HETA 99-0173-2856

Turnbull National Wildlife Refuge

Cheney, Washington

Steven A. Lee, CIH

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

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

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

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

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

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

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

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

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

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

PREFACE

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

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

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

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

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

to determine whether any substance normally found in the place of employment has potentially toxic effects

in such concentrations as used or found.

HETAB also provides, upon request, technical and consultative assistance to Federal, State, and local

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

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

by NIOSH.

ACKNOWLEDGMENTS AND AVAILABILITY OF REPORT

This report was prepared by Steven A. Lee of HETAB, Division of Surveillance, Hazard Evaluations and

Field Studies (DSHEFS). Desktop publishing was performed by Pat Lovell. Review and preparation for

printing were performed by Penny Arthur.

Copies of this report have been sent to employee and management representatives and the OSHA Regional

Office. This report is not copyrighted and may be freely reproduced. Single copies of this report will be

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

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

NIOSH Publications Office

4676 Columbia Parkway

Cincinnati, Ohio 45226

800-356-4674

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

5825 Port Royal Road, Springfield, Virginia 22161. Information regarding the NTIS stock number may be

obtained from the NIOSH Publications Office at the Cincinnati address.

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

posted by the employer in a prominent place accessible to the employees for a period

of 30 calendar days.
iii

Highlights of the NIOSH Health Hazard Evaluation

Exposure to Chainsaw Exhaust among Foresters

This NIOSH Health Hazard Evaluation (HHE) was requested by management at Turnbull National Wildlife

Refuge (TNWR) in Cheney, Washington. It was conducted in April 1999 and May 2000 to document exposure

to chainsaw emissions among foresters thinning pine trees. 

What NIOSH Did

# We visited the TNWR to conduct an

environmental investigation of exposure to chainsaw

emissions.

# We collected air samples for carbon monoxide

(CO), benzene, aldehydes, and polynuclear aromatic

hydrocarbons (PNAs). 

# We measured CO in exhaled breath to give us

an estimate of each forester’s carboxyhemoglobin

(COHb) level.

# We interviewed foresters to see if they had any

work-related health problems.

What NIOSH Found

# Exposure to CO exceeded recommended limits

when foresters cut larger trees on calm days.

# COHb levels in foresters also exceeded

recommended limits. 

# We found airborne exposure to low levels of the

following potential occupational carcinogens:

benzene, formaldehyde, acetaldehyde, and PNAs.

# All of the foresters reported having recurring

musculoskeletal symptoms, such as soreness of the

fingers, wrists, elbows, and back.

What Managers Can Do

# Reduce full-shift exposure to chainsaw exhaust

and musculoskeletal strains by replacing some of the

sawyer work with other duties during the shift. 

# Ensure that new employees are thoroughly

trained in proper felling techniques and safe work

practices.

# Enforce the safety procedures applicable to the

felling of larger trees in accordance with OSHA 29

CFR 1910.266.

What the Employees Can Do

# Keep your chainsaws as sharp as possible to

reduce the duration of peak CO exposure, especially

when cutting larger trees.

# Avoid excessive muscle fatigue during treecutting to help reduce the possibility of accidents

and musculoskeletal problems.

# Closely follow proper safety procedures when

felling larger trees.

What To Do For More Information:

We encourage you to read the full report. If you

would like a copy, either ask your health and

safety representative to make you a copy or call

1-513/841-4252 and ask for

 HETA Report # 99-0172-2856

Health Hazard Evaluation Report 99-0173-2856
iv

U.S. Park Service

Cheney, Washington

July 2001

Steven A. Lee, CIH

SUMMARY

In April 1999, the U.S. Park Service, Turnbull National Wildlife Refuge (TNWR), Cheney, Washington, asked

NIOSH to evaluate exposure to chainsaw exhaust among forestry workers. Although workers had not reported any

symptoms related to chainsaw exhaust, management wanted to have some documentation of their exposure.

Six to eight foresters are employed to thin the forest of pine trees up to 22 inches in diameter. Exposure to airborne

carbon monoxide (CO), benzene, aldehydes, and polynuclear aromatic hydrocarbons (PNAs) was evaluated during

four days of sampling with wind conditions ranging from calm to 11 miles per hour (mph). Also,

carboxyhemoglobin (COHb) levels in each forester were estimated by measuring CO in exhaled breath.

On two days of cutting larger trees during light wind conditions (up to 7 mph), full-shift exposure to CO ranged

from 8 to 31 parts per million (ppm), with 40% of the exposures exceeding the most protective evaluation criterion

of 25 ppm. Peak CO exposures (up to 1100 ppm) were found to occur primarily when foresters were bent or

kneeling to cut the stumps of larger trees close to ground level. Estimated COHb levels ranged up to 4.9% with

33% of COHb levels exceeding the evaluation criterion of 3.5%. On two days of cutting smaller trees during wind

conditions up to 11 mph, no full-shift CO exposures exceeded the evaluation criterion.

Full-shift time-weighted average (TWA) exposures to the following occupational carcinogens were found:

(1) benzene ranged from 0.03 to 0.1 ppm, with a mean of 0.05 ppm, (2) formaldehyde ranged from 0.013 to

0.029 ppm, with a mean of 0.018 ppm, (3) acetaldehyde ranged from 0.008 to 0.015 ppm, with a mean of 0.01 ppm,

and (4) low levels of eight PNAs were detected including five that are known to have carcinogenic potential.

All of the interviewed foresters reported having some recurring musculoskeletal problems associated with working

with chainsaws. These primarily consisted of soreness in the fingers, wrists, elbows, and back. 

According to the most protective evaluation criteria, there was overexposure to CO among foresters at TNWR.

Also, exposures to benzene, formaldehyde, acetaldehyde, and PNAs were detected. NIOSH recommends that

exposure to occupational carcinogens be reduced as low as possible. Recommendations were provided to reduce

exposure to chainsaw emissions by reducing the amount of chainsaw work per shift and to keep chainsaws as sharp

as possible to reduce the duration of peak exposure when cutting larger trees.

Keywords: SIC Code 0851(Forestry Services) chainsaw exhaust, carbon monoxide, CO, carboxyhemoglobin,

COHb, benzene, formaldehyde, acetaldehyde, polynuclear aromatic hydrocarbons, PNAs, PAHs
TABLE OF CONTENTS

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

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

HHE Supplement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iii

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

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

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

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

Evaluation Criteria . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

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

Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

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

Recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Health Hazard Evaluation Report No. 99-0173-2856 Page 1

INTRODUCTION

In April 1999, the National Institute for Occupational

Safety and Health (NIOSH) received a request for a

health hazard evaluation (HHE) from the U.S.

Department of Interior to evaluate exposure to

chainsaw exhaust among forestry workers at the

Turnbull National Wildlife Refuge (TNWR),

Cheney, Washington. Workers had not reported any

adverse health effects that they associated with

chainsaw exhaust. The requester was aware of

studies demonstrating elevated carboxyhemoglobin

(COHb) levels in loggers using chainsaws and

wanted some documentation of exposure for workers

at TNWR. 

In April 1999, a NIOSH industrial hygienist

conducted an initial evaluation of forestry workers

using chainsaws at the TNWF. Exposure to carbon

monoxide (CO) was assessed, and employee

interviews were conducted. Environmental

monitoring results along with recommendations to

reduce exposure to chainsaw exhaust and ergonomic

strains were presented at the end of the NIOSH visit.

In May 2000, a follow-up study was conducted to

evaluate exposure to CO, benzene, polynuclear

aromatic hydrocarbons (PNAs), total hydrocarbons,

formaldehyde, acetaldehyde, and benzaldehyde.

BACKGROUND

The Turnbull National Wildlife Refuge is a wetland

habitat that was nearly lost in the early 1900s as

settlers attempted to drain the area for agriculture.

Failure of the lake beds to produce crops combined

with the efforts of conservationists resulted in the

creation of the refuge in 1937. Many of the lakes and

marshes have been restored and the refuge is now

used by migrating waterfowl of the Pacific Flyway.

The refuge also has large areas of Ponderosa pine

forest consisting of an unnaturally thick growth of

stunted trees due to many years of fire suppression.

This limits the variety of grasses and forbs needed to

support a variety of wildlife. Also, unnaturally thick

forests are susceptible to wildfires that are more

destructive than those that occur in thin forests. 

Eight foresters are employed by the TNWR to thin

out some of the thicker growth of pine trees.

Thinning involves cutting all trees less than eight

inches in diameter, except in thick stands of larger

trees where trees up to 22 inches in diameter may be

cut. Larger trees are initially cut about four feet

above the ground, and the stump is then cut to within

four inches of the ground. Larger trees are cut into

pieces and scattered, and controlled burns are later

conducted in some areas. The chainsaws primarily

used are Stihl Models 036 and 044. The Model 036

has a two-stroke 4.6 horse power (hp) engine and was

fitted with 20-inch guide bars during the initial

NIOSH visit. The Model 044 has a 5.4 hp engine and

a 25-inch guide bar. During the NIOSH follow-up

visit, all saws of both models had 25-inch guide bars.

Both models are equipped with anti-vibration

systems and quick-stop chain brakes. Fuel consists of

Chevron Mid-Grade (87 octane) gasoline mixed at a

50:1 ratio with L-J two-stoke engine oil.

Foresters wear hard hats with attached Stihl Promark

ear muffs in addition to foam ear plugs, safety glasses

with side shields, and cotton or leather gloves. They

work a 9-hour shift that includes a 30-minute lunch

break and two 15-minute rest breaks. Chains are

sharpened one to three times per shift which requires

about 10 minutes. One hour is used for cleaning and

maintaining equipment at the end of the shift. The

total amount of time spent operating chainsaws is

about 5 hours per shift. 

METHODS

On April 27-28, 1999, the NIOSH investigator

conducted an evaluation of forester exposure to CO,

and conducted private interviews to determine the

extent of work-related health problems. Each

forester’s exposure to CO was measured using

Biosystems Toxi-Ultra or Toxilog single-sensor gas

detectors. These dataloggers continuously monitor by

diffusion through an electrochemical sensor specific

for CO. The monitors were worn in the personal

breathing-zone (PBZ) of the employees during the

eight hours they were working in the forest. Each

instrument was pre- and post-calibrated using 50 ppm

CO span gas. The units displayed the 8-hour timeweighted average (TWA), the maximum 15-minute

exposure, and the maximum peak exposure for each

worker. The peak exposure audible alarm of the

monitors was set at 400 ppm and the foresters were

asked to note what task they were performing each

time the alarm sounded. Wind velocities were

measured each day with a Kurz Mini Anemometer

Model 490.

Estimates of COHb levels in each employee were

calculated by collecting exhaled breath in a balloon

by the method described in the documentation of the

American Conference of Governmental Industrial
Page 2 Health Hazard Evaluation Report No. 99-0173-2856

Hygienists (ACGIH®) Biological Exposure Index.1

Mid- and post- shift exhaled breath measurements

were conducted on the first day of sampling, and pre-,

mid-, and post- shift measurements were conducted

on the second day. The exhaled breath was measured

for CO using the dataloggers, and the estimated

percentage of carboxyhemoglobin in the blood was

calculated using the formula: -0.5 + (expired CO in

ppm/5).1

Seven (88 %) of the foresters were privately

interviewed by the NIOSH investigator who asked

them, “have you experienced any health problems

that you think might be related to your work?” 

On May 2-3, 2000, exposure to CO was again

measured along with estimates of COHb levels in

each of the six foresters working at TNWR at that

time. Full-shift PBZ air samples were collected on

charcoal tubes at a flow rate of 0.2 liters per minute

and analyzed by gas chromatography for benzene and

total hydrocarbons according to NIOSH Methods

1501 and 1550, respectively.2

 PBZ air samples for

PNAs were collected on Teflon filters followed by

Orbo 43 sorbent tubes at a flow rate of 2.0 liters per

minute and analyzed by high performance liquid

chromatography (HPLC) according to NIOSH

Method 5506.2

 PBZ air samples for formaldehyde,

acetaldehyde, and benzaldehyde were collected on

DNPH-treated silica gel cartridges at a flow rate of

0.3 liters per minute and analyzed by HPLC

according to NIOSH Method 2016.2

 A bulk sample

of the chainsaw fuel was analyzed for benzene by gas

chromatography according to NIOSH Method 1501.2

EVALUATION CRITERIA

As a guide to the evaluation of the hazards posed by

workplace exposures, NIOSH field staff employ

environmental evaluation criteria for the assessment

of a number of chemical and physical agents. These

criteria are intended to suggest levels of exposure to

which most workers may be exposed up to 10 hours

per day, 40 hours per week for a working lifetime

without experiencing adverse health effects. It is,

however, important to note that not all workers will

be protected from adverse health effects even though

their exposures are maintained below these levels. A

small percentage may experience adverse health

effects because of individual susceptibility, a preexisting medical condition, and/or a hypersensitivity

(allergy). In addition, some hazardous substances

may act in combination with other workplace

exposures, the general environment, or with

medications or personal habits of the worker to

produce health effects even if the occupational

exposures are controlled at the level set by the

criterion. These combined effects are often not

considered in the evaluation criteria. Also, some

substances are absorbed by direct contact with the

skin and mucous membranes, and thus potentially

increases the overall exposure. Finally, evaluation

criteria may change over the years as new

information on the toxic effects of an agent become

available.

The primary sources of environmental evaluation

criteria for the workplace are: (1) NIOSH

Recommended Exposure Limits (RELs),3

 (2) the

ACGIH® Threshold Limit Values (TLVs®),4

 and

(3) the U.S. Department of Labor, Occupational

Safety and Health Administration (OSHA)

Permissible Exposure Limits (PELs).5

 Employers are

encouraged to follow the OSHA limits, the NIOSH

RELs, the ACGIH TLVs, or whichever are the more

protective criterion.

OSHA requires an employer to furnish employees a

place of employment that is free from recognized

hazards that are causing or are likely to cause death or

serious physical harm [Occupational Safety and

Health Act of 1970, Public Law 91–596, sec.

5.(a)(1)]. Thus, employers should understand that not

all hazardous chemicals have specific OSHA

exposure limits such as PELs and short-term

exposure limits (STELs). An employer is still

required by OSHA to protect their employees from

hazards, even in the absence of a specific OSHA

PEL.

A time-weighted average (TWA) exposure refers to

the average airborne concentration of a substance

during a normal 8- to 10-hour workday. Some

substances have recommended STEL or ceiling

values which are intended to supplement the TWA

where there are recognized toxic effects from higher

exposures over the short term.

Carbon Monoxide

Carbon monoxide is a colorless, odorless, tasteless

gas produced by incomplete burning of carboncontaining materials; e.g., gasoline. Carbon

monoxide displaces oxygen in the blood and

combines with hemoglobin to form COHb. The

initial symptoms of CO poisoning may include

headache, dizziness, drowsiness, and nausea. These

initial symptoms may advance to vomiting, loss of

consciousness, and collapse if prolonged or high
Health Hazard Evaluation Report No. 99-0173-2856 Page 3

exposures are encountered. Coma or death may

occur if high exposures continue.6

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

TWA exposure, with a ceiling limit of 200 ppm

which should not been exceeded.7

 The NIOSH REL

of 35 ppm is designed to protect workers from health

effects associated with COHb levels in excess of 5%.6

The ACGIH recommends a TLV of 25 ppm as an

8-hour TWA, and this is designed to protect workers

from health effects associated with COHb levels in

excess of 3.5%.1

 COHb concentrations in the blood

are most accurately determined by analyzing blood

samples. However, COHb levels can be estimated

more easily by measuring CO in exhaled breath. A

person with 20 ppm of CO in their exhaled breath has

a COHb level of approximately 3.5%.1

 The OSHA

PEL for CO is 50 ppm for an 8-hour TWA exposure.5

In addition to these standards, the National Research

Council has developed a CO exposure standard of

15 ppm, based on a 24 hours per day, 90-day TWA

exposure.8

Benzene

Benzene is an aromatic organic hydrocarbon

containing a six carbon ring with alternating double

bonds. Benzene was formerly an important solvent

especially in the rubber and surface coating

industries, but now is rarely used as a solvent because

of its toxicity. It is, however, present as a trace

contaminant in gasoline and other petroleum

solvents.1

 The nationwide average of benzene

content in gasoline is 1.5%, although studies have

found benzene content as high as 5%.9

 A previous

NIOSH evaluation involving six service stations

measured benzene content in gasoline from 0.3 to

1.9%. The exposures to benzene among the service

station attendants were measured and the results of

the PBZ samples associated with these gasolines

ranged from 0.01 to 0.26 parts per million (ppm).10

Acute inhalation exposure to high concentrations of

benzene can cause drowsiness, fatigue, nausea,

vertigo, narcosis, and other symptoms of central

nervous system (CNS) depression as noted with

excessive exposure to other aromatic hydrocarbons.11

However, the most remarkable health effects

associated with benzene exposure are chronic effects

due to repeated exposure to low concentrations over

many years.12

Benzene is classified by the International Agency for

Research on Cancer (IARC) as a known human

carcinogen and has been associated with irreversible

bone marrow injury and the development of

hematopoietic toxicity, including aplastic anemia and

leukemia in humans.11,13,14 NIOSH classifies benzene

as a human carcinogen, and recommends that

occupational exposures be controlled to

prevent employees from being exposed to

concentrations greater than 0.1 ppm, determined as a

TWA concentration for up to a 10-hour work shift in

a 40-hour work week. NIOSH further recommends

a 15-minute STEL of 1.0 ppm. Although NIOSH has

established these guidelines which should not be

exceeded, the Institute still urges that exposures be

reduced to the "lowest feasible level" (LFL) because

it is not possible to establish thresholds for

carcinogens which will protect 100% of the

population. The OSHA PEL is 1 ppm for an 8-hour

TWA with a 15-minute STEL of 5 ppm. However,

the PEL does not apply to "... storage, transportation,

distribution, dispensing, sale, or use of gasoline,

motor fuels, or other fuels containing benzene

subsequent to its final discharge from bulk wholesale

storage facilities, except operations where gasoline or

motor fuels are dispensed for more than four hours

per day in an indoor location..." The current ACGIH

TLV® is 0.5 ppm as a confirmed human carcinogen.

Polynuclear Aromatic Hydrocarbons

Polynuclear aromatic compounds (PNAs) are

chemical species that consist of two or more fused

aromatic rings. They are often associated with the

combustion or pyrolysis of organic matter, especially

coal, wood, and petroleum products. Materials

associated with these processes have been

demonstrated to contain compounds that have been

shown to cause cancer in laboratory animals and, in

some cases, humans. There are few dose-related

relationships for the PNA mixtures that may be found

in these industrial processes, and no "safe" exposures

to PNA aerosols have been established. Since the

application of laboratory animal data for PNA

compounds to estimate human risk is very difficult,

any occupational exposure to potentially carcinogenic

matter is a cause for concern and exposures should be

kept to an absolute minimum.

NIOSH recommends that occupational exposures to

coal tar be controlled so that employees are not

exposed to coal tar, coal tar pitch, creosote, or

mixtures of these substances at a concentration

greater than 0.1 milligrams per cubic meter (mg/m3

)

of the benzene- (or cyclohexane-) extractable fraction

of the sample, determined as a TWA concentration

for up to a 10-hour work shift in a 40-hour work

week. Both ACGIH and OSHA set their standards at
Page 4 Health Hazard Evaluation Report No. 99-0173-2856

0.2 mg/m3 for a normal 8-hour workday or 40-hour

work week. Individual PNA measurements serve to

establish the presence of coal tar pitch volatiles

(CTPVs) and indicate the presence of known or

suspected carcinogens or other genotoxic compounds

in the workplace, which would dictate additional

control measures.

The potential adverse health effects of PNAs are well

recognized.15,16,17,18 Several PNAs, such as

benzo(a)anthracene and pyrene, have been shown to

be carcinogenic in animals. Excess risk of lung

cancer, oral cancer, and skin neoplasms (benign and

malignant) have been found in working populations

handling coal tar products which NIOSH has defined

to include coal tar, coal tar pitch, and creosote. A

TWA exposure of 0.2 μg/m3

 was recommended by

the coke oven advisory committee for

benzo(a)pyrene under the OSHA 29 CFR 1910.1029

coke oven emissions standard, but was not adopted.

A special NIOSH hazard review of chrysene

recommended that it be controlled as an occupational

carcinogen. Also, ACGIH includes chrysene and

benzo(a)pyrene in its list of industrial substances

suspected of having carcinogenic potential in man.

The carcinogenic potential of other PNAs

(benzo(a)anthracene, anthracene, pyrene, and

fluoranthene) has also been documented.16

Formaldehyde 

Formaldehyde is a colorless gas with a strong odor.

Exposure can occur through inhalation and skin

absorption. The acute effects associated with

formaldehyde are irritation of the eyes and

respiratory tract and sensitization of the skin. The

first symptoms associated with formaldehyde

exposure, at concentrations ranging from 0.1 to 5

(ppm), are burning of the eyes, tearing, and general

irritation of the upper respiratory tract. There is

variation among individuals, in terms of their

tolerance and susceptibility to acute exposures of the

compound.19

In two separate studies, formaldehyde has induced a

rare form of nasal cancer in rodents. Formaldehyde

exposure has been identified as a possible causative

factor in cancer of the upper respiratory tract in a

proportionate mortality study of workers in the

garment industry.20 NIOSH has identified

formaldehyde as a suspected human carcinogen and

recommends that exposures be reduced to the lowest

feasible concentration. The OSHA PEL is 0.75 ppm

as an 8-hour TWA and 2 ppm as a STEL.21 ACGIH

has designated formaldehyde to be a suspected

human carcinogen and therefore, recommends that

worker exposure by all routes should be carefully

controlled to levels "as low as reasonably achievable"

below the TLV.1

 ACGIH has set a ceiling limit of

0.3 ppm.

Note: NIOSH testimony to DOL on May 5, 1986,

stated the following: "Since NIOSH is not aware of

any data that describe a safe exposure concentration

to a carcinogen NIOSH recommends that

occupational exposure to formaldehyde be controlled

to the lowest feasible concentration; 0.1 ppm in air by

collection of an air sample for any 15-minute period

as described in NIOSH analytical method 3500 which

is the lowest reliably quantifiable concentration at the

present time." NIOSH also lists an REL for

formaldehyde of 0.016 ppm for up to a 10-hour TWA

exposure (again using NIOSH analytical method

3500) and indicates that this is the lowest reliably

quantifiable concentration at the present time.

Investigators should be aware that formaldehyde

levels can currently be measured below 0.016 ppm.

It may be appropriate to refrain from using numerical

limits and instead state that concentrations should be

the lowest feasible (in some situations, this may be

limited by the ambient background concentration). 

RESULTS

Initial Survey

On the first day of sampling in April 1999, eight

foresters were exposed to 8-hr TWA concentrations

of CO ranging from 8 to 31 ppm, with a mean of

20 ppm (Table 1). Four exposures were above the

ACGIH TLV of 25 ppm. Maximum 15-minute

exposure concentrations ranged from 40 to 170 ppm,

with a mean of 100 ppm. No STEL has been

developed for CO. Maximum peak (ceiling)

exposure concentrations ranged from 150 to

1100 ppm with a mean of 500 ppm. Seven exposures

were above the NIOSH ceiling exposure limit of

200 ppm. 

On the second day of sampling, the work schedule

was altered slightly by replacing the two 15-minute

rest breaks with four 10-minute rest breaks. Seven

foresters were exposed to 8-hr TWA CO

concentrations ranging from 10 to 31 ppm, with a

mean of 18 ppm (Table 1). Two exposures were

above the ACGIH TLV. Maximum 15-minute

exposure concentrations ranged from 45 to 110 ppm,

with a mean of 69 ppm. Maximum peak exposures
Health Hazard Evaluation Report No. 99-0173-2856 Page 5

ranged from 290 to 770 ppm, with a mean of

460 ppm. 

On the first day of sampling, mid-shift estimated

COHb concentrations in non-smoking workers

ranged from 0.7 to 4.9%, with a mean of 2.3%

(Table 1). Post-shift estimated COHb concentrations

in non-smokers ranged from 0.5 to 4.7%, with a mean

of 2.1%. On the second day, mid-shift estimated

COHb concentrations in non-smoking workers

ranged from 0.5 to 3.9%, with a mean of 1.9%, and

the post-shift estimated COHb concentrations in nonsmokers ranged from 0.5 to 3.7%, with a mean of

2.1%. A total of five estimated COHb concentrations

in non-smokers were above the ACGIH

recommended biological exposure index (BEI) of

3.5% during the two days of sampling. The mean

pre-shift (mid-week) estimated COHb concentration

in non-smoking workers was 1.3%. Background

levels of COHb in the general population of nonsmokers are 0.5 to 1.5%.1

 

Foresters reported that the CO alarms most frequently

sounded as they were kneeling or bending and cutting

the stumps of larger trees. Figure I displays a

forester’s exposure to CO during the second day of

sampling. The full-shift TWA exposure is 19 ppm

and there were eight peak exposures above 200 ppm

that occurred during the cutting of larger trees. Light

winds ranging up to seven miles per hour (mph)

occurred during both days of sampling.

Follow-up Survey

In May 2000, six foresters were exposed to full-shift

TWA CO concentrations ranging from 5 to 23 ppm,

with a mean of 11 ppm during two days of sampling

(Table 2). Maximum 15-minute exposure

concentrations ranged from 0 to 9.0 ppm, with a

mean of 2.7 ppm. Maximum peak exposures ranged

from 90 to 530 ppm, with a mean of 260 ppm. Midshift estimated COHb concentrations in non-smokers

ranged from 0.9 to 1.9%, with a mean of 1.4%. Postshift estimated COHb concentrations in non-smokers

ranged from 0.5 to 4.5%, with a mean of 1.7%. One

non-smoker and two smokers had estimated COHb

concentrations above the ACGIH BEI of 3.5%. The

mean Monday morning pre-shift estimated COHb

concentration in non-smoking workers was 0.65%.

The mean Tuesday morning pre-shift estimated

COHb concentration in non-smokers was 1.7%. 

Winds were slightly stronger during the follow-up

survey with velocities ranging up to 9 mph on the

first day and 11 mph during the afternoon of the

second day. Also, foresters reported that they were

working in an area that had smaller trees than the area

being thinned during the initial NIOSH survey. 

The chainsaw fuel contained 1.6 % benzene. Fullshift TWA air exposure to benzene ranged from 0.03

to 0.1 ppm, with a mean of 0.05 ppm (Table 3). Fullshift exposure to total airborne hydrocarbons ranged

from 3.8 to 17 mg/m3

, with a mean of 8.2 mg/m3.

The NIOSH REL for total hydrocarbons is

350 mg/m3

. 

Full-shift TWA exposure to formaldehyde ranged

from 0.013 to 0.029 ppm, with a mean of 0.018 ppm

(Table 3). Full-shift TWA exposure to acetaldehyde

ranged from 0.008 to 0.02 ppm, with a mean of

0.01 ppm. NIOSH considers both formaldehyde and

acetaldehyde to be potential occupational

carcinogens. Exposure should be reduced as low as

possible. Full-shift TWA exposure to benzaldehyde

ranged from non-detectable (<0.0002 ppm) to

0.002 ppm. Exposure limits have not been

established for benzaldehyde. 

Of the 16 PNAs that were analyzed, 8 of the lower

molecular weight PNAs up through chrysene were

detected (Table 4). Naphthalene and acenaphthene

were detected in the highest concentrations.

Exposure to naphthalene ranged from 6.3 to

12 micrograms per cubic meter (ug/m3

), and exposure

to acenaphthene ranged from 7.7 to 17 ug/m3

. Five of

the detected PNAs are known to have carcinogenic

potential. These are anthracene, fluoranthene, pyrene,

benzo(a)anthracene, and chrysene.16

Employee Interviews

The NIOSH investigator interviewed five men and

two women ranging in age from 27 to 50 years, with

a mean age of 37 years. All of the foresters are

certified wildland firefighters who are annually

required to pass physical fitness requirements. Two

of the interviewed workers are light smokers (two or

three cigarettes/day). The health effects reported by

the interviewed foresters consisted of recurring

musculoskeletal symptoms. All seven (100%)

reported having at least one symptom and four (57%)

had multiple symptoms. Four (57%) reported sore or

stiff finger joints, primarily in the morning. Two

(29%) reported sore or fatigued lower backs, and one

(14%) had soreness in the upper back. Two (29%)
Page 6 Health Hazard Evaluation Report No. 99-0173-2856

had sore elbows of the dominant arm, and one (14%)

reported that both elbows became sore. One (14%)

had a sore wrist of the dominant arm, and one (14%)

reported soreness in both wrists. One (14%)

experienced soreness of the dominant shoulder, and

one (14%) reported a sore neck.

There have been no accidents resulting in lost-time

injuries associated with tree cutting at TNWR,

however, foresters reported that there have been some

“close calls,” such as chainsaws accidently cutting

through clothing or workers nearly being struck when

cutting through spring poles (a tree under tension

from the weight of another tree). 

DISCUSSION

Much of the CO exposure among foresters occurs

during very brief (<1 minute) periods when CO

levels frequently exceed the NIOSH ceiling limit of

200 ppm. It would be impossible to work with

chainsaws and stay below the ceiling limit when

cutting larger trees. Realistically, peak CO exposures

among TNWR foresters are too brief to be considered

immediately hazardous. Even a CO exposure of

1000 ppm during a moderate work load (alveolar

ventilation rate of 20 liters per minute) requires eight

minutes to reach 3.5% COHb in an average-sized

adult.1,22 Furthermore, TNWR foresters were found

to have peak CO exposures exceeding 200 ppm up to

eight times per shift without exceeding a full-shift

TWA exposure of 25 ppm, or an estimated COHb

concentration of 3.5%.

Probably the most useful measures of exposure to CO

among foresters at TNWR are the full-shift TWAs

along with mid-shift and post-shift COHb estimates.

Although no foresters were exposed to full-shift

TWA CO levels above the NIOSH REL and none of

their estimated COHbs exceeded the NIOSH

recommendation, exposures did exceed the more

protective ACGIH TLV of 25 ppm. Also, the

foresters’ estimated COHb levels exceeded the

ACGIH BEI of 3.5%. ACGIH lists the following

reasons for their more conservative

recommendations:1

 (1) minimize decrements in

psychomotor function that may increase the potential

for accidents, (2) maintain cardiovascular work and

exercise capacities, and (3) provide a greater margin

of safety for people more susceptible to the effects of

CO, such as pregnant workers and their fetuses,

people with chronic heart and respiratory disease, and

smokers who already have elevated COHb levels.

People who smoke one pack of cigarettes per day

have COHb levels of 5% to 6%, and heavy smokers

may have COHb levels up to 20%.23 

It could be argued that the superior physical fitness of

TNWR foresters combined with their good safety

record provide reasons for not needing to follow the

more protective ACGIH TLV for CO. However,

chainsaws are potentially dangerous tools and tree

cutting is physically demanding work that requires

optimum mental alertness. Therefore, it would be

prudent to reduce CO exposure in accordance with

the ACGIH TLV and BEI to minimize decrements in

psychomotor function that may increase the potential

for serious accidents.1

Environmental monitoring indicated that exposure to

chainsaw exhaust was higher during the initial

survey. This was most likely due to a combination of

the larger trees being cut and the lower wind

velocities that occurred at that time. During the

follow-up survey, all of the full-shift TWA exposures

were below 25 ppm, however, three of the foresters

had mid- or post-shift estimated COHb levels above

3.5 %. The correlation between environmental CO

exposure and COHb levels can vary considerably due

to body size and work load.22 Also, two of the

workers with elevated COHb concentrations were

light smokers who had one or two cigarettes during

the shift. 

There are few options for reducing exposure to

chainsaw exhaust. Studies have found no difference

in emissions between differing brands of saws, and

worn-out chainsaws do not emit higher levels of

contaminants than new saws.24 There have been no

recent technical improvements to reduce exhaust

emissions in 2-stroke engines which are particularly

troublesome because up to 30% of their fuel is

unburned and emitted as part of the exhaust.25 A

leaner fuel-air mixture can reduce emissions of CO

and most hydrocarbons, however, this increases the

emission of aldehydes.24 Previous studies of

exposure to chainsaw emissions among logging

workers have produced the following

recommendations: (1) reduce the amount of chainsaw

use during the work shift, (2) avoid working during

conditions of low wind speed,24,25 and (3) avoid

working in deep snow or in thick timber stands.24

Only the first of these recommendations appears to be

a feasible option at TNWR. Avoiding work on days

with light wind could greatly reduce the number of

tree-cutting opportunities, considering that treecutting is also avoided for safety reasons on days

when wind velocities exceeds 15 mph. Deep snow is

rarely a problem at TNWR and avoiding thick timber
Health Hazard Evaluation Report No. 99-0173-2856 Page 7

1. ACGIH [2001]. Documentation of threshold

limit values and biological exposure indices for

chemical substances and physical agents.

stands is not an option because that is the primary

purpose for cutting trees at TNWR.

The increased rest breaks that were recommended

during the initial survey could have helped reduce

full-shift exposure to chainsaw exhaust in addition to

relieving some of the musculoskeletal symptoms.

However, the additional breaks were discontinued

after the first NIOSH visit because most of the

foresters did not like them. They reported that each

time they rested for more than a few minutes their

muscles became stiff, and two additional rest breaks

just meant two more times they had to get “limbered

up” and get moving again. This seemed to make the

work day last longer. A better option that could have

a dual effect on reducing exposure would be to

sharpen saws more frequently. Sharper saws cut

through trees faster and shorten the duration of peak

exposures, especially when cutting larger trees. Also,

each 10 minutes taken to sharpen the saws reduces

overall chainsaw use during the shift while improving

the forester’s efficiency.

It should be noted that exposure to hydrocarbons and

aldehydes were measured during the cutting of

smaller trees and stronger wind conditions. Exposure

to these compounds would be higher during more

adverse conditions, such as those that occurred during

the first NIOSH visit. Assuming no change in the

chainsaw fuel-air mixture, exposure to these

contaminants directly correlate with exposure to CO.

Therefore, exposure to hydrocarbons and aldehydes

could be up to 60 % higher when cutting larger trees

during light wind conditions.

 

It is interesting to note the difference in health effects

reported by European studies of loggers exposed to

chainsaw exhaust. Headache, fatigue, cough, and

irritation of the eyes, nose, and throat were the

primary symptoms reported by loggers.24,26 Minor

pulmonary function changes were also detected.26

The level of full-shift TWA exposure to potential

irritants, such as formaldehyde and total

hydrocarbons were similar to the levels that likely

occur at TNWR during adverse conditions.

However, foresters at TNWR did not report any

irritative symptoms. Full-shift exposure to

formaldehyde among both occupations was below

0.1 ppm, which usually is not high enough to cause

irritative symptoms. The major difference between

the work done by TNWR foresters and loggers is

probably the size of the trees being felled. Cutting

larger trees likely results in higher short term

exposure to aldehydes and other irritants. 

CONCLUSIONS

Environmental monitoring indicated that TNWR

foresters were exposed to increased health and safety

risks due to overexposure to CO, according to the

most protective evaluation criteria. Reducing the

potential CO hazard would also reduce the possible

health risks posed by exposure to several confirmed

and suspected occupational carcinogens found in

chainsaw emissions. 

RECOMMENDATIONS

1. Foresters should reduce daily exposure to

chainsaw exhaust by replacing some of the time spent

on chainsaw work with other duties during the shift.

This could also help reduce musculoskeletal

problems.

2. Saws should be kept as sharp as possible, and

should be operated, adjusted, and maintained

according to the manufacturer’s instructions.

3. Ensure that new employees are thoroughly

trained in proper felling techniques and safe work

practices.

4. Foresters at TNWR are also wildland firefighters

who take care to maintain top physical condition.

However, during tree-cutting they should avoid

excessive muscle fatigue which may increase the

possibility of accidents and musculoskeletal

problems. 

5. Follow safety procedures applicable to the felling

of larger trees in accordance with OSHA 29 CFR

1910.266,27 such as: (a) The distance between

adjacent occupied work areas must be at least two

tree lengths of the trees being felled. (b) If a tree is

lodged against another tree, remove it before any

further work begins in the area by using mechanical

means or other techniques that minimize worker

exposure. (c) When cutting a spring pole or other tree

under stress, permit no one but the feller to be closer

than two tree lengths when the stress is released. 

REFERENCES
Page 8 Health Hazard Evaluation Report No. 99-0173-2856

Cincinnati, OH: American Conference of

Governmental Industrial Hygienists. 

2. NIOSH [1994]. NIOSH manual of analytical

methods. 4th ed. Cincinnati, OH. DHHS (NIOSH)

Publication No. 94-113.

3. NIOSH [1992]. Recommendations for

occupational safety and health: compendium of

policy documents and statements. Cincinnati, OH:

U.S. Department of Health and Human Services,

Public Health Service, Centers for Disease Control

and Prevention, National Institute for Occupational

Safety and Health, DHHS (NIOSH) Publication

No. 92-100.

4. ACGIH [2001]. 2001 TLVs® and BEIs®:

threshold limit values for chemical substances and

physical agents. Cincinnati, OH: American

Conference of Governmental Industrial Hygienists.

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

Federal regulations. Washington, DC: U.S.

Government Printing Office, Office of the Federal

Register.

6. NIOSH [1972]. Criteria for a recommended

standard: occupational exposure to carbon

monoxide. Cincinnati, OH: U.S. Department of

Health, Education, and Welfare, Health Services

and Mental Health Administration, National

Institute for Occupational Safety and Health,

DHEW (NIOSH) Publication No. 73-11000.

7. CDC [1988]. NIOSH recommendations for

occupational safety and health standards 1988.

Atlanta, GA: U.S. Department of Health and

Human Services, Public Health Service, Centers

for Disease Control; National Institute for

Occupational Safety and Health. MMWR 37

(supp. S-7).

8. NRC [1985]. Emergency and continuous

exposure guidance levels for selected

contaminants. Washington, DC: National

Research Council. National Academy Press.

9. ENVIRON Corporation [1990]. Summary

report on individual and population exposures to

gasoline. Arlington, VA: ENVIRON Corporation.

November 28.

10. NIOSH [1992]. Health hazard evaluation

report: American Petroleum Institute, Washington,

D.C. Cincinnati, OH: U.S. Department of Health

and Human Services, Public Health Service,

Centers for Disease Control and

Prevention, National Institute for Occupational

Safety and Health, NIOSH Report No. 88-304-

2326.

11. NIOSH [1974]. Criteria for a recommended

standard: occupational exposure to benzene.

Cincinnati, OH: U.S. Department of Health,

Education, and Welfare, Public Health Service,

Center for Disease Control, National Institute for

Occupational Safety and Health, DHEW (NIOSH)

Publication No. 74-137.

12. Proctor NH, Hughes JP, Fischman ML [1988].

Chemical hazards of the workplace. Philadelphia,

PA: J.B. Lippincott Company.

13. WHO [1989]. IARC monographs on the

evaluation of carcinogenic risks to humans:

occupational exposures to the petroleum refining;

crude oil and major petroleum fuels. World Health

Organization 45: 159-201. 1-8 March 1988.

14. NTP [1991]. Sixth annual report on

carcinogens: 1991 summary. Research Triangle

Park, NC: U.S. Department of Health and Human

Services, National Toxicology Program.

15. Harrison's Principles of Internal Medicine

[1980]. Ninth Edition. New York, NY: McGrawHill Book Company, pp 255-262.

16. NIOSH [1978]. Criteria for a recommended

standard: occupational exposure to coal-tar

products. Cincinnati, OH: U.S. Department of

Health, Education, and Welfare, Public Health

Service, Center for Disease Control, National

Institute for Occupational Safety and Health,

DHEW (NIOSH) Publication No. 78-107.

17. Herwin RL, Effect EA [1976]. Health Hazard

Evaluation Report No. 75-194-324. Cincinnati,

OH: U.S. Department of Health, Education, and

Welfare, Public Health Service, Center for Disease
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Control, National Institute for Occupational Safety

and Health.

18. Gorman RW, Liss GM [1981]. Health Hazard

Evaluation Report No. 80-206-1164. Cincinnati,

OH: U.S. Department of Health and Human

Services, Public Health Service, Centers for

Disease Control, National Institute for

Occupational Safety and Health.

19. NIOSH [1977]. Criteria for a recommended

standard: occupational exposure to formaldehyde.

Cincinnati, OH: U.S. Department of Health,

Education, and Welfare, Public Health Service,

Center for Disease Control, National Institute for

Occupational Safety and Health, DHEW (NIOSH)

Publication No. 77-126.

20. Stayner L, Smith AB, Reeve G, Blade L,

Keenlyside R, Halperin W [1985]. Proportionate

mortality study of workers exposed to

formaldehyde. Am J Ind Med 7:229-40.

21. OSHA [1992]. Occupational exposures to

formaldehyde: final rule. Occupational Safety

and Health Administration, Washington, DC:

Federal Register 57(102)22289-22328. U.S.

Government Printing Office.

22. Coburn RF, Forster RE, Kane PB [1965].

Considerations of the physiological variables that

determine the blood carboxyhemoglobin

concentration in man. J. Clin. Invest. 44(1):1899-

1910.

23. Stewart RD, Baretta ED, Platte LR, [1974].

Carboxyhemoglobin levels in American blood

donors. JAMA 229(9):1187-1195.

24. Nilsson CA, Lindahl R, Norstrom A [1987].

Occupational exposure to chainsaw exhausts in

logging operations. AIHAJ 48(2):99-105.

25. Bunger J, Bombosch F, Mesecke U, Hallier E

[1997]. Monitoring and analysis of occupational

exposure to chainsaw exhausts. AIHAJ 58:747-

751.

26. Hagberg M, Kolmodin-Hedman B, Lindahl R,

Nilsson CA, Norstrom A [1985]. Irritative

complaints, carboxyhemoglobin increase and

minor ventilatory function changes due to

exposure to chain-saw exhaust. Eur. J. Respir. Dis.

66:240-247.

27. CFR [1997] 29 CFR 1910.266. Code of

Federal regulations. Washington, DC: U.S.

Government Printing Office, Office of the Federal

Register.
Page 10 Health Hazard Evaluation Report No. 99-0173-2856

Figure 1

Typical Full-Shift CO Exposure During Tree Thinning

Turnbull National Wildlife Refuge

HETA 99-0173

 CO

(ppm)

Time of

Day
Health Hazard Evaluation Report No. 99-0173-2856 Page 11

Table 1

Exposure to CO (ppm) and Estimated COHb Concentrations (%)

Turrnbull National Wildlife Refuge

HETA 99-0173

Job Sample

Duration (min.)

Full-Shift TWA

CO Exposure

Maximum 15-

minute TWA

Maximum Peak Pre-Shift 

COHb 

Mid-Shif

COHb 

April 27, 1999

Forester 1 465 8 40 150 - 4.9 Forester 2 465 19 69 200 - 2.5 Forester 3 470 31 170 590 - 3.1 Forester 4 470 8 52 260 - 0.7 

Forester 5 465 26 110 760 - 1.3 

Forester 6 470 27 150 710 - 1.3 Forester 7 470 13 72 290 - 2.5 Forester 8 470 27 170 1100 - 2.5 

April 28, 1999

Forester 1 480 10 45 340 1.9 2.5 Forester 2 465 15 49 340 2.5 3.9 Forester 3 465 26 110 490 2.3 1.9 Forester 4 480 19 90 770 0.1 0.5 Forester 5 470 14 45 290 0.5 1.1 Forester 6 490 31 92 550 0.7 1.7 Forester 7 500 11 55 440 1.1 1.7 

Evaluation Criteria 25 200 3.5 
Page 12 Health Hazard Evaluation Report No. 99-0173-2856

Table 2

Exposure to CO (ppm) and Estimated COHb Concentrations (%)

Turnbull National Wildlife Refuge

HETA 99-0173

Job Sample

Duration (min.)

Full-Shift TWA

CO Exposure

Maximum 15-

minute TWA

Maximum Peak Pre-Shift 

COHb

Mid-Shif

COHb

May 2, 2000

 Forester 1* 350 5 0 90 1.1 1.9 

Forester 2 350 7 1 110 0.1 1.3 

 Forester 3** 355 11 3 200 1.7 2.1 

Forester 4 355 13 2 520 0.9 0.9 

 Forester 5** 360 9 4 220 1.5 3.7 

Forester 6 360 23 0 - 0.5 1.9 

May 3, 2000

Forester 1 320 14 4 300 3.5 0.9 Forester 2 340 16 3 530 0.9 1.9 

 Forester 3** 345 8 0 210 1.9 2.3 

Forester 4 245 8 4 330 0.7 0.9 

 Forester 5** 315 10 9 220 2.1 0.9 

Forester 6 340 12 2 170 1.7 1.1 

Evaluation Criteria 25 200 3.5 

* Forester # matches those in Tables 3 and 4.** light smokers (2-3 cigarettes per day)
Health Hazard Evaluation Report No. 99-0173-2856 Page 13

Table 3

Exposure to Airborne Aldehydes and Other Hydrocarbons

Turnbull National Wildlife Refuge

HETA 99-0173

Job Sample Duration

(min.)

Total

Hydrocarbons

(mg/m3

)

Benzene (ppm) Formaldehyde

(ppm)

Acetaldehyde

(ppm)

May 2, 2000

 Forester 1* 350 3.8 0.03 - - 

Forester 2 350 5.8 0.03 - - Forester 3 355 7.9 0.05 0.015 0.008 Forester 4 355 11 0.07 0.013 0.007 Forester 5 360 17 0.1 0.015 0.009 Forester 6 360 5.7 0.03 - - 

May 3, 2000

Forester 1 320 4.4 0.03 - - Forester 2 340 8.2 0.06 - - Forester 3 345 8.9 0.06 0.014 0.008 Forester 4 245 5.8 0.04 0.022 0.01 Forester 5 315 10 0.05 - - Forester 6 340 9.4 0.07 0.029 0.02 

Evaluation Criteria 350 0.1 0.016 LFL 

C Forester # matches those in Tables 2 and 4.

** ND = below the sampling and analytical limit of detection (approx. 0.0002 ppm)
Page 14 Health Hazard Evaluation Report No. 99-0173-2856

Table 4

Exposure to Airborne PNAs (

μg/m3

)

Turnbull National Wildlife Refuge (HETA 99-0173)

Job

 Sample Duration (min)

Naphthalene

Acenaphthylene

Acenaphthene

Fluorene

Phenanthrene

Anthracene

Fluoranthene

Pyrene

Benzo(a)anthracene

Chrysene

Benzo(b)fluoranthene

Benzo(k)fluoranthene

Benzo(a)pyrene

Indeno(1,2,3-cd)pyrene

May 2, 2000

For 1* 350 11 ND** 12 0.53 0.19 (.06)

+ (.56) (0.1) ND ND ND ND ND ND 

For 2 350 12 ND 10 0.40 ND (.06) (.42) (0.2) ND ND ND ND ND ND For 6 360 11 4.2 17 0.54 ND (.07) 0.76 0.12 (.04) ND ND ND ND ND 

 May 3, 2000

For 1 320 7.5 ND 7.7 0.44 0.30 (.03) ND (.06) ND ND ND ND ND ND For 2 340 6.9 ND 8.2 0.32 ND (.04) ND (.06) ND ND ND ND ND ND For 5 315 6.3 ND 7.8 0.30 ND (.05) (0.5) ND ND (.06) ND ND ND ND 

* Forester # matches those in Tables 2 and 3.** ND = below the sampling and analytical limit of detection+ = Values in parenthesis are above the limit of detection but below the limit of quantitation
For Information on Other

Occupational Safety and Health Concerns

Call NIOSH at:

1–800–35–NIOSH (356–4674)

or visit the NIOSH Web site at:

www.cdc.gov/niosh

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