high 

exposures continue.6,14,15,16,17,18 

The NIOSH REL for CO is 35 ppm for an 8-hour 

TWA exposure, with a ceiling limit of 200 ppm 

that should not be exceeded.3,19 The NIOSH REL 

of 35 ppm is designed to protect workers from 

health effects associated with carboxyhemoglobin 

(COHb) levels in excess of 5%.14 The ACGIH 

recommends an 8-hour TWA TLV of 25 ppm.2

The OSHA PEL for CO is 50 ppm for an 8-hour 

TWA exposure. 

Ventilation

To minimize exposures to contaminants resulting 

from weapons fire, ventilation systems of indoor 

firing ranges should provide favorable conditions 

with regard to at least four criteria: filtration 

efficiency, range pressurization, volumetric flow 

rate, and airflow patterns. Any air filtered and re–

circulated through the range must be highefficiency particulate air (HEPA) filtered. Firing 

ranges should be under slight negative pressure so 

that no contaminants escape the range under 

normal operating conditions. The volumetric flow 

rate of air supplied to and exhausted from the range 

should provide a minimum average downrange air 

velocity at the firing line of 50 feet per minute 

(fpm), as recommended in ACGIH’s Industrial 

Ventilation manual.20 Finally, air moving 

downrange in as laminar (nonturbulent) a flow as 

possible, especially near the firing line. Even if the 

range is pressurized correctly and a minimum 
Page 4 Health Hazard Evaluation Report No. 2000-0191-2960

downrange air velocity of 50 fpm is achieved at the 

firing line, range users may still receive excessive 

exposures to lead if large-scale eddies exist that 

create “backflow” and bring contaminated air back 

into their breathing zones. 

Noise 

Noise-induced hearing loss (NIHL) is an 

irreversible, sensorineural condition that progresses 

with exposure. Although hearing ability declines 

with age (presbycusis) in all populations, exposure 

to noise produces hearing loss greater than that 

resulting from the natural aging process. NIHL is 

caused by damage to nerve cells of the inner ear 

(cochlea) and, unlike some conductive hearing 

disorders, limited medical treatment is available for 

acoustic trauma.21 While loss of hearing may result 

from a single exposure to a very brief impulse noise 

or explosion, such traumatic losses are rare. In most 

cases, noise-induced hearing loss is insidious. 

Typically, it begins to develop at 4000 or 6000 Hz 

(the hearing range is 20 Hz to 20000 Hz) and 

spreads to lower and higher frequencies. Often, 

material impairment has occurred before the 

condition is clearly recognized. Such impairment is 

usually severe enough to permanently affect a 

person's ability to hear and understand speech 

under everyday conditions. Although the primary 

frequencies of human speech range from 300 Hz to 

3000 Hz, research has shown that the consonant 

sounds, which enable people to distinguish words 

such as "fish" from "fist," have spectral energy out 

to 6000 and 8000 Hz.22

The A-weighted decibel [dBA] is the preferred unit 

for measuring sound levels to assess worker noise 

exposures. The dBA scale is weighted to 

approximate the sensory response of the human ear 

to sound frequencies near the threshold of hearing. 

The decibel unit is dimensionless, and represents 

the logarithmic relationship of the measured sound 

pressure level to an arbitrary reference sound 

pressure (20 micropascals, the normal threshold of 

human hearing at a frequency of 1000 Hz). Decibel 

units are used because of the very large range of 

sound pressure levels which are audible to the 

human ear. Because the dB scale is logarithmic, 

increases of 3 dB, 10 dB, and 20 dB represent a 

doubling, a tenfold increase, and a 100-fold 

increase of sound energy, respectively. It should be 

noted that noise exposures expressed in decibels 

cannot be averaged by taking the simple arithmetic 

mean. 

The OSHA standard for occupational exposure to 

noise (29 CFR 1910.95)23 specifies a maximum 

PEL of 90 dBA for a duration of 8 hours per day. 

The regulation, in calculating the PEL, uses a 5 dB 

time/intensity trading relationship, or exchange 

rate. This means that a person may be exposed to 

noise levels of 95 dBA for no more than 4 hours, to 

100 dBA for 2 hours, etc. Conversely, up to 16 

hours exposure to 85 dBA is allowed by this 

exchange rate. The duration and sound level 

intensities can be combined in order to calculate a 

worker's daily noise dose according to the formula: 

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

where Cn indicates the total time of exposure at a 

specific noise level and Tn indicates the reference 

duration for that level as given in Table G-16a of 

the OSHA noise regulation. During any 24-hour 

period, a worker is allowed up to 100% of his daily 

noise dose. Doses greater than 100% are in excess 

of the OSHA PEL. 

The OSHA regulation has an additional action level 

(AL) of 85 dBA; an employer shall administer a 

continuing, effective hearing conservation program 

when the 8-hour time-weighted average (TWA) 

value exceeds the AL. The program must include 

monitoring, employee notification, observation, 

audiometric testing, hearing protectors, training, 

and record keeping. All of these requirements are 

included in 29 CFR 1910.95, paragraphs (c) 

through (o). Finally, the OSHA noise standard 

states that when workers are exposed to noise 

levels in excess of the OSHA PEL of 90 dBA, 

feasible engineering or administrative controls shall 

be implemented to reduce the workers' exposure 

levels. 

NIOSH, in its Criteria for a Recommended 

Standard,24 and the ACGIH2

 propose exposure 

criteria of 85 dBA as a TWA for 8 hours, 5 dB less 

than the OSHA standard. The criteria also use a 

more conservative 3 dB time/intensity trading 

relationship in calculating exposure limits. Thus, a 

worker can be exposed to 85 dBA for 8 hours, but 
Health Hazard Evaluation Report No. 2000-0191-2960 Page 5 

to no more than 88 dBA for 4 hours or 91 dBA for 

2 hours. 

NIOSH recommends that exposure to peak 

impulsive noise not exceed 140 dB. The OSHA 

PEL for impulsive noise is also 140 dB for peak-. 

However, peak impulse noise is not the sole factor 

in hearing damage. Other factors such as the 

duration of the impulse and frequency of exposure 

also have an effect on hearing loss. In an indoor 

firing range, reverberation also becomes an 

important factor. 

METHODS AND 

RESULTS: LEAD, 

CARBON MONOXIDE, 

AND VENTILATION

April 2000 

At the time of the April 2000 site visit, a 

corrugated metal overhead roll-top garage door 

was on the range-right wall of the building, 

behind the firing line. This door was used to 

bring in equipment too large to pass through the 

employee entrance. When the range was in use, 

the ventilation system kept the range under 

negative pressure relative to the interior building 

hallways and to the outdoors. To re-establish 

pressure equilibrium, the easiest path for outdoor 

air to enter the range is through the doorframe of 

the overhead door, which is not sealed tightly. 

With the HVAC system running at optimum 

conditions immediately after its construction, the 

closed overhead door constantly flapped and 

distracted the range users. Several months before 

the HHE, the HVAC system was adjusted to 

supply and exhaust less air through the range in 

an attempt to stop the overhead door from 

rattling. 

An INS contractor conducted air sampling for 

lead under these sub-optimum ventilation 

conditions. During that evaluation, area air 

samples were collected at each firing station 

during three consecutive shooting qualification 

exercises (two pistol exercises, one shotgun 

exercise) completed by 19 shooters, taking 3 

hours. Under these conditions, five of the 19 

samples exceeded the OSHA action level of 

30 μg/m3

 as an 8-hour TWA. The contractor 

simulated ‘worst case’ conditions by using a 

course of fire more rigorous than what is typical 

of training at the NFU. Typically, agents training 

at the NFU undergo 1 to 2 hours of indoor range 

use per day, and would not conduct three 

consecutive qualification exercises. 

During the April 2000 site visit by NIOSH 

investigators, all 20 firing stations were used at 

once. Shooters and observers within the range 

were required to wear ear plugs, ear muffs, and 

safety glasses. Each pistol qualification exercise 

consisted of each agent firing 73 rounds of 155 

grain jacketed hollow point .40 Smith and 

Wesson (S&W) ammunition at targets of 

varying distances. The shotgun proficiency 

exercise consisted of each agent firing 30 rounds 

using 12 gauge shotguns, 25 rounds of 23⁄4" 

00 Buck and five 23⁄4" slugs. During all firing 

exercises, the motors controlling the target 

distance on lanes 19 and 20 were not working. 

The shooters using these lanes crossed the firing 

line and manually moved their targets to the 

correct distance downrange at the beginning of 

each portion of the exercise. The shooters using 

the other 18 lanes did not move downrange at 

any time. 

Air sampling for lead was conducted during 

three separate periods of time. During the 

morning of April 19, 2000, 20 shooters 

completed a single pistol qualification exercise; 

personal breathing zone samples (PBZs) were 

collected on 10 of them. That afternoon, the 

same shooters completed two consecutive pistol 

qualification exercises while PBZs were 

collected. On the morning of April 20, 2000, the 

20 shooters completed a single shotgun 

qualification exercise; 10 PBZs were collected 

from those not sampled the previous day. 

Air samples for lead were collected using 

battery-operated personal sampling pumps 

calibrated at a nominal flow rate of 3 liters per 

minute (Lpm) to draw air through a sampling 

train consisting of a length of TygonTM tubing 
Page 6 Health Hazard Evaluation Report No. 2000-0191-2960

and a 37-millimeter (mm) mixed cellulose ester 

filter in a 3-piece cassette. The filter samples 

were analyzed according to NIOSH Manual of 

Analytical Methods (NMAM) Method 7082.25

Each filter was digested with nitric acid and 

analyzed using a Varian FS 220 Flame Atomic 

Absorption Spectrometer. The limit of detection 

(LOD) for this method is 7 micrograms (μg) per 

sample, and the limit of quantitation (LOQ) is 

20 μg/sample. Samples for which the lead 

concentration was below the LOQ were 

subsequently analyzed using a Perkin-Elmer 

Model 5100 Graphite Furnace Atomic 

Absorption Spectrometer with Zeeman 

background correction, according to NMAM 

Method 7105.26 The LOD for this second 

analysis was 0.07 μg/sample and the LOQ was 

0.2 μg/sample. A 250 L sample volume yields a 

minimum detectable concentration (MDC) of 

0.3 micrograms per cubic meter of air (μg/m3

) 

and a minimum quantifiable concentration 

(MQC) of 0.8 μg/m3

 for graphite furnace atomic 

absorption analysis. 

Six Wash’n DriTM wipe samples collected from 

floors, diffusers, and tabletops were analyzed by 

flame atomic absorption spectrometry using a 

Varian FS 220 Flame Atomic Absorption 

Spectrometer according to NIOSH Method 

9100.27 The LOD for this method was 

3 μg/sample, and the LOQ was 8 μg/sample. 

During the initial NIOSH evaluation, airflow 

patterns in the range were observed using a fog 

machine (Roscoe Model 1500TM) to generate a 

visible, non-toxic "smoke." Smoke was released 

at different heights from the floor to shoulder 

height at the firing line at different shooting 

lanes, as well as downrange. Observations were 

made regarding airflow patterns within the range 

and whether the range was under positive or 

negative pressure. A visual inspection of the air 

handling units (AHUs) was made. 

Table 1 lists the air sampling results from the 

single pistol qualification exercise. No sample 

collected during this exercise exceeded the 

OSHA PEL or action level, the NIOSH REL, or 

the ACGIH TLV. During this time period, PBZ 

samples ranged in average concentration (the 

concentration during the time sampled) from 

4 μg/m3

 (shooters on lanes 3, 5, and 7) to 

89 μg/m3

 (shooter on lane 19). Assuming that 

the shooters received no further exposure to 

airborne lead during that work shift, these results 

equate to 8–hr TWAs ranging from 0.4 μg/m3

 to 

10 μg/m3

. Lead was not detected in the PBZ 

sample collected on the range master working in 

the control room or on the area sample collected 

near the West rooftop AHU exhaust (the unit to 

the left as one faces the AHUs from the top of 

the roof hatch). The area sample collected in the 

range before beginning the shooting exercise 

detected only trace amounts of lead. The area 

sample collected inside the range near the rear 

range wall during the shooting exercise had 

3 μg/m3

 lead, indicating that small amounts of 

airborne lead could migrate behind the firing 

line. 

The results from samples collected during two 

consecutive pistol qualifications are shown in 

Table 2. No sample collected during these 

exercises exceeded the OSHA PEL or action 

level, the NIOSH REL, or the ACGIH TLV. 

Average PBZ sample concentrations ranged 

from 4 μg/m3

 (shooter on lane 5) to 159 μg/m3

(shooter on lane 19). Assuming the shooters 

received no other exposure to airborne lead 

during the work shift, these concentrations 

translate into 8-hr TWAs ranging from 1 μg/m3

to 25 μg/m3

. The average concentration detected 

by the sampler near the rear range wall was the 

same as during the single qualification exercise: 

3 μg/m3

. The range master’s PBZ sample 

collected in the control room detected lead, but 

at levels too low to accurately quantify. The line 

safety officer’s 8-hr TWA was 3 μg/m3

. 

Table 3 shows the results of air sampling done 

on April 20, 2000. During the shotgun 

qualification exercise, average lead 

concentrations ranged from trace (shooter on 

lane 6) to 718 μg/m3

 (shooter on lane 20). 

Assuming that shooters received no other 

airborne lead exposure during their work shift, 

this equates to 8-hour TWAs ranging from trace 

to 84 μg/m3

. Two samples exceeded the OSHA 

action level of 30 μg/m3

 on an 8-hr TWA basis; 

one of these was over the REL and PEL of 

50 μg/m3

 8-hr TWA. No lead was detected on 
Health Hazard Evaluation Report No. 2000-0191-2960 Page 7 

the sample collected on the range master in the 

control room, and the line safety officer’s 8-hr 

TWA was 2 μg/m3

. Only a trace amount of lead 

was detected near the East rooftop AHU 

exhaust. One sample, collected in the PBZ of the 

ballistics lab worker in the smaller of the two 

indoor ranges (while evaluating .40 S&W 

handgun ammunition), had an 8-hr TWA of 

3 μg/m3

. This level is similar to that of the range 

users, who had a much higher rate of fire during 

a comparable amount of time. 

There are two likely reasons for the shooters on 

lanes 19 and 20 receiving a much higher 

exposure than their colleagues. First, the inflow 

of air through the overhead roll-top garage door 

immediately behind these firing stations resulted 

in stronger eddies near the firing line and more 

backflow along the adjacent range-right wall 

compared to the range-left wall adjacent to Lane 

1. The second explanation is that these shooters 

had to move downrange several times during 

each qualifier to adjust their target to the proper 

distance from the firing line. This caused them 

to walk through an area of the range with more 

lead aerosol than the area at the firing line, and 

which is not typical of an exposure during 

normal range use. 

All three of the pistol qualification exercises 

were conducted on one day. Therefore, the 

shooters’ total exposure to lead that day was 

greater than the levels listed in either Table 1 or 

2. The shooters’ combined exposures are 

calculated in Table 4. Assuming the agents did 

not receive any other lead exposure beyond that 

of the three pistol qualifications that day, the 8-

hr TWAs ranged from 1 μg/m3

 (shooters on 

lanes 5 and 7) to 35 μg/m3

 (shooter on lane 19). 

The shooter on lane 19 received the only 

combined exposure above the OSHA action 

level. 

The levels of surface lead loading in various 

parts of the range building are shown in Table 5. 

Three of the six samples resulted in nondetectable levels of lead: a supply air diffuser in 

the range, the control room tabletop, and a 

classroom tabletop. The floor at lane 1, and 

between lanes 10 and 11, and the hallway 

leading from the range to the outside door had 

2.9, 8.1, and 1.6 μg/ft2

 lead, respectively. These 

levels are much lower than both the most 

conservative federal limits in residential settings 

and other indoor firing ranges investigated by 

NIOSH.28,29,30 This reflects both the limited use 

of the range thus far and that good housekeeping 

practices are being used. 

In general, without shooters standing at the 

firing line, the supply air effectively pushed the 

smoke emitted by the smoke machine at the 

firing line toward the downrange exhaust plena. 

When the smoke machine was used at Lanes 1 

and 20, the smoke flowed downrange a short 

distance before a portion of it began to migrate 

uprange along the walls. This backflow 

continued to the firing line before it was again 

pushed downrange by the air supplied from the 

rear of the range. This effect was more 

pronounced near lane 20 where the inflow of air 

from the overhead door created air currents that 

drew smoke from downrange of the firing line to 

the uprange side. The smoke machine was not 

used while people were standing at the firing 

line. Immediately before the air sampling was 

done for this HHE, the INS ventilation 

contractor balanced the ventilation system and 

set it as close as possible to its design 

specifications. 

March 2002 

After the roll-top door in the wall of the range 

was replaced with brick, NIOSH conducted a 

lead exposure assessment on March 26, 2002. 

Three shooting periods were monitored: (1) a 

single shotgun qualification; (2) two 

immediately consecutive pistol qualifications 

(double pistol qualification); (3) one single 

pistol qualification. The number of rounds fired 

per qualification was the same as those during 

the April 2000 exposure assessment reported 

above. PBZ samples were collected on shooters 

in the same manner as the previous evaluation. 

Area air samples were also collected along the 

rear range wall behind lanes 3, 9, and 19. The 

same methods were also used in the analysis of 

these samples. 
Page 8 Health Hazard Evaluation Report No. 2000-0191-2960

Air samples for lead were collected using battery 

operated personal sampling pumps calibrated at 

a nominal flow rate of 3 Lpm to draw air 

through a sampling train consisting of a length 

of TygonTM tubing and a 37-mm mixed cellulose 

ester filter in a 3-piece cassette. The filter 

samples were analyzed according to NIOSH 

NMAM Method 7300 modified for microwave 

digestion.31

The results from air sampling conducted March 

26, 2002 are listed in Tables 6, 7, and 8. Table 6 

shows the PBZ exposures received during a 

shotgun qualification and the area air sampling 

results collected during the entire shooting day. 

Eight-hour TWA PBZ levels ranged from 

0.72 μg/m3

 to 9.37 μg/m3 for shotgun users. 

Area samples collected at the rear of the range 

all had quantifiable amounts of lead on them. 

Table 7 shows the 8-hr TWA exposures to 

shooters during consecutive pistol qualifications; 

all exposures were less than 1 μg/m3

. Table 8 

shows that during the last sampling period of the 

day, the single pistol qualification, 8-hr TWA 

exposures were all below 5 μg/m3

. 

September 2002 

After a horsepower upgrade of the fan’s electric 

motor had been made to improve the airflow 

past the firing line, NIOSH investigators 

collected PBZ and area air samples for lead 

during two sessions of qualification exercises on 

September 25, 2002. The first session consisted 

of fifteen shooters completing a single pistol 

qualification round in lanes 2 through 9 and 11 

through 17. PBZ samples were collected on each 

of the shooters and the qualification instructor. 

Area air samples were collected at the firing line 

of two unoccupied lanes (lanes 10 and 18) and at 

the doorway entrance to the range. A second 

round of sampling was performed while 

shotguns were used during the second 

qualification exercise using the same sampling 

protocol. 

Air samples for lead were collected using battery 

operated personal sampling pumps calibrated at 

a nominal flow rate of 3 Lpm to draw air 

through a sampling train consisting of a length 

of TygonTM tubing and a 37-mm mixed cellulose 

ester filter in a 3-piece cassette. The filter 

samples were analyzed according to NIOSH 

NMAM Method 7300 modified for microwave 

digestion.31 The MDC was 0.28 micrograms per 

cubic meter (μg/m3

) calculated using the 

analytical LOD, reported as 0.05 micrograms 

per filter (μg/filter), and a 180-liter sample 

volume. An MQC of 1.1 μg/m3

 was calculated 

using the analytical LOQ of 0.2 μg/filter and a 

180-liter sample volume. 

Additionally, PBZ samples for carbon monoxide 

(CO) were collected using real-time monitoring 

equipment placed on six of the shooters. A 

Biosystems Inc. ToxiUltra Gas Detector 

recorded CO concentrations in the PBZ of the 

shooters every 20 seconds during the 

qualification exercises. The recorded 

measurements were then downloaded to a 

computer. The monitor measures CO 

concentrations from 0–500 parts per million 

(ppm). 

The results from the lead sampling performed on 

September 25, 2002, during a typical pistol 

qualification exercise (consisting of each agent 

firing 72 rounds of 155 grain jacketed hollow 

point .40 S&W ammunition) are summarized in 

Table 9. Calculating an 8-hour TWA from these 

results with the assumption that they were the 

sole lead exposures experienced during the 8-

hour work shift allows comparison to the OSHA 

PEL and the NIOSH REL. Accordingly, the 8-

hour TWA results for these individuals due to 

exposures solely received during the pistol 

qualification exercise ranged from 0.14 μg/m3

 to 

4.04 μg/m3

. Therefore, a single pistol 

qualification round during an 8-hour shift 

appears to cause lead exposure well below 

applicable exposure limits. The performance of a 

single pistol qualification exercise during an 

officer’s shift is a typical scenario. However, if 

individuals were to perform more than one pistol 

qualification exercise during a shift under these 

same conditions, the exposure would be 

expected to increase correspondingly. 

The results from the lead sampling performed 

during a typical shotgun qualification exercise 

(consisting of each agent firing 25 rounds of 
Health Hazard Evaluation Report No. 2000-0191-2960 Page 9 

23⁄4" 00 Buck and five 23⁄4" slugs rounds) are 

summarized in Table 10. Again, assuming no 

other lead exposures were experienced during 

the 8-hour work shift besides that from the 

shotgun qualification exercise, 8-hour TWA 

results for these individuals ranged from 1.0 

μg/m3

 to 59.9 μg/m3. The performance of a 

single shotgun qualification exercise during the 

shift is also a typical scenario. Although 

performing shotgun qualification exercises for a 

full 8-hour shift would be rare, if individuals 

were to perform more than one shotgun 

qualification exercise during a shift, or 

combinations of shotgun and pistol qualification 

exercises, the exposure would be expected to 

increase correspondingly. The results returned 

from sampling performed during the single 

shotgun qualification exercise were considerably 

higher than those returned during the pistol 

exercise, with one sample returning an 8-hour 

TWA result higher than the OSHA PEL and two 

other samples above the OSHA AL of 30 μg/m3

as an 8-hour TWA. 

Figures 1 through 6 show the results of CO 

monitoring conducted on six individuals during 

the qualification rounds. On each figure, two 

identifiable periods of exposure are visible. The 

first period, approximately 2:05 pm to 2:25 pm, 

corresponds to the pistol qualification exercise. 

The second period, corresponding to the shotgun 

qualification exercise, runs from 2:40 pm to 

2:55 pm. Exposure to CO was considerably 

higher during rounds of shooting with the 

shotgun versus the pistol. Although the 8-hour 

TWA exposures for all individuals sampled 

would be quite low, peaks of CO exposure were 

highest in lane 17, with one peak of 294 ppm, 

surpassing the NIOSH-recommended ceiling 

limit of 200 ppm (a level that should not be 

exceeded at any time during a workday). 

METHODS AND 

RESULTS: NOISE

April 2000 

On April 19–20, 2000, NIOSH investigators 

conducted a noise exposure assessment at the 

firing range. Quest® Electronics Model Q-300 

Noise Dosimeters were worn by two officers 

during each of the two pistol qualification 

rounds and one shotgun qualification round. The 

noise dosimeters were attached to the wearer’s 

belt, and a small remote microphone was 

fastened to the wearer’s shirt at a point midway 

between the ear and the outside of the officer’s 

shoulder. At the end of a weapons qualification 

round, the dosimeters were removed and paused 

to stop data collection. Additionally, dosimeters 

were placed in the range master’s control room 

and in the adjacent classroom during 

qualification rounds to collect area 

measurement. The information stored in the 

dosimeters was downloaded to a personal 

computer for interpretation with QuestSuite for 

Windows® computer software. The dosimeters 

were calibrated before and after the 

measurement periods according to the 

manufacturer’s instructions. 

Two officers were asked to wear a noise 

dosimeter during a qualification round for either 

a pistol or shotgun. The pistol qualifications 

consisted of one or two complete rounds of 

weapon firing; the shotgun qualification was 

only one complete round of shooting. All 20 

firing stations were used at once. 

The officers were centrally located on the firing 

line, either in Lanes 7 or 8 and Lanes 12 or 13. 

The dosimeter was placed on the officer shortly 

before the qualification began. For the double 

set of pistol qualifications, the dosimeter 

remained on the officer and recorded noise 

levels for both rounds and the period between 

them. 

The Quest dosimeters collect data so that one 

can directly compare the information with the 

two noise criteria used in this survey, the OSHA 

PEL and Action Level (AL), and the NIOSH 

REL. The OSHA criteria use a 90 dBA criterion 

and 5 dB exchange rate for both the PEL and 

AL. The difference between the two is the 

threshold level employed, with a 90 dBA 

threshold for the PEL and an 80 dBA threshold 

for the AL. The threshold level is the lower limit 

of noise values included in the calculation of the 
Page 10 Health Hazard Evaluation Report No. 2000-0191-2960

criteria; the dosimeter ignores values less than 

the threshold. The NIOSH criterion differs from 

OSHA’s in that the criterion is 85 dBA, the 

threshold is 80 dBA, and it uses a 3 dB exchange 

rate. 

The personal noise dosimeter results are shown 

in Table 11. All data are presented as the 

accumulated dose percentage for the time 

necessary to complete the qualification round 

and as an 8-hr TWA that assumes that the 

remainder of the 8-hour day is spent in noise less 

than 80 dBA. The noise exposure for both 

officers exceeded all the evaluation criteria 

when shooting the pistol either for one or two 

qualification rounds. When the shotgun was 

fired on the range, the TWA levels were less 

than 90 dBA when calculated according to the 

OSHA PEL. However, the recorded levels of 

87 dBA and 88 dBA did exceed the OSHA AL 

of 85 dBA. The NIOSH REL was exceeded by 

18–25 dBA for all qualification conditions. 

The noise levels from the weapons in the control 

room and adjacent classroom were much less 

than for the officers on the firing line. The 

control room noise average ranged from 83 dBA 

to 87 dBA during the qualifications using the 

most conservative evaluation criteria (REL). The 

1-minute noise averages for pistol and shotgun 

qualifications are graphically displayed in 

Figures 7–10 for the control room and 

classroom. The highest level approaches 95 dBA 

in the control room and 80 dBA in the 

classroom. 

During weapons qualification, all officers on the 

firing line and all observers behind the line in 

the range wore double hearing protection, i.e., 

earplugs under earmuffs. The National Firearms 

Unit provided Moldex Purafit® earplugs (6800) 

and Peltor® earmuffs (H7A) at the range. 

Personnel assigned to the Altoona facility had 

been fitted with custom-molded earplugs. Also, 

some of the officers who participated in 

qualification shooting brought their own HPDs 

with them, including sound restoration earmuffs. 

The instructions from the range master were 

delivered to the firing line through an 

amplification system with a microphone in the 

control room and loudspeakers in the range. The 

amplification system was set near or at the 

maximum output level during the weapons firing 

exercise. 

The noise produced by gunfire has sufficient 

intensity to permanently damage the unprotected 

ear in a very short period of time. The damage 

can occur in minutes rather than the days or 

years typical of industrial noise exposure. 

Because of the noise levels in this environment, 

the INS practice of wearing double hearing 

protection is justified. Research has reported that 

double hearing protection can provide the 

additional noise reduction needed in high noiselevel environments.32 This same research 

reported that the earplug was the more important 

component of the double protection, with greater 

attenuation afforded when the earplug was 

properly inserted into the ear canal. Some of the 

participants of weapons qualification and the 

INS officials observing the evaluation had not 

deeply inserted the earplugs before placing the 

earmuffs over their ears. 

Some officers were wearing sound restoration 

earmuffs over earplugs on the firing line. They 

reported that this combination helped them hear 

instructions from the range master while 

wearing double protection. The earmuffs 

amplified the instructions to the wearer as long 

as no weapons were fired. As soon as the firing 

commenced, the amplification system shut off 

and the earmuffs acted as passive, noiseattenuating devices. Many of the officers 

wearing the double protection issued by the INS 

were unable to hear directions from the control 

room, even with the amplification system at or 

near the maximum level. The range master 

attempted to overcome this condition by raising 

his voice and speaking directly into the 

microphone with his mouth nearly touching it. 

The roll top garage door on the wall of the firing 

range rattled whenever the ventilation system 

was set for range use. Air leakage around the 

door frame caused the door to bang into the 

metal frame and the door housing on the top of 

the opening. The intensity of this door noise was 

much less than that from the weapons. By itself 

the door noise is not hazardous to the hearing of 

individuals on the range, but it can annoy and 
Health Hazard Evaluation Report No. 2000-0191-2960 Page 11 

distract officers attempting to be very accurate in 

their shooting. Similarly, noise from the range, 

while not hazardous may annoy and distract 

control room and classroom users. This finding 

is more critical for the classroom if the INS 

intends to use it for training simultaneously with 

use of the indoor firing range. The shots on the 

range were audible in the classroom; an 

instructor would probably have to stop lecturing 

until firing stopped. 

March 2001 

NIOSH investigators visited the NFU on March 

15, 2001, to conduct a noise exposure 

assessment. The purpose of this visit was to 

identify the acoustical environment parameters, 

conduct preliminary noise measurements, and 

provide noise abatement recommendations. 

Sound reaches a shooter’s ears by two paths: the 

direct field and the reverberant (reflected) field. 

The direct field is emitted directly from the 

sound source. The reverberant field is the sound 

echo. The direct sound field dominates near the 

noise source (pistol, rifle, etc.) and is 

independent of the room properties (geometry, 

absorption, etc.). Direct field diminishes with 

distance from the source. The reverberant field 

dominates far from the source, depends on room 

properties, and does not vary with distance from 

the source.33 While INS’s initial request focused 

on the potential for noise reduction on the firing 

range (direct field), NIOSH investigators were 

also asked to comment on the potential for 

reducing sound levels in the adjacent spaces 

(control room, cleaning room, office, and 

classroom). 

The noise assessment of the firing range 

consisted of: (1) conducting reverberation 

measurements to identify the acoustical 

parameters that may contribute to increased 

noise levels in the firing range and (2) 

conducting SPL measurements in the firing 

range and the adjacent areas. The equipment 

used to document SPLs and reverberation 

characteristics were factory calibrated within the 

previous year by the respective manufacturer. 

Field calibration was conducted on the survey 

date by NIOSH investigators. The sound level 

meters (SLMs) conform to the American 

National Standards Institute (ANSI) 

Specification for Sound Level Meters.34

Measured reverberation times were obtained 

using a Model 2900B real time analyzer/sound 

level meter (RTA/SLM) (Larson Davis, Provo, 

Utah). The RTA/SLM with built-in building 

acoustics software was operated in accordance 

with manufacturer recommendations.35 The 

firing range was acoustically excited using pink 

noise. Pink noise (noise with equal energy 

across octave bands) was generated from the 

RTA/SLM. The noise signal was boosted 

through an Electro Voice (Buchanan, Michigan) 

P1250 amplifier and played into the room 

through an Electro Voice Sx 80 speaker. The 

RTA/SLM was set to allow a noise build up 

time of 5 seconds prior to triggering the pinknoise generator to off. Reverberation decay time 

(time required for levels to fall 60 dB after 

signal cutoff) measurements were set to 6 

seconds after the noise generator triggered to 

off. 

Peak SPLs were measured using a 1/4" type 

4135 microphone (Bruel & Kjaer, Decatur, 

Georgia). The SPLs were recorded on digital 

audio tape (DAT) using a DAT recorder Model 

SV 255 (Panasonic, Secaucus, New Jersey). The 

B&K 4135 Microphone operates without 

distortion to a level of 167 dB. The microphone 

was located approximately 6–7 feet behind the 

shooter at ear level. 

Area measurements were conducted using a 

Model 1800 SLM (Quest, Oconowoc, 

Wisconsin). The SLM was set to operate in the 

"80–140 dB" range with response set to "Peak". 

Peak SPLs were obtained at several locations 

when one shooter was using either a 0.40 caliber 

Beretta pistol or a Remington 12 gauge shotgun. 

Reverberation measurements are summarized in 

Table 12. The maximum reduction of SPLs in a 

best case scenario (all current surfaces offering 

"perfect" absorption) would be 12 dB. Given 

measured peak SPLs of 147–153 dBA, there is 

no opportunity to lower the noise to acceptable 

levels through sound absorption techniques of 
Page 12 Health Hazard Evaluation Report No. 2000-0191-2960

current surface areas and geometries. In fact, 

removing the walls and ceiling (i.e., outdoor 

conditions) would not achieve the desired 

reduction. Double hearing protection would still 

be required at this level. Given the lack of 

benefit and the high cost associated with 

absorption treatment of these surfaces, no 

change would be recommended regarding 

treatment of the reverberant environment of the 

indoor firing range. 

The measured peak SPLs from the B&K 4135 

microphone and the Quest 1800 SLM are shown 

in Table 13 for the firing range, control room, 

cleaning room, office, and classroom. The 

maximum exposure times at NIOSH RELs and 

the ACGIH TLVs are also noted in Table 13. 

The data reflect measurements collected using 

one shooter only. A typical training session 

involves 15–20 shooters firing multiple weapons 

for an extended period of time. The preliminary 

data show levels that exceed the OSHA 

maximum allowable exposure level of 140 dB 

inside the firing range. Measurements in the 

control room and cleaning room show personnel 

should not be exposed to more than 3 minutes 

during an 8-hour work shift. Even in the office 

area, INS personnel may be exposed to harmful 

levels when multiple shooters use the range. 

Without regard to the need for hearing 

protection, the classroom and office areas cannot 

be used for their intended purpose during a 

shooting session. 

June 2001 

NIOSH researchers returned on June 15, 2001, 

to conduct an additional noise exposure 

assessment. The equipment used to document 

SPLs and reverberation characteristics had been 

factory calibrated within the previous year by 

the respective manufacturer. Field calibration 

was conducted on the survey dates by NIOSH 

investigators. The SLMs conform to the ANSI 

Specification for Sound Level Meters.34 The 

noise dosimeters conform to the ANSI 

Specification for Personal Noise Dosimeters.36

Noise measurements were obtained at 11 

different positions throughout the firing range 

and adjacent areas as outlined in Figure 11. The 

positions were primarily chosen to measure a 

typical INS officer’s noise exposure in the firing 

range and the noise reductions afforded by the 

current building structure in the adjacent areas. 

The B&K 4136 microphone and dosimeters 

microphones were placed at the height of an 

average officer’s ear when firing (approximately 

5 feet above the floor). Ten INS officers 

conducted a typical firing session that lasted 

approximately 1 hour using three different 

weapons (Remington 870 Shotgun, M4 Rifle, 

Beretta Pistol). Three INS officers wore personal 

dosimeters for the entire session. DAT 

recordings were obtained for 3 to 5 minute 

intervals at each of the 11 positions. 

The measured peak SPLs and equivalent levels 

from the B&K 4136 microphone are shown in 

Table 14 for the firing range, control room, 

cleaning room, classroom, and office. The data 

show levels that exceed the OSHA maximum 

allowable exposure level of 140 dB inside the 

firing range. Interestingly, the data collected 

from the B&K4136 microphone and DAT setup 

measured peak sound levels more accurately 

than the dosimeters because of the limitations of 

the Q400 dosimeter microphone. The data 

collected from the Q400 dosimeters were not 

included in this report because they did not give 

an accurate representation of the sound pressure 

levels in the firing range. 

The data in Table 14 show the maximum time 

durations that an INS officer can be exposed to 

noise. Dual hearing protection must be worn at 

all times during a firing session, especially in the 

firing range and control room. While the data 

collected in the classroom and office areas show 

average sound pressure levels that are 

considered acceptable according to NIOSH 

noise exposure criteria, measured peak levels 

indicate the presence of impulses that might be 

considered hazardous to hearing. There are also 

non-auditory noise effects such as physiologic 

changes, fatigue, increased reaction time, 

reduced concentration, and irritability.37,38,39 The 

data shown in Table 14 clearly indicate that the 

classroom and office areas cannot be used 

successfully for their intended purposes during 

training. 
Health Hazard Evaluation Report No. 2000-0191-2960 Page 13 

The calculated noise reductions in octaves for 

the cleaning room, control room, classroom and 

office are shown in Table 15. The noise 

reductions are presented in octave bands because 

transmission loss of materials used in noise 

controls is normally specified according to their 

octave band absorption coefficients. One-third 

octave band spectra of the firing range and the 

adjacent areas are shown in Figures 12–16. The 

one-third octave data provide information on the 

frequency spectra for each of the positions. The 

data can be used to assess how to provide the 

necessary noise reductions and to choose the 

right transmission loss materials in case INS 

decides to modify to the range to achieve their 

intended goals for hearing loss prevention and 

improved conditions in the adjacent spaces 

during firing sessions. The average A-weighted 

sound pressure levels in the cleaning room and 

control room are 91 dBA and 94 dBA 

respectively. Currently, the noise reductions in 

the cleaning room and control room are 33 dBA 

and 30 dBA. To achieve the NIOSHrecommended exposure limit of 85 dBA in the 

cleaning room and control room, substantial 

additional noise reductions (6 dBA to 9 dBA) 

will be needed. 

September 2002 

The noise exposure assessment consisted of (1) 

personal exposure monitoring of officers during 

a live-fire session, (2) measuring sound levels in 

the firing range, and (3) assessing the 

effectiveness of various HPDs. 

Personal exposure measurements were made 

using Quest 400 and Larson-Davis 706 

dosimeters. Peak sound levels were measured 

using a B&K 4136 1/4" microphone, B&K 2615 

pre-amplifier, and B&K 2807 power supply, and 

were recorded on Panasonic SV-255 and 

Tascam DA-P1 DAT recorders at 48,000 

samples per second. The maximum sound 

pressure for the 4136 microphone was rated at 

172 decibels (dB SPL). Area measurements 

were made using a Larson-Davis 824A sound 

level meter. Hearing protectors were evaluated 

using an artificial head mannequin built 

specifically for measuring impact and impulse 

noise. The mannequin consists of Head Acoustic 

pinnae and ear canals, Bruel and Kjaer 4157 

middle ear simulator, and a Bruel and Kjaer 

4165 1⁄2" microphone. The maximum peak sound 

pressure level that could be measured with the 

mannequin was 148 decibels (dB SPL re 

20 μPa). Because all mannequin measurements 

were performed under hearing protection, the 

maximum sound pressure level was not 

exceeded. Figure 17 shows the mannequin setup. 

The mannequin microphone and the external 

microphone were calibrated with a Bruel and 

Kjaer 4228 piston-phone that produced a 124 dB 

SPL tone at 250 Hz. The sound level meters and 

dosimeters conformed to the American National 

Standards Institute (ANSI) specifications.34,36

The equipment was calibrated before the visits 

by the manufacturers. Field calibrations were 

conducted before and after measurements. 

Sound level measurements were obtained 

throughout the firing range while shooting 

occurred. Three officers and a NIOSH 

researcher wore personal noise dosimeters. The 

mannequin was set up in lane 10, and protected 

measurements were recorded to the DAT. The 

B&K 4136 microphone was set up to the right of 

the mannequin head to measure the unprotected 

impulses. Fifteen INS officers conducted a 

typical live-fire exercise that lasted 

approximately 1 hour using two different 

weapons (Remington 870 Shotgun and Beretta 

9mm Pistol). Because noise dosimeters were 

suspected to overload under such extreme 

conditions, backup measurements were made 

using the B&K 4136 microphone and DAT 

recorder as well as sound level meters. 

Microphones were positioned at an average 

officer’s ear height (approximately 5 ft above 

ground). Data from the dosimeters were 

downloaded and analyzed using the LarsonDavis Blaze software and QuestSuite software. 

Data from the sound level meter were 

downloaded and analyzed using the LarsonDavis 824 Utility 3.0 software. Data from the 

DAT were digitally transferred to a computer as 

‘.wav’ files via a AUDIOTRAK Waveterminal 

U2A 24 bit audio card and CoolEditPro 6.0 

software. Spectral analysis was performed using 

MATLAB software routines to obtain peak 

levels, equivalent levels (Leq), time durations, 
Page 14 Health Hazard Evaluation Report No. 2000-0191-2960

frequency, octave, and one-third octave band 

spectra. 

Table 16 shows average and peak sound level 

measurements obtained throughout the firing 

range and adjacent areas. The measurements 

were obtained using the B&K4136/DAT setup. 

As shown, minor differences appeared between 

the pistol and shotgun firing exercises in terms 

of sound energy and overall time-weighted 

average noise exposures. 

Figure 18 shows a frequency spectrum 

comparison between the pistol and the shotgun 

firing exercises. As the figure shows, firing 

shotguns produces more low-frequency energy 

than firing pistols. Studies have shown that 

exposure to weapons with low frequency energy 

(shotgun) is less harmful to hearing than 

weapons with spectral peaks at the higher 

frequencies (pistol and M4 rifle).40,41 

The effectiveness of the hearing protection used 

by INS officers was evaluated by measuring 

sound levels outside and inside the same hearing 

protectors on the artificial head fixture during 

both firing exercises (pistols and shotguns), and 

separately using the three different weapons 

most commonly tested at the range (Beretta 

pistols, Remington shotguns, and M4 rifles). 

Three different protectors were evaluated—EAR 

earplugs, Bilsom 707 earmuffs, and Peltor H10 

earmuffs—as representative samples to examine 

peak reductions. The earplugs and earmuffs 

were evaluated separately and in combination. 

Table 17 shows the results of various 

measurements conducted using double hearing 

protection. Figure 19 shows the peak reduction 

performance of various HPDs when using the 

Beretta pistol. 

DISCUSSION AND 

CONCLUSIONS

Lead 

Based on the limited wipe sample results, 

current housekeeping practices at the firing 

range appear to be effective in both keeping the 

range clean and minimizing the migration of 

lead dust from the range to areas outside the 

range. 

The air sampling results demonstrate that when 

pistols are used, the lead exposures remain low 

even after consecutive qualifiers. The potential 

remains for shotgun users to receive airborne 

lead exposure above the OSHA action level in 

the main indoor firing range under the 

conditions experienced during the April 2000 

site visit. The exposures received by shooters in 

the lanes nearest the walls were consistently 

among the highest of the data set. This was 

likely due at least in part to the migration of air 

along the walls from downrange back toward the 

firing line. Because the shooters in lanes 19 and 

20 also moved downrange at times during the 

shooting exercises, it is not possible to 

accurately estimate what portion of their 

exposure is due solely to the increased backflow 

created by air entering through the roll-top door 

entrance adjacent to their shooting station. The 

two highest exposures documented during this 

site visit occurred during the shotgun qualifier. 

One of these samples collected during the 

shotgun qualifier exceeded the OSHA PEL. 

While the population of shooters at the NFU 

changes throughout the year as different agents 

come for short-term training, on-site personnel 

such as the range master and line safety officers 

are likely to receive the most frequent 

exposures. Based on the results from this site 

visit, these individuals do not appear to be at 

significant risk. The highest exposure 

documented in this group was 3 μg/m3

. 

Results from the September 2002 lead sampling 

continued to reveal a pattern of increased 

exposures to individuals shooting in lanes 14–18 

relative to the exposures received by individuals 

at other lanes during the respective qualification 

exercises. These patterns can best be seen 

graphically in Figures 20 and 21. 

Results from the sampling for CO show a 

similar pattern of increased exposure for 

individuals in the lanes where lead exposure was 

highest. 
Health Hazard Evaluation Report No. 2000-0191-2960 Page 15 

The results from the lead and carbon monoxide 

sampling reinforce the results from smoke 

release tests performed during the site visit. In 

the area of lanes 15–18, smoke released at the 

firing line revealed a high level of turbulence 

and the presence of eddies and backflow of air 

that circulated the smoke back into the breathing 

zone of the individual at each position on the 

firing line. 

Disturbances at the firing line of these lanes may 

be the result of poor distribution of air due to the 

size, type or position of the supply air diffusers 

located at the ceiling level of the back wall of 

the range. These diffusers are smaller and 

located at a higher position than those behind 

other firing lanes. During a conference call on 

October 21, 2002, the recommendation for new 

diffusers to improve the laminar flow of air 

across the firing line of all the lanes was 

discussed with INS officials. The diffusers 

would decrease exposure levels of lead and CO 

for individuals at the firing line, particularly in 

the lanes of concern. 

BULLET TRAP DESIGN 

Traditional bullet trap design typically involves 

the bullet striking an inclined metal surface, 

removing kinetic energy from the projectile as it 

guides the bullet into a collection device. 

Smashing of the bullet onto the bullet trap 

surface contributes to the ambient airborne lead 

concentration. Because this occurs far 

downrange from the shooters, typically this does 

not increase the lead exposure of range 

occupants. It can, however, accelerate lead 

loading on HVAC and dust collection unit 

filters, decreasing their service life and 

increasing the rate at which they must be 

cleaned and/or replaced. The feasibility of 

rubber bullet traps should be investigated for 

future range development and modification. In 

decreasing the total amount of lead aerosol 

created in the range (by limiting the lead aerosol 

produced to that coming directly from the 

firearm when it is fired), the INS may realize 

long-term cost savings in both filter replacement 

costs and other maintenance activities. 

Decreasing lead aerosol would also help 

alleviate the high airborne lead concentrations in 

access areas behind the bullet trap, as 

documented in the survey done by Berger and 

Associates at the AIFR in 1999. 

Ventilation 

The objective for the Altoona indoor firing range 

study is to reduce the lead exposures in the 

facility to the lowest technically feasible levels. 

The recommendations associated with these 

strategies can be phased-in in order of their 

expected increasing cost until the lead exposure 

issues in the AIFR have been adequately 

resolved. These recommendations can be 

implemented in three phases. In Phase I, the 

least costly recommendations associated with 

fixing major air leaks and operational variables 

contributing to increased air turbulence can be 

implemented. If implementing Phase I fails to 

lower airborne lead to acceptable levels, then 

Phase II recommendations associated with 

optimizing the ventilation systems should be 

implemented. If Phase II fails to adequately 

lower the lead exposures in all of the firing 

lanes, then Phase III recommendations 

associated with upgrading the ventilation 

systems for the AIFR should be implemented. 

PHASE I 

Leaks 

All major leaks in the range must be closed to 

ensure successful ventilation in indoor firing 

ranges. Because these leaks are difficult to 

characterize, they are typically not accounted for 

in the overall design of the ventilation system. 

These leaks overburden the range ventilation 

system, and negatively affect its overall 

performance. Large leaks in the building can (1) 

prevent the range from being maintained at a 

negative pressure, (2) create temperature and 

humidity variations throughout the facility, (3) 

influence the formation of eddy currents that 

disturb the range airflow, making it more 

turbulent, and (4) reduce the amount of air 

flowing past the firing line. 

The identification process for leaks in the range 

consists of leak testing all the entrances followed 

by leak testing the overall structure of the range. 
Page 16 Health Hazard Evaluation Report No. 2000-0191-2960

All direct entrances into the range should be leak 

proofed. Doors opening directly into the range 

should be individually tested for leaks and 

repaired to make them airtight. The overhead 

door located behind the firing line on the east 

wall of the AIFR should be replaced with an 

airtight door. The doors leading directly into the 

range, including the door behind the bullet trap, 

should also be made airtight. 

The building structure of the AIFR should be 

visually examined for major leaks. Minor leaks 

can be identified using smoke tubes and fog 

generation machines. All identified leaks should 

be repaired. 

Turbulence 

Ideally, airflow within the range should be 

uniformly laminar, flowing smoothly without 

swirling or turbulence. Introduction of any 

turbulence, particularly behind or at the firing 

line, can compromise the safe operation of the 

range. During future range design, all sources 

potentially capable of enhancing turbulence in 

the range should be identified so that appropriate 

actions can be taken to resolve them prior to the 

start up of the range. In the AIFR currently there 

are two sources responsible for increased 

turbulence in the range: 

1) Leaks negatively affect overall range 

operation because they tend to reduce the 

airflow near the firing line and influence the 

formation of eddy currents throughout the range. 

If not eliminated, these eddy currents can cause 

lead-contaminated air to stop moving downrange 

away from shooters, swirl in a circular motion, 

and move back up range to the firing line. Fixing 

these leaks as described in the previous section 

is critical for ensuring proper airflow at the 

firing line, and for keeping turbulence to a 

minimum. 

2) The widest section of the lane partition 

should always be installed parallel to the airflow 

to minimize the obstruction of the range airflow. 

Currently, in the AIFR the widest section of the 

partitions are installed perpendicularly to the 

airflow, partially obstructing range airflow. This 

induces the formation of eddy currents and thus 

creates more turbulence near the firing line. This 

may become important especially when shooters 

use the firing line ahead of the lane partitions, if 

turbulence is created behind them by the 

partitions. 

PHASE II 

Optimization 

The optimization process should be executed as 

follows: 

1) The first step involves verifying whether 

equal airflow is discharged from all of the 

supply diffusers. If not, then the supply airflow 

dampers should be appropriately adjusted until 

the airflow is equally distributed to all of the 

diffusers. 

2) The second step is twofold. The first part 

is optimizing the exhaust airflow between the 

midrange exhaust and the downrange exhaust. 

The second part is ensuring equal distribution of 

exhaust airflow to all the inlets in each location. 

The balancing of the exhaust among inlets at 

each location should be implemented using the 

same procedure employed in balancing the 

supply airflow. 

3) The third step involves determining the 

recirculation fan speed at which the air velocity 

for all of the lanes at the firing line can be 

maintained at a minimum of 75 feet per minute 

(fpm) (recommended in NIOSH Document 

No.76-130, entitled "Lead Exposure and Design 

Consideration for Indoor Firing Ranges"). This 

is accomplished by increasing the speed of the 

recirculation fans for system 1 and system 2 in 

fixed increments until the desired air velocity 

across each lane is attained. If the amperage on 

the 30 horsepower (HP) electric motor peaks out 

prior to achieving the desired air velocity in each 

lane, then phase III should be implemented. 

4) The design of the supply airflow diffusers 

plays a critical role in ensuring uniform airflow 

in each lane. The performance of the supply 

airflow diffusers can be determined by 

measuring the air velocity variations within each 
Health Hazard Evaluation Report No. 2000-0191-2960 Page 17 

lane. Since there are no standards for the 

maximum air velocity variations permitted, the 

goal for the AIFR should be to target the 

variations within 50%. If the air velocity 

variations in the majority of the lanes of the 

AIFR exceed 50%, attempts should be made to 

modify the existing supply airflow diffusers to 

minimize the turbulence. If these attempts are 

unsuccessful in reducing air velocity variations 

below 50%, then the option for replacing the 

existing supply airflow diffusers with newer 

commercially available diffusers that are laminar 

airflow-friendly should be explored. 

PHASE III 

Ventilation Systems 

ScanCo Environmental System Inc. designed the 

ventilation systems for the AIFR facility. The 

original design for the ventilation systems called 

for 40HP recirculation fan motors. However, the 

roof of the range reportedly could not 

accommodate the weight of the proposed fans. 

The fan motors were therefore downsized from 

40HP to 30HP to meet the roof’s weight 

limitations. 

Noise 

The April 2000 exposure assessments show that 

a hazard to hearing exists at the indoor firing 

range at the INS facility. Because of this hazard, 

INS officials need to continue their practice of 

requiring double hearing protection for officers 

on the firing line and for any individual in the 

firing range when weapons are fired. 

The June 2001 noise assessment of the NFU 

firing range showed peak sound pressure levels 

that exceeded the OSHA maximum exposure 

limits. INS officers can be exposed to levels that 

exceed 160 dB during a firing session. The 

control room roof structure allows for 

unnecessary noise leakage because of its weak 

design. While average sound pressure level 

measurements in the classroom and office area 

show acceptable average noise levels, NIOSH 

investigators recorded peak sound pressure 

levels of 108–110 dB. Hearing protection is 

warranted throughout the range and dual hearing 

protection must be worn in the range during 

firing sessions. INS indicated its intention to 

explore modifications to the range for noise, 

ventilation, visibility (more glass in the control 

room) and reducing of the number of shooting 

lanes. 

The noise levels resulting from shooting 

activities have rendered the classroom unsuitable 

for training because the sound isolation between 

the areas is inadequate. The office, though 

farther away from the actual range noise, is still 

essentially unusable as an office during firing. 

Because the noise environment is far from 

optimum, conducting telephone conversations or 

concentrating on tasks is adversely affected by 

intermittent noise. The control room presents a 

special problem in that the range officer must 

use hearing protection while inside the control 

room. The cleaning room is usable, but high 

noise levels limits conversation. 

Three of the four areas (cleaning room, 

classroom and office) share common 

deficiencies: The transmission loss through the 

existing wall structure is too low, and the 

leakage and flanking paths other than the wall 

are significant. While it is possible to build a 

second wall to alleviate much of the noise 

intrusion problem, the limitation of the 

effectiveness of the final result in each room will 

be leakage and flanking paths that cannot be 

treated effectively after the fact. The fourth area 

(control room) has high noise levels because the 

bullet proof glass does not provide sufficient 

transmission loss, the roof is essentially a single 

layer of sheet metal with no absorption, and the 

door is not acoustically rated. The following 

paragraphs summarize recommendations to 

maximize the amount of improvement that can 

be expected. 

Shooting Range 

Lowering the noise in the firing range to 

acceptable levels through sound absorption 

techniques of current surface areas is not 

feasible or practical. Double hearing protection 

would still be required for each shooter and 

anyone else in the range area. Since INS is 

considering reducing the number of firing lanes 
Page 18 Health Hazard Evaluation Report No. 2000-0191-2960

from 21 to 15, absorptive "septum" barriers 

should be installed between these firing lanes. 

While this would reduce a shooter’s exposure 

level to the direct sound field of other shooters, 

it would have limited effect in protecting the 

shooter from the direct sound field of his/her 

own activities in the firing range. If barriers are 

used, care must be taken when placing them to 

ensure a clear and unobstructed view of each 

shooter from the control room. Such a design 

change should include a number of alternative 

arrangements to allow the selection of a barrier 

arrangement that provides acceptable visibility 

from the control room and does not degrade the 

ventilation requirements. 

Adjacent Areas 

To significantly reduce noise reduction from the 

firing range into the adjacent spaces, treat both 

the direct sound paths and all flanking paths. To 

improve the transmission loss of an existing wall 

structure, build a second wall with an air gap 

between both walls. These measures increase the 

mass in the sound path, break vibration paths 

and add cavity absorption. 

The results from the September 2002 exposure 

assessment have shown that noise dosimeters 

can not provide accurate measures of the 

impulse sounds commonly encountered in firing 

ranges. Current noise dosimeters are not 

designed to handle impulse noise, but rather to 

provide standard compliance measurements. The 

electro-acoustic limitations associated with 

dosimeter use in impulsive noise environments 

include peak level clipping, dose response 

uncertainties, and underestimation of the hazard 

to hearing.42

The results show that earplugs generally 

performed better than earmuffs when used as the 

only protector. The electronic level-limiting 

earmuffs (Bilsom 707) performed better than the 

standard-issue Peltor H10. However, both 

earmuffs provided the same peak reductions 

when used in combination with the EAR® 

earplugs. These results agree with findings from 

previous studies on hearing protector attenuation 

against weapon noise.43,44 These studies have 

also shown that using personal safety glasses 

degrades the earmuff performance because 

safety glasses produce a leak under the earmuff 

cushion. Special consideration should be given 

to the proper use and fitting of hearing 

protectors with safety glasses. 

Current impulse noise damage risk criteria45,46

suffer from a lack of empirical data needed to 

quantify impulse noise exposures and assess 

potential damage to hearing. The scientific, 

occupational, and military communities have not 

reached a consensus regarding the risk of 

hearing loss from exposure to impulse noise. 

NIOSH recommends that exposure to impulse 

noise not exceed 140 dB peak sound pressure. 

Based on the above recommendations, NIOSH 

proposes a simplified formula to evaluate the 

risk of exposure to impulse noise in terms of the 

number of impulses to which an officer can be 

exposed during each firing session: 

N = 10((140 - PI )/10)

where PI is the peak impulsive level in dB SPL 

under hearing protection. Applying this formula 

to the peak level of 121 dB from the pistol firing 

session in Table 17 yields N=80 shots. This 

conservative formula does not take into account 

the duration of the impulse, its spectral content, 

or energy. The Military Standard (MIL-1474D) 

in contrast, indicates that people wearing double 

protection can be exposed to 1000 shots a day as 

long as they do not exceed 162 dB peak sound 

pressure level. Another method used to examine 

the hearing hazard from noise impulses is based 

on the French criterion.47 This criterion uses the 

measurement of the integrated A-weighted 

acoustic energy that enters the cochlea. It 

reconciles with the current NIOSH 

recommended exposure limit of Leq/TWA of 

85 dBA. Table 17 shows overexposure for 

officers (wearing double protection) using the 

Beretta pistol and M4 rifle. 

Conclusion 

The noise assessment of the firing range showed 

peak sound levels that exceed the ceiling limits 

for safe exposure. INS officers were exposed to 

noise levels that reach 163 dB during a live-fire 

session. Current damage risk criteria lack the 
Health Hazard Evaluation Report No. 2000-0191-2960 Page 19 

empirical data to establish a quantitative 

relationship between these levels and hearing 

damage. Two significant findings have been 

identified as a result of this study. First, personal 

noise dosimeters cannot produce accurate 

measurements in impulsive noise environments 

nor are they suitable for characterizing the 

impulse noise hazard. Second, other parameters 

such as peak pressure, time duration, rise time, 

energy, spectral content, number and mixture of 

impulses, and temporal spacing must be 

considered to understand the full extent of the 

hearing hazard. Given the poor noise control in 

the spaces adjacent to the range, hearing 

protection should be worn throughout the 

facility, and dual hearing protection must be 

worn inside the range during firing sessions. The 

suggested noise abatement techniques reduce 

airborne sounds by sealing leaks and airtight 

insulation around doors, windows, and 

ventilation ducts. Structural-borne transmission 

and vibration were limited by applying 

acoustical treatment to walls, windows, doors, 

and the roof structure. 

RECOMMENDATIONS

Lead 

• Continue investigating the feasibility of 

using a completely lead-free practice round. 

• Use future wipe sampling results as an 

indicator of ongoing housekeeping 

effectiveness. 

• Use a HEPA vacuum on the range before it 

is wet mopped. 

• Include range housekeeping personnel, and 

anyone else with regular occupational 

exposure to lead, in the blood lead and zinc 

protoporphyrin monitoring program. 

• Investigate the feasibility of rubber bullet 

traps for future range development and 

modification. 

Ventilation 

The NFU should minimize the lead exposures to 

all range users, especially shooters who may 

encounter relatively high concentrations of lead 

for short periods of time. This can in part be 

accomplished by the following: 

• Prohibit shooters from moving 

downrange. 

• Repair or replace the roll-top door. 

• Investigate ventilation/engineering 

solutions that can minimize the amount of 

backflow along both side walls of the range. 

• Require range users to wash their face 

and hands upon leaving the range and before 

eating, drinking, or smoking. 

Listed below is a summary of the 

recommendations for overcoming the 

operational problems associated with leaks and 

increased turbulence in the AIFR. 

• Test all of the doors that provide direct 

entrance to the range for leaks and repair 

them to make them leak tight. The overhead 

roll-top garage door should be replaced with 

an airtight door. 

• Turn the lane partitions so their widest 

section is parallel with the airflow when 

shooters use the firing line closest to the 

bullet trap, ahead of the lane partitions. Turn 

them approximately 90 degrees from their 

current position when they are not being 

used for shooting exercises simulating firing 

from behind cover. 

• Identify and fix all major leaks associated 

with the range’s building structure. 

Listed below are recommendations for further 

reducing the turbulence in the operation of the 

AIFR. Implementation of these 

recommendations should result in more 

laminar airflow throughout the range. 
Page 20 Health Hazard Evaluation Report No. 2000-0191-2960

• It is very difficult to maintain uniform 

laminar airflow in the end lanes. During 

smoke testing of the range, smoke was first 

pushed downrange, but then small amounts 

migrated along the side walls toward the 

firing line. This creates eddy currents 

making the end lane airflow more turbulent. 

As a result of lead contaminated air flowing 

from downrange back toward the firing line, 

shooters in the end lanes may receive a 

higher lead exposure than the shooters in 

adjacent lanes. Lab Crafters Inc. is 

conducting research in developing baffles 

that minimize the end lane effects. 

• In many ranges, direct entrances into the 

range are through air locks. These air locks 

allow entrance into and exit from the range 

without disturbing the pressure barrier 

conditions established inside the range itself. 

Modify all entrances (excluding the access 

door behind the bullet trap) to the ranges so 

that entering the range will be through an 

airlock to minimize the impact on the 

pressure barrier conditions maintained in the 

overall range. 

• Reevaluate the design of the supply 

airflow diffusers and the configuration of the 

exhaust inlets if there are significant air 

velocity variations in the breathing zone of 

the shooter near the firing line of each lane. 

The current supply airflow diffusers may 

have to be replaced with diffusers that 

provide laminar airflow. The exhaust inlets, 

currently spread over two locations, may 

have to be consolidated to a single new 

location, perhaps behind the bullet trap. 

Listed below is a summary of 

recommendations for upgrading the ventilation 

systems of the AIFR. 

• Upgrade the capacities of these fans if the 

optimization of the ventilation systems with 

the 30HP fan motors fails to produce 75 fpm 

airflow across each lane. This may involve 

substituting the current 30HP electrical 

motors with larger 40HP electrical motors or 

replacing the current fans with new fans. 

• The installation of larger and heavier 

40HP fan motors on to the existing roof may 

require major renovation and upgrading 

during reinforcement of the AIFR roof. This 

process will likely be expensive and time 

consuming. 

Listed below is a recommendation for upgrading 

the supply diffusers for particular lanes of the 

AIFR. 

• Install new diffusers on lanes near the end 

of the firing range that showed higher levels 

of exposure to lead and carbon monoxide 

during practice rounds. The diffusers cause 

turbulence and eddies in these lanes, leading 

to the higher exposures. New diffusers 

installed at a lower height equal to the other 

diffusers in the other lanes of the firing 

range will improve the laminar flow of air 

across the firing line. 

Noise 

A full hearing conservation program should be 

implemented at the NFU.24,48 The noise 

intensity on an indoor firing range can cause 

permanent damage in a very short period of 

time. Using double hearing protection can 

attenuate noise to a safer exposure level. 

However, the use of HPDs is subject to many 

problems, such as discomfort, incorrect use with 

other safety equipment, dislodging, 

deterioration, and abuse.49 HPDs also perform 

differently in workplace settings as compared to 

the laboratories where the noise reduction 

ratings (NRR) are determined.50,51 NIOSH 

recommends conducting monitoring audiograms 

at least annually.24 While annual audiometric 

monitoring identifies persons who have lost 

hearing or are at risk due to the presence of a 

noise-induced notch in the audiogram, the INS 

should consider implementing a more 

comprehensive hearing protector fit-testing 

program in addition to audiometry.52 Fit-testing 

identifies those persons who have poorly 

inserted earplugs and therefore are at increased 

risk of NIHL. 
Health Hazard Evaluation Report No. 2000-0191-2960 Page 21 

• Conduct training on HPD use at the INS. 

Earplugs that barely entered the ear canal 

after insertion and earmuffs that were placed 

on officers’ legs or heads when not in use 

show that the users of these devices need to 

be instructed on their proper use. Foam 

earplugs must be rolled down into a small 

cylinder before being deeply inserted into 

the ear canal. Earmuffs should be placed on 

the floor or tables or in a clip when not in 

use so that the headbands are not sprung. 

The pressure necessary to provide a seal 

with the side of the wearer’s head is 

compromised when the earmuff cups are 

forced apart for long periods of time. 

• Address maintenance of the different 

kinds of HPDs. The disposable foam 

earplugs used at the INS should be worn just 

for the day of weapons qualifications then 

discarded. The custom-made earplugs that 

have been issued may deteriorate. This type 

of HPD should be replaced every 3 to 5 

years. The cushions of the earmuff cups may 

deteriorate and should be inspected every 6 

months to see if they are still flexible. 

Replace them if they become stiff and 

nonpliant. 

• NIOSH investigators provided electronic 

stereo amplification earmuffs to a few of the 

officers to wear while they completed a 

qualification round. Some of the officers 

reported that these earmuffs helped them to 

hear the range master better than with the 

passive earmuffs provided by the NFU. 

However, not all officers preferred the 

electronic earmuffs. Provide a limited 

number of these devices for officers who 

may need additional amplification to hear 

commands from the range master. Officers 

who have pre-existing, high frequency 

hearing loss may find the amplification 

beneficial. 

• Integrate the amplification system with 

sound restoration earmuffs capable of local 

FM communication broadcast and reception. 

Such earmuffs could be combined with 

passive earplugs to enhance noise protection 

and improved communication. 

• Some officers were wearing sound 

restoration earmuffs on the firing line. Test 

the sound restoration muffs in accordance 

with EN 352.2 and 352.4, which specify 

maximum levels under the earmuff. 

The following recommendations are suggested 

to reduce noise levels in the adjacent areas of the 

control room, cleaning room, classroom, and 

office: 

• Construct a stud wall on the cleaning 

room and classroom side of common 

concrete block wall with an air gap, wood or 

metal stud farming, absorption batts, and a 

double layer dry wall finish (5/8" type X 

Gypsum). This measure can provide a 

transmission loss of upwards of 70 dB in the 

500–1000 Hz range. 

• Seal the gap between the roof deck and 

the top of the concrete block wall to 

eliminate air leakage path. 

• Stagger 110 V outlets in the common 

wall. The existing outlets on the common 

wall are placed in such a manner that they 

form a direct acoustic path for the noise. The 

cavities around the outlets should be caulked 

to reduce leaks. 

• Place absorption batts in the plenum over 

the ceiling area of the range (approximately 

22 feet) to reduce noise by a major flanking 

path. Adding absorption materials above the 

dropped ceiling over the classroom and 

office might also be necessary. 

• Design a new ceiling with significant 

improvement in sound transmission loss 

over the control room area. 

• Place magnetic seals or double sweeps on 

all doors to seal existing air gaps. 

• Place double-paned laminated glass of 

different thickness to maximize the sound 
Page 22 Health Hazard Evaluation Report No. 2000-0191-2960

transmission loss everywhere there is glass: 

Cleaning room, control room, three glass 

panels to right of control room. Another 

option is to remove glass where it is not 

needed and fill in with block (e.g., cleaning 

room and hallway adjacent to the control 

room). The control room still needs double 

glass with maximum air gap possible. 

The following recommendations assume that 

INS is interested in making fundamental 

structural changes to the shooting range to 

accomplish several goals including noise 

reduction. Furthermore, it was understood that 

the INS is seeking to significantly improve the 

firing range structure and operations in the 

following areas: 

• Reduce the number of shooting lanes 

from 20 to 15. 

• Improve ventilation system performance 

so that indoor testing of a wider range of 

weapons can be achieved than with the 

present system. 

• Alter the control room structure to 

improve visibility to all shooting lanes. 

• Reduce sound levels to accomplish 

several objectives: 

o Reduce sound levels in the control 

room so that the range officer can be 

in the room without hearing 

protection. 

o Improve sound isolation between the 

range and the classroom so that 

classes can be conducted without 

undue interference while shooting is 

ongoing. 

o Reduce sound levels in the office are 

so that it can be occupied and used 

during shooting sessions with a 

minimum of speech interference, 

such as for telephone use. 

o Improve sound levels in the cleaning 

room so that occupants do not need to 

wear hearing protection and can 

converse freely without speech 

interference from the range. 

The following recommendations are suggested 

to reduce noise levels in the cleaning room, 

classroom and office: 

• Construct a nominal 6-inch stud wall on 

the cleaning room and classroom side of the 

existing common block wall, including the 

hallway area leading from the tower door to 

the classroom hallway. The stud wall should 

be set apart from the existing concrete block 

wall by a minimum of three inches. The stud 

wall construction should be a double layer 

unbalanced wall of 2X6" metal stud 

framing, sound absorption batts, resilient 

channel, and a dry wall double layer finish 

(5/8" type X Gypsum, two thicknesses on 

the quieter side). This measure can provide 

noise reduction that can increase the Sound 

Transmission Class of the existing wall to an 

STC 72 rating. The added stud wall should 

be non-load bearing and extend up to the 

roof of the building, including the area over 

the control room. The top edge of the new 

wall would be sealed against the corrugated 

roof system in the same manner as the 

existing concrete block wall (filled with 

acoustic fiberglass, drywall piece fit to roof). 

We recommend replacing the window in the 

cleaning room wall and the three windows 

in the short hallway leading to the control 

room door with the same block construction 

as the rest of the wall. Windows present 

special problems in sound reduction, and the 

likelihood of achieving the intended 

improvement will be much higher than if 

these windows are removed. 

• Seal the gap between the roof deck and 

the top of the concrete block wall to 

eliminate air leakage path. In a like manner, 

seal the second stud wall at the roof line to 

prevent sound leakage. 
Health Hazard Evaluation Report No. 2000-0191-2960 Page 23 

• Remove 110 V outlets that back onto 

each other in the common wall. The existing 

outlets on the common wall are placed in 

such a manner that they form a direct 

acoustic path for the noise. 

• Place absorption batts in the plenum over 

the ceiling area of the range (over a distance 

of approximately 22 feet) to reduce noise by 

a major flanking path. Adding absorption 

materials above the dropped ceiling over the 

classroom and office is also necessary to 

reduce sound through this flanking path to 

the extent possible. 

• Design a new roof with significant 

improvement in sound transmission loss 

over the control room area. The roof 

structure should be specified to provide a 

minimum of at least STC 60 performance 

(Sound Transmission Class). 

• The existing doors are fire rated without 

any special acoustical properties. Replace 

existing doors with sound rated doors having 

an STC rating of at least 50. 

• Install double bullet proof glass with the 

maximum air gap possible (3 inches 

minimum is suggested) in the control room. 

In addition, to minimize vibration 

transmission form one pane of glass to the 

next (what is known as inter panel resonance 

effect), the first and second glass layers 

should differ in thickness by 30%–50% and 

the second panel should be installed on a 

slight angle so that the two panes are not 

parallel. To make the control room useable 

without the need for hearing protectors, the 

total glass area should be minimized and the 

air space between panes should be 

maximized (at least 3 inches). 

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24. NIOSH [1998]. Criteria for a recommended 

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 28. NIOSH [1999]. Hazard evaluation and 

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Public Health Service, Centers for Disease 

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no. HHE 97-0255-2735. 

 29. NIOSH [1990]. Hazard evaluation and 

technical assistance report: Kansas City, Kansas 

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Institute for Occupational Safety and Health, 

NIOSH Report no. 90-084-2219. 

 30. NIOSH [1990]. Hazard evaluation and 

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2248. 

 31. NIOSH [1994]. LEAD by ICP: Method 

number 7300. In: Eller PM, ed. NIOSH Manual 

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OH: U.S. Department of Health and Human 

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Disease Control and Prevention, National 

Institute for Occupational Safety and Health, 

DHHS (NIOSH) Publication no. 94-113. 

 32. Berger EH [1983]. Laboratory attenuation 

of earmuffs and earplugs both singly and in 

combination. American Industrial Hygiene 

Association Journal, 44(5): 321-329. 

 33. Beranek LL and Ver IL. [1992]. Noise and 

Vibration Control Engineering, Principles, and 

Applications. New York, NY: John Wiley & 

Sons. pp 178-182. 

 34 American National Standards Institute: 

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ANSI S1.4-1983. ANSI, New York, NY. 

 35. Larson-Davis Model 2900B Reference 

Manual [1998]. Provo, Utah. Chapter 21. 

 36. American National Standards Institute: 

Specification for Personal Noise Dosimeters. 

[1991]. ANSI S1.25-1991 (R1997). ANSI, New 

York, NY. 

 37. Kjellberg A, Skoldstrom B [1991]. Noise 

annoyance during the performance of different 

nonauditory tasks. Percept Mot Skills, 73:39-49. 

 38. Belojevic G, Ohrstrom E, Rylander R 

[1992]. Effects of noise on mental performance 

with regard to subjective noise sensitivity. Int 

Arch Occup Environ Health, 64:293-301. 
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 39. Heslegrave RJ, Furedy JJ [1978]. 

Anticipatory HR deceleration as a function of 

perceived control and probability of aversive 

loud noise: a deployment of attention account. 

Biol Psychol, 7:147-166. 

 40. Price GR. Impulse noise hazard as a 

function of level and spectral distribution. In 

Salvi RJ, Henderson D, Hamernik RP, Colletti 

V. Basic and Applied Aspects of Noise-Induced 

Hearing Loss, pp. 379-392. New York: Penum 

Publishers, 1986. 

 41. Patterson JH Jr, Carrier M Jr, Bordwell K, 

Hamernik RP, Anroon WA, and Hargett CE Jr 

[1991]. The hazard of exposure to impulse noise 

as a function of frequency. Vol I & II, US Army 

Aeromedical Research Laboratory, USAARL 

Report No. 91-18, Fort Rucker, AL. 

 42. Kardous CA, Willson RD [2004]. 

Limitations of using dosimeters in impulse noise 

environments. J Occup Environ Hyg. 2004 

Jul;1(7):456-62. 

 43. Dancer A, Grateau A, Barnabe G [1992]. 

Effectiveness of earplugs in high-intensity 

impulse noise. J Acoust Soc Am 91(3). 

 44. Paakonen R, Lehtomaki K, Savolainen S 

[2000]. Noise attenuation of hearing protectors 

against heavy weapon noise. Military Medicine, 

Vol. 165. 

 45. Committee on Hearing, Bioaccoustics, and 

Biomechanics. Proposed damage risk criterion 

for impulse noise (Gunfire). Washington, DC, 

CHABA, 1968. 

 46. Department of Defense. US MIL-STD1474D. Design Criteria Standard, Noise Limits, 

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 47. Direction Technique des Armements 

Terrestres. Recommendation on evaluation the 

possible harmful effect of noise on hearing. AT83/27/28, 1983. 

48. NIOSH [1996]. Preventing Occupational 

Hearing Loss-A Practical Guide. Cincinnati, 

OH: US Department of Health and Human 

Services, Public Health Service, Centers for 

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Institute for Occupational Safety and Health, 

DHHS (NIOSH) Publication No. 96-110. 

 49. Berger EH [1980]. EARLOG monographs 

on hearing and hearing protection : hearing 

protector performance: how they work and what 

goes wrong in the real world. Indianapolis, IN: 

Cabot Safety Corporation, EARLOG 5. 

 50. Berger EH, Franks JR, Lindgren F [1996]. 

International review of field studies of hearing 

protector attenuation. In: Axelsson A, 

Borchgrevink H, Hamernik RP, Hellstrom P, 

Henderson D, Salvi RJ, eds. Scientific basis of 

noise-induced hearing loss. New York, NY: 

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Group versus Individual Training. PhD 

dissertation, Department of Audiology and 

Speech Sciences, Michigan State University, 

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Health Hazard Evaluation Report No. 2000-0191-2960 Page 27 

Table 1. Airborne Lead Exposures During One Pistol Qualification Exercise 

HETA 2000–0191 

U.S. INS–NFU 

April 19, 2000 

Lane # 

or area 

Sample time 

[min] 

Sample volume 

[L] 

Pb conc. [μg/m3] 8-hr TWA Pb 

conc. [μg/m3] 

1 57 169 32 4 

3 56 167 4 0.4 

5 60 179 4 1 

7 64 190 4 1 

9 pump failed pump failed n/a n/a 

11 58 175 7 1 

13 53 158 15 2 

15 58 172 37 5 

17 55 163 12 1 

19 56 168 89 10 

6, area, 

preshooting 

88 263 trace trace 

West rooftop 

exhaust 

295 876 ND ND 

rear range 

wall 

40 119 3 0.3 

control room 

PBZ 

42 122 ND ND 

NIOSH REL 

ACGIH TLV–TWA 

OSHA PEL 

OSHA action level 

50 

50 

50 

30 

ND = ‘not detected,’ contaminant was present at levels below the analytical limit of detection 

trace = contaminant was detected at levels between the limit of detection and the limit of quantitation
Page 28 Health Hazard Evaluation Report No. 2000-0191-2960

Table 2. Airborne Lead Exposures During Two Consecutive 

Pistol Qualification Exercises 

HETA 2000–0191 

U.S. INS–NFU 

April 19, 2000 

ND = ‘not detected,’ contaminant was present at levels below the analytical limit of detection 

trace = contaminant was detected at levels between the limit of detection and the limit of quantitation

Lane # 

or area 

Sample time 

[min] 

Sample volume 

[L] 

Pb conc. [μg/m3] 8-hr TWA Pb 

conc. [μg/m3] 

1 100 297 22 5 

3 96 285 18 4 

5 75 217 4 1 

7 76 225 5 1 

9 71 212 6 1 

11 73 219 23 4 

13 79 236 16 3 

15 76 226 58 10 

17 79 236 22 4 

19 74 221 159 25 

line safety 

officer 

79 235 19 3 

rear range 

wall 

72 215 3 1 

control room 

PBZ 

71 213 trace trace 

NIOSH REL 

ACGIH TLV–TWA 

OSHA PEL 

OSHA action level 

50 

50 

50 

30 
Health Hazard Evaluation Report No. 2000-0191-2960 Page 29 

Table 3. Airborne Lead Exposures During Shotgun Qualification Exercises 

HETA 2000–0191 

U.S. INS–NFU 

April 20, 2000 

ND = ‘not detected,’ contaminant was present at levels below the analytical limit of detection 

trace = contaminant was detected at levels between the limit of detection and the limit of 

quantitation 

Lane # 

or area 

Sample time 

[min] 

Sample volume 

[L] 

Pb conc. [μg/m3] 8-hr TWA Pb 

conc. [μg/m3] 

2 56 169 130 15 

4 54 158 11 1 

6 47 140 trace trace 

8 56 165 31 4 

10 51 151 56 6 

12 59 172 44 5 

14 54 159 314 35 

16 52 155 116 13 

18 52 155 97 11 

20 56 167 718 84 

line safety 

officer 

33 98 21 2 

control room 

PBZ 

37 110 ND ND 

ballistics lab 

worker 

79 235 20 3 

East rooftop 

exhaust 

147 435 trace trace 

NIOSH REL 

ACGIH TLV–TWA 

OSHA PEL 

OSHA action level 

50 

50 

50 

30 
Page 30 Health Hazard Evaluation Report No. 2000-0191-2960

Table 4. Total* Airborne Lead Exposures During Pistol Qualification Exercises 

HETA 2000–0191 

U.S. INS–NFU 

April 19, 2000 

Lane # Sample time 

[min] 

Sample volume 

[L] 

Pb conc. 

[μg/m3] 

8-hr TWA Pb 

conc. [μg/m3] 

1 157 467 25 8 

3 152 452 12 4 

5 135 397 4 1 

7 140 415 5 1 

11 131 394 16 4 

13 132 394 15 4 

15 134 398 49 14 

17 134 399 18 5 

19 130 388 129 35 

NIOSH REL 

ACGIH TLV–TWA 

OSHA PEL 

OSHA action level 

50 

50 

50 

30 

ND = ‘not detected,’ contaminant was present at levels below the analytical limit of detection 

trace = contaminant was detected at levels between the limit of detection and the limit of 

quantitation 

* = these values were calculated based on the data in Tables 1 and 2; they do not represent 

discrete samples
Health Hazard Evaluation Report No. 2000-0191-2960 Page 31 

Table 5. Surface Lead Concentrations 

HETA 2000–0191 

U.S. INS–NFU 

April 19, 2000 

Sample location Sample number Surface Pb concentration 

[μg/ft2] 

Lane 1, floor behind barricade wipe #1 2.9 

Floor between lanes 10 & 11 wipe #2 8.1 

Supply–air diffuser, 2nd from 

left of control room

wipe #3 ND 

Control room – tabletop, right 

side of track control box 

wipe #4 ND 

Classroom – 3rd row tabletop 

closest to wall

wipe #5 ND 

Hallway from range to outer 

door, outside classroom door 

wipe #6 1.6 

ND = ‘not detected,’ contaminant was present at levels below the analytical limit of detection 
Page 32 Health Hazard Evaluation Report No. 2000-0191-2960

Table 6. Airborne Lead Exposures During One Shotgun Qualification Exercise 

HETA 2000-0191 

U.S. INS-NFU 

March 26, 2002 

Lane # or area Sample time [min] Sample volume [L] Pb conc. [μg/m3

] 8hr TWA Pb conc. 

[μg/m3] 

1 18 52 249.9 9.37 

2 18 54.5 86.2 3.23 

9 16 47 36.1 1.2 

10 16 46.7 59.7 2 

11 14 43.3 83.2 2.43 

12 15 43.5 23 .72 

19 13 37.7 318.3 8.62 

20 10 30.1 192.7 4 

Area, behind lane 

19 

75 213.8 28.54 4.46 

Area, behind lane 

9 

75 219 16.9 2.64 

Area, behind lane 

3 

75 228.8 28 4.43 

NIOSH REL 50 

ACGIH TLV-TWA 50 

OSHA PEL 50 

OSHA action level 30 
Health Hazard Evaluation Report No. 2000-0191-2960 Page 33 

Table 7. Airborne Lead Exposures During Two Pistol Qualification Exercises 

HETA 2000-0191 

U.S. INS-NFU 

March 26, 2002 

Lane # Sample time 

[min]

Sample volume 

[L]

Pb conc. [μg/m3] 8hr TWA Pb conc. 

[μg/m3]

1 47 135.8 2.04 0.2 

2 42 127.7 .52 0.05 

6 45 131.9 .2 0.02 

11 46 142.1 .44 0.04 

12 43 126.4 .37 0.03 

18 49 147.5 2.65 0.27 

19 55 156.8 .96 0.11 

20 48 144.5 .81 0.08 

NIOSH REL 50 

ACGIH TLV-TWA 50 

OSHA PEL 50 

OSHA action level 30
Page 34 Health Hazard Evaluation Report No. 2000-0191-2960

Table 8. Airborne Lead Exposures During One Pistol Qualification Exercise 

HETA 2000-0191 

U.S. INS-NFU 

March 26, 2002 

Lane # Sample time 

[min]

Sample volume [L] Pb conc. 

[μg/m3] 

8hr TWA Pb conc. 

[μg/m3]

1 18 52 117.3 4.4 

2 23 69.7 38.7 1.86 

6 16 46.9 27.7 0.92 

11 16 47 21.3 0.71 

12 19 58.7 37.5 1.48 

18 16 48.2 149.5 4.98 

19 16 48.2 60.2 2.01 

20 16 45.6 52.6 1.75 

NIOSH REL 

ACGIH TLV-TWA 

OSHA PEL 

OSHA action level 

50 

50 

50 

30
Health Hazard Evaluation Report No. 2000-0191-2960 Page 35 

Table 9. Airborne Lead Exposures during Single Pistol Qualification 

HETA 2000-0191 

U.S. INS-NFU 

September 25, 2002 

Lane # or area Sample time 

[min]

Sample volume 

[L] 

Pb conc. 

[:g/m3]

8-hr TWA 

[:g/m3]

Lane 2 60 177.1 3.50 0.44 

Lane 3 50 146.3 1.91 0.20 

Lane 4 61 183.6 2.89 0.37 

Lane 5 61 180.9 12.16 1.55 

Lane 6 53 158.7 5.10 0.56 

Lane 7 50 149.5 1.34 0.14 

Lane 8 51 152.4 2.36 0.25 

Lane 9 49 146.9 3.81 0.39 

Lane 10 38 143.6 6.62 0.66 

Lane 11 32 95.9 7.61 0.51 

Lane 12 47 140.6 7.11 0.70 

Lane 13 47 140.4 8.55 0.84 

Lane 14 46 137.8 8.71 0.83 

Lane 15 44 131.7 10.63 0.97 

Lane 16 43 128.1 29.66 2.66 

Lane 17 43 128.6 45.10 4.04 

Lane 18 36 108.3 43.40 3.25 

Qualification instructor 33 98.6 9.13 0.63 

Range Entrance Door 34 101.8 2.65 0.19 

NIOSH REL 

ACGIH TLV-TWA 

OSHA PEL 

OSHA action level

50 

50 

50 

30 
Page 36 Health Hazard Evaluation Report No. 2000-0191-2960

Table 10. Airborne Lead Exposures during Single Shotgun Qualification 

HETA 2000-0191 

U.S. INS-NFU 

September 25, 2002 

Lane # or area Sample time 

[min]

Sample 

volume 

[L] 

Pb conc. 

[g/m3]

8-hr TWA :g 

[lead/m3]

Lane 2 26 76.7 69.08 3.74 

Lane 3 25 73.2 19.14 1.0 

Lane 4 25 75.3 97.01 5.05 

Lane 5 24 71.2 252.95 12.65 

Lane 6 24 71.9 37.56 1.88 

Lane 7 23 68.8 21.81 1.05 

Lane 8 24 71.7 33.46 1.67 

Lane 9 23 68.9 31.92 1.53 

Lane 10 24 71.8 153.24 7.66 

Lane 11 29 86.9 57.53 3.48 

Lane 12 24 71.8 89.13 4.46 

Lane 13 25 74.7 125.88 6.56 

Lane 14 25 74.9 333.89 17.39 

Lane 15 21 62.9 715.72 31.31 

Lane 16 22 65.5 732.40 33.57 

Lane 17 19 56.8 1,513.31 59.90 

Lane 18 23 69.2 477.15 22.86 

Qualification instructor 22 65.7 365.10 16.73 

Range Entrance Door 22 65.9 36.42 1.67 

NIOSH REL 

ACGIH TLV-TWA 

OSHA PEL 

OSHA action level

50 

50 

50 

30
Health Hazard Evaluation Report No. 2000-0191-2960 Page 37 

Table 11. Personal Noise Dosimeter Results 

HETA 2000-0191 

U.S. INS-NFU 

April 19-20, 2000 

Location/ 

Qualification OSHA - PEL OSHA - AL NIOSH - REL 

% Dose TWA % Dose TWA % Dose TWA 

Lanes 7-8

Single Pistol 103.98 91.9 dBA 132.01 92.0 dBA 13,326.61 106.2 dBA 

Double Pistol 254.75 96.7 dBA 256.00 96.8 dBA 26,005.76 109.1 dBA 

Single Shotgun 75.16 87.9 dBA 75.90 88.0 dBA 7,897.97 104.0 dBA 

Lanes 12-13

Single Pistol 160.06 93.4 dBA 161.07 93.4 dBA 18,551.03 107.7 dBA 

Double Pistol 249.60 96.6 dBA 251.00 96.6 dBA 24,929.81 109.0 dBA 

Single Shotgun 68.68 87.3 dBA 69.59 87.4 dBA 6,784.19 103.3 dBA 
Page 38 Health Hazard Evaluation Report No. 2000-0191-2960

Table 12. Reverberation Time Measurements 

HETA 2000-0191 

U.S. INS-NFU 

March 15, 2001 

Frequency (Hz) 

 125 250 500 1000 2000 4000 

Measured T60 (seconds) 1.97 2.38 2.91 2.81 2.02 1.42 

Calculated Sabin Absorptive 

Area - Acurrent (m2) 

186 119 137 157 163 216 

* Sound Level Reductions 

(dB) 

10 12 12 11 11 10 

*given Anew=1963 m2 to achieve perfect absorption across octave bands for existing surfaces provides 

the best case scenario for using sound absorption techniques to reduce the sound pressure level. 

Table 13. Peak Sound Pressure Levels 

HETA 2000-0191 

U.S. INS-NFU 

March 15, 2001 

Location Peak SPL (dB) 

.40 Caliber S&W 

Beretta 

Peak SPL (dB) 

12 gauge shotgun

Maximum Exposure Time 

NIOSH REL/ACGIH TLV** 

Firing Range * 147 153 < 1 Second 

Control Room 107 110 1 minute 

29 seconds 

Cleaning Room 101 107 2 min. 

59 Seconds 

Office 91.2 99 18 min. 

59 Seconds 

Classroom 103 102 9 min. 

27 Seconds 

* Firing Range measurements were made using the B&K 4135 microphone and the Panasonic SV-255 

Digital Audio Tape recorder approximately 6-7 feet behind the shooter at ear level. 

** NIOSH Recommended Exposure Limit (REL)/ACGIH Threshold Limit Value (TLV) 
Health Hazard Evaluation Report No. 2000-0191-2960 Page 39 

Table 14. Measured Sound Pressure Levels 

HETA 2000-0191 

U.S. INS-NFU 

June 6, 2001 

Area* Peak SPL (dB) Equivalent Level Leq 

(dBA) 

NIOSH Recommended 

Exposure Limits 

Firing Range 151.4 122 6 Seconds 

Control Room 136 93 1 hr 16 minutes 

Cleaning Room 115 90 2 hr 31 minutes 

Classroom 110.4 79 No Hazard 

Office 108 77 No Hazard 

*B&K4136 and DAT setup 

Table 15. Calculated noise reductions for adjacent areas by octave-band

HETA 2000-0191 

U.S. INS-NFU 

September 25, 2002

Octave level 125 250 500 1000 2000 4000 8000 

Outside 110 116 121 119 116 113 110 

Inside 84 87 88 88 84 77 73 

Cleaning 

Room 

Noise reduction 26 29 33 31 32 36 37 

Outside 111 116 122 119 117 114 111 

Inside 84 89 91 91 86 80 75 

Control 

Room 

Noise reduction 27 27 31 28 31 34 36 

Outside 109 117 121 119 117 114 111 

Inside 83 86 80 72 70 66 68 

Classroom 

Noise reduction 26 31 41 47 47 48 43 

Outside 111 116 122 119 117 114 111 

Inside 75 78 73 69 67 66 68 

Office 

Noise reduction 36 38 49 50 50 48 43 
Page 40 Health Hazard Evaluation Report No. 2000-0191-2960

Table 16. Sound Level Measurements 

HETA 2000-0191 

U.S. INS-NFU 

September 25, 2002

 

Position TWA/Leq (dB) TWA/Leq (dBA) Peak Level (dB) 

Firing Range* 128 126 157 

Pistol Exercise* 127.6 126 157 

Shotgun Exercise* 126.8 124.4 156 

Observation Station 95.5 93 136 

Cleaning Room 92 90 115 

Classroom 80 79 110 

Office 78 77 108 

* Measurements taken at ear level, center lane (tripod) 

Table 17. Hearing Protectors Noise Reductions

HETA 2000-0191 

U.S. INS-NFU 

September 25, 2002

 

* Protected measurements were made with the Artificial Head and the Peltor H10 earmuffs and EAR 

Classic earplugs. 

** LeqA(2hr) is the A-weighted equivalent sound level for 2 hours of continuous exposure. 

Unprotected Protected* 

Weapon Peak Leq Leq 

A 

Leq A 

(2 hr) 

Peak Leq Leq 

A 

Leq A 

(2 hr)** 

Peak Reduction 

Pistol 157 128 126 134 121 95 84 92 36 

Shotgun 156 127 124 132 107 92 71 79 49 

Rifle 157 128 127 135 127 102 93 101 30 
Health Hazard Evaluation Report No. 2000-0191-2960 Page 41 

Figure 1. Carbon Monoxide Exposure during Qualification Exercises, Lane 5

HETA 2000-0191 

U.S. INS-NFU 

September 25, 2002 

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Page 42 Health Hazard Evaluation Report No. 2000-0191-2960

Figure 2. Carbon Monoxide Exposures during Qualification Exercises, Lane 7 

HETA 2000-0191 

U.S. INS-NFU 

September 25, 2002

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Health Hazard Evaluation Report No. 2000-0191-2960 Page 43 

Figure 3. Carbon Monoxide Exposures during Qualification Exercises, Lane 10 

HETA 2000-0191 

U.S. INS-NFU 

September 25, 2002 

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Time

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Page 44 Health Hazard Evaluation Report No. 2000-0191-2960

Figure 4. Carbon Monoxide Exposures during Qualification Exercises, Lane 13 

HETA 2000-0191 

U.S. INS-NFU 

September 25, 2002 

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Time

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Health Hazard Evaluation Report No. 2000-0191-2960 Page 45 

Figure 5. Carbon Monoxide Exposures during Qualification Exercises, Lane 15 

HETA 2000-0191 

U.S. INS-NFU 

September 25, 2002

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C

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Page 46 Health Hazard Evaluation Report No. 2000-0191-2960

Figure 6. Carbon Monoxide Exposures during Qualification Exercises, Lane 17 

HETA 2000-0191 

U.S. INS-NFU 

September 25, 2002 

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Health Hazard Evaluation Report No. 2000-0191-2960 Page 47 

 Figure 7. Control Room Noise Levels During Pistol Qualification 

 HETA 2000-0191 

U.S. INS-NFU 

April 19-20, 2000

 

12:45 PM 12:55 PM 1:05 PM 1:15 PM 1:25 PM 1:35 PM 1:45 PM 1:55 PM

Time of Day

0

20

40

60

80

100

Sound 

Level 

[dB(A) 

1-min 

Leq] 
Page 48 Health Hazard Evaluation Report No. 2000-0191-2960

Figure 8. Control Room Noise Levels During Shotgun Qualifications 

HETA 2000-0191 

U.S. INS-NFU 

April 19-20, 2000 

 

8:35 AM 8:40 AM 8:45 AM 8:50 AM 8:55 AM 9:00 AM 9:05 AM 9:10 AM 9:15 AM

Time of Day

0

20

40

60

80

100 Sound 

Level 

[dB(A) 

1-min 

Leq] 
Health Hazard Evaluation Report No. 2000-0191-2960 Page 49 

Figure 9. Classroom Noise Levels During Pistol Qualification 

HETA 2000-0191 

U.S. INS-NFU 

April 19-20, 2000 

 

12:45 PM 12:55 PM 1:05 PM 1:15 PM 1:25 PM 1:35 PM 1:45 PM 1:55 PM

Time of Day

0

20

40

60

80

100

Sound 

Level 

 

[dB(A) 

1-min 

Leq] 
Page 50 Health Hazard Evaluation Report No. 2000-0191-2960

Figure 10. Classroom Noise Levels During Shotgun Qualifications 

HETA 2000-0191 

U.S. INS-NFU 

April 19-20, 2000 

 

8:35 AM 8:40 AM 8:45 AM 8:50 AM 8:55 AM 9:00 AM 9:05 AM 9:10 AM 9:15 AM

Time of Day

0

20

40

60

80

100

Sound 

Level 

[dB(A) 

1-min 

Leq] 
Health Hazard Evaluation Report No. 2000-0191-2960 Page 51 

Figure 11. Diagram of Firing Range 

HETA 2000-0191 

U.S. INS-NFU 

June 15, 2001 

11

4 9

Firing Lanes

Cleaning Room

Observation Tower

Office Area

Classroom

2

0

1

3

5

6

7

8

10

Measurement Positions

Diagram of Measurement Positions at INS Firing Rnage
Page 52 Health Hazard Evaluation Report No. 2000-0191-2960

Figure 12. One-Third Octave Spectrum - Position 1 (Firing Range) 

HETA 2000-0191 

U.S. INS-NFU 

June 6, 2001 

100 160 250 400 630 1000 1600 2500 4000

60 

80 

100

120

Frequency band [Hz]

Level [dB]

1/3 octave spectrum position 1 (Firing Range)
Health Hazard Evaluation Report No. 2000-0191-2960 Page 53 

Figure 13. One-Third Octave Spectrum - Position 4 (Cleaning Room) 

HETA 2000-0191 

U.S. INS-NFU 

June 6, 2001 

 

100 160 250 400 630 1000 1600 2500 4000

60

70

80

90

100

110

120

Frequency band [Hz]

Level [dB]

1/3 octave spectrum position 4 (Cleaning Room)
Page 54 Health Hazard Evaluation Report No. 2000-0191-2960

Figure 14. One-Third Octave Spectrum - Position 7 (Control Room) 

HETA 2000-0191 

U.S. INS-NFU 

June 6, 2001 

100 160 250 400 630 1000 1600 2500 4000

60

70

80

90

100

110

120

Frequency band [Hz]

Level [dB]

1/3 octave spectrum position 7 (Observation Tower)
Health Hazard Evaluation Report No. 2000-0191-2960 Page 55 

Figure 15. One-Third Octave Spectrum - Position 9 (Classroom) 

HETA 2000-0191 

U.S. INS-NFU 

June 6, 2001 

100 160 250 400 630 1000 1600 2500 4000

60

70

80

90

100

110

120

Frequency band [Hz]

Level [dB]

1/3 octave spectrum position 9 (Classroom)
Page 56 Health Hazard Evaluation Report No. 2000-0191-2960

Figure 16. One-Third Octave Spectrum - Position 11 (Office Area) 

HETA 2000-0191 

U.S. INS-NFU 

June 6, 2001 

100 160 250 400 630 1000 1600 2500 4000

60

70

80

90

100

110

120

Frequency band [Hz]

Level [dB]

1/3 octave spectrum position 11 (Office Area)
Health Hazard Evaluation Report No. 2000-0191-2960 Page 57 

Figure 17. Artificial Head Measurement Setup 

HETA 2000-0191 

U.S. INS-NFU 

September 25, 2002 
Page 58 Health Hazard Evaluation Report No. 2000-0191-2960

Figure 18. One-third Octave Spectrum - Pistols vs. Shotguns

HETA 2000-0191 

U.S. INS-NFU 

September 25, 2002 

Frequency (Hz)

25 50 100 200 400 1000 2000 4000 10000

L

e

v

el (d

B)

90

100

110

120

Shotguns

Pistols
Health Hazard Evaluation Report No. 2000-0191-2960 Page 59 

Figure 19. Peak Level Reductions for Hearing Protectors 

HETA 2000-0191 

U.S. INS-NFU 

September 25, 2002 

0 5 10 15 20 25 30 35 40

EAR® Plugs and Peltor

Earmuffs

EAR® Plugs

Peltor Earmuffs

Bilsom Earmuffs

EAR® Plugs and Bilsom

Earmuffs

Peak Level Reductions (dB SPL)
Page 60 Health Hazard Evaluation Report No. 2000-0191-2960

Figure 20. Lead Exposures during Single Pistol Qualification Exercise 

HETA 2000-0191 

U.S. INS-NFU 

September 25, 2002 

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 2.6 2.8 3.0 3.2 3.4 3.6 3.8 4.0 4.2 4.4

Lane 2

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Lane 18

Instructor

Area Sample

8-hr TWA μg/m 3
Health Hazard Evaluation Report No. 2000-0191-2960 Page 61 

Figure 21. Lead Exposures during Single Shotgun Qualification Exercise 

HETA 2000-0191 

U.S. INS-NFU 

September 25, 2002 

02468 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60 62

Lane 2

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Instructor

Area Sample

8-hr TWA μg/m 3
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