Evaluation of Fire Debris Cleanup 

Employees’ Exposure to Silica, 

Asbestos, Metals, and 

Polyaromatic Hydrocarbons

HHE Report No. 2018-0094-3355

August 2019
Authors: Catherine Beaucham, MPH, CIH, RS/REHS

Judith Eisenberg, MD, MS

Analytical Support: Bureau Veritas North America, Inc.

Desktop Publisher: Jennifer Tyrawski

Editor: Cheryl Hamilton

Industrial Hygiene Field Assistance: Donnie Booher, Pita Gomez, Adrienne Eastlake

Logistics: Kevin Moore

Keywords: North American Industry Classification System (NAICS) 924110 (Administration of Air 

and Water Resource and Solid Waste Management Programs), California, Wildfire Debris, Silica, 

RCS, Asbestos, Polyaromatic Hydrocarbons, Polycyclic Aromatic Hydrocarbons, PAH, Metals

Disclaimer 

The Health Hazard Evaluation Program investigates possible health hazards in the workplace under 

the authority of the Occupational Safety and Health Act of 1970 [29 USC 669a(6)]. The Health 

Hazard Evaluation Program also provides, upon request, technical assistance to federal, state, and 

local agencies to investigate occupational health hazards and to prevent occupational disease or 

injury. Regulations guiding the Program can be found in Title 42, Code of Federal Regulations, 

Part 85; Requests for Health Hazard Evaluations [42 CFR Part 85]. 

Availability of Report

Copies of this report have been sent to the employer, employees, and unions. The state and local 

health departments and the Occupational Safety and Health Administration Regional Office have 

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

Recommended Citation

NIOSH [2019]. Evaluation of fire debris cleanup employees’ exposure to silica, asbestos, metals, 

and polyaromatic hydrocarbons. By Beaucham C, Eisenberg J. Cincinnati, OH: U.S. Department of 

Health and Human Services, Centers for Disease Control and Prevention, National Institute for 

Occupational Safety and Health, Health Hazard Evaluation Report 2018-0094-3355,

https://www.cdc.gov/niosh/hhe/reports/pdfs/2018-0094-3355.pdf. 
Table of Contents

Main Report

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

Our Approach ................................................................................................................................................... 1

Our Key Findings.............................................................................................................................................. 2

Our Recommendations.................................................................................................................................... 3

Supporting Technical Information 

Section A: Workplace Information............................................................................................................ A-1

Background Information......................................................................................................................... A-1

Section B: Methods, Results, and Discussion .......................................................................................... B-1

Methods: Respirable Crystalline Silica................................................................................................... B-1

Results: Respirable Crystalline Silica...................................................................................................... B-1

Methods: Asbestos Fibers....................................................................................................................... B-1

Results: Asbestos Fibers.......................................................................................................................... B-2

Methods: Metals in Air and on Skin...................................................................................................... B-2

Results: Metals in Air and on Skin......................................................................................................... B-2

Methods: Polyaromatic Hydrocarbons in Air and on Skin ................................................................ B-3

Results: Polyaromatic Hydrocarbons in Air and on Skin ................................................................... B-3

Methods: Confidential Medical Interviews........................................................................................... B-3

Results: Confidential Medical Interviews.............................................................................................. B-4

Methods: Observations of Work Practices, Processes, and Conditions .......................................... B-5

Results: Observation of Work Practices, Processes, and Conditions............................................... B-5

Discussion ................................................................................................................................................. B-7

Limitations................................................................................................................................................. B-9

Conclusions............................................................................................................................................... B-9

Section C: Tables.......................................................................................................................................... C-1

Section D: Occupational Exposure Limits............................................................................................... D-1

Respirable Crystalline Silica.................................................................................................................... D-2

Asbestos.................................................................................................................................................... D-4

Metals........................................................................................................................................................ D-6

Polyaromatic Hydrocarbons................................................................................................................ D-13

Section E: Fire Debris Cleanup Exposure: Information for Construction Employees..................... E-1

Section F: References.................................................................................................................................... F-1
This page left intentionally blank
1

Introduction

Request

In March 2018, an employer representative with a government agency for the state of California 

requested a health hazard evaluation concerning exposures to asbestos, heavy metals, respirable 

crystalline silica (respirable particles are 10 micrometers or less in diameter), and polyaromatic 

hydrocarbons during cleanup of structural debris and burn ash after wildfires spread into areas where 

homes and business were located. Union representatives from the Operating Engineers Local 3 and the 

Construction and General Laborer’s Local 185 also submitted requests. Management representatives 

from three of the most frequently contracted construction companies for fire debris cleanup also 

submitted health hazard evaluation requests. Because all of these evaluation requests concerned 

employees’ exposures during fire debris cleanup, they were consolidated into one overall health hazard 

evaluation response. This response was conducted at worksites managed by the company (one of the 

three mentioned above) that won the contract for the Carr Fire cleanup.

Background

The Carr Fire was the sixth most destructive wildfire in California history. The fire burned in Shasta and 

Trinity counties in Northern California over approximately 2 months (July and August) in 2018. The 

Carr Fire burned 229,651 acres and destroyed 1,079 residences, 22 commercial buildings, and 503 

outbuildings before it was fully contained. When structures are destroyed, hazardous materials may be 

left behind and must be cleaned up to limit the impact to the public and the surrounding environment.

To learn more about the workplace, go to Section A in the Supporting Technical Information

Our Approach

In August 2018, we met with employee and employer representatives to get a better understanding of 

the processes and the challenges associated with fire debris cleanup work. We also reviewed 

environmental sampling records from previous exposure assessments during wildfire debris cleanup 

work. In September 2018, we returned to California for a site visit during fire debris cleanup. During 

the site visit, we did the following:

• Observed work practices.

• Measured employees’ exposures to respirable crystalline silica, asbestos, metals, and 

polyaromatic hydrocarbons in air.

• Measured metals and polyaromatic hydrocarbons on skin.

• Interviewed employees about their work and their health.

To learn more about our methods, go to Section B in the Supporting Technical Information
2

Our Key Findings

Some employees were overexposed to respirable crystalline silica 

• Skid steer operators had the highest average exposure to silica (quartz) and two operators had 

exposure levels over occupational exposure limits.

• Laborers and excavator operators were not overexposed to respirable crystalline silica.

• We observed several instances where employees working inside the lot footprint did not use 

dust suppression with water (Figure 1).

Figure 1. Two employees working inside the lot footprint with no dust suppression, surrounded 

by dust that may contain silica. Photo by NIOSH.

Employees were not overexposed to asbestos, metals, or polyaromatic hydrocarbons 

in air

• Asbestos was not detected in any of the air samples.

• All metals were at least 10 times lower than their lowest applicable exposure limit.

• Naphthalene was detected at levels well below occupational exposure limits in all of the air 

samples. The average concentration was 0.6 micrograms per cubic meter (range: 0.17 to 

2.8 micrograms per cubic meter).

Employees had metals and polyaromatic hydrocarbons on their skin

• We sampled 15 employees’ hands at lunch and all had metals including lead on them.

• We detected phenanthrene in one preshift neck wipe sample and four postshift neck 

wipe samples. 

• We detected fluoranthene in one preshift and one postshift handwipe sample.
3

Some employees did not wear personal protective equipment correctly

• We observed some employees not wearing respirators at all and others not wearing them 

correctly. Examples of incorrect wear included: wearing them over the chin instead of covering 

the nose and mouth, and wearing respirators when not clean-shaven.

• We observed inconsistent use and enforcement of personal protective equipment use across 

task forces. 

• We observed that the types of personal protective equipment available and the decontamination 

procedures used appeared to vary across task forces.

To learn more about our results, go to Section B in the Supporting Technical Information

Our Recommendations

The Occupational Safety and Health Act requires employers to provide a safe workplace.

Benefits of Improving Workplace Health and Safety:

 Improved worker health and well-being  Enhanced image and reputation 

 Better workplace morale  Superior products, processes, and services

 Easier employee recruiting and retention  May increase overall cost savings

The recommendations below are based on the findings of our evaluation. For each recommendation, 

we list a series of actions you can take to address the issue at your workplace. The actions at the 

beginning of each list are preferable to the ones listed later. The list order is based on a well-accepted 

approach called the “hierarchy of controls.” The hierarchy of controls groups actions by their likely 

effectiveness in reducing or removing hazards. In most cases, the preferred approach is to eliminate 

hazardous materials or processes and install engineering controls to reduce exposure or shield 

employees. Until such controls are in place, or if they are not effective or practical, administrative 

measures and personal protective equipment might be needed. Read more about the hierarchy of 

controls at https://www.cdc.gov/niosh/topics/hierarchy/. 

We encourage the company to use a health and safety committee to discuss our 

recommendations and develop an action plan. Both employee representatives and 

management representatives should be included on the committee. Helpful guidance can be 

found in “Recommended Practices for Safety and Health Programs” at

https://www.osha.gov/shpguidelines/index.html. 
4

Recommendation 1: Reduce employee exposures to respirable crystalline silica and 

educate employees on silica and silicosis.

Why? Occupational exposure to respirable crystalline silica has been associated with silicosis, lung 

cancer, pulmonary tuberculosis disease, and other airway diseases. The Occupational Safety and 

Health Administration (OSHA) permissible exposure limit and National Institute for Occupational 

Safety and Health (NIOSH) recommended exposure limit for respirable crystalline silica exposure is 

50 micrograms per cubic meter, with OSHA also defining a 25 micrograms per cubic meter action 

level. The American Conference of Governmental Industrial Hygienists threshold limit value for 

quartz is 25 micrograms per cubic meter. We found two exposures above the American Conference 

of Governmental Industrial Hygienists threshold limit value and OSHA action level. One of these 

exposures was also above the OSHA permissible exposure limit and NIOSH recommended 

exposure limit.

How? At your workplace, we recommend these specific actions:

Ensure that water spray is consistently used to reduce dust.

Improve silica hazard education.

• OSHA requires employers to ensure that each employee with potential silica exposure 

above the OSHA action level can do the following:

o Demonstrate knowledge and understanding of the health hazards associated with 

exposure to silica. 

o Identify specific tasks in the workplace that could result in exposure to silica. 

o Identify specific measures the employer has implemented to protect employees 

from exposure to silica. 

o Understand the purpose of the medical surveillance program. 

• The OSHA hazard communication standard also requires training for silica regardless of 

airborne exposure level.

• Training may include existing silica-related NIOSH documents:

o Silicosis-Working with Cement Roofing Tiles: A Silica Hazard

 Designed for roofers and exposures from dry cutting cement tiles, the 

document may be useful for general construction because it directly 

addresses silica exposure as a result of mechanically breaking cement 

materials, which often occurs during fire debris cleanup.
5

 Available in English and Spanish: 

(https://www.cdc.gov/niosh/docs/2006-110/) 

(https://www.cdc.gov/spanish/niosh/docs/2006-110_sp/). 

o Silicosis: Learn the Facts!

 Designed for the construction and abrasive blasting industries, the 

document describes silica exposures, the effects of silicosis, and methods 

to protect against silicosis.

 Available in English and Spanish: 

(https://www.cdc.gov/niosh/docs/2004-108/default.html) 

(https://www.cdc.gov/spanish/niosh/docs/2004-108_sp/).

Develop a medical surveillance program for workers exposed to silica—see 

Section D for more information.

• Construction companies whose employees are likely to be exposed to respirable 

crystalline silica above the OSHA action level for ≥ 30 days per year must have a medical 

surveillance program.

• Medical surveillance for silica-exposed workers should include the following: 

o Preplacement, annual, and exit medical examinations focused on the respiratory 

system.

o Medical history including an extensive work history, history of preexisting 

respiratory conditions (like asthma), and a smoking history.

o Spirometry prior to first fire debris cleanup and annually as long as engaging in 

work with potential exposures to respirable crystalline silica and/or asbestos.

• Employees should be encouraged to inform their primary care provider of their

workplace exposure to silica.

o Provide employees with copies of any air sampling results documenting silica 

exposure and medical surveillance results obtained through the medical

surveillance program.

o Incorporate documentation of respirable crystalline silica exposure into 

employees’ medical records to ensure that this information is available for their 

healthcare provider to allow for the most complete medical care.
6

Recommendation 2: Reduce the amount of lead and other metals on the 

employees’ hands and work clothes.

Why? Exposure to lead and other metals on hands can lead to ingestion of those contaminants by 

transfer from the hands to the mouth when proper handwashing is not practiced. Although no 

occupational exposure limits exist for the permissible amount of lead on the skin, OSHA requires 

work areas such as eating areas or break area to be as free as practicable from lead contamination. In 

addition, occupational lead exposure can result in exposures of household members, including 

children, from take-home contamination. We found lead and other metals on the hands of fire debris 

cleanup employees at lunch and before they went home for the day.

How? At your workplace, we recommend these specific actions:

Add handwashing facilities and lead-removal handwipes at the 

decontamination tent.

Require employees to wash their hands after leaving the lot footprint, and 

before eating, drinking, or smoking.

Require employees to change shoes prior to going home to avoid tracking 

dust containing lead and other heavy metals at home.

Recommendation 3: Require consistent use and enforcement of personal protective 

equipment and decontamination procedures among all contractors and 

subcontractors.

Why? Lack of or improper personal protective equipment use when necessary exposes employees to 

hazards. We observed inconsistent use and enforcement of personal protective equipment use across 

task forces. We also observed that the types of personal protective equipment available and the 

decontamination procedures varied across task forces. In addition, we found that some employees 

used latex gloves, which can cause allergic sensitization.
7

How? At your workplace, we recommend these specific actions:

Enforce consistent personal protective equipment use across all task 

forces and by all task force leads.

• Improve communication and consistency of personal protective equipment selection 

and use among all contractors, subcontractors, and task forces.

o Standard operating procedures, job hazard analyses, and required personal 

protective equipment should be documented, disseminated, explained, and 

reinforced equally for all subcontractors and task forces.

• Provide periodic refresher training on the specific hazards and personal protective 

equipment that employees must use during fire debris cleanup work.

• Collaborate with the unions, contractors, and subcontractors to develop standardized 

training materials for fire debris cleanup workers.

• Take immediate corrective action when improper use of personal protective equipment 

is noted on the job site.

Provide only nitrile gloves to employees.

• Use only nitrile gloves when tight-fitting chemical resistant gloves are required. Do not 

use latex gloves.

• Remove latex gloves from the decontamination tent area due to potential for 

latex sensitization.

Ensure methods used to decontaminate footwear on exiting the lot 

footprint are adequate and followed.

• We observed that the boot covers that laborers used disintegrated during the shift. 

Therefore, laborers should not wear boot covers and instead should use a boot wash on 

exiting the footprint.

Ensure all task forces comply with the respiratory protection standard.

• Ensure that all employees are fit-tested, trained, and medically cleared to wear 

a respirator.

• Emphasize the proper use, training, cleaning, maintenance, and storage of respirators.

o Include the requirement to be clean-shaven, when to wear the respirator, filter 

change-out schedule, and how to properly store and clean the respirator.
8

Recommendation 4: Measure employees’ full-shift noise exposures to determine if 

exposures are above the NIOSH recommended exposure limit. 

Why? Although we did not include noise dosimetry or audiometry during our assessment, noise from 

construction equipment could expose operators and laborers to noise levels above NIOSH’s 

recommended exposure limit of 85 decibels as an 8-hour time weighted average. We observed that 

not all employees wore hearing protection when in the lot footprint.

How? At your workplace, we recommend these specific actions:

Ensure all employees who are exposed to hazardous levels of noise are 

properly protected.

• Include any overexposed employees in a hearing conservation program.

o The program should include initial and annual audiometric exams, providing 

hearing protection, training on hearing loss and use of hearing protection, and 

include periodic noise exposure assessments.

• For additional information on noise and guidance on developing a hearing loss 

prevention program, refer to the NIOSH document Occupational Noise Exposures at 

https://www.cdc.gov/niosh/docs/98-126/default.html. 
Supporting Technical Information

Evaluation of Fire Debris Cleanup Employees’ 

Exposure to Silica, Asbestos, Metals, and 

Polyaromatic Hydrocarbons 

HHE Report No. 2018-0094-3355

August 2019
A-1

Section A: Workplace Information

Background Information

The national trend in wildfires since 1998 shows that, although the total number of fires is decreasing, 

each fire is burning more land. In 2017 alone, over 10 million acres of land were ravaged by wildfires, 

and the 2018 fire season in California reached historic levels [NIFC 2017, 2018]. When wildland fires 

extend into residential areas, after the fire has been extinguished, construction crews must be brought in 

to clean up the debris that has been left behind. Remnants of burned residential structures may contain 

respirable crystalline silica (RCS) (typically quartz) from demolished concrete used in foundations, walls, 

and roofing tiles or naturally occurring in the rocks and soil. Cristobalite (another form of RCS) is 

typically found in igneous rocks, which are formed as a result of previous volcanic activity. Depending 

on the age of the building, asbestos can also be present. Home electronics and melted vehicles can leave 

behind various metals such as lead, cadmium, and aluminum. Additionally, potentially carcinogenic 

substances found in soot (burn ash) called polyaromatic hydrocarbons (PAHs), also known as polycyclic 

aromatic hydrocarbons, may also be exposure hazards.

After a wildfire has been contained and the burned area declared safe to enter, the state agency 

responsible for overseeing and managing contractors and consultants involved in wildfire debris 

cleanup and removal begins a stepwise process to initiate cleanup and eventual reoccupation of the area. 

The agency starts this process with an initial site hazard assessment that includes identifying sites that 

potentially contain asbestos and a visual inspection for presence of explosive hazards such as propane 

cylinders, etc. The initial hazard assessment can be contracted to another company depending on the 

number and type (i.e., residential or industrial) of damaged lots. Afterward, the agency creates a contract 

for the fire debris cleanup. The contract specifies how the contractor must address the identified on-site 

hazards (i.e., asbestos abatement, propane cylinder removal), what environmental sampling should be 

done during the cleanup, and how removed debris will be transferred to the final disposal sites. Due to 

environmental regulations, only specific sites are certified by the state as acceptable for receiving 

wildfire debris. The agency then collects bids from construction companies and selects a 

primary contractor.

Depending on the size of area to be cleaned and the available resources of the primary contractor, other 

construction companies may be subcontracted to ensure completion of the cleanup by the date 

specified in the contract. In this evaluation, we refer to the primary contractor as Company A. The 

agency also contracted an engineering services company (Company B) that subsequently subcontracted 

a portion of their tasks to two additional companies (which we refer to collectively as Company C). 

Company A also selected three subcontractors to carry out the debris removal (Companies D, E, 

and F). 

After the home owner indicates that they wish to have the fire debris removed by the state by signing a 

right of entry form, debris removal is done in phases. The first phase, completed by the California 

Department of Toxic Substances Control (or other dedicated agency), is household hazardous waste 
A-2

removal. In the second phase, the California Department of Resources Recycling and Recovery assesses 

and documents the site. This phase includes evaluating soil samples to establish cleanup goals for the 

project and removing asbestos-containing material. The third phase is debris removal, done by the 

subcontractor. After the lot has been certified by the state that it has been cleared of hazards and that all 

debris has been removed in accordance with state regulations, the lot occupants can return to rebuild. 

An additional state requirement is to collect personal and environmental samples during debris cleanup 

to ensure that potential exposures are controlled. See Section E for additional information on the 

hazardous exposures from fire debris cleanup activities and how the state of California approaches fire 

debris cleanup activities.

The task force leader, who supervised on-site operations, kept track of departing loads. Typically, task 

force leads were not represented by a union and were employed by Company B or C. The construction 

employees (from Companies D, E, and F) in this evaluation were represented by two separate unions, 

the Operating Engineers Local 3 and the Construction and General Laborer’s Unions. The Operating 

Engineers union represented employees who operated the heavy equipment, such as front-end loaders 

and backhoes. Heavy equipment was needed to move large pieces of remaining structures (i.e., lift out 

chimney stacks, pull down partially standing walls, break up concrete foundations, remove fallen trees, 

etc.) and potentially contaminated dirt. These vehicles were also used to load debris into the removal 

trucks that would take the debris to a predetermined site for disposal. 

After removal of all the debris, heavy equipment was used to level the lot. The Laborers’ Union 

represented those employees who manually removed debris, handled the water sprays for dust 

suppression inside the lot footprint during debris removal, identified hazards in the lot, covered trucks 

that were loaded with debris with a tarp before it departed for the debris disposal site, and removed 

items such as metal screws and nails from the lot upon completion of the debris cleanup. Some laborers 

also operated skid steers. The Laborers’ union in California is divided into regions, and each region has 

several local chapters. Due to the extensive areas impacted by the Carr Fire, the laborers in this 

evaluation were represented by six different local chapters (local Chapters 185, 203, 261, 294, 324, and 

1130) from many regions in California and several other states. 

A typical lot footprint for fire debris cleanup is depicted in Figure 2. The footprint usually consisted of a 

residence, such as a house and any outlying structures like pools, sheds, or guest houses. The lot 

footprint size range depended on the size of the house and the location of the outlying structures. The 

perimeter of the lot footprint was set to encompass all burned structures within the footprint and was 

demarcated by using caution tape. The driveway was typically used to park, load, and tarp trucks that 

carried fire debris to be disposed. 

All employees were required to wear personal protective equipment (PPE), including respirators, 

Tyvek® suits, boots or boot covers, hearing protection (sometimes), and gloves (work gloves and/or 

nitrile) when they entered the lot footprint. All required PPE were to be donned before passing though 

the decontamination area at the front of the lot. All employees were also required to leave the lot 

footprint through the decontamination area. Also located in the decontamination area was a 

decontamination table. They first removed their boot covers (if they had them on) or walked through a 

boot wash. Afterwards, they remove their Tyvek suits and disposed of them in the trashcan. Next, 
A-3

employees removed their respirators, and then removed their tight-fitting chemical resistant gloves last. 

The task force lead and/or an environmental sampling technician typically remained at the table in the 

decontamination tent.

Figure 2. Typical lot footprint for fire debris cleanup activities. 
B-1

Section B: Methods, Results, and Discussion

Our objective was to evaluate fire debris cleanup employees’ exposure to RCS and asbestos in air, and 

metals and PAH in air and on the skin. During the Carr Fire cleanup, 35 different “task forces,” each 

typically consisting of one task force lead, one equipment operator, and two laborers, were located on 

damaged lots throughout Shasta County. On Days 1, 2, and 3 of our evaluation we evaluated four or 

five task forces for RCS and PAH. On Days 4 and 5 of our evaluation we evaluated three or four task 

forces for metals and asbestos. We selected the lots that met the following criteria: (1) for RCS and 

PAH sampling, we specified lots that were on Days 1, 2, and 3 of their cleanup operations and (2) for 

the asbestos samples, we specified lots that had previously been identified as needing an asbestos 

abatement. NIOSH invited all of the employees who were participating in exposure monitoring to also

complete a confidential medical interview. We also interviewed task force leads and other personnel 

who were conducting environmental monitoring if they were working around the lot footprint.

Methods: Respirable Crystalline Silica

Silica can occur in one of three crystalline forms: quartz, cristobalite, and tridymite. We sampled for all 

3 crystalline forms. We collected samples for RCS using NIOSH Manual of Analytical Method 7500 

[NIOSH 2019]. We collected 42 personal silica air samples for 17 different employees over 3 days. We 

also collected area air samples for RCS at three of the decontamination tables.

Results: Respirable Crystalline Silica

We detected RCS in 33 (73%) of 45 samples. Results for the RCS quartz samples are displayed in 

Table C1. The mean air concentration for all personal RCS quartz air samples was 13.2 micrograms per 

cubic meter (μg/m3) and ranged from 2.4–76 μg/m3. Of the seven skid steer operators sampled, two 

had air RCS concentrations above the American Conference of Governmental Industrial Hygienists 

(ACGIH) threshold limit value (TLV) and OSHA action level (AL) of 25 μg/m3. One of these two was 

also exposed above the NIOSH recommended exposure limit (REL) and OSHA permissible exposure 

limit (PEL) of 50 μg/m3 [OSHA 2019a]. 

We also detected RCS cristobalite in 3 (6%) of 45 samples, but at a concentration well below 

occupational exposure limits (OELs). The cristobalite concentrations ranged 2.9–3.4 μg/m3, which were 

between the minimum detectable concentration (MDC) of 2.6 μg/m3 and minimum quantifiable 

concentration (MQC) of 9.4 μg/m3. This indicates more uncertainty associated with these results. Area 

air sample results for RCS ranged from not detected to 2.7 μg/m3. 

Methods: Asbestos Fibers

We collected samples for asbestos and other fibers using NIOSH Method 7400 and phase contrast 

microscopy (PCM). We collected 21 personal air samples (4 skid steer operators, 10 laborers, and 

7 excavator operators) for 17 different employees over 2 days. We also collected area air samples at all 

five decontamination tables. We further analyzed the fiber samples that had 0.01 fibers per cubic meter 

(f/cc) or more using NIOSH Method 7402, transmission electron microscopy, to identify whether the 

fibers were asbestos. The OSHA PEL for asbestos fibers is 0.01 f/cc.
B-2

Results: Asbestos Fibers

Air sampling results for fiber concentrations in the 21 personal air samples are displayed in Table C2. 

All air sample results were below OELs. Laborers had the highest mean concentration of fibers 

(0.090 f/cc), followed by skid steer operators (0.03 f/cc), and last by excavator operators (0.007 f/cc). 

The fiber concentrations across these jobs ranged from 0.004–0.15 f/cc. The fiber concentration of the 

area samples ranged from 0.002–0.007 f/cc. Thirteen air samples were above 0.01 f/cc; however, 

transmission electron microscopy revealed that none of these fibers were asbestos. The primary type of 

fibers found in the samples were organic fibers. We also detected iron, aluminum silicate, calcium 

silicate, and hornblende fibers; none of which have OELs.

Methods: Metals in Air and on Skin 

We collected and analyzed samples for metals and metalloids in air using NIOSH Method 7303 and on 

the skin using NIOSH Method 9102. We collected 20 air samples on 17 employees over 2 days. We 

took these samples on the same 17 employees on whom we also collected asbestos fiber samples. We 

did not analyze one of the air samples we took because the sample media had fallen off and could have 

been contaminated. We collected handwipe samples before the shift began, at lunch, and after the shift 

was over just before the employee went home. If the employee chose to wash his or her hands, we 

collected the handwipe samples afterwards.

Results: Metals in Air and on Skin 

Metals in Air

The sources of metals exposure can include electronics, cars, refrigerators, stoves, etc. (Figure 3). When 

these items are burnt by the fire, these metals, such as lead, cadmium, and aluminum, can melt and 

contaminate the ground below them and be found in the debris and dust in the lot footprint. 

Employees could potentially inhale the metals while cleaning up this dirt and debris. No air samples 

exceeded any OELs for any metals or metalloids, and all samples were at least an order of magnitude 

below applicable OELs. Results are shown in Table C3. 

Figure 3. Cars and trucks that had been burnt 

in the fire. Photo by NIOSH. 
B-3

Metals on Skin 

Employees could also ingest these metals if they are on their hands before eating or smoking. Results of 

handwipe samples for metals and metalloids are displayed in Table C4. We found metals on employees’ 

hands before their shift started, at lunch, and after their shift was over before leaving the worksite. We 

observed slightly higher levels for most metals at the end of the work shift compared to the before shift 

samples, however this difference was not statistically significant. We also observed that some employees 

did not wash their hands before eating lunch or leaving the worksite at the end of the day. Although 

there were sinks located at the portable restrooms, many were not very convenient to all of the lots, 

which could have made washing hands a lunch difficult.

Methods: Polyaromatic Hydrocarbons in Air and on Skin

We took 49 full-shift personal air samples for PAHs on the same 17 employees on which we collected 

RCS and asbestos air samples. We did not analyze one of the samples because the air sampling pump 

had stopped working. We analyzed the PAHs in air according to NIOSH Method 5506. We collected 

dermal skin wipes on the hand and the back of the neck before and after a shift. We also collected an 

additional handwipe after a shift on the second day of sampling. We analyzed the PAHs in wipes by 

NIOSH Method 5506, modified for the wipe material.

Results: Polyaromatic Hydrocarbons in Air and on Skin

Polyaromatic Hydrocarbons in Air 

Table C5 shows the personal air sampling results for naphthalene and phenanthrene. All air samples 

were well below the lowest OEL for naphthalene. No OELs exist for phenanthrene. However, all but 

15 samples were below the MDC, and all were below the MQC. We detected acenaphthene in one 

sample. However, the air sampling pump had failed during sample collection, so we could not calculate 

the concentration. We also analyzed the samples for anthracene, benzo(a)anthracene, benzo(a)pyrene, 

benzo(b)fluoranthene, benzo(g,h,i,)perylene, benzo(k)fluoranthene, chrysene, dibenzo(a,h)anthracene, 

fluoranthene, fluorine, indeno(1,2,3-cd)pyrene, and pyrene. We did not detect any of these in any 

sample.

Polyaromatic Hydrocarbons on Skin 

We detected phenanthrene in one preshift neck wipe sample (0.2 micrograms per sample [μg/sample]), 

3 postshift handwipe samples (0.3–0.4 μg/sample), and 1 postshift neck wipe sample (0.2 μg/sample). 

We detected fluoranthene in one preshift handwipe sample (0.2 μg/sample) and in one postshift 

handwipe sample (0.6 μg/sample). We also collected hand and neck wipe samples for acenaphthene, 

anthracene, benzo(a)anthracene, benzo(a)pyrene, benzo(b)fluoranthene, benzo(g,h,i,)perylene, 

benzo(k)fluoranthene, chrysene, dibenzo(a,h)anthracene, fluorine, indeno(1,2,3-cd)pyrene, and pyrene. 

None of these were detected in any sample.

Methods: Confidential Medical Interviews

We invited all 40 employees from the selected task forces to participate in confidential medical 

interviews in either English or Spanish. The interview covered work history, work practices and tasks 

based on their reported job title, union affiliation, prior wildfire debris cleanup experience, hazard 
B-4

training, PPE use, and pertinent medical history. The medical history questions focused on diagnoses 

and symptoms associated with exposure to lead, asbestos, and RCS.

Results: Confidential Medical Interviews

We interviewed all 40 of the employees during the September site visit. Table C6 shows the number of 

employees we interviewed from each company. We did not interview any employees from the agency or 

Company A because none were working in or around the lot footprints that we evaluated. We 

interviewed employees from Company B (n = 3) and subcontractors for Company B (n = 2) who were 

responsible for on-site supervision (known as task force leaders) and/or environmental sampling. These 

employees worked outside of the lot footprint. We also interviewed 35 employees from three 

subcontracted construction companies (Companies D, E, and F). These employees worked inside the 

lot footprint as laborers or equipment operators. All employees we interviewed reported being 

represented by their respective unions.

Interview Results 

For the five participants who worked outside the lot footprint, the median age was 35 years (range: 

31−40 years), three were male, and the median years working in construction was 1.5 years (range: 

0.1−25 years). Four of these participants (all of the task force leaders) reported that they had prior fire 

debris cleanup work experience, and that they started working fire debris cleanup within the previous 

2 years.

We aggregated the remainder of the interview results based on employees’ on-site roles as operators or 

laborers because of the small employee numbers from individual companies and the job tasks being 

similar no matter which company the employee worked for. Details of the interview responses for the 

operators and laborers can be found in Table C7. All of the laborers and all but one of the operators 

were male, and the majority of both groups of employees had previous experience working fire 

debris cleanups. 

Of the 14 interviewed operators, 11 indicated that that were concerned about “other” exposures 

including unknown chemicals, toxic gases, live power lines, and sharp objects. Seven operators indicated 

being concerned about smoke, ash, and dust. Three operators were concerned about exposure to 

asbestos and metals other than lead. The 21 laborers reported that they were primarily concerned about 

exposure to asbestos (n = 10), silica (n = 8), and lead (n = 6). Some additional concerns included 

vehicle accidents, dust, ash, vapors, explosions, toxic substances from plastics, dead animals, and odors. 

The majority of both groups reported that their employer did not provide lead-removal handwipes 

(n = 8 operators; n = 10 laborers). All participants reported having received “adequate information 

and/or training regarding potential health hazards likely to be encountered during fire debris cleanup” 

from their employer.

The 14 operators reported that their most common tasks were operating a closed cab excavator 

(n = 13), a skid steer/bobcat (n = 9), open cab excavator (n = 4), and front-end loader (n = 4). Other 

operator tasks included operating a grading/paving vehicle (n = 2) and operating a street sweeper 

(n = 1). For the laborers, all 21 participants reported they did raking/shoveling ash or debris, 

raking/shoveling soil, operating water hoses, and securing debris loads with tarps once loaded onto 
B-5

removal trucks. The most common tasks reported by the laborers were manual handling and removal of 

metal debris (n = 17), manual removal of concrete debris (n = 15), and flagger operations or traffic 

control (n = 13). 

The PPE reportedly used by both employee groups is detailed in Table C8. Both groups of employees 

we interviewed seemed to be confused regarding the differences between a dust mask, disposable 

respirator, and a half-mask elastomeric respirator. In addition, some employees were uncertain 

regarding the composition of their gloves. Both groups reported that when hearing protection was used, 

earplugs were used more frequently than earmuffs. Only five interviewed employees reported that they 

always wore earplugs, and only one employee reported always wearing earmuffs. Three employees 

reported never using either earplugs or earmuffs.

Since working on their first fire debris cleanup, none of the laborers or operators reported the 

following:

• Receiving a diagnosis of asbestosis, silicosis, asthma, emphysema/chronic obstructive 

pulmonary disease (COPD), cancer, lead poisoning/toxicity, or anemia by a healthcare provider.

• Experiencing difficulty breathing or shortness of breath, chest tightness, wheezing, dry or 

nonproductive cough, unusual fatigue, or severe, unexplained abdominal pain they felt may be 

work-related.

• Having any current health problems they thought were work-related.

Methods: Observations of Work Practices, Processes, and Conditions

We observed work processes, practices, and conditions in the lot footprint. We observed employee use 

of PPE and dust suppression methods including water spray from a large tanker and from a hand-held 

hose spray from a portable water tanker.

Results: Observation of Work Practices, Processes, and Conditions

We observed that the activities of the excavator and skid steer generated fairly large dust clouds, 

especially when felling chimneys (excavator), breaking concrete (excavator), and piling up debris (skid 

steer). The dust clouds were more noticeable when the dust suppression methods were either not in use 

or when the water spray was not able to reach the location where the activities were occurring 

(Figure 4). Although laborers were sometimes in the dust clouds generated by the heavy equipment, the 

only visible dust cloud generated by laborers occurred when they cut concrete without a water spray. 

This happened just once for about 2 minutes before employees realized that they needed to have 

dust suppression.
B-6

One of the primary activities done by laborers was dust suppression using a handheld hose attached to a 

“water buffalo,” which is a tank holding about 100 gallons of water that could be transported from lot 

to lot on the back of a small trailer. In some neighborhoods, we observed a large tanker truck full of 

water. This truck drove through the neighborhood and wet all of the damaged structures throughout 

the area using a large hose with a directional spray attachment. This was to ensure that all lots were wet 

for dust suppression even if they were not being worked on. This tanker truck was also used when 

felling a chimney near the back of the lot footprint. The laborer’s handheld spray could not reach the 

top of the chimney, so they would not fell the chimney until dust suppression was made available.

At times, we observed homeowners or construction companies that had been hired directly by the 

homeowner working in lots in the vicinity of those that we were sampling. These companies did not 

always adhere to the same safety protocols and dust suppression protocols. 

We observed that adherence to the required PPE varied between the task forces. Some task force leads 

began each shift with a reminder of the required PPE and reminded employees throughout the day if 

observed without the correct PPE. Other task force leads were not as strict about the rules. We 

observed several employees with full beards under their respirators and some respirators worn 

incorrectly (i.e., on the chin instead of covering the nose and mouth). Although the required glove type 

was nitrile, we observed the use of latex gloves at some of the lot footprints.

Decontamination procedures varied across task forces, especially as it pertained to footwear. Some task 

forces required reusable rubber boots in the footprint, which required using a boot wash when exiting 

the lot footprint (Figure 5). However, some task forces did not enforce the use of the boot wash and we 

observed employees exiting the lot footprint without washing their boots. Some task forces required 

disposable boot covers while working in the footprint, which required that the boot covers be removed 

when exiting the lot footprint. Many times the boot covers disintegrated while working in the lot and, 

Figure 4. An employee standing inside 

the lot footprint was not wearing the 

required respirator and protective suit. In 

addition, no dust suppression spray was 

being applied. Photo by NIOSH. 

Figure 5. Employee utilizing a boot wash. 

Photo by NIOSH. 
B-7

therefore, there was nothing to remove. If the boot covers disintegrate and the boot is not washed, 

contamination from inside the lot footprint can be tracked outside of the footprint.

Discussion 

Our personal air sampling results showed that some of the skid steer operators were overexposed to 

RCS. During fire debris cleanup, the skid steers generated substantial visible dust clouds while moving 

debris into piles for removal by excavators. The skid steers were equipped with rollover cages; however, 

these cages were not enclosed, leaving the operator exposed to dust. We found the highest exposure on 

the first day of fire debris cleanup. It is likely that more dust is generated on the first day and then 

decreases as the burnt debris is removed. 

We observed that the other skid steer operator who was overexposed to RCS worked on a lot where 

dust suppression methods did not fully cover the worksite. This likely contributed to more dust being 

generated, possibly leading to the higher RCS concentration. Other factors that could influence RCS 

exposures include wind speed and direction and silica concentration in dust. In contrast to skid steer 

operators, we found that excavator operators and laborers were not overexposed to RCS. Excavator 

operators were enclosed in cabs, which limited their exposures, even though substantial dust was 

generated by the excavators. Laborer RCS exposures were likely mitigated by the type of work 

(i.e., hand picking debris and holding the water suppression hose) and by the distance maintained from 

the skid steers and excavators. 

A previous study of RCS exposure in the construction industry demonstrated that exposure control 

methods could reduce silica exposures significantly [Rappaport et al. 2003]. These researchers found 

that with consistent use, wet dust suppression reduced laborers’ silica exposures approximately 

threefold and the use of enclosed ventilated cabs in construction vehicles reduced operating engineers’ 

exposures approximately sixfold. Our finding of RCS exposures above the ACGIH TLV and OSHA 

AL of 25 μg/m3 indicate the need for periodic monitoring to assess the need for or effectiveness of 

control measures.

Although silica has been a known occupational hazard for centuries, silicosis remains a largely 

underestimated disease. Silicosis is an irreversible, progressive, but preventable lung disease caused by 

the inhalation of RCS particles. A silicosis diagnosis requires a history of exposure to RCS and chest 

imaging or lung biopsy findings consistent with this condition. 

Silicosis is often underdiagnosed. This may be because the employee is unaware of their workplace 

exposure to RCS or does not relay the exposure history to their healthcare provider not knowing its 

importance. This breakdown in communication may result in silicosis symptoms being misdiagnosed as 

COPD or other nonspecific lung disorders.

Although no employees reported being diagnosed with silicosis or described symptoms that could be 

consistent with silicosis, the establishment of a medical surveillance program is an important 

cornerstone to ensure an early and accurate diagnosis of silicosis in employees with potential 

overexposures to RCS. Employee hazard training should also emphasize the importance of informing 

their healthcare providers of their work history. This is especially important when documented RCS 
B-8

exposures occurred in that workplace, no matter how much time has passed, because of the potential 

long latency period for chronic silicosis. 

Three subcontractors indicated that they had a silicosis medical surveillance program. However, the 

records provided to us by their occupational medicine clinic did not contain the elements needed to 

make the diagnosis of silicosis. These elements should include clinic visit notes documenting reported 

symptoms, physical examination findings, pulmonary function testing, chest imaging studies (i.e., chest 

X-rays or CT), or pulmonologist referral for lung biopsy. Details on the components of a medical 

surveillance program for silica can be found in Section D.

Even though none of our air sampling results indicated overexposures to metals, we detected metals on 

the hands of employees before the shift started, prior to lunch, and prior to going home at the end of 

their shift. This is a concern because of the potential for hand-to-mouth transfer of metals such as lead 

that can readily be absorbed into the body after ingestion. The presence of metals on hands before the 

start of the shift could indicate that soap and water alone are not effective in completely removing these 

metals, which is consistent with NIOSH research [Esswein et al. 2011]. Our interviews revealed the 

need for more frequent handwashing.

Employees reported that they had received adequate training; our interviews revealed that employees 

were doing tasks such as dry sweeping, which is known to reaerosolize dusts containing lead. Although 

no employee reported being diagnosed with lead poisoning or toxicity since working their first fire 

debris cleanup, we do not know what their actual blood lead levels (BLLs) were because the medical 

records we reviewed did not contain BLL test results. Taking lead home to family members is an 

additional concern if work boots and other potentially contaminated clothing is not left at the worksite. 

Since employees reported wearing their work boots home at the end of their workday, and this may 

expose others in the home to lead from the workplace.

Employees need to be familiar with the hazards that they may encounter when cleaning up fire debris 

and the methods used to reduce those hazards (i.e., dust suppression via water spray), including the 

required PPE. Based on our interviews and observations, many employees were uncertain about the 

specific types of required PPE (e.g., type of respirator, use of Tyvek coverall). We observed incorrect 

use of respirators, which can lead to employees inhaling air contaminants because air bypasses the 

respirator filters. In addition, we observed employees working at some lots had been provided the 

wrong type of gloves (i.e., latex gloves instead of nitrile), which could lead to latex sensitization. We also 

observed variability of PPE enforcement depending on the lot, specific task force, task force leads, and 

other factors. This variability demonstrates the importance that all task force leads undergo refresher 

training for on-site hazards, PPE requirements, and proper use of the required PPE. It is important that 

rules be consistently reinforced across all subcontractors, lots, and task forces.

Although we did not include noise dosimetry or audiometry during our assessment, noise from 

construction equipment could potentially expose operators and laborers to noise levels above the 

NIOSH REL of 85 decibels as an 8-hour time-weighted average (TWA) [NIOSH 1998]. Most (36 of 

40) employees indicated that they only “sometimes” wore hearing protection inside the lot footprint 

during fire debris cleanup. This could increase their risk of hearing loss, particularly from noise 

exposure to construction equipment or powered tools. In addition, noise exposures combined with 
B-9

exposures to ototoxic (damage to the ear) agents, such as lead and carbon monoxide from equipment 

exhaust, can increase hearing loss risk [OSHA 2019b]. An accurate assessment of the sound levels 

produced by the heavy equipment and employees’ noise exposures during use or working near this 

equipment would determine which employees would need to be included in a hearing loss prevention 

program. This information can also help determine what level of hearing protection is needed.

Limitations 

Our evaluation was subject to some limitations. First, the exposure monitoring results taken over two or 

three days might not be representative of every type of fire debris cleanup operation. Cleanup 

operations occurring in housing developments with a different predominant type of building structure, 

industrial/manufacturing locations, and geographic areas containing natural deposits of heavy metals 

and/or asbestos may result in exposures to additional hazards or to similar hazards found during this 

evaluation but at varying concentrations. In addition, dust suppression varied greatly between 

neighborhoods and lot footprints, which could impact the quantity of airborne dust. Lastly, although 

the construction employees were reportedly enrolled in a silicosis surveillance program, none of the 

employee medical records documented annual physical examinations, spirometry, or chest imaging 

studies, therefore we were unable to review these documents during our evaluation.

Conclusions

Many of the fire debris cleanup employees we evaluated were exposed to RCS. Two of the skid steer 

operators were exposed to concentrations above the ACGIH TLV and the OSHA AL. Employees were 

not overexposed to asbestos, metals, and PAHs in air. Employees’ hands had detectable amounts of 

metals on them; most of the skin wipes had nondetectable amounts of PAHs. Respirators were required

at all times within the lot footprint, but they were not worn consistently and some instances of 

improper use were not corrected by the task force leader. Improving dust suppression and employee 

education, as well as consistently and properly wearing PPE, will likely help reduce employee exposures.

The employee silicosis surveillance program should include a chest X-ray or CT scan along with 

documented RCS exposure to ensure a diagnosis of silicosis can be made in the future.
C-1

Section C: Tables

Table C1. Full-shift personal air sample results for quartz in μg/m3

Job title Number of samples Mean concentration (range)

Skid steer operators 7 25.7 (3.5–76*)

Laborers 20 10.5 (ND–17)

Excavator operators 12 4.5 (ND–5.0)

NIOSH REL 50 μg/m3

ACGIH TLV 25 μg/m3

OSHA AL 25 μg/m3

OSHA PEL 50 μg/m3

ND = Not detected above the MDC of 2.6 μg/m3. 

* Two samples were above 25 μg/m3 and one was above 50 μg/m3. 

Table C2. Full-shift personal air sample results for fibers* in f/cc

Job title Number of samples Mean concentration (range)

Skid steer operators 4 0.03 (0.004–0.096) 

Laborers 10 0.09 (0.003–0.15)

Excavator operators 7 0.007 (0.002–0.019)

* Fibers are defined as particles having a length-to-width aspect ratio equal to or greater than 3:1.
C-2

Table C3. Full-shift personal air sample results for metals and metalloids (n = 20)

What we sampled,

MQC:

% Detected Air concentration, μg/m3

Mean Minimum Maximum Lowest OEL

Aluminum,

MQC = 2.7

95 14 > 0.75 46 10,000 NIOSH

Arsenic,

MQC = 1.0

40 [0.44] > 0.28 [0.70] 10 ACGIH

Barium,

MQC = 0.28

80 0.61 > 0.090 1.9 500 OSHA, NIOSH, ACGIH

Cadmium,

MQC = 0.06

40 [0.0061] > 0.019 [0.030] 5 OSHA

Calcium,

MQC = N/A

95 76 > 9.5 226 None

Chromium,

MQC = 0.35

30 [0.24] > 0.090 0.37 500 NIOSH, ACGIH

Cobalt,

MQC = 0.16

15 [0.059] > 0.050 [0.078] 20 ACGIH

Copper,

MQC = 0.16

90 0.60 > 0.070 2.3 1,000 OSHA, NIOSH, ACGIH

Iron,

MQC = 0.57

95 25 > 0.19 82 5,000 NIOSH

Lead,

MQC = 0.95

25 [0.47] > 0.28 [0.69] 50 OSHA, NIOSH, ACGIH

Lithium,

MQC = 0.11

5 [0.033] > 0.038 [0.033] 25 OSHA, NIOSH, ACGIH

Magnesium,

MQC = 7.1

95 8.0 > 1.9 26 10,000 ACGIH

Manganese,

MQC = 0.045

95 0.90 > 0.0095 3.4 100 ACGIH

Nickel,

MQC = 0.17

35 [0.08] > 0.047 [0.14] 15 NIOSH

Phosphorus,

MQC = 2.6

45 [2.2] > 0.76 5.3 100 OSHA, NIOSH, ACGIH

Potassium,

MQC = 1.4

95 3.5 > 0.47 9.4 2,000 NIOSH, ACGIH

Selenium,

MQC = 4.4

10 [1.6] 0.95 [2.0] 200 OSHA, NIOSH, ACGIH

Strontium,

MQC = 0.11

85 0.24 > 0.080 0.94 None

Titanium,

MQC = 0.11

95 0.79 > 0.037 2.5 10,000 ACGIH

Vanadium,

MQC = 0.46

10 [0.12] > 0.095 [0.12] 50 ACGIH

Yttrium,

MQC = 0.0089

70 0.017 > 0.0028 0.065 1,000 OSHA, NIOSH, ACGIH

Zinc,

MQC = 0.29

90 1.3 > 0.085 2.9 5,000 NIOSH

Zirconium,

MQC = 0.064

25 0.067 > 0.019 0.11 5,000 NIOSH, ACGIH

[ ] = Estimated concentration. When between the MDC and MQC, indicates more uncertainty associated 

with this value.

Note: Antimony, beryllium, lanthanum, molybdenum, silver, tellurium, thallium, and tin were analyzed for 

but not found in any air sample.
C-3

Table C4. Results of dermal handwipe samples for metals and metalloids 

What we sampled, LOD Dermal handwipes, mean micrograms per handwipe

 Preshift (n = 15)

No. (%) detected

Lunch (n = 15)

No. (%) detected

Postshift (n = 17)

No. (%) detected

Aluminum, LOD = 0.9 178 (100%) 251 (100%) 386 (94%)

Antimony, LOD = 0.7 ND (0%) 0.81 (6.6%) 1 (6%)

Arsenic, LOD = 0.9 ND (0%) 2.3 (13%) 4.3 (29%)

Barium, LOD = 0.02 8.2 (100%) 7.4 (100%) 12 (100%)

Beryllium, LOD = 0.008 ND (0%) ND (0%) 0.0085 (6%)

Cadmium, LOD = 0.02 0.19 (73%) 0.16 (87%) 0.21 (88%)

Calcium, LOD = 7 628 (100%) 942 (100%) 1,269 (100%)

Chromium, LOD = 0.05 1.3 (100%) 0.97 (100%) 2.3 (100%)

Cobalt, LOD = 0.05 0.25 (73%) 0.24 (87%) 0.39 (76%)

Copper, LOD = 0.4 13 (100%) 17 (100%) 15 (94%)

Iron, LOD = 3 526 (100%) 460 (100%) 656 (94%)

Lanthanum, LOD = 0.03 ND (0%) ND (0%) ND (0%)

Lead, LOD = 0.3 2.5 (93%) 2.2 (100%) 3.3 (94%)

Lithium, LOD = 0.02 0.28 (100%) 0.45 (100%) 1.3 (94%)

Magnesium, LOD = 2 140 (100%) 139 (100%) 220 (94%)

Manganese, LOD = 0.09 11 (100%) 10 (100%) 16 (94%)

Molybdenum, LOD = 0.04 0.26 (100%) 0.25 (100%) 0.75 (82%)

Nickel, LOD = 0.06 2.6 (100%) 1.3 (100%) 2.0 (88%)

Phosphorus, LOD = 7 43 (93%) 26 (100%) 49 (82%)

Potassium, LOD = 7 1,431 (100%) 1,147 (100%) 1,436 (100%)

Selenium, LOD = 0.8 ND (0%) ND (0%) 1.1 (100%)

Silver, LOD = 0.04 0.27 (53%) 0.08 (47%) 0.17 (71%)

Strontium, LOD = 0.03 1.7 (100%) 2.4 (100%) 3.0 (100%)

Tellurium, LOD = 0.8 1.5 (47%) 1.3 (47%) 1.7 (59%)

Thallium, LOD = 1 ND (0%) ND (0%) ND (0%)

Tin, LOD = 0.9 1.8 (33%) 0.96 (13%) 1.9 (6%)

Titanium, LOD = 0.02 6.6 (100%) 8.7 (100%) 13 (100%)

Yttrium, LOD = 0.01 0.21 (100%) 0.28 (100%) 0.34 (94%)

Zinc, LOD = 7 44 (93%) 46 (100%) 72 (94%)

Zirconium, LOD = 0.02 3.9 (100%) 1 (100%) 1.8 (94%)
C-4

Table C5. Full-shift personal air sample results for naphthalene and phenanthrene (n = 49)

What we sampled % Detected Air concentration, μg/m3

 Mean Min Max Lowest OEL

Naphthalene 100% 0.60 0.17 2.8 50,000

Phenanthrene 31% [0.17] ND [0.33] — 

[ ] = Estimated concentration. When between the MDC and MQC, indicates more uncertainty associated 

with this value. The MDC of naphthalene was 0.07 μg/m3, and MQC was 0.24 μg/m3. The MDC of 

phenanthrene was 0.01 μg/m3, and MQC was 0.4 μg/m3. 

Table C6. Number of interviewed employees by company and job title

Company Number of employees interviewed (n = 40) by job title

 Task force leaders 

(n = 5)

Operators

(n = 14)

Laborers 

(n = 21)

B 3 0 0 

C 2 0 0 

D 0 2 6 

E 0 6 4 

F 0 6 11
C-5

Table C7. Demographic and work characteristics of interviewed operators and laborers

Demographic No. (%) operators

(n = 14)

No. (%) laborers

(n = 21)

Age, median 

Range

37 years

(21–52 years)

35 years

(23–64 years)

Sex, male 13 (93%) 21 (100%)

Total years in construction, median 

Range

16.5 years

(2–35 years)

6 years

(0.1–28 years)

Had prior fire debris cleanup experience 10 (71%) 12 (57%)

Reported receiving adequate information and/or 

training on hazards

14 (100%) 21 (100%)

Reported frequency of handwashing 

After toilet use 12 (86%) 19 (90%)

Before lunch 9 (65%) 15 (71%)

At the end of the shift 9 (64%) 15 (71%)

Anytime leaving lot footprint 7 (50%) 15 (71%)

Does employer provide lead removal handwipes? 

Yes 1 (1%) 4 (19%)

No 8 (57%) 10 (48%)

Don’t know 5 (36%) 7 (33%)
C-6

Table C8. Number of employees who reported using various types of PPE 

 Laborers (n = 21) Operators (n = 14)

 Always Sometimes Never Always Sometimes Never

Hard hat 21 0 0 13 1 0 

Safety glasses/goggles 20 1 0 12 1 1 

Safety vest 15 5 1 14 0 0 

Earmuffs 1 4 16 0 5 9 

Earplugs 4 15 2 1 12 1 

Dust mask 2 4 15 1 4 9 

Disposable respirator 

(i.e., N95)

3 4 14 0 4 10

Half-mask respirator 14 5 2 11 2 1 

Full-face respirator 1 1 19 1 3 10

Protective coveralls with 

hood

6 7 8 8 4 2 

Protective coveralls 

without hood

10 2 9 3 1 10

Shoe covers/booties 11 8 2 10 2 2 

Steel toed boots 17 1 3 10 2 2 

Chemical resistant boots 

(i.e., rubber boots)

4 7 10 2 4 8 

Leather work gloves 2 7 12 1 3 10

Nitrile/chemical resistant 

gloves

11 7 3 7 6 1 
D-1

Section D: Occupational Exposure Limits

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

physical, and biological agents when evaluating workplace hazards. OELs have been developed by 

federal agencies and safety and health organizations to prevent adverse health effects from workplace 

exposures. Generally, OELs suggest levels of exposure that most employees may be exposed to for up 

to 10 hours per day, 40 hours per week, for a working lifetime, without experiencing adverse health 

effects. 

However, not all employees will be protected if their exposures are maintained below these levels. Some 

may have adverse health effects because of individual susceptibility, a preexisting medical condition, or 

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

exposures, with the general environment, or with medications or personal habits of the employee to 

produce adverse health effects. Most OELs address airborne exposures, but some substances can be 

absorbed directly through the skin and mucous membranes.

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

8- to 10-hour workday. Some chemical substances and physical agents have recommended short-term 

exposure limits (STEL) or ceiling values. Unless otherwise noted, the STEL is a 15-minute TWA 

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

exceeded at any time.

In the United States, OELs have been established by federal agencies, professional organizations, state 

and local governments, and other entities. Some OELs are legally enforceable limits; others are 

recommendations. 

• OSHA, an agency of the U.S. Department of Labor, publishes permissible exposure limits 

[29 CFR 1910 for general industry; 29 CFR 1926 for construction industry; and 29 CFR 1917 for 

maritime industry] called PELs. These legal limits are enforceable in workplaces covered under 

the Occupational Safety and Health Act of 1970. 

• NIOSH RELs are recommendations based on a critical review of the scientific and technical 

information and the adequacy of methods to identify and control the hazard. NIOSH RELs are 

published in the NIOSH Pocket Guide to Chemical Hazards [NIOSH 2007]. NIOSH also 

recommends risk management practices (e.g., engineering controls, safe work practices, 

employee education/training, PPE, and exposure and medical monitoring) to minimize the risk 

of exposure and adverse health effects.

• Another set of OELs commonly used and cited in the United States include the threshold limit 

values or TLVs, which are recommended by ACGIH. The ACGIH TLVs are developed by 

committee members of this professional organization from a review of the published, peerreviewed literature. TLVs are not consensus standards. They are considered voluntary exposure 

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

control of health hazards” [ACGIH 2019].
D-2

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

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

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

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

(Québec), Japan, Switzerland, and the United States. The database, available at 

https://www.dguv.de/ifa/gestis/gestis-stoffdatenbank/index-2.jsp, contains international limits for 

more than 2,000 hazardous substances and is updated periodically. 

OSHA (Public Law 91-596) requires an employer to furnish employees a place of employment free 

from recognized hazards that cause or are likely to cause death or serious physical harm. This is true in 

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

health-based information.

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

employers to use the lowest OEL when making risk assessment and risk management decisions.

Respirable Crystalline Silica

Silica, or silicon dioxide, occurs in a crystalline or noncrystalline (amorphous) form. In crystalline silica, 

the silicon dioxide molecules are oriented in a fixed pattern versus the random arrangement of the 

amorphous form. The more common crystalline forms in workplace environments are quartz and 

cristobalite, and to a lesser extent, tridymite. Occupational exposures to RCS have been associated with 

silicosis, lung cancer, pulmonary tuberculosis, and airway diseases. Several serious nonrespiratory 

diseases are associated with occupational exposure to crystalline silica. These include immunologic 

disorders and autoimmune diseases (including systemic sclerosis, rheumatoid arthritis, and systemic 

lupus erythematosis) and renal diseases [NIOSH 2002].

Silicosis is a fibrotic disease of the lung caused by the deposition of fine crystalline silica particles in the 

lungs. It is the disease most often associated with exposure to RCS. This lung disease is caused by the 

inhalation and deposition of crystalline silica particles that are 10 micrometers (μm) or less in diameter. 

Particles 10 μm and below are considered respirable particles and classified as having the potential to 

reach the lower portions of the human lung (alveolar region). Although particle sizes 10 μm and below 

are considered respirable, some of these particles can be deposited before they reach the alveolar region 

[Hinds 2012]. Symptoms of silicosis usually develop insidiously, with cough, shortness of breath, chest 

pain, weakness, wheezing, and nonspecific chest illnesses. Silicosis usually occurs after years of exposure 

(chronic), but may appear in a shorter period of time (acute) if exposure concentrations are very high. 

Acute silicosis is typically associated with a history of high exposures from tasks that produce small 

particles of airborne dust with a high silica content [NIOSH 2002]. Chronic silicosis can develop or 

progress even if exposure to silica ends [NIOSH 2002].

The International Agency for Research on Cancer (IARC) [2012] and NIOSH [2002] have classified 

inhaled crystalline silica in the form of quartz or cristobalite as carcinogenic to humans in reference to 

lung cancer. While individuals with silicosis clearly are at risk of lung cancer, exposure to silica in the 

absence of silicosis also increases the risk for lung cancer [Liu et al. 2013]. 
D-3

Several forms of nonmalignant respiratory disease are associated with exposure to silica [NIOSH 2002]. 

These include chronic obstructive pulmonary disease (emphysema and chronic bronchitis) and asthma. 

Silica exposure is also related to other abnormalities noted on pulmonary function tests.

Exposure to silica increases the risk of developing tuberculosis even in the absence of silicosis [NIOSH

2002]. This increase is due to impaired macrophage function from silica. This risk for individuals with 

silicosis is even higher. The odds of an individual with silicosis dying with tuberculosis are 19 to 

40 times higher than for individuals without silicosis [Calvert et al. 2003]. 

Exposure to crystalline silica is also associated with development of several autoimmune diseases. The 

strongest evidence exists for an association with systemic sclerosis, rheumatoid arthritis, systemic lupus 

erythematosis, and antineutrophil cytoplasmic autoantibody related vasculitis [Cooper et al. 2002; Lee et 

al. 2014]. 

Silica exposure is also related to an increased risk of end-stage kidney disease [Ghahramani 2010; 

NIOSH 2002]. Kidney disease is associated with the effect of silica deposited in the kidneys and with an 

autoimmune process with activated macrophages. A wide range of kidney pathology is associated with 

silica exposure. 

When proper practices are not followed or controls not maintained, RCS exposures can exceed the 

OSHA PEL, NIOSH REL, or the ACGIH TLV. For general industry, the OSHA PEL for respirable 

dust containing 1% or more of quartz is calculated by dividing 10 milligrams per cubic meter by the 

percent quartz in the sample, plus 2 [OSHA 2019b]. OSHA instituted an updated silica PEL on June 23, 

2016. The updated silica PEL (50 μg/m3 as an 8-hour TWA) is the same as the NIOSH REL (which is 

applied as a TWA up to 10 hours). This updated silica PEL is now being enforced for general industry, 

construction and the maritime industry, which began 2 years after the effective date (June 23, 2018). 

The NIOSH REL is intended to reduce the risk of developing silicosis, lung cancer, and other adverse 

health effects [NIOSH 2007]. The OSHA AL and the ACGIH TLV for quartz is 25 μg/m3 as an 

8-hour TWA [ACGIH 2019].

OSHA currently requires that medical surveillance for silicosis be offered to employees who will be 

exposed above the PEL for 30 or more days a year, and after June 23, 2020, employers must offer the 

same surveillance for employees exposed above OSHA AL of 25 μg/m3 for 30 or more days per year. 

The OSHA standard calls for an initial examination within 30 days of initial assignment to the job. It 

should be noted that use of a respirator for any amount of time during the workday for potential silica 

exposures over the AL counts as a full day of respirator use toward the 30 days of use that would 

require the employee’s enrollment in medical surveillance for silicosis.

The surveillance examination must include the following: 

• A medical and work history with emphasis on past, present, and anticipated exposure to RCS, 

dust, and other agents affecting the respiratory system; any history of respiratory system 

dysfunction, including signs and symptoms of respiratory disease (e.g., shortness of breath, 

cough, wheezing); history of tuberculosis; and smoking status and history. The healthcare 

provider must also complete OSHA’s Mandatory Medical Questionnaire or an equivalent.

• A physical examination with special emphasis on the respiratory system. 
D-4

• A chest X-ray interpreted and classified according to the International Labour Office 

International Classification of Radiographs of Pneumoconioses by a NIOSH-certified B Reader. 

• A pulmonary function test to include forced vital capacity and forced expiratory volume in one 

second administered by a spirometry technician with a current certificate from a NIOSHapproved spirometry course. 

• Testing for latent tuberculosis infection. 

• Any other tests deemed appropriate by the physician or licensed healthcare provider [NIOSH 

2014]. 

Periodic examinations including the same elements must be offered at least once every 3 years or more 

often if recommended by the physician or licensed healthcare provider.

The healthcare provider conducting the silicosis medical surveillance must provide the employee a 

written medical report of the result of their evaluation within 30 days. This report must include “any 

recommended limitations on the employee’s use of respirators, any recommended limitations on the 

employee’s exposure to respirable crystalline silica, and a statement that the employee should be 

examined by a board certified specialist in pulmonary disease or occupational medicine if the chest 

X-ray is classified as 1/0 or higher by the B Reader, or if referral to a specialist is otherwise deemed 

appropriate by the primary licensed healthcare provider [OSHA 2017].” The healthcare provider must 

also provide documentation to the employer regarding the employee’s medical condition. In order to 

protect their privacy, the contents must remain limited to the date of the examination with a statement 

that the examination contained all the required components and any recommendation regarding the 

employee’s ability to safely wear a respirator unless the employee provides written authorization for the 

healthcare provider to release additional information to their employer.

Asbestos

Asbestos is a commercial name, not a mineralogical definition, given to a group of six different fibrous 

minerals (amosite, chrysotile, crocidolite, and the fibrous varieties of tremolite, actinolite, and 

anthophyllite) that occur naturally in the environment. One of these, chrysotile, belongs to the 

serpentine family of minerals, while all of the others belong to the amphibole family. These minerals 

possess high tensile strength, flexibility, resistance to chemical, biological, and thermal degradation, and 

electrical resistance. Because of these properties, asbestos has been mined for use in a wide range of 

manufactured products, mostly in building materials, friction products, and heat-resistant fabrics. 

Chrysotile, also known as white asbestos, is the predominant commercial form of asbestos. Amphiboles 

are considered of minor commercial importance. Historically, chrysotile accounted for more than 90% 

of the world’s mined asbestos; it presently accounts for over 99% [Ross and Virta 2001; USGS 2019]. 

Chrysotile asbestos has been used in a number of applications in the United States, including thermal 

piping and industrial oven insulation, floor tile, vehicle brake pads, and in building material such as 

soffits. More information about asbestos is available at the NIOSH asbestos topic page 

http://www.cdc.gov/niosh/topics/asbestos/. 
D-5

The current OSHA occupational 8-hour TWA exposure limit for airborne asbestos as determined by 

PCM is 0.1 f/cc for fibers greater than 5 μm in length and an aspect ratio (length to width) greater than 

or equal to 3:1 [29 CFR 1910.1001]. This includes Libby amphibole, a complex mixture of amphibole 

fibers found in the rocks and ore of Zonolite Mountain, 6 miles northeast of Libby, Montana. OSHA 

has also established an excursion limit that requires the employer to ensure that no employee is exposed 

to an airborne concentration of asbestos in excess of 1.0 f/cc as averaged over a sampling period of 

30 minutes. Exposure limits or risk criteria for bulk or surface samples for asbestos have not been 

established. The OSHA definition of asbestos applies to chrysotile, amosite, crocidolite, tremolite 

asbestos, anthophyllite asbestos, actinolite asbestos, and any of these minerals that have been chemically 

treated and/or altered [29 CFR 1910.1001]. The OSHA definition of asbestos-containing material is any 

material containing more than 1% asbestos.

In 1990, NIOSH reviewed the available information on elongate mineral particles and concerns about 

potential health risks associated with employee exposures to the analogs of the asbestos minerals 

[NIOSH 1990a,b]. These analogs occur in a different mineral “habit” and are often referred to as 

cleavage fragments. PCM, the analytical method routinely used for characterizing airborne exposures, is 

incapable of differentiating these nonasbestiform analogs from asbestos fibers on the basis of physical 

appearance. To address these concerns and ensure that employees are protected, NIOSH defined 

“airborne asbestos fibers” to encompass not only fibers from the six asbestos minerals (chrysotile, 

crocidolite, amosite, anthophyllite asbestos, tremolite asbestos, and actinolite asbestos) but also elongate 

mineral particles from their nonasbestiform analogs as a precautionary measure. NIOSH retained the 

use of PCM for measuring airborne fiber concentrations and counting those elongate mineral particles 

having an aspect ratio of 3:1 or greater and a length greater than 5 μm. The REL (0.1 f/cc) was set at 

the limit of quantification for the PCM analytical method for a 400-liter sample, but risk estimates 

indicated that exposure at 0.1 f/cc throughout a working lifetime would be associated with a residual 

risk for lung cancer. No risk-free level of exposure to airborne asbestos fibers has been established 

[NIOSH 1984, 2011]. More information on asbestos from NIOSH can be found at 

http://www.cdc.gov/niosh/docs/2011-159/. 

Inhalation exposure to asbestos can result in a scarring disease of the lung known as asbestosis, 

inflammation of the chest cavity (pleuritis) with or without fluid build-up, lung cancer, and another type 

of cancer known as malignant mesothelioma. The risk of these diseases, which can be disabling or fatal, 

generally increases with intensity and duration of exposure. The risk of lung cancer from inhaling 

asbestos fibers is also increased in smokers. Most people who get asbestos-related diseases have been 

exposed to high levels of asbestos for a long time. Most asbestos-related diseases rarely occur until at 

least 15 years after first exposure to asbestos. All forms of asbestos are hazardous, and all can cause 

cancer, but amphibole forms of asbestos are considered to be somewhat more hazardous to health than 

chrysotile [ATSDR 2001]. Asbestos fibers have no detectable odor or taste and fibers associated with 

these health risks are too small to be seen with the naked eye. A summary of asbestos-related diseases 

are listed below:

• Asbestosis – a serious, progressive, long-term disease of the lungs. It is caused by inhaling 

asbestos fibers that irritate lung tissues and cause the tissues to scar. The scarring makes it hard 

for oxygen to get into the blood. 
D-6

• Lung cancer – people who mine, mill or manufacture asbestos, and those who use asbestos, and 

products containing asbestos, are more likely than the general population to develop lung 

cancer, as well as other cancers of the respiratory tract, including tracheal, laryngeal and 

bronchial cancers. 

• Mesothelioma – a rare form of cancer that is found in the thin membrane lining (pleura) of the 

lung, chest, abdomen, and heart. The vast majority of cases are linked to asbestos exposure. 

Exposure may also occur through ingesting (swallowing) asbestos, especially where airborne asbestos 

may deposit in the nose and mouth. Although some gastrointestinal cancers have been reported in 

asbestos-exposed employees, the evidence is considered suggestive, but not sufficient, to link asbestos 

exposure to those cancers [Institute of Medicine 2006].

Asbestos minerals are widespread in the environment. They may occur in large natural deposits, or as 

contaminants in other minerals. Low levels of asbestos can be detected in almost any air sample. The 

results of numerous measurements indicate that average concentrations of asbestos in ambient outdoor 

air are within the range of 10−8 to 10−4 f/cc; levels in urban areas may be an order of magnitude higher 

than those in rural areas [ATSDR 2001]. In indoor air, the concentration of asbestos depends on 

whether asbestos was used for insulation, ceiling or floor tiles, or for other purposes, and whether these 

asbestos-containing materials are in good condition or are deteriorated and easily crumbled.

Metals 

Lead

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

times. It comes in many forms (e.g., lead acetate, lead chloride, lead chromate, lead nitrate, lead oxide, 

lead phosphate, and lead sulfate). Lead is considered toxic to all organ systems and serves no useful 

purpose in the body. 

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

ingestion of lead particles from contact with lead-contaminated surfaces. Exposure may also occur 

through transfer of lead to the mouth from contaminated hands or cigarettes when careful attention to 

hygiene, particularly hand washing, is not practiced. In addition to the inhalation and ingestion routes of 

exposure, lead can be absorbed through the skin, particularly through damaged skin [ATSDR 2019; 

Filon et al. 2006; Stauber et al. 1994; Sun et al. 2002].

Blood Lead Levels

In most cases, an individual’s BLL is a good indication of recent exposure to lead because the half-life 

of lead (the time interval it takes for the quantity in the body to be reduced by half its initial value) is 

1–2 months [CDC 2013a; Lauwerys and Hoet 2001; Moline and Landrigan 2005]. Most lead in the body 

is stored in the bones, with a half-life of years to decades. Measuring bone lead, however, is primarily 

done only for research. Elevated zinc protoporphyrin levels have also been used as an indicator of 

chronic lead intoxication. However, other factors, such as iron deficiency, can cause an elevated zinc 

protoporphyrin level, so monitoring the BLL over time is more specific for evaluating chronic 

occupational lead exposure. 
D-7

BLLs in adults in the United States have declined consistently over time. The geometric means BLL 

decreased from 1.75 micrograms per deciliter (μg/dL) in 1999–2000 to 1.09 μg/dL in 2011–2012 [CDC 

2015]. The NIOSH Adult Blood Lead Epidemiology and Surveillance System (ABLES) uses a 

surveillance case definition for an elevated BLL in adults of 5 μg/dL of blood or higher [NIOSH 2018]. 

Very high BLLs are defined as BLLs ≥ 40 μg/dL. From 2002–2011, occupational exposures accounted 

for 91% of adults with very high BLLs (where the exposure source was known) [CDC 2013b]. This 

underscores the need to increase efforts to prevent lead exposures in the workplace.

Occupational Exposure Limits

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

standard [29 CFR 1910.1025]. This standard was established in 1978 and has not yet been updated to 

reflect the current scientific knowledge regarding the health effects of lead exposure. Under this 

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

requires lowering the PEL for shifts that exceed 8 hours, medical monitoring for employees exposed to 

airborne lead at or above the action level of 30 μg/m3 (8-hour TWA), medical removal of employees 

whose average BLL is 50 μg/dL or greater, and economic protection for medically removed workers. 

Medically removed workers cannot return to jobs involving lead exposure until their BLL is below 

40 μg/dL. 

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

followed. Similar to the OSHA lead standard, these guidelines were set years ago and have not yet been 

updated to reflect current scientific knowledge. NIOSH has a REL for lead of 50 μg/m3 averaged over 

an 8-hour work shift [NIOSH 2007]. 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. ACGIH designates lead as an animal carcinogen 

[ACGIH 2019]. In 2013, the California Department of Public Health (CDPH) recommended that 

Cal/OSHA lower the PEL for lead to 0.5 to 2.1 μg/m3 (8-hour TWA) to keep BLLs below the range of 

5 to 10 μg/dL [Billingsley 2013]. 

Neither NIOSH nor OSHA has established surface contamination limits for lead in the workplace. The 

U.S. Environmental Protection Agency and the U.S. Department of Housing and Urban Development 

limit lead on surfaces in public buildings and child-occupied housing to less than 40 micrograms of lead 

per square foot [EPA 1998; HUD 2012]. OSHA requires in its substance-specific standard for lead that 

all surfaces be maintained as free as practicable of accumulations of lead [29 CFR 1910.1025(h)(1)]. An 

employer with workplace exposures to lead must implement regular and effective cleaning of surfaces in 

areas such as change areas, storage facilities, and lunchroom/eating areas to ensure they are as free as 

practicable from lead contamination [CFR 2019]. 

Health Effects

The PEL, REL, and TLV may prevent overt symptoms of lead poisoning, but do not protect 

employees from lead’s contributions to conditions such as hypertension, renal dysfunction, 

reproductive, and cognitive effects [Brown-Williams et al. 2009; Holland and Cawthorn 2016; Institute 

of Medicine 2012; Schwartz and Hu 2007; Schwartz and Stewart 2007]. Generally, acute lead poisoning 

with symptoms has been documented in persons having BLLs above 70 μg/dL. These BLLs are rare 

today in the United States, largely as a result of workplace controls put in place to comply with current 
D-8

OELs. When present, acute lead poisoning can cause myriad adverse health effects including abdominal 

pain, hemolytic anemia, and neuropathy. Lead poisoning has, in very rare cases, progressed to 

encephalopathy and coma [Moline and Landrigan 2005]. 

The National Toxicology Program (NTP) recently released a monograph on the health effects of lowlevel lead exposure [NTP 2012]. For adults, the NTP concluded the following about the evidence 

regarding health effects of lead (Table D1).

Table D1. Evidence regarding health effects of lead in adults

Health area NTP conclusion Principal health effects Blood lead evidence

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

 Limited Psychiatric effects, decreased hearing, 

decreased cognitive function, increased 

incidence of amyotrophic lateral sclerosis

Yes, < 10 μg/dL

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

Immune Inadequate Unclear

Cardiovascular Sufficient Increased blood pressure and 

increased risk of hypertension

Yes, < 10 μg/dL

 Limited Increased cardiovascular-related mortality 

and electrocardiography abnormalities

Yes, < 10 μg/dL

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

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

 Sufficient Men: adverse changes in sperm parameters 

and increased time to pregnancy

Yes, ≥ 15–20 μg/dL

 Limited Women: increase in spontaneous abortion 

and preterm birth

Yes, < 10 μg/dL

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

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

 Inadequate Women and Men: stillbirth, endocrine effects, 

birth defects

Unclear

People with chronic lead poisoning, which is more likely at current OELs, may not have symptoms or 

they may have nonspecific symptoms that may not be recognized as being associated with lead 

exposure. These symptoms include headache, joint and muscle aches, weakness, fatigue, irritability, 

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

recently released a monograph on the health effects of low-level lead exposure [NTP 2012].

Medical Management 

To prevent acute and chronic health effects, a panel of experts convened by the Association of 

Occupational and Environmental Clinics published guidelines for the management of adult lead 

exposure [Kosnett et al. 2007]. The panel recommended BLL testing for all lead-exposed employees, 

regardless of the airborne lead concentration. These recommendations do not apply to pregnant 

women, who should avoid BLLs ≥ 5 μg/dL. Removal from lead exposure should be considered if 

control measures over an extended period do not decrease BLLs to < 10 μg/dL or an employee has a 

medical condition that would increase the risk of adverse health effects from lead exposure. These 
D-9

guidelines were endorsed by the Council of State and Territorial Epidemiologists (CSTE) and the 

CDPH in 2009 and the American College of Occupational and Environmental Medicine (ACOEM) in 

2010 [CDPH 2009; CSTE 2009; Holland and Cawthon 2016]. CSTE published updated guidelines in 

2013 to reflect the new definition of an elevated BLL in adults of 5 μg/dL [CSTE 2013]. The CDPH 

recommended keeping BLLs below 5 to 10 μg/dL in 2013 [Billingsley 2013] and updated their medical 

management guidelines in 2014 [CDPH 2014]. In 2015, NIOSH designated 5 μg/dL of whole blood, in 

a venous blood sample, as the reference BLL for adults. An elevated BLL is defined as a BLL 

≥ 5 μg/dL. In 2016, the ACOEM released a position statement entitled Workplace Lead Exposure that 

reinforces the guidelines and recommendations above [Holland and Cawthorn 2016]. Table D2 

incorporates recommendations from the expert panel guidelines and those from CDPH, CSTE, 

and ACOEM.
D-10

Table D2. Health-based medical surveillance recommendations for lead-exposed employees

Category of exposure Recommendations

All lead exposed 

workers

• Baseline or preplacement medical history and physical examination, baseline 

BLL, and serum creatinine

BLL < 5 μg/dL • BLL monthly for first 3 months placement, or upon change in task to higher 

exposure, then BLL every 6 months; if BLL increases ≥ 5 μg/dL, evaluate 

exposure and protective measures, and increase monitoring if indicated

BLL 5–9 μg/dL • Discuss health risks

• Minimize exposure

• Consider removal for pregnancy and certain medical conditions

• BLL monthly for first 3 months placement or every 2 months for the first 

6 months placement, or upon change in task to higher exposure, then BLL 

every 6 months; if BLL increases ≥ 5 μg/dL, evaluate exposure and protective 

measures, and increase monitoring if indicated

BLL 10–19 μg/dL • Discuss health risks

• Decrease exposure

• Remove from exposure for pregnancy

• Consider removal for certain medical conditions or BLL > 10 μg/dL for 

extended period

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

practices; consider removal. 

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

BLL 20–29 μg/dL • Remove from exposure for pregnancy

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

• Annual lead medical exam recommended

• Monthly BLL testing

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

above

BLL 30–49 μg/dL • Remove from exposure

• Prompt medical evaluation

• Monthly BLL testing

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

above

BLL 50–79 μg/dL • Remove from exposure

• Prompt medical evaluation

• Consider chelation with significant symptoms

BLL > 80 μg/dL • Remove from exposure

• Urgent medical evaluation

• Chelation may be indicated

Adapted from Kosnett et al. 2007, CSTE 2013, and CDPH 2014
D-11

Take-home Contamination 

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

take-home contamination. Take-home contamination occurs when lead dust is transferred from the 

workplace on employees’ skin, clothing, shoes, and other personal items to their vehicle and home 

[CDC 2009, 2012]. 

The Centers for Disease Control and Prevention (CDC) considers a BLL in children of 5 μg/dL or 

higher as a reference level above which public health actions should be initiated. OSHA further states 

that there is no role for lead in the body and no safe BLL in children or adults [CDC 2013a].

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

requires NIOSH to study take-home contamination from workplace chemicals and substances, 

including lead. NIOSH found that take-home exposure is a widespread problem [NIOSH 1995]. 

Workplace measures effective in preventing take-home exposures were (1) reducing exposure in the 

workplace, (2) changing clothes before going home and leaving soiled clothing at work for laundering, 

(3) storing street clothes in areas separate from work clothes, (4) showering before leaving work, and 

(5) prohibiting removal of toxic substances or contaminated items from the workplace. NIOSH noted 

that preventing take-home exposure is critical because decontaminating homes and vehicles is not 

always effective. Normal house cleaning and laundry methods are inadequate, and decontamination can 

expose the people doing the cleaning and laundry.
D-12

Beryllium, Cadmium, Chromium, Nickel, Manganese, and Cobalt 

Table D3 summarizes the OELs for the other common metals found in electronics, as well as a 

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

Table B3. Chemical health effects

Chemicals Health effects IARC OEL (μg/m3) 

Beryllium ● Beryllium exposure may cause 

dermatitis, lung inflammation, 

and chronic beryllium disease in 

humans [Proctor et al. 1991].

● Exposure to beryllium can lead 

to sensitization.

● Exposure also slightly increases 

the risk for lung cancer 

[Schubauer-Berigan et al. 2010].

Group 1: 

carcinogenic 

to humans 

[IARC 2012]

OSHA PEL: 0.2

NIOSH REL: 0.5

ACGIH TLV: 0.05

Cadmium ● Long-term occupational 

exposure to cadmium is 

associated with increased 

occurrence of lung cancer, 

kidney damage, and chronic 

obstructive lung disease 

[WHO 1992].

Group 1: 

carcinogenic 

to humans 

[IARC 2012]

OSHA PEL: 5.0

NIOSH REL: Cancer

ACGIH TLV: 10 

(2 respirable fraction)

Chromium ● The toxic effects of chromium 

exposure, including lung and 

nasal cancer, are primarily 

related to hexavalent chromium.

● Skin exposure to chromium dust 

can cause skin irritation and skin 

ulceration, and allergic contact 

dermatitis.

Group 1: 

carcinogenic 

to humans 

[IARC 2012]

OSHA PEL: 1000

NIOSH REL: 500

ACGIH TLV: 500

Cobalt ● Exposure to elevated levels of 

cobalt can cause gastrointestinal 

irritation, nausea, and vomiting.

● Skin exposure can cause irritant 

and allergic contact dermatitis 

[Vincoli 1997].

Group 2B: 

possibly carcinogenic 

to humans 

[IARC 2006]

OSHA PEL: 100 

NIOSH REL: 50 

ACGIH TLV: 20

Manganese ● Subclinical neurological effects, 

such as decreased performance on 

neurobehavioral tests; significantly 

poorer eye-hand coordination, hand 

steadiness, and reaction time; 

poorer postural stability; and lower 

levels of cognitive flexibility. 

None OSHA PEL: 5,000

NIOSH REL: 1,000

ACGIH TLV: 100

Nickel ● Allergic contact dermatitis, 

respiratory irritation, chronic 

bronchitis, asthma, reduced lung 

function. 

Nickel compounds, 

Group 1: 

carcinogenic to 

humans; paranasal 

sinus, nasal cavity, 

and lung 

[IARC 2006]

OSHA PEL: 1,000

NIOSH REL: 15 

ACGIH TLV: 1,500

IARC = International Agency for Research on Cancer
D-13

Polyaromatic Hydrocarbons

PAHs are products of incomplete combustion that can exist in particle and gas phases and are often 

found as a result of structural and wildland fires. Of the 18 PAHs that are commonly produced during 

fires, IARC classified benzo[a]pyrene as carcinogenic to humans; dibenz[a,h]anthracene as probably 

carcinogenic to humans; and seven others (benz[a]anthracene, benzo[b]fluoranthene, 

benzo[j]fluoranthene, benzo[k]fluoranthene, chrysene, indeno[1,2,3-c,d]pyrene, and naphthalene) as 

possibly carcinogenic to humans [IARC 2002, 2010]. Occupational epidemiology studies have primarily 

found associations between exposures to PAHs (typically as a mixture with other chemicals) and lung, 

skin, or bladder cancer, depending on the route of exposure [ATSDR 1995; Boffetta et al. 1997; IARC 

2002, 2010]. Occupational exposure to benzene has been consistently linked to leukemia [ATSDR 2007; 

IARC 1982].

Additional information about PAH exposure in firefighters can be found in the NIOSH health hazard 

evaluation final (https://www.cdc.gov/niosh/hhe/reports/pdfs/2010-0156-3196.pdf) and summary 

(https://www.cdc.gov/niosh/hhe/reports/pdfs/2010-0156-3196S.pdf) reports [NIOSH 2013a,b].
E-1

Section E: Fire Debris Cleanup Exposure: Information for Construction 

Employees

Clearing a burned out area after the passage of a wildfire, including when the wildfire enters residential 

areas, can be handled by employees of general construction companies that may not have previous 

experience with fire debris cleanup. Although structural and wildland firefighters are typically wellinformed of the potential health hazards associated with fires, construction employees may not be 

aware of hazardous exposures to things such as the carcinogens in soot and ash. However, the potential 

health hazards of on-site exposures vary depending on mineral deposits in the soil, materials used in the 

construction of the damaged buildings, and the items that were in the building. Clearing these 

residential areas must be done in a manner that protects the employees from harmful exposures and in 

compliance with local environmental regulations. 

This section outlines the process developed by the state of California during the last several years of 

increased wildfire activity. The state agency typically approaches fire debris cleanup in the 

following manner:

• Once the wildfire has been contained, the state draws up a contract to clean up all occupied 

areas impacted by the wildfire. This contract is then placed for bidding, and it includes work 

practices and employee PPE to be used if specific hazards are likely to be found or have been 

identified on the site. 

o The state also contracts out to separate companies to do the following: 

 Conduct initial site sampling and periodic environmental sampling as the 

cleanup progresses. 

 Provide on-site supervision of cleanup crews as task force leader.

• Representatives of the state contact each lot owner. Those who want the state to handle their 

property cleanup sign a right of entry form. A property owner may decide to use a private 

contractor to clear and the prep site for rebuild. 

o The hazards associated with fire debris cleanup should be communicated to these 

construction companies as well.

• The state hires a company to perform an initial site hazard survey. Those companies select 

representative lots in a geographic area to sample for the following: 

o Asbestos (especially if worksite had structures on it known to have been built 

before 1984). 

 If asbestos is present, then the lot is identified as such and separated out to be 

worked by contractors as per asbestos remediation guidelines. 
E-2

 If asbestos is not present, then immediate safety hazards on site are identified 

(i.e., propane tanks and other safety hazards) and removed by the 

appropriate personnel.

o Metals, including cadmium, chromium, copper, iron, lead, manganese, nickel, silver, 

and zinc. 

o RCS from soil, concrete, or other housing material.

 
F-1

Section F: References 

Asbestos Exposure in the Workplace

ATSDR [2001]. Toxicological profile for asbestos. Atlanta, GA: U.S. Department of Health and Human 

Services, Agency for Toxic Substances and Disease Registry, 

https://www.atsdr.cdc.gov/toxprofiles/tp.asp?id=30&tid=4. 

Institute of Medicine [2006]. Asbestos: selected cancers. Washington, DC: National Academies Press, 

https://doi.org/10.17226/11665. 

NIOSH [1984]. Testimony of the National Institute for Occupational Safety and Health to the U.S. 

Department of Labor. Presented at the public hearing on occupational exposure to asbestos, June 21, 

1984. NIOSH policy statements. Cincinnati, OH: U.S. Department of Health and Human Services, 

Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, 

https://www.osti.gov/biblio/5479342-testimony-national-institute-occupational-safety-healthoccupational-safety-health-administration-proposed-rule-hazard-communication. 

NIOSH [1990a]. Comments of the National Institute for Occupational Safety and Health on the 

Occupational Safety and Health Administration’s notice of proposed rulemaking on occupational 

exposure to asbestos, tremolite, anthophyllite, and actinolite, April 9, 1990. OSHA Docket No. H-033d. 

NIOSH policy statements. Cincinnati, OH: U.S. Department of Health and Human Services, Centers 

for Disease Control and Prevention, National Institute for Occupational Safety and Health, 

https://www.osti.gov/biblio/5760689-niosh-comments-dol-occupational-safety-health-administrationnotice-proposed-rulemaking-occupational-exposure-asbestos-tremolite-anthophyllite-actinolite. 

NIOSH [1990b]. Testimony of the National Institute for Occupational Safety and Health on the 

Occupational Safety and Health Administration’s notice of proposed rulemaking on occupational 

exposure to asbestos, tremolite, anthophyllite, and actinolite, May 9, 1990. OSHA Docket No. H-033d. 

NIOSH policy statements. Cincinnati, OH: U.S. Department of Health and Human Services, Centers 

for Disease Control and Prevention, National Institute for Occupational Safety and Health, 

https://www.osti.gov/biblio/5639115-niosh-testimony-dol-occupational-safety-health-administrationnotice-proposed-rulemaking-occupational-exposure-asbestos-tremolite-anthophyllite-actinolite. 

NIOSH [2011]. Current intelligence bulletin 62: asbestos fibers and other elongate mineral particles; 

state of the science and roadmap for research, revised edition. Cincinnati, OH: U.S. Department of 

Health and Human Services, Centers for Disease Control and Prevention, National Institute for 

Occupational Safety and Health, DHHS (NIOSH) Publication No. 2011-159, 

https://doi.org/10.26616/nioshpub2011159. 

Ross M, Virta RL [2001]. Occurrence, production and uses of asbestos. In: Nolan RP, Langer AM, Ross 

M, Wicks FJ, Martin RF, eds. The health effects of chrysotile asbestos: contribution of science to riskmanagement decisions. Can Mineral (Special Publication) 5:79–88.

USGS [2008]. Mineral commodity summaries. United States Geological Survey, 

https://www.usgs.gov/centers/nmic/mineral-commodity-summaries.
F-2

Background Information

NIFC [2017]. National report of wildland fires and acres burned by state 2017. Boise, ID: National 

Interagency Fire Center, 

https://www.predictiveservices.nifc.gov/intelligence/2017_statssumm/fires_acres17.pdf. 

NIFC [2018]. National report of wildland fires and acres burned by state 2018. Boise, ID: National 

Interagency Fire Center, 

https://www.predictiveservices.nifc.gov/intelligence/2018_statssumm/fires_acres18.pdf. 

Lead Exposure in the Workplace

ACGIH [2019]. 2019 TLVs® and BEIs®: threshold limit values for chemical substances and physical 

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

Industrial Hygienists, https://www.acgih.org/tlv-bei-guidelines/policies-procedurespresentations/overview. 

ATSDR [2019]. Toxicological profile for lead. Atlanta, GA: U.S. Department of Health and Human 

Services, Agency for Toxic Substances and Disease Registry, 

https://www.atsdr.cdc.gov/ToxProfiles/tp.asp?id=96&tid=22.

Billingsley KJ [2013]. Letter from K.J. Billingsley, California Department of Public Health, to Juliann 

Sum, Division of Occupational Safety and Health (Cal/OSHA), California Department of Industrial 

Relations, September 30.

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

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

http://www.healthresearchforaction.org/sites/default/files/PDF_PERSPECTIVES_IndecentExp%20

FNL_0.pdf. 

CDC [2009]. Childhood lead poisoning associated with lead dust contamination of family vehicles and 

child safety seats—Maine, 2008. MMWR 58(32):890–893, 

https://www.cdc.gov/mmwr/preview/mmwrhtml/mm5832a2.htm. 

CDC [2012]. Take-home lead exposure among children with relatives employed at a battery recycling 

facility—Puerto Rico, 2011. MMWR 61(47):967–970, 

https://www.cdc.gov/mmwr/preview/mmwrhtml/mm6147a4.htm. 

CDC [2013a]. Blood lead levels in children aged 1–5 years—United States, 1999–2010. MMWR 

62(13):245–248, https://www.cdc.gov/mmwr/preview/mmwrhtml/mm6213a3.htm. 

CDC [2013b]. Very high blood lead levels among adults—United States, 2002–2011. MMWR 

62(47):967–971, 

https://www.cdc.gov/mmwr/preview/mmwrhtml/mm6247a6.htm?s_cid=mm6247a6_w. 

CDC [2015]. Fourth national report on human exposure to environmental chemicals updated tables, 

February 2015, http://www.cdc.gov/biomonitoring/pdf/FourthReport_UpdatedTables_Feb2015.pdf. 
F-3

CDPH [2009]. Medical guidelines for the lead‐exposed worker. Sacramento, CA: California Department 

of Public Health, Occupational Lead Poisoning Prevention Program, 

https://www.cdph.ca.gov/Programs/CCDPHP/DEODC/OHB/OLPPP/CDPH Document 

Library/medgdln.pdf. 

CDPH [2014]. Medical management guidelines for blood lead levels in adults. Sacramento, CA: 

California Department of Public Health, Occupational Lead Poisoning Prevention Program, 

https://www.cdph.ca.gov/Programs/CCDPHP/DEODC/OHB/OLPPP/Pages/MedGuidelines.aspx. 

CFR [2019]. Code of Federal Regulations. Washington, DC: U.S. Government Printing Office, Office 

of the Federal Register, https://www.ecfr.gov/cgi-bin/ECFR?page=browse. 

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

position statement 09-OH-02. Atlanta, GA: Council of State and Territorial Epidemiologists, 

http://c.ymcdn.com/sites/www.cste.org/resource/resmgr/PS/09-OH-02.pdf. 

CSTE [2013]. Management guidelines for blood lead levels in adults. Atlanta, GA: Council of State and 

Territorial Epidemiologists, 

http://c.ymcdn.com/sites/www.cste.org/resource/resmgr/OccupationalHealth/ManagementGuidelin

esforAdult.pdf. 

CSTE [2015]. Public health reporting and national notification for elevated blood lead levels. CSTE 

position statement 15-EH-01. Atlanta, GA: Council of State and Territorial Epidemiologists, 

http://c.ymcdn.com/sites/www.cste.org/resource/resmgr/2015PS/2015PSFinal/15-EH-01.pdf. 

EPA [1998]. Risk analysis to support standards for lead in paint, dust, and soil, Vol. 1, Chapters 1–7 and 

Appendix A. EPA Publication EPA-747-R097-006. Washington, DC: U.S. Environmental Protection 

Agency, http://www2.epa.gov/lead/risk-analysis-support-standards-lead-paint-dust-and-soil-volume-ichapters-1-7-and-appendix-epa. 

Esswein EJ, Boeniger MF, Ashley K [2011]. Handwipe method for removing lead from skin. J ASTM 

Int 8(5):1–10, https://doi.org/10.1520/JAI103527.

Filon FL, Boeniger M, Maina G, Adami G, Spinelli P, Damian A [2006]. Skin absorption of inorganic 

lead (PbO) and the effect of skin cleansers. J Occup Environ Med 48(7):692–699, 

https://doi.org/10.1097/01.jom.0000214474.61563.1c. 

Holland MG, Cawthorn D [2016]. ACOEM position statement: workplace lead exposure. JOEM 

58(12): 371–373, https://doi.org/10.1097/JOM.0000000000000928.

HUD [2012]. Guidelines for the evaluation and control of lead-based paint hazards in housing, 

Washington, DC: Department of Housing and Urban Development,

http://portal.hud.gov/hudportal/HUD?src=/program_offices/healthy_homes/lbp/hudguidelines. 

Institute of Medicine [2012]. Potential health risks from recurrent lead exposure of DOD firing range 

personnel. Washington, DC: National Academies Press, 

https://www.ncbi.nlm.nih.gov/books/NBK206966/.
F-4

Kosnett MJ, Wedeen RP, Rothenberg SJ, Hipkins KL, Materna BL, Schwartz BS, Hu H, Woolf A 

[2007]. Recommendations for medical management of adult blood lead exposure. Environ Health 

Perspect 115(3):463–471, https://doi.org/10.1289/ehp.9784. 

Lauwerys RR, Hoet P [2001]. Industrial chemical exposure: guidelines for biological monitoring. 3rd ed. 

Boca Raton, FL: CRC Press, LLC. 

Moline JM, Landrigan PJ [2005]. Lead. In: Rosenstock L, Cullen MR, Brodkin CA, Redlich CA, eds. 

Textbook of clinical occupational and environmental medicine. 2nd ed. Philadelphia, PA: Elsevier 

Saunders, https://doi.org/10.1016/B978-0-7216-8974-6.X5001-5. 

NIOSH [1995]. Report to Congress on the workers’ home contamination study conducted under the 

Workers’ Family Protection Act (29 U.S.C. 671a). Cincinnati, OH: U.S. Department of Health and 

Human Services, Centers for Disease Control and Prevention, National Institute for Occupational 

Safety and Health, DHHS (NIOSH) Publication No. 95-123, http://www.cdc.gov/niosh/docs/95-

123/. 

NIOSH [2002]. NIOSH hazard review: health effects of occupational exposure to respirable crystalline 

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

and Prevention, National Institute for Occupational Safety and Health, DHHS (NIOSH) Publication 

No. 2002-129, https://www.cdc.gov/niosh/docs/2002-129/pdfs/2002-

129.pdf?id=10.26616/NIOSHPUB2002129. 

NIOSH [2007]. NIOSH pocket guide to chemical hazards. Cincinnati, OH: U.S. Department of Health 

and Human Services, Centers for Disease Control and Prevention, National Institute for Occupational 

Safety and Health, DHHS (NIOSH) Publication No. 2005-149,

https://www.cdc.gov/niosh/docs/2005-149/default.html. 

NIOSH [2018]. Adult blood lead epidemiology and surveillance (ABLES), 

http://www.cdc.gov/niosh/topics/ables/description.html. 

NTP [2012]. Monograph on the health effects of low-level lead. Research Triangle Park, NC: U.S. 

Department of Health and Human Services, National Institutes of Health, National Institute of 

Environmental Health Sciences, National Toxicology Program, 

https://ntp.niehs.nih.gov/ntp/ohat/lead/final/monographhealtheffectslowlevellead_newissn_508.pdf. 

OSHA [2019]. OSHA Bulletin: preventing hearing loss caused by chemical (ototoxicity) and noise 

exposure. Washington, DC: U.S. Department of Labor, Occupational Safety and Health 

Administration, https://www.osha.gov/dts/shib/shib030818.html. 

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

454, https://doi.org/10.1289/ehp.9782. 

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

approach to a review of the evidence for cause, treatment, and prevention. Int Rev Psychiatry 

19(6):671–692, https://doi.org/10.1080/09540260701797936.

Stauber JL, Florence TM, Gulson B, Dale L [1994]. Percutaneous absorption of inorganic lead 

compounds. Sci Total Environ 145(1–2):55–70, https://doi.org/10.1016/0048-9697(94)90297-6. 
F-5

Sun CC, Wong TT, Hwang YH, Chao KY, Jee SH, Wang JD [2002]. Percutaneous absorption of 

inorganic lead compounds. Am Ind Hyg Assoc J 63(5):641–646, 

https://doi.org/10.1080/15428110208984751. 

Methods

NIOSH [2019]. NIOSH manual of analytical methods (NMAM). 5th ed. O’Connor PF, Ashley K, eds. 

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

Prevention, National Institute for Occupational Safety and Health, DHHS (NIOSH) Publication No. 

2014-151, http://www.cdc.gov/niosh/nmam. 

Noise Exposure 

NIOSH [1998]. Criteria for a recommended standard: occupational noise exposure (revised criteria 

1998). Cincinnati, OH: U.S. Department of Health and Human Services, Centers for Disease Control 

and Prevention, National Institute for Occupational Safety and Health, DHHS (NIOSH) Publication 

No. 98-126, http://www.cdc.gov/niosh/docs/98-126/pdfs/98-126.pdf. 

Other Metals Exposure in the Workplace

IARC [2006]. IARC monographs on the evaluation of carcinogenic risks to humans: cobalt in hard 

metals and cobalt sulfate, gallium arsenide, indium phosphide and vanadium pentoxide. Vol. 86. Lyon, 

France: World Health Organization, International Agency for Research on Cancer, 

https://monographs.iarc.fr/iarc-monographs-on-the-evaluation-of-carcinogenic-risks-to-humans-35/. 

Proctor NH, Hughes JP, Fischmann ML [1991]. Chemical hazards of the workplace. 3rd ed. New York, 

NY: Van Nostrand Reinhold.

Schubauer-Berigan MK, Deddens JA, Couch JR, Petersen MR [2010]. Risk of lung cancer associated 

with quantitative beryllium exposure metrics within an occupational cohort. Occup Environ Med 

68(5):354–360, http://dx.doi.org/10.1136/oem.2010.056515. 

Vincoli JW [1997]. Risk management for hazardous chemicals. Boca Raton, FL: CRC Press.

WHO [1992]. Environmental health criteria 134. Cadmium. Geneva, Switzerland: World Health 

Organization, http://www.inchem.org/documents/ehc/ehc/ehc134.htm. 

Polyaromatic Hydrocarbons (Polycyclic Aromatic Hydrocarbons)

ATSDR [1995]. Toxicological profile for polycyclic aromatic hydrocarbons (PAHs). Atlanta, GA: U.S. 

Department of Health and Human Services, Agency for Toxic Substances and Disease Registry, 

https://www.atsdr.cdc.gov/toxprofiles/tp.asp?id=122&tid=25. 

ATSDR [2007]. Toxicological profile for benzene. Atlanta, GA: U.S. Department of Health and Human 

Services, Agency for Toxic Substances and Disease Registry, 

https://www.atsdr.cdc.gov/toxprofiles/tp.asp?id=40&tid=14. 

Boffetta P, Jourenkova N, Gustavsson P [1997]. Cancer risk from occupational and environmental 

exposure to polycyclic aromatic hydrocarbons. Cancer Causes Control 8(3):444–472, 

https://www.ncbi.nlm.nih.gov/pubmed/9498904. 
F-6

IARC [1982]. Monographs on the evaluation of the carcinogenic risks to humans: some industrial 

chemicals and dyestuffs. Vol. 29. Lyon, France: World Health Organization, International Agency for 

Research on Cancer, https://monographs.iarc.fr/wp-content/uploads/2018/06/mono29.pdf. 

IARC [2002]. Monographs on the evaluation of the carcinogenic risks to humans: some traditional 

herbal medicines, some mycotoxins, naphthalene and styrene. Vol. 82. Lyon, France: World Health 

Organization, International Agency for Research on Cancer, https://monographs.iarc.fr/iarcmonographs-on-the-evaluation-of-carcinogenic-risks-to-humans-39/. 

IARC [2010]. Monographs on the evaluation of the carcinogenic risks to humans: some nonheterocyclic polycyclic aromatic hydrocarbons and some related exposures. Vol. 92. Lyon, France: 

World Health Organization, International Agency for Research on Cancer, 

https://monographs.iarc.fr/iarc-monographs-on-the-evaluation-of-carcinogenic-risks-to-humans-29/. 

NIOSH [2013a]. Evaluation of dermal exposure to polycyclic aromatic hydrocarbons in fire fighters. By 

Fent KW, Eisenberg J, Evans D, Sammons D, Robertson S, Striley C, Snawder J, Mueller C, 

Kochenderfer V, Pleil J, Stiegel M, Horn G. Cincinnati, OH: U.S. Department of Health and Human 

Services, Centers for Disease Control and Prevention, National Institute for Occupational Safety and 

Health, Health Hazard Evaluation Report 2010-0156-3196, 

https://www.cdc.gov/niosh/hhe/reports/pdfs/2010-0156-3196.pdf. 

NIOSH [2013b]. Evaluation of dermal exposure to polycyclic aromatic hydrocarbons in fire fighters. 

Summary. By Fent KW, Eisenberg J, Evans D, Sammons D, Robertson S, Striley C, Snawder J, Mueller 

C, Kochenderfer V, Pleil J, Stiegel M, Horn G. Cincinnati, OH: U.S. Department of Health and Human 

Services, Centers for Disease Control and Prevention, National Institute for Occupational Safety and 

Health, Health Hazard Evaluation Report 2010-0156-3196S, 

https://www.cdc.gov/niosh/hhe/reports/pdfs/2010-0156-3196S.pdf. 

Silica Exposure in the Workplace

ACGIH [2019]. 2019 TLVs® and BEIs®: threshold limit values for chemical substances and physical 

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

Industrial Hygienists.

Calvert GM, Rice FL, Boiano JM, Sheehy JW, Sanderson WT [2003]. Occupational silica exposure and 

risk of various diseases: an analysis using death certificates from 27 states of the United States. Occup 

Environ Med 60(2):122–129, https://doi.org/10.1136/oem.60.2.122. 

Cooper GS, Miller FW, Germolec DR [2002]. Occupational exposures and autoimmune diseases. Int 

Immunopharmacol 2(2–3):303–313, https://doi.org/10.1016/S1567-5769(01)00181-3. 

Ghahramani N [2010]. Silica nephropathy. Int J Occup Environ Med 1(3):108–115, 

http://www.theijoem.com/ijoem/index.php/ijoem/article/viewFile/45/93. 

Hinds WC [2012]. Aerosol technology: properties, behavior, and measurement of airborne particles. 

New York, NY: John Wiley & Sons. 
F-7

IARC [2012]. IARC monographs on the evaluation of the carcinogenic risks to humans. A review of 

human carcinogens: arsenic, metals, fibres, and dusts. Vol. 100C. Lyon, France: World Health 

Organization, International Agency for Research on Cancer, https://monographs.iarc.fr/iarcmonographs-on-the-evaluation-of-carcinogenic-risks-to-humans-19/. 

Lee S, Matsuzaki H, Kumagai-Takei N, Yoshitome K, Maeda M, Chen Y, Kusaka M, Urakami K, 

Hayashi H, Fujimoto W, Nishimura Y, Otsuki T [2014]. Silica exposure and altered regulation of 

autoimmunity. Environ Health Prev Med 19(5):322–329, https://dx.doi.org/10.1007/s12199-014-0403-

9. 

Liu Y, Steenland K, Rong Y, Hnizdo E, Huang X, Zhang H, Shi T, Sun Y, Wu T, Chen W [2013]. 

Exposure-response analysis and risk assessment for lung cancer in relationship to silica exposure: a 44-

year cohort study of 34,018 workers. Am J Epidemiol 178(9):1424–1433, 

https://dx.doi.org/10.1093/aje/kwt139. 

NIOSH [2002]. Health effects of occupational exposure to respirable crystalline silica. Cincinnati, OH: 

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

Institute for Occupational Safety and Health, DHHS (NIOSH) Publication No. 2002-129, 

https://www.cdc.gov/niosh/docs/2002-129/. 

NIOSH [2007]. NIOSH pocket guide to chemical hazards. Cincinnati, OH: U.S. Department of Health 

and Human Services, Centers for Disease Control and Prevention, National Institute for Occupational 

Safety and Health, DHHS (NIOSH) Publication No. 2005-149, http://www.cdc.gov/niosh/npg/. 

NIOSH [2014]. Comments of the National Institute for Occupational Safety and Health on the 

Occupational Safety and Health Administration proposed rule on occupational exposure to respirable 

crystalline silica. Docket No. OSHA-2010-0034; RIN 1218-AB70. Centers for Disease Control and 

Prevention, National Institute for Occupational Safety and Health, 

https://www.nfib.com/assets/NFIB-OSHA-Silica-NPRM-Comments-02-10-14.pdf. 

OSHA [2017]. OSHA small entity compliance guide for the respirable crystalline silica standard for 

construction. Washington DC: U.S. Department of Labor, Occupational Safety and Health 

Administration, https://www.osha.gov/Publications/OSHA3902.pdf. 

OSHA [2019a]. OSHA Complying with the construction standard. Washington DC: U.S. Department 

of Labor, Occupational Safety and Health Administration, 

https://www.osha.gov/dsg/topics/silicacrystalline/construction.html. 

OSHA [2019b]. OSHA sampling and analytical methods. Washington DC: U.S. Department of Labor, 

Occupational Safety and Health Administration, http://www.osha.gov/dts/sltc/methods/index.html. 

Rappaport SM, Goldberg M, Susi P, Herrick RF [2003]. Excessive exposure to silica in the U.S. 

construction industry. Ann Occup Hyg 47(2):111−122, https://doi.org/10.1093/annhyg/meg025. 
Delivering on the Nation’s promise:

Promoting productive workplaces through safety 

and health research

Get More Information

Find NIOSH products and get answers to workplace safety 

and health questions: 

1-800-CDC-INFO (1-800-232-4636) | TTY: 1-888-232-6348 

CDC/NIOSH INFO: cdc.gov/info | cdc.gov/niosh

Monthly NIOSH eNews: cdc.gov/niosh/eNews