TM

NIOSH HEALTH HAZARD EVALUATION REPORT 

HETA #2002-0393-2928 

Lake Havasu Municipal Employees 

Lake Havasu City, Arizona 

February 2004 

DEPARTMENT OF HEALTH AND HUMAN SERVICES 

Centers for Disease Control and Prevention 

National Institute for Occupational Safety and Health

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

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

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

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

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

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

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

PREFACE

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

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

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

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

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

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

potentially toxic effects in such concentrations as used or found. 

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

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

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

endorsement by NIOSH. 

ACKNOWLEDGMENTS AND AVAILABILITY OF REPORT

This report was prepared by Robert E. McCleery, MSPH; Loren Tapp, MD, MS; and Jane McCammon, 

MS, CIH, of HETAB; and Kevin L. Dunn of Industrywide Studies Branch (IWSB), Division of 

Surveillance, Hazard Evaluations and Field Studies (DSHEFS). Analytical support was provided by 

Ardith Grote, Division of Applied Research and Technology (DART); and Data Chem Laboratories, Salt 

Lake City, Utah. Desktop publishing was performed by Robin Smith. Review and preparation for printing 

were performed by Penny Arthur. 

Copies of this report have been sent to employee and management representatives at Lake Havasu City 

(LHC) and the OSHA Regional Office. This report is not copyrighted and may be freely reproduced. The 

report may be viewed and printed from the following internet address: 

www.cdc.gov/niosh/hhe/hhesearch.html. 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

Evaluation of Carbon Monoxide Exposures in the Bridgewater Channel in 

Lake Havasu, Arizona

In August 2002, NIOSH received a health hazard evaluation request for assistance in evaluating carbon 

monoxide (CO) exposures in the Bridgewater Channel (BC) in Lake Havasu, Arizona. The request expressed 

concern about police and fire department personnel who patrol the BC on holiday weekends and their exposures to 

CO. In response to this request, NIOSH conducted an initial evaluation in August 2002 and a follow-up evaluation 

in May 2003.

What NIOSH Did

# We evaluated Lake Havasu City (LHC) employee 

exposures by measuring CO in air and in exhaled 

breath. 

# We measured area concentrations of airborne CO, 

formaldehyde, acrolein, and VOCs (volatile 

organic compounds). 

# We surveyed LHC employees about job duties, 

work locations, and possible CO-related 

symptoms. 

What NIOSH Found

# We found that over half of LHC employees 

working in the BC were overexposed to CO during 

the 2003 Memorial Day weekend. 

# More than half of all LHC employees reported 

post-shift symptoms on days with highest CO 

exposures. 

# Airborne formaldehyde in two of four samples 

collected at the back of boats was below irritant 

levels, but above the NIOSH recommended 

exposure limit. Acrolein in air was not detectable. 

Highlights of HHE Report 

What LHC Managers Can Do

# Determine actions to reduce overall CO 

concentrations in the BC area during high boattraffic days. 

# Develop an LHC employee exposure monitoring 

program to determine patterns of employee 

overexposure. 

# Until CO concentrations are reduced within the 

BC, reduce the number of hours LHC employees 

are exposed to high CO concentrations by rotating 

assignment locations. 

# Assure the effectiveness of control measures 

through continued LHC employee exposure 

monitoring. 

What LHC Employees Can Do

# Report symptoms of CO poisoning to designated 

health and safety personnel. 

# Stay as far away from the CO source as possible. 

# Deactivate engines whenever possible. 

# Ask visitors to deactivate their boat engines when 

you pull alongside them for your work. 

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 #2002-0393-2928
iv 

 Highlights of the HHE Report 

Health Hazard Evaluation Report 2002-0393-2928 

Lake Havasu Municipal Employees 

Lake Havasu City, Arizona 

February 2004 

Robert E. McCleery, MSPH 

Loren Tapp, MD, MS 

Jane McCammon, MS, CIH 

Kevin L. Dunn 

SUMMARY

In August 2002, the National Institute for Occupational Safety and Health (NIOSH) was asked for 

assistance in evaluating carbon monoxide (CO) at the Bridgewater Channel (BC) in Lake Havasu 

City (LHC), Arizona. The request, from the Medical Director for Emergency Medical Services at Lake 

Havasu (also a physician at the Havasu Regional Medical Center), expressed concern about police and 

fire department personnel who patrol the BC on holiday weekends, and also about visitors in the BC who 

had been treated for CO poisoning in the Havasu Regional Medical Center Emergency Department (ED). 

These visitors had carboxyhemoglobin (COHb) concentrations greater than 30%, indicating severe 

poisoning. LHC Police officers (POs) and Emergency Medical Service/Firefighter (EMS/Fire) personnel 

patrol the waterway for as much as 10 hours per workshift on holiday weekends, when the boat traffic is 

excessive. In response to this request, subsequently supported by a letter from an LHC spokesperson 

(Chief of the Fire Department), NIOSH investigators conducted an initial investigation in the BC during 

the 2002 Labor Day weekend and a follow-up investigation during the 2003 Memorial Day weekend. 

Real-time CO monitoring was conducted on POs and EMS/Fire personnel with additional general area air 

sampling in and around the BC. Daily pre-shift, mid-shift, and post-shift questionnaires were 

administered in conjunction with exhaled breath CO measurements. Questionnaires included information 

on work duties and location, tobacco use, and potential CO exposure symptoms. 

There were 78 total workshifts where real-time CO monitoring was performed. Of those 78 workshifts, 

54 exceeded the NIOSH ceiling limit of 200 parts per million (ppm), 64 exceeded the American 

Conference of Governmental Industrial Hygienists (ACGIH) excursion limit of 125 ppm, 7 exceeded the 

Occupational Safety and Health (OSHA) Permissible Exposure Limit (PEL) of 50 ppm, 17 exceeded the 

NIOSH Recommended Exposure Limit (REL) of 35 ppm, and 33 exceeded the ACGIH Threshold Limit 

Value (TLV) of 25 ppm. 

Exhaled breath CO analyses and symptom questionnaires were conducted for 81 workshifts. Forty of the 

81 workshifts had cross-shift COHb increases of at least 3.5%. Nonsmoking participants made up 63 of 

the 81 workshifts. Among the 63 nonsmoker workshifts, 42 had a post-shift %COHb at or above the 

ACGIH Biological Exposure Index (BEI) of 3.5%, with some levels approaching 15%. Questionnaire 
v 

responses indicated that the most frequent symptom was headache, followed by fatigue or weakness, 

visual disturbances, and dizziness. 

NIOSH investigators conclude that a health hazard related to CO exposure generated 

from boat exhaust exists for Lake Havasu City municipal employees and visitors of Lake 

Havasu, Arizona. Real-time CO monitoring indicates that Lake Havasu City POs and 

EMS/Fire personnel working in the canal over the 2002 Labor Day weekend and the 

2003 Memorial Day weekend were exposed to CO concentrations approaching and/or 

exceeding relevant evaluation criteria. Exhaled breath CO analyses over the 

2003 Memorial Day weekend revealed estimated %COHb levels above established 

occupational biological exposure criteria. These elevated %COHb levels indicate 

employee overexposure to CO and a potential for adverse health effects. Suggested 

improvements for Lake Havasu municipal employees are presented in the 

Recommendations section of this report. 

Keywords: SIC 9221 (Police Protection), carbon monoxide, CO, carboxyhemoglobin, COHb, police, 

emergency medical services, firefighter, EMS/Fire, boats, exhaust 
Table of Contents 

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

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

Highlights of HHE Report.........................................................................................................................iii

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

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

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

Methods........................................................................................................................................................3

Logistics ...................................................................................................................................................3

Industrial Hygiene ..................................................................................................................................3

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

Formaldehyde......................................................................................................................................3

Acrolein................................................................................................................................................3

Volatile Organic Compounds.............................................................................................................3

Medical.....................................................................................................................................................4

Evaluation Criteria .....................................................................................................................................4

Carbon Monoxide ...................................................................................................................................5

Occupational Exposure Criteria........................................................................................................5

Health Criteria Relevant to the General Public...............................................................................6

Formaldehyde..........................................................................................................................................6

Results ..........................................................................................................................................................7

Industrial Hygiene ..................................................................................................................................7

Carbon monoxide................................................................................................................................7

May 23, 2003....................................................................................................................................7

May 24, 2003....................................................................................................................................7

May 25, 2003....................................................................................................................................7

May 26, 2003....................................................................................................................................8

Formaldehyde......................................................................................................................................8

Acrolein................................................................................................................................................8
Volatile Organic Compounds.............................................................................................................8

Medical.....................................................................................................................................................8

Exhaled Breath CO Monitoring ........................................................................................................9

Cross-shift Change in %COHb .....................................................................................................9

Comparing post-shift %COHb to the BEI ...................................................................................9

Questionnaire ......................................................................................................................................9

Level of post-shift %COHb and nonsmoking employee reporting of symptoms........................10

Discussion ..................................................................................................................................................10

Industrial Hygiene ................................................................................................................................10

Medical...................................................................................................................................................11

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

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

References..................................................................................................................................................12

Tables .........................................................................................................................................................15

Industrial Hygiene ................................................................................................................................15

Medical...................................................................................................................................................24

Figures........................................................................................................................................................26

May 23, 2003..........................................................................................................................................26

May 24, 2003..........................................................................................................................................31

May 25, 2003..........................................................................................................................................38

May 26, 2003..........................................................................................................................................45

Appendices.................................................................................................................................................50

Appendix A. 2002 Labor Day Weekend Interim Report...................................................................50

Appendix B. AZ Department of Health Services CO Study .............................................................60

Appendix C. Volatile Organic Compounds ........................................................................................68

Health Hazard Evaluation Report No. 2002-0393-2928 Page 1 

INTRODUCTION

In August 2002, the National Institute for 

Occupational Safety and Health (NIOSH) was 

asked for assistance in evaluating carbon 

monoxide (CO) at the Bridgewater Channel 

(BC) in Lake Havasu City (LHC), Arizona. The 

request, from the Medical Director for 

Emergency Medical Services at Lake Havasu 

(also a physician at the Havasu Regional 

Medical Center), expressed concern about police 

and fire department personnel who patrol the BC 

on holiday weekends, and also about visitors in 

the BC who had been treated for CO poisoning 

in the Havasu Regional Medical Center 

Emergency Department (ED). These visitors 

had carboxyhemoglobin (COHb) concentrations 

greater than 30%, indicating severe poisoning. 

LHC Police officers (POs) and Emergency 

Medical Service/Firefighter (EMS/Fire) 

personnel patrol the waterway for as much as 

10 hours per workshift on holiday weekends 

when the boat traffic is excessive. 

In response to this request, which was 

subsequently supported by a letter from a LHC 

spokesperson (Chief of the Fire Department), 

NIOSH investigators conducted an initial 

investigation in the BC during the 2002 Labor 

Day weekend (August 31 and September 1, 

2002) and a follow-up investigation during the 

2003 Memorial Day weekend (May 23-26, 

2003). 

The initial investigation included preliminary 

CO exposure assessments to determine the 

necessary scope of a more comprehensive 

evaluation. The follow-up investigation included 

(1) full workshift CO exposure monitoring of 

LHC municipal employees working in the BC, 

and (2) measuring CO in exhaled breath and 

conducting symptom questionnaires with LHC 

municipal employees in cooperation with 

Mohave County Department of Public 

Health (MCDPH) personnel. This report 

summarizes the NIOSH evaluations and 

provides recommendations for improving the 

occupational health of LHC municipal 

employees. 

BACKGROUND

LHC, Arizona, borders the Colorado River and 

is located south of Lake Mead and Las Vegas, 

Nevada. The name “Havasu” came from a 

Mojave Indian and means “blue water”.1

 Lake 

Havasu is a 45-mile long body of water created 

by Parker Dam.2

 The city is most famous for the 

London Bridge, which crosses the BC. The LHC 

area has extensive outdoor activities for tourists, 

many of which revolve around the lake itself. 

Lake Havasu and the BC are popular weekend 

destinations. For this reason, NIOSH and 

hospital ED staff gathered preliminary rangefinding data regarding airborne CO 

concentrations in the BC on August 31st and 

September 1st of the 2002 Labor Day weekend 

to determine if there was need for a more 

extensive evaluation. Results of this preliminary 

effort are included as Appendix A. In addition, 

hospital ED staff measured CO in exhaled breath 

of symptomatic people reporting to the ED on 

these days. 

The data collected during the 2002 Labor Day 

weekend indicated that employees and 

vacationers spending lengthy periods within the 

BC during days of high traffic may be 

experiencing CO poisoning. This was based 

upon the following: 

1. Two BC visitors reporting to the hospital 

ED during the second day of air sampling had 

lost consciousness in the water, and both were 

non-smokers and had elevated COHb 

measurements (9.4% and 28.3%). The latter 

patient had received oxygen therapy for 

approximately 30 minutes prior to the 

measurement of COHb level, and thus the 

COHb at the time consciousness was lost would 

have been even higher. If the hospital the patient 

was treated at had not been conducting exhaled 

CO measurements as part of this research, this 

patient’s loss of consciousness may well have 

been attributed to other factors, such as heat 

stress, dehydration, or alcohol consumption. 

2. Four of twelve (33%) patients tested by ED 

staff after boating activities had estimated COHb 
Page 2 Health Hazard Evaluation Report No. 2002-0393-2928 

concentrations that substantially exceeded 

guidelines of 2.5% (World Health Organization 

[WHO]) or 2.1% (Environmental Protection 

Agency [EPA]).3,4 These four patients had 

COHb concentrations 4 to 11 times these 

criteria, and two were transported to the hospital 

after being pulled unconscious from the water. 

All patients tested were non-smokers. 

3. Spot checks of CO concentrations near 

vacationers on and near moored boats in the BC 

were in excess of every recognized short-term 

exposure limit. 

4. Average CO concentrations measured for 

20-40 minute periods ranged from 77 to 

131 parts per million (ppm), and indicated that 

employees who spend lengthy periods patrolling 

the BC or responding to incidents may be 

overexposed to CO. 

These data, in combination with information 

subsequently obtained regarding BC visitor COassociated poisonings (two drownings and four 

cases of lost consciousness in 2001-2002), 

indicated the need for more complete 

characterization. 

Recommendations in the NIOSH report from the 

2002 Labor Day study included the following: 

1. Conduct full workshift CO exposure 

monitoring for LHC municipal employees 

working in the BC to determine if they are 

overexposed to CO during high traffic days, and 

measure pre- and post-shift exhaled CO 

accompanied by employee surveys to 

determine if they experience symptoms of CO 

overexposure during their duties within the BC. 

2. Collect further data related to visitor CO 

exposures within the BC area, to possibly 

include measurement of CO in exhaled breath of 

visitors and/or placement of stationary CO air 

sampling monitors at fixed locations among the 

moored boats where visitors linger during high 

traffic days. 

3. Measure COHb concentrations among ED 

patients who have been boating in the BC during 

high traffic days. 

4. Develop a more comprehensive research and 

intervention program related to the issue of boatrelated CO exposures. 

The following actions addressed the 

recommendations contained in the 2002 Labor 

Day report. 

1. LHC hired a contractor to place stationary 

CO air sampling monitors and gather additional 

environmental data in and near the BC through 

the summer of 2003. The contractor conducted 

further characterization of CO concentrations 

and meteorologic conditions within the BC 

through placement of stationary and mobile air 

sampling equipment prior to the 2003 Memorial 

Day weekend. 

2. At the request of the MCDPH, the Arizona 

Department of Health Services conducted 

exhaled CO measurements among visitors to 

the BC during the 2003 Memorial Day weekend 

(May 25-26). Appendix B presents the results of 

these measurements. 

3. NIOSH provided two exhaled breath CO 

monitors for use by hospital ED staff during the 

2003 Memorial Day weekend. Hospital staff 

used these monitors to measure CO in exhaled 

breath of ED patients who had been in the BC 

when they experienced symptoms. 

4. NIOSH assisted LHC and Mohave County 

in obtaining educational brochures which 

were distributed by the City during the 

2003 Memorial Day weekend. LHC also 

developed and distributed other educational 

materials warning visitors and employees about 

the dangers of exposure to CO in boat engine 

exhaust. 

5. LHC responded to the intervention portion 

of recommendation #4 by developing warning 

signs to be posted at the BC entry. 
Health Hazard Evaluation Report No. 2002-0393-2928 Page 3 

METHODS

Logistics 

LHC municipal employees who were scheduled 

to work in the BC area during the 

2003 Memorial Day weekend were asked to 

participate in the NIOSH study. Special unit POs 

were assigned to work one of the following 

locations: the East or West bank booking station, 

the East or West bank police patrol (on either 

electric-powered or gas-powered golf carts, or 

gas-powered quads), or on the police boats that 

patrolled the BC. EMS/Fire personnel were 

assigned to work one of the following locations: 

the East or West bank (each bank had an 

EMS/Fire station with electric golf carts) or on 

one of the fire boats that would respond to 

emergencies on Lake Havasu, including the BC 

area. Each morning of the four day study, LHC 

employees received their CO monitor and 

provided exhaled breath for the pre-shift 

%COHb reading. Every 3-4 hours throughout 

the day (a “session” in Tables 1-4), if available, 

LHC employees went to East or West bank 

locations where NIOSH and MCDPH personnel 

were stationed for a midshift %COHb reading. 

After their workshift, LHC employees went to 

the NIOSH/MCDPH stations to drop off their 

CO monitors and provide their post-shift 

%COHb reading. In addition to the personal air 

samples collected for CO, general area (GA) air 

samples for formaldehyde, acrolein, and volatile 

organic compounds (VOCs) were collected in 

the BC area because these substances are known 

components of vehicle exhaust due to 

incomplete combustion.5

Industrial Hygiene 

Carbon Monoxide 

CO concentrations were measured on LHC 

municipal employees (POs and EMS/Fire 

personnel) and at GA work locations using 

ToxiUltra Atmospheric Monitors (Biometrics, 

Inc.) with CO sensors. All ToxiUltra CO 

monitors were zeroed and calibrated before each 

use according to the manufacturer’s 

recommendations. These monitors are directreading instruments with data logging 

capabilities. The instruments were operated in 

the passive diffusion mode, with a one-minute 

sampling interval. The instruments have a 

nominal range from 0 to 500 ppm with the 

highest instantaneous reading of 1000 ppm. 

Formaldehyde 

Four GA air samples were collected for 

formaldehyde. Samples were collected on silica 

gel sorbent tubes (containing a cartridge coated 

with 2,4-dinitrophenylhydrazine), at a calibrated 

flow rate of 0.2 liters per minute (lpm). The 

tubes were analyzed by high pressure liquid 

chromatography (HPLC) according to NIOSH 

Method 2016.6

 The analytical limit of 

detection (LOD) was 0.1 micrograms per 

sample (μg/sample), which is equivalent to a 

minimum detectable concentration (MDC) of 

0.0007 ppm, assuming a sample volume of 

118 liters. The limit of quantitation (LOQ) was 

0.4 μg/sample, which is equivalent to a 

minimum quantifiable concentration (MQC) of 

0.0028 ppm, assuming a sample volume of 

118 liters. 

Acrolein 

Four GA air samples were collected for acrolein. 

Samples were collected on sorbent tubes 

(10% 2-(hydroxymethyl)piperidine on XAD-2, 

120 milligrams (mg)/60 mg), at a calibrated flow 

rate of 0.05 lpm. The tubes were analyzed by 

gas chromatography (GC) according to NIOSH 

Method 2539.6

 The analytical LOD was 

0.7 μg/sample, which is equivalent to a MDC of 

0.01 ppm, assuming a sample volume of 

30 liters. The LOQ was 2.0 μg/sample, which is 

equivalent to a MQC of 0.03 ppm, assuming a 

sample volume of 30 liters. 

Volatile Organic Compounds 

Eight thermal desorption tube area air samples 

were collected for qualitative analysis of VOCs 

in accordance with NIOSH Method 2549.6

Samples were collected on three beds of sorbent 

material enclosed in a stainless steel tube using 

personal sampling pumps at a calibrated flow 

rate of 0.05 lpm. The thermal desorption tubes 

were purged with helium to remove any water 
Page 4 Health Hazard Evaluation Report No. 2002-0393-2928 

and then analyzed using gas chromatography/ 

mass spectrometry (GC/MS). 

Medical 

LHC POs and EMS/Fire personnel, who worked 

in the BC area during the 2003 Memorial Day 

weekend, were included in the evaluation. Daily 

pre-shift, mid-shift, and post-shift questionnaires 

were conducted in conjunction with exhaled 

breath CO measurements on May 23-26, 2003. 

Questionnaires included information on work 

duties and location, tobacco use, and CO 

exposure symptoms. Mid-shift questionnaires 

and exhaled breath CO measurements were 

performed at varying times (typically at 3-

4 hours and 6-7 hours) during the shift. 

The breath analysis for CO was performed by 

using a Breath Analyzer Module which attaches 

to the top of a Toxi-Ultra monitor. Participants 

were asked to inhale, then exhale completely, 

and then inhale deeply and hold their breath 

for 20 seconds. At the end of 20 seconds the 

individual exhaled a small amount of air into the 

atmosphere, then blew the remainder of their 

exhalation into a balloon. The one-way valve on 

the Module forced the participant’s exhaled air 

from the balloon through the CO monitor, which 

read the CO concentration of the breath in 

ppm. This concentration was converted from 

ppm into an estimate of the %COHb level in 

the body using the following formula from 

the American Conference of Governmental 

Industrial Hygienists (ACGIH):7

%COHb = (CO [in ppm]/5) - 0.5 

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 

pre-existing medical condition, and/or 

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, which 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),8

 (2) ACGIH® Threshold Limit Values 

(TLVs®),9

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

Occupational Safety and Health Administration 

(OSHA) Permissible Exposure Limits (PELs).10

Employers are encouraged to follow the OSHA 

limits, the NIOSH RELs, the ACGIH TLVs, or 

whichever is 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 
Health Hazard Evaluation Report No. 2002-0393-2928 Page 5 

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 

CO is a colorless, odorless, tasteless gas 

produced by incomplete burning of carboncontaining materials such as gasoline or propane 

fuel. The initial symptoms of CO poisoning may 

include headache, dizziness, drowsiness, or 

nausea. Symptoms may advance to vomiting, 

loss of consciousness, and collapse if prolonged 

or high exposures are encountered. If the 

exposure level is high, loss of consciousness 

may occur without other symptoms. Coma or 

death may occur if high exposures 

continue.7,11,12,13,14,15 The display of symptoms 

varies widely from individual to individual, and 

may occur sooner in susceptible individuals such 

as young or aged people, people with preexisting 

lung or heart disease, or those living at high 

altitudes. 

Exposure to CO limits the ability of the blood to 

carry oxygen to the tissues by binding with the 

hemoglobin to form COHb. Once exposed, the 

body compensates for the reduced bloodborne 

oxygen by increasing cardiac output, thereby 

increasing blood flow to specific oxygendemanding organs such as the brain and heart. 

This ability may be limited by preexisting heart 

or lung diseases that inhibit increased cardiac 

output. 

Blood has an estimated 210-250 times greater 

affinity for CO than oxygen, thus the presence of 

CO in the blood can interfere with oxygen 

uptake and delivery to the body. Once absorbed 

into the bloodstream, the half-time of CO 

disappearance from blood (referred to as the 

“half-life”) varies widely by individual and 

circumstance (i.e., removal from exposure, 

initial COHb concentration, partial pressure of 

oxygen after exposure, etc.). Under normal 

recovery conditions breathing ambient air, the 

half-life can be expected to range from 2 to 6.5 

hours.3

 This means that if the initial COHb level 

were 10%, it could be expected to drop to 5% in 

2 or more hours, and then 2.5% in another 2 or 

more hours. If the exposed person is treated with 

oxygen, as happens in emergency treatment, the 

half-life time is decreased again by as much as 

75% (or to as low as approximately 40 minutes). 

Delivery of oxygen under pressure (hyperbaric 

treatment) reduces the half-life to approximately 

20 minutes. 

Occupational Exposure Criteria 

Occupational criteria for CO exposure are 

applicable to employees who may be at risk of 

CO poisoning. The occupational exposure limits 

noted below should not be used for interpreting 

general population exposures (such as visitors 

engaged in boating activities) because 

occupational standards are intended for healthy 

worker populations. The effects of CO are more 

pronounced in a shorter time if the person is 

physically active, very young, very old, or has 

preexisting health conditions such as lung or 

heart disease. Persons at extremes of age and 

persons with underlying health conditions may 

have marked symptoms and may suffer serious 

complications at lower levels of COHb.16

Standards relevant to the general population take 

these factors into consideration, and are listed 

following the evaluation criteria to aid in 

understanding information presented in the 

discussion section of this report, as well as 

Appendix B. 

The NIOSH REL for CO is 35 ppm for full shift 

TWA exposure, with a ceiling limit of 200 ppm 

which should never be exceeded.8

 The NIOSH 

REL of 35 ppm is designed to protect workers 

from health effects associated with COHb levels 

in excess of 5%.11 NIOSH has established 

the immediately dangerous to life and health 

(IDLH) value for CO as 1,200 ppm.17 An IDLH 

value is defined as a concentration at which an 

immediate or delayed threat to life exists or that 

would interfere with an individual's ability to 

escape unaided from a space. 

The ACGIH recommends an 8-hour TWA TLV 

of 25 ppm based upon limiting shifts in COHb 

levels to less than 3.5%, thus minimizing 

adverse neurobehavioral changes such as 

headache, dizziness, etc., and to maintain 
Page 6 Health Hazard Evaluation Report No. 2002-0393-2928 

cardiovascular exercise capacity.7 ACGIH also 

recommends that exposures never exceed five 

times the TLV (thus, never to exceed 125 ppm).9

ACGIH recommends a Biological Exposure 

Index (BEI) for end of shift exhaled breath 

analysis in nonsmoking workers (exposed to 

CO) of 3.5% COHb (or 20 ppm).9

 The BEI 

generally indicates a concentration below which 

nearly all workers should not experience adverse 

health effects. The BEI cannot be applied to 

current smokers since smokers have been shown 

to have %COHb levels between 4% and 10%,7,18

and can exceed 15% in heavy smokers.19

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

TWA exposure.10

Health Criteria Relevant to the 

General Public 

The US EPA has promulgated a National 

Ambient Air Quality Standard (NAAQS) for 

CO. This standard requires that ambient air 

contain no more than 9 ppm CO for an 8-hour 

TWA, and 35 ppm for a one-hour average.4

The NAAQS for CO was established to protect 

“the most sensitive members of the general 

population” by maintaining increases in COHb 

to less than 2.1%. 

The WHO has recommended guideline values 

and periods of TWA exposures related to CO 

exposure in the general population.3

 WHO 

guidelines are intended to ensure that COHb 

levels not exceed 2.5% when a normal subject 

engages in light or moderate exercise. Those 

guidelines are: 100 mg/m3

 (87 ppm) for 

15 minutes, 60 mg/m3

 (52 ppm) for 30 minutes, 

30 mg/m3

 (26 ppm) for 1 hour, and 10 mg/m3

(9 ppm) for 8 hours. 

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.20

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.21

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 2.0 ppm as a STEL.22

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.9

 

ACGIH has set a ceiling limit of 0.3 ppm.9

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 a REL for formaldehyde of 

0.016 ppm for up to a 10-hour TWA exposure 

(again using NIOSH analytical method 3500 

and indicating 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.)23
Health Hazard Evaluation Report No. 2002-0393-2928 Page 7 

RESULTS

Tables 1-4 present the individual daily results 

for those employees who participated in the realtime CO monitoring during the four days of 

sampling over the 2003 Memorial Day weekend. 

The tables also provide the COHb information if 

the individual participated during the four days 

of sampling. Each table provides the location(s) 

and times worked by the employee, the preshift COHb reading and each COHb reading 

thereafter. Each subsequent COHb reading has 

the average and peak CO concentration for 

the time period between COHb readings. 

Additionally, a cumulative average CO 

concentration from the beginning of the 

workshift to each additional COHb reading is 

provided. Figures 1-85 present the graphical 

representations of (1) the real-time CO 

monitoring and (2) the COHb readings if the 

employees participated. 

Industrial Hygiene 

Carbon monoxide 

May 23, 2003 

Fourteen LHC municipal employees wore CO 

monitors during their workshift (Table 1). 

Additionally, three GA CO monitors were used 

in the following locations: one near 

pumpstation #3, which was moved near the 

Westside booking station; one used as a exhaled 

breath monitor, then moved close to the 

Westside booking station; and one at the 

restroom located near pumpstation #3 (along 

with instruments from Sanoma Technologies 

Inc. - picked-up on May 24). 

Eleven of the fourteen employees exceeded 

the NIOSH ceiling limit of 200 ppm at some 

point during the day. All employees had peak 

exposures exceeding the ACGIH excursion limit 

of 125 ppm. The average CO concentration of 

each monitor indicated that there was the 

potential to exceed 8-hour TWA limits. One 

employee’s average readings exceeded and two 

employee’s approached (within 5 ppm) the 

OSHA PEL of 50 ppm. Three employee’s 

average readings exceeded and three employee’s 

approached (within 5 ppm) the NIOSH REL of 

35 ppm. Eight employee’s average readings 

equaled or exceeded and two employee’s 

approached (within 5 ppm) the ACGIH TLV of 

25 ppm. The GA monitor near the Westside 

booking station indicated an average CO 

concentration of 15 ppm with a peak reading 

of 188 ppm. The GA monitor near the Westside 

booking station indicated an average CO 

concentration of 20 ppm with a peak reading of 

197 ppm. The GA monitor at the restroom 

(collected readings until the morning of May 24) 

indicated an average CO concentration of 19 

ppm with a peak reading of 437 ppm. 

May 24, 2003 

Twenty-four LHC municipal employees wore 

CO monitors during their workshift (Table 2). 

Additionally, two GA CO monitors were used 

in the following locations: one on police boat 

#1297 and one near the trailer used by NIOSH 

personnel on the West side. 

All employees exceeded the NIOSH ceiling 

limit of 200 ppm and the ACGIH excursion limit 

of 125 ppm at some point during the day. The 

average CO concentration of each monitor 

indicated that there was the potential to exceed 

8-hour TWA limits. Six employee’s average 

readings exceeded and three employee’s 

approached (within 5 ppm) the OSHA PEL of 

50 ppm. Ten employee’s average readings 

exceeded and two employee’s approached 

(within 5 ppm) the NIOSH REL of 35 ppm. 

Sixteen employee’s average readings exceeded 

and six employee’s approached (within 5 ppm) 

the ACGIH TLV of 25 ppm. The GA monitor 

on the police boat indicated an average CO 

concentration of 180 ppm with a peak reading of 

1179 ppm. The GA monitor near the trailer used 

by NIOSH personnel indicated an average CO 

concentration of 17 ppm with a peak reading of 

116 ppm. 

May 25, 2003 

Twenty-four LHC municipal employees wore 

CO monitors during their workshift (Table 3). 

Additionally, two GA CO monitors were used in 

the following locations: one on police boat 
Page 8 Health Hazard Evaluation Report No. 2002-0393-2928 

#2196 and one near the trailer used by NIOSH 

personnel on the West side. 

Eighteen of the twenty-four employees 

exceeded the NIOSH ceiling limit of 200 ppm 

at some point during the day. Twenty-two of 

the twenty-four employees had peak exposures 

exceeding the ACGIH excursion limit of 

125 ppm. The average CO concentration of each 

monitor indicated that there was the potential to 

exceed 8-hour TWA limits. Three employee’s 

average readings exceeded the OSHA PEL of 

50 ppm. Six employee’s average readings 

exceeded and three employee’s approached 

(within 5 ppm) the NIOSH REL of 35 ppm. 

Eleven employee’s average readings exceeded 

and one employee approached (within 5 ppm) 

the ACGIH TLV of 25 ppm. The GA monitor 

on the police boat indicated an average CO 

concentration of 111 ppm with a peak reading of 

1053 ppm. The GA monitor near the trailer used 

by NIOSH personnel indicated an average CO 

concentration of 12 ppm with a peak reading of 

135 ppm. 

May 26, 2003 

Fifteen LHC municipal employees wore CO 

monitors during their workshift (Table 4). 

Additionally, two GA CO monitors were used 

in the following locations: one by the Eastside 

booking station and one by the Westside 

booking station. All employees’ monitoring 

times were less than 8-hours due in part to 

employees being released for the day from work 

early. 

One of the fifteen employees exceeded the 

NIOSH ceiling limit of 200 ppm at some point 

during the day. Four of fifteen employees had 

peak exposures exceeding the ACGIH excursion 

limit of 125 ppm. No employee’s average 

reading exceeded the OSHA PEL of 50 ppm, the 

NIOSH REL of 35 ppm, or the ACGIH TLV of 

25 ppm. The GA monitor at the Eastside 

booking station indicated an average CO 

concentration of 22 ppm with a peak reading of 

75 ppm. The GA monitor at the Westside 

booking station indicated an average CO 

concentration of 24 ppm with a peak reading of 

137 ppm. 

Formaldehyde 

Four GA air samples for formaldehyde were 

collected and results are presented in Table 5. 

Sample concentrations ranged from 0.004 to 

0.047 ppm. The highest formaldehyde 

concentration (0.047 ppm) was located on the 

backseat of the police boat in the BC on 

May 24, 2003. Calculated GA, 8-hour TWA 

concentrations are intended as representations of 

potential exposure. Two of four formaldehyde 

concentrations were above the NIOSH REL of 

0.016 ppm. 

Acrolein 

All four GA air samples for acrolein were below 

the analytical LOD. 

Volatile Organic Compounds 

Eight thermal tube GA air samples were 

collected and results are presented in Table 6. 

Chromatographs are provided in Appendix C. 

The major peaks detected were various 

aliphatic and aromatic hydrocarbons. Aliphatic 

hydrocarbons included hexane, isooctane, 

butane, pentane, and other alkanes primarily in 

the C4-C9 range. Aromatics included benzene, 

toluene, ethyl benzene, xylenes, and higher alkyl 

benzenes. Other compounds detected included 

methyl tert-butyl ether (MTBE), acetone, 

acetonitrile, naphthalene, methyl naphthalenes, 

methanol, and ethanol. Based on the peak shapes 

of the early eluting compounds, sample A39694 

(from the police boat) appeared to be saturated 

and may have still contained some moisture 

even after the initial helium purge. This sample 

also contained acetonitrile as a major 

component. 

Medical 

Thirty-six of forty available LHC municipal 

employees participated in the exhaled breath 

analysis for CO and questionnaires over the 

2003 Memorial Day weekend (four of the forty 

workers did not complete one full day of testing 

and were excluded from the data analysis). Of 

the 36 employees who participated, 23 were POs 

and 13 were EMS/Fire personnel. These 

participants worked from one to four days 
Health Hazard Evaluation Report No. 2002-0393-2928 Page 9 

during the evaluation period of May 23-26, 

2003. Seven of the thirty-six were smokers; 

three smoked between 11⁄2 to 21⁄2 packs of 

cigarettes per day; four smoked 2 to 5 

cigarettes per day. The average age among the 

36 participants was 34 years (ranging from 25 to 

46). Two reported a history of respiratory 

disorder. There was one female participant. 

Exhaled Breath CO Monitoring 

Exhaled breath CO measurements were analyzed 

in two ways: (1) for the greatest cross-shift 

difference observed for all participating 

employees on each day of testing, and 

(2) comparing the daily post-shift estimated 

%COHb levels with the ACGIH BEI criteria. 

Cross-shift Change in %COHb 

Table 7 presents the change (increase) in 

%COHb levels from pre-shift to post-shift 

(cross-shift difference) by date. For example, if 

the employee’s pre-shift level was 1.0% COHb 

and his/her post-shift level was 8.0%, then the 

level increased by 7% COHb. The cross-shift 

difference was used to minimize the effect of 

smoking and capture the effects of CO exposure 

from the work environment. To date, there are 

no specific cross-shift levels of %COHb that 

have been recommended as criteria or guidelines 

for workplace exposures. We chose to use an 

increase of 3.5% COHb or greater as an 

indication of potential occupational CO overexposure based on the ACGIH BEI 

recommendation for end-of-shift %COHb. 

Among the 18 participating employees on 

May 23, 9 (50%) had a cross-shift increase of 

%COHb at or above 3.5% COHb. Of the 24 

employees participating on May 24, 17 (71%) 

had a cross-shift increase at or above 3.5%. 

Thirteen of the twenty-five (52%) participants 

on May 25 had a cross-shift increase %COHb 

level at or above 3.5%. One of fourteen 

employees participating on May 26 had a crossshift increase in %COHb level at or above 3.5%. 

Looking at the three heaviest boating days, 

May 23, 24, and 25, the average %COHb among 

nonsmoking employees increased from 1% to 

6% between initial testing hours (8-10 a.m.) and 

final testing hours (6-8 p.m.). The average 

%COHb in smoking employees increased from 

3% to 7% between the same testing periods. The 

maximum %COHb level observed among 

nonsmoking employees was 13%; among 

smoking employees, the maximum was 11%. 

Comparing post-shift %COHb to the BEI 

Table 8 presents the post-shift %COHb levels by 

day among the 29 nonsmoking participants in 

relation to the ACGIH BEI. We found that on 

May 23, 24, and 25, more than 60% of these 

employees had post-shift %COHb levels at or 

above the BEI (64%, 100%, and 67%, 

respectively). On May 24 and 25, two (11%) and 

four (19%) nonsmoking participants, 

respectively, had post-shift % COHb levels 

above 10%. On the least crowded day, May 26, 

2 out of 12 nonsmoking workers (17%) had 

levels that were at or above the BEI. 

Questionnaire 

Pre-shift questionnaires included questions 

concerning possible CO exposure symptoms 

ever experienced while working in the BC. 

Twenty-four of thirty-six (67%) reported that 

they had previously experienced at least one 

symptom while working in this area. All 24 

reported experiencing headache; 7 (19%) 

reported fatigue or weakness, 6 (17%) 

drowsiness, 6 (17%) dizziness, 3 (8%) nausea or 

vomiting, and 1 (3%) vision disturbances. 

Table 9 describes the post-shift symptoms 

reported by participants during the 2003 

Memorial Day weekend by date. The most 

frequently reported symptom was headache, 

followed by fatigue or weakness, visual 

disturbances, and dizziness. Of the 17 

employees completing the post-shift symptom 

survey on May 23, 12 (71%) reported having 

one or more symptom at the end of the shift. On 

May 24, 25, and 26, 16 of 24 (67%), 13 of 

25 (52%), and three of 14 (21%), respectively, 

reported having one or more symptom post-shift. 
Page 10 Health Hazard Evaluation Report No. 2002-0393-2928 

Level of post-shift %COHb and 

nonsmoking employee 

reporting of symptoms 

Table 10 shows the number of nonsmoking city 

employees reporting symptoms in relation to 

their post-shift %COHb. As seen in Table 10, 

when summary data are evaluated, reported 

symptoms consistent with excessive exposure to 

CO appeared to increase with increasing 

%COHb. 

DISCUSSION

The integrated multiagency study conducted 

during the 2003 Memorial Day weekend 

combined information related to visitors and 

employees in the BC of Lake Havasu. BC visitor 

poisonings and exhaled CO data (presented in 

Appendix B) collected concurrent with the 

NIOSH data are relevant to the risk of 

poisoning among EMS/Fire responders and law 

enforcement officers who are in the same 

environment. 

The Arizona State Health Department concluded 

that the COHb levels observed among BC 

visitors late in the day demonstrated a public 

health hazard during the 2003 Memorial Day 

weekend. They found that the average %COHb 

among non-smoking BC visitors participating in 

CO breath tests rose dramatically after 4:00 p.m. 

on the days of their study. This finding was 

temporally consistent with data collected among 

those occupationally exposed. 

Three clinically evident CO poisonings 

occurred among BC visitors during the 2003 

Memorial Day weekend - while the various 

aspects of the study reported here (and related 

information dissemination) were underway. 

First, on May 28, a 31-year-old man lost 

consciousness in the BC, drowned, and was 

found to have a COHb of 40.6% by the Medical 

Examiner. Second, on May 29, a 21-year-old 

woman who was transported to the hospital ED 

after losing consciousness in the BC was found 

to have a COHb of 47% measured in blood. 

Finally, her 22-year-old companion was found to 

have a COHb of 19% measured by exhaled CO. 

During the subsequent Labor Day weekend, 

August 2003, a 23-year-old female standing in 

waist deep water behind two idling boats in the 

BC lost consciousness. Her COHb from a blood 

specimen drawn at the site was determined to be 

42.7%. 

Industrial Hygiene 

The real-time CO monitoring over the 

2003 Memorial Day weekend indicated that 

there was potential for POs and EMS/Fire 

personnel to be exposed to elevated CO 

concentrations resulting in an average CO 

concentration during the workshift in excess of 

OSHA, NIOSH, and ACGIH evaluation criteria. 

Overall, there were 78 total workshifts where 

real-time CO monitoring was performed. Of 

those 78 workshifts, 54 exceeded the NIOSH 

ceiling limit of 200 ppm, 64 exceeded the 

ACGIH excursion limit of 125 ppm, 7 exceeded 

the OSHA PEL of 50 ppm, 17 exceeded the 

NIOSH REL of 35 ppm, and 33 exceeded the 

ACGIH TLV of 25 ppm. 

In general, POs and EMS/Fire personnel on 

boats working in the BC had the highest 

exposures to CO; some were exposed to peak 

CO concentrations in excess of 1000 ppm. 

However, all jobs had exposures to elevated CO 

concentrations. It is difficult to say whether the 

elevated CO concentrations were a reflection of 

the job for the day (working at the booking 

station, operating a gas-powered quad, etc.) 

and/or where a PO or EMS/Fire employee was 

located in the BC and what he/she was doing at 

the time. However, it stands to reason that as one 

approaches the area where the CO is being 

generated (the BC), the greater opportunity there 

is to be exposed to higher CO concentrations. It 

was not possible for detailed information to be 

collected about every PO’s or EMS/Fire 

employee’s whereabouts during the day to be 

able to correlate an activity with a particular CO 

concentration. 

Although we did not characterize exhaust 

emissions from the carts or quads, we did find 

that employees on both gas- and electric-
Health Hazard Evaluation Report No. 2002-0393-2928 Page 11 

powered land vehicles experienced elevated 

estimated COHb levels. This fact combined with 

the overall exposure and COHb data indicate 

that the carts and quads themselves had little 

impact on the employees’ exposures. 

NIOSH investigators observing the BC noticed a 

haze above the water beginning in the late 

afternoon, and the real-time CO monitoring 

indicated that the CO concentrations became 

elevated late in the afternoon through the early 

evening. This suggests that as the day 

progresses, the boat exhaust possibly increases 

due to insufficient natural removal (wind), 

temperatures over 100oF, and/or increased boat 

traffic. This information was also in agreement 

with findings of the Arizona State Health 

Department report discussed above. 

Air sampling results (VOC air samples) 

indicated chemicals consistent with what is 

typically found in boat exhaust. Formaldehyde 

air sampling results compared to relevant 

evaluation criteria, revealed concentrations 

above the NIOSH REL in the back of the 

boats in the BC. As stated in the Evaluation 

Criteria section in this report, formaldehyde 

concentrations ranging from 0.12-6.15 mg/m3

(0.1-5 ppm) have resulted in symptoms of 

burning eyes, tearing, and general irritation of 

the upper respiratory tract. Formaldehyde levels 

found during the 2003 Memorial Day weekend 

did not fall within the aforementioned range. 

However, formaldehyde in combination with 

other contaminants found in boat exhaust may 

possibly result in the above listed symptoms. 

Medical 

Results of the employee exhaled breath analyses 

for CO are consistent with the results of the realtime CO monitoring, with %COHb levels rising 

throughout the day to peak at post-shift. The 

majority of non-smoking post-shift breath 

measurements had estimated %COHb levels at 

or above the BEI of 3.5%, representing a 

hazardous occupational exposure to CO. Using a 

more stringent criteria (cross-shift increase in 

%COHb), over half of all cross-shift exhaled 

breath measurements had elevations of COHb 

greater than 3.5%. In general, LHC municipal 

employees working on boats in the BC had the 

highest %COHb levels. Symptom questionnaires 

found that more than half of all employees 

reported post-shift symptoms consistent with 

CO exposure on the three days with the highest 

CO exposures. When summary data are 

evaluated, reported symptoms appeared to 

increase with increasing %COHb. However, due 

to the non-specific nature of these symptoms and 

other factors (including the cross sectional 

nature of our evaluation), conclusions regarding 

CO exposure as the only potential etiology of 

these symptoms cannot be made. The NIOSH 

Criteria for a Recommended Standard: 

Occupational Exposure to Carbon Monoxide

document finds that studies “concerning the 

effect of CO on behaviors ranging from 

vigilance to cognitive function are sufficient to 

suggest possible safety hazards for the worker 

exposed to CO. A review of the above studies 

indicates that a value of 5% COHb should not be 

exceeded if these behavioral effects are to be 

avoided.”11 Elevated COHb levels in employees 

responsible for public safety are an even greater 

concern. 

Based on data from the Arizona Department of 

Health Services, 2003 Memorial Day weekend 

survey, BC visitors had COHb levels twice as 

high as the LHC municipal employees, likely 

due to extended lengths of time on boats or 

wading in the BC. Elevated COHb levels are 

especially dangerous for susceptible individuals 

such as children, pregnant women and their 

fetuses, and persons with cardiovascular or 

respiratory disease. The safety of individuals is 

also compromised when wading or swimming in 

the water near congested boat areas, operating 

watercraft, or recreating in the rear area of boats. 

CONCLUSIONS

• During periods of increased public recreational 

activities in the BC area, LHC municipal 

employees working in this area (and BC visitors) 

have the potential to be exposed to elevated CO 

concentrations. 
Page 12 Health Hazard Evaluation Report No. 2002-0393-2928 

• PO and EMS/Fire personnel working on boats 

in the BC have the potential to be exposed to 

CO approaching and/or exceeding IDLH 

concentrations. Additionally, these personnel also 

have the potential to have COHb levels 

approaching or in excess of 15%. 

• The CO concentrations tend to become more 

elevated as the day progresses, which results in the 

potential for PO and EMS/Fire personnel to be 

exposed to elevated CO concentrations. 

• LHC municipal employees with occupational 

CO exposures resulting in elevated COHb levels 

may develop symptoms of CO poisoning which 

could affect their health and safety and the safety of 

the public they serve. 

RECOMMENDATIONS

The following recommendations are based on 

the findings of this investigation and are 

intended to reduce the health hazard for 

employees. Similar measures should be 

considered related to visitor exposures. 

• LHC should determine what actions to take 

to bring about a reduction of overall CO 

concentrations within the BC area during high 

boat-traffic days, thus reducing the potential for 

employee over-exposure. 

• Employees assigned to duty within the BC 

or on boats elsewhere should receive training 

about the health effects of CO, how to recognize 

symptoms of CO poisoning in themselves and 

co-workers, and work-practices that can reduce 

exposure to vehicle and boat exhaust. 

• Until CO concentrations are reduced within 

the BC, LHC should periodically rotate 

employee assignments to areas where CO 

exposure does not occur, particularly in the late 

afternoon and early evening hours when CO 

concentrations elevate in the BC. 

• LHC should develop an employee exposure 

monitoring program to determine patterns of 

overexposure for employees (i.e., are they 

overexposed only on warm-weather holiday 

weekends, or at other times or during certain job 

tasks) and to ensure that control measures such 

as assignment rotation, or reduction of CO 

concentrations within the BC, are effective. 

• Employees should be encouraged to report 

symptoms of CO poisoning to designated health 

and safety personnel and should be provided 

with appropriate medical evaluation of 

symptoms. 

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(NIOSH) Publication No. 81-111. 
Health Hazard Evaluation Report No. 2002-0393-2928 Page 15 

TABLES

Industrial Hygiene 

Abbreviations and Symbols Used in the Following Tables 

COHb = carboxyhemoglobin 

CO = carbon monoxide 

Avg. = average 

Cumul. = cumulative 

* = light smokers (five or less cigarettes per day) 

** = moderate to heavy smokers (over 15 cigarettes per day) 

PO = police officer 

EMS/Fire = emergency medical service 

Chan = channel 

E = East 

W = West 

GG = gas-powered golf cart 

GQ = gas-powered quad 

EG = electric-powered golf cart 

F = foot patrol 

BS = booking station 

ppm = parts per million 

C = ceiling concentration - a concentration which should not be exceeded at any time 

LFC = lowest feasible concentration - see formaldehyde in Evaluation Criteria section 

STEL = short-term exposure limit - a 15-minute exposure limit that should not be 

 exceeded at any time during the day 

A2 = suspected human carcinogen 

NIOSH REL = National Institute for Occupational Safety and Health, Recommended Exposure 

 Limit 

OSHA PEL = Occupational Safety and Health Administration, Permissible Exposure Limit 

ACGIH TLV = American Conference of Governmental Industrial Hygienists, Threshold Limit 

 Value 
Page 16 Health Hazard Evaluation Report No. 2002-0393-2928 

Table 1. COHb Readings & Coinciding CO Monitor Averages and Peaks (in parts per million) on May 23, 2003 at Lake Havasu, Arizona 

ID Location Sample 

Time 

(military)

Preshift 

COHb

2nd

COHb

Session 

CO 

Avg. 

(Peak)

3rd

COHb

Session CO 

Avg. 

(Peak)

Cumul. 

CO 

Avg.

4th

COHb

Session CO 

Avg. 

(Peak)

Cumul

CO 

Avg.

101 PO, chan, boat 1046-1846 0.5% 1.7% 13 (99) 2.3% 26 (131) 20 

102* PO, chan, boat 1052-1847 0.3% 1.5% 13 (102) 3.9% 27 (138) 20 

103** PO, E/W, GG, GQ, 

F 

1056-1939 5.5% 5.7% 4 (34) 5.9% 17 (124) 12 

104 PO, E, GG 1101-1927 0.3% 0.9% 8 (64) 1.5% 16 (130) 13 1.9% 26 (474) 17 105 PO, E, GG 1053-1932 0.5% 1.3% 4 (54) 2.7% 10 (100) 8 3.3% 31 (490) 15 

106* EMS/Fire, E, GG 1102-1901 2.5% 2.5% 7 (55) 

107** PO, W, GQ 1107-1900 2.1% 6.7% 12 (88) 4.3% 16 (65) 14 

108* PO, W, EG 1107-1908 0.7% 2.1% 15 (34) 2.3% 25 (63) 20 

109** PO, E, BS 1113-1949 4.5% 

110 EMS/Fire, W, EG 1117-1848 0.3% 1.9% 10 (40) 2.1% 10 (60) 10 

111* PO, E, GQ 1108-1936 1.3% 2.1% 5 (19) 1.3% 11 (78) 9 

112 EMS/Fire, E, EG 1114-1901 1.1% 2.1% 10 (79) 114 PO, W, BS 1404-1959 2.7% 2.3% 17 (90) 115 PO, chan, boat 1314-1953 0.7% 2.3% 32 (157) 4.7% 87 (590) 61 
Health Hazard Evaluation Report No. 2002-0393-2928 Page 17 

Table 2. COHb Readings & Coinciding CO Monitor Averages and Peaks (in parts per million) on May 24, 2003 at Lake Havasu, Arizona 

ID Location Sample 

Time 

(military)

Preshift 

COHb

2nd

COHb

CO 

Monitor 

Avg. 

(Peak)

3rd

COHb

Session 

CO 

Avg. 

(Peak)

Cumul. 

CO 

Avg.

4th

COHb

Session 

CO 

Avg. 

(Peak)

Cumul. 

CO 

Avg.

101 PO, chan, boat 1037-2058 1.9% 5.3% 36 (175) 4.1% 49 (260) 41 11.7% 270 (1090) 101 103** PO, E/W, GG, GQ, 

EG 

1048-1954 3.7% 4.1% 11 (56) 

104 PO, E, GG 123 min. 0.5% 0.5% 3.7% 105 PO, E, GG 1051-1913 0.7% 2.7% 8 (157) 106* EMS/Fire, 

bay/chan, boat 

1345-1924 1.5% 2.9% 

107** PO, E, GG, GQ, 

EG, F 

0955-1745 4.1% 3.9% 8(73) 3.7% 21 (118) 12 

108* PO, W, EG 0950-2008 1.3% 1.5% 3 (16) 2.9% 20 (132) 9 109** PO, E, BS 1009-1934 5.3% 7.1% 5 (44) 8.9% 22 (203) 14 114 PO, W, BS, boat 1001-2117 3.9% 4.1% 6 (41) 4.3% 10 (89) 8 120 PO, W, GG 0941-2031 0.1% 0.7% 9 (78) 3.9% 49 (460) 27 121 PO, W, GQ 0957-2048 0.3% 1.9% 17 (127) 2.5% 35 (288) 25 122 PO, W, GQ, boat 1033-2117 0.5% 1.9% 16 (90) 3.3% 31 (222) 22 
Page 18 Health Hazard Evaluation Report No. 2002-0393-2928 

Table 2. COHb Readings & Coinciding CO Monitor Averages and Peaks (in parts per million) on May 24, 2003 at Lake Havasu, Arizona 

ID Location Sample 

Time 

(military)

Preshift 

COHb

2nd

COHb

Session 

CO 

Avg. 

(Peak)

3rd

COHb

Session 

CO 

Avg. 

(Peak)

Cumul. 

CO 

Avg.

4th

COHb

Session 

CO 

Avg. 

(Peak)

Cumul. 

CO 

Avg.

123 PO, W, GG 1008-2044 0.7% 1.9% 11 (56) 4.7% 16 (121) 14 124 PO, W, EG 1036-2025 0.9% 2.3% 23 (322) 126 PO, W, GG 1039-2051 0.5% 1.5% 11 (164) 127 PO, chan, boat 0912-1908 0.9% 2.3% 28 (194) 128 PO, chan, boat 0910-1859 129 PO, E, GQ 1042-1922 1.1% 2.3% 10 (98) 1.3% 15 (168) 13 130 PO, chan, boat, W, BS 1043-2038 1.5% 4.3% 43 (185) 2.7% 58 (480) 48 10.1% 290 (1109) 114 131 EMS/Fire, W, EG 0940-2001 0.9% 4.9% 12 (167) 5.5% 20 (229) 16 132 EMS/Fire, W, EG 0957-2005 0.9% 1.3% 14 (82) 3.3% 21 (191) 17 133 EMS/Fire, chan, boat 1004-1921 1.1% 4.3% 15 (206) 134 EMS/Fire, E, EG 1014-2053 0.5% 5.5% 36 (580) 137 EMS/Fire, chan, boat 1018-1931 0.5% 1.3% 13 (214) 
Health Hazard Evaluation Report No. 2002-0393-2928 Page 19 

Table 3. COHb Readings & Coinciding CO Monitor Averages and Peaks (in parts per million) on May 25, 2003 at Lake Havasu, Arizona 

ID Location Sample 

Time 

(military)

Preshift 

COHb

2nd

COHb

Session 

CO 

Avg. 

(Peak)

3rd

COHb

Session 

CO 

Avg. 

(Peak)

Cumul. 

CO 

Avg.

4th

COHb

Session 

CO Avg. 

(Peak)

Cumul. 

CO 

Avg.

101 PO, chan, boat 0934-2054 2.7% 2.5% 15 (119) 2.3% 14 (111) 14 103** PO, E/W, GG, GQ, 

EG 

0912-2002 5.9% 5.5% 4 (33) 7.1% 13 (179) 8 

104 PO, E, GG 0957-1936 1.5% 1.5% 7 (260) 105 PO, E, GG 1018-1935 0.9% 3.9% 4 (44) 107** PO, E, GG, GQ, 

EG, F 

0939-2023 3.3% 3.5% 5 (12) 5.9% 16 (93) 10 

109** PO, E, BS 0900-2042 5.3% 114 PO, W, BS, boat, F 0946-2041 1.5% 3.5% 4 (12) 3.7% 41 (294) 24 118 EMS/Fire, W, EG 0943-1926 2.5% 2.3% 4 (16) 5.7% 25 (175) 15 120 PO, W, GG 1622-1919 0.5% 0.9% 0.9% 53 (327) 121 PO, W, GQ 0949-2038 0.9% 2.5% 11 (82) 2.7% 28 (101) 17 122 PO, W, GQ, boat 0940-2039 1.9% 4.1% 10 (175) 4.5% 56 (221) 24 123 PO, W, GG 0930-2019 2.1% 1.7% 12 (81) 1.1% 15 (53) 14 
Page 20 Health Hazard Evaluation Report No. 2002-0393-2928 

Table 3. COHb Readings & Coinciding CO Monitor Averages and Peaks (in parts per million) on May 25, 2003 at Lake Havasu, Arizona 

ID Location Sample 

Time 

(military)

Preshift 

COHb

2nd

COHb

Session 

CO 

Avg. 

(Peak)

3rd

COHb

Session 

CO 

Avg. 

(Peak)

Cumul. 

CO 

Avg.

4th

COHb

Session 

CO Avg. 

(Peak)

Cumul. 

CO 

Avg.

124 PO, W, EG 0954-2029 1.1% 2.3% 15 (86) 2.9% 36 (204) 22 125 PO, E, GG, GQ 0936-1949 1.5% 3.3% 6 (46) 4.5% 18 (88) 10 126 PO, W, GG, chan, 

boat 

1003-2044 1.1% 1.5% 10 (71) 3.1% 29 (261) 20 

127 PO, chan, boat 0909-1834 1.3% 2.1% 16 (168) 5.9% 23 (242) 20 128 PO, chan, boat 0907-1833 129 PO, E, GQ, chan, boat 0929-1953 1.1% 0.7% 15 (62) 4.5% 66 (365) 38 130 PO, chan, boat, W, BS 0944-2045 2.3% 2.5% 15 (122) 2.9% 14 (63) 15 131 EMS/Fire, W, EG 1005-1927 0.9% 1.9% 2 (20) 2.3% 5 (38) 3 133 EMS/Fire, lake, boat 0923-1941 2.5% 2.7% 8 (109) 137 EMS/Fire, W, EG 1012-1921 1.5% 1.5% 4 (13) 3.3% 26 (221) 17 140 EMS/Fire, lake, boat 0917-2013 0.0% 0.7% 10 (98) 141 EMS/Fire, lake, boat 0917-2010 0.3% 1.3% 13 (570) 142 EMS/Fire, E, EG 0954-1931 0.9% 1.3% 3 (46) 3.7% 5 (38) 4 
Health Hazard Evaluation Report No. 2002-0393-2928 Page 21 

Table 4. COHb Readings & Coinciding CO Monitor Averages and Peaks (in parts per million) on May 26, 2003 at Lake Havasu, Arizona 

ID Location Sample 

Time 

(military)

Preshift 

COHb

2nd

COHb

Session 

CO 

Avg. 

(Peak)

3rd

COHb

Session 

CO 

Avg. 

(Peak)

Cumul. 

CO 

Avg.

4th

COHb

Session 

CO Avg. 

(Peak)

Cumul. 

CO 

Avg.

104 PO, E, GG 0932-1411 0.9% 105 PO, E, GG 0949-1411 1.1% 107** PO, chan, boat 0921-1639 3.1% 109** PO, E, BS 0923-1503 4.1% 114 PO, W, BS, boat 0930-1537 3.9% 7.1% 15 (120) 120 PO, W, other 

vehicle 

0948-1425 0.5% 

121 PO, W, GQ 0953-1524 1.1% 122 PO, chan, boat 0951-1538 1.1% 5.7% 16 (602) 123 PO, W, GG 0926-1518 1.1% 1.9% 7 (128) 124 PO, W, GQ 0945-1513 1.1% 2.1% 6 (54) 125 PO, E, GQ 0916-1408 1.3% 126 PO, W, GG 1002-1532 1.5% 1.9% 4 (52) 127 PO, chan, boat 0910-1446 0.9% 1.9% 17 (117) 128 PO, chan, boat 0903-1449 129 PO, E, GQ 0936-1411 1.9% 
Page 22 Health Hazard Evaluation Report No. 2002-0393-2928 

Table 5. General Area Air Sampling for Formaldehyde on May 24 & 25, 2003 

Date Location Sample 

Time 

(military)

Sample 

Volume 

(liters)

8-hour TWA 

concentration 

(ppm) 

5/24/03 Backseat, police boat # 1297 1227 - 2110 106 0.047 

 Park Host sign by W-side Booking Station 1250 - 2051 96.5 0.008 

5/25/03 Backseat, police boat # 2196 1054 - 2046 118 0.034 

 Park Host sign by W-side Booking Station 1126 - 2054 113 0.004 

Minimum Detectable Concentration (MDC) 0.0007 

Minimum Quantifiable Concentration (MQC) 0.0028 

0.016, C 0.1, LFC 

0.75, STEL 2.0 

Evaluation Criteria NIOSH REL 

 OSHA PEL 

 ACGIH TLV C 0.3, A2 
Health Hazard Evaluation Report No. 2002-0393-2928 Page 23 

Table 6. General Area Air Sampling for Volatile Organic Compounds on May 24, 2003 

Location Sample # Sample Time 

(military)

Major Compounds

Backseat, police boat # 1297 A41198 1227 - 1421 Acetone 

Isooctane 

Toluene 

Xylenes 

Alkyl benzenes 

“ AO5370 1421 - 1624 Acetone 

Isooctane 

Toluene 

Xylenes 

Alkyl benzenes 

“ A39694 1624 - 1845 Acetonitrile 

Isooctane 

Toluene 

“ AO3998 1845 - 2110 Butane 

Isopentane 

Isooctane 

Toluene 

Xylenes 

Alkyl benzenes 

Park Host sign by W-side Booking 

Station 

A39892 1250 - 1451 Acetone 

Toluene 

“ AO4085 1451 - 1645 Acetone 

Toluene 

“ A40989 1645 - 1900 Acetonitrile 

Isooctane 

Toluene 

“ AO5036 1900 - 2051 Acetone 

Isooctane 

Toluene 

Ethyl benzene/ xylene isomers 

Alkyl benzenes 
Page 24 Health Hazard Evaluation Report No. 2002-0393-2928 

Medical 

Table 7. Exhaled Breath CO Monitoring: Estimated Cross-shift Increase in %COHb by Date 

Estimated Cross-shift %COHb* 

(postshift minus preshift)

5/23/2003 

N=18

5/24/2003 

N=24

5/25/2003 

N=25

5/26/2003 

N=14

< 3.5 9 (50%) 7 (29%) 12 (48%) 13 (93%) 

3.5 - 5 3 (17%) 5 (21%) 4 (16%) 1 (7%) 

> 5 - 10 6 (33%) 12 (50%) 5 (20%) 0 

> 10 - 15 0 0 4 (16%) 0 

Total > 3.5% COHb 9 (50%) 17 (71%) 13 (52%) 1 (7%) 

Mean increase over day 3.82 5.33 4.77 1.39 

Mean increase (of those reporting 

symptoms) 

4.27 5.33 5.51 2.53 

* = The cross-shift difference is the change (increase) in %COHb levels from pre-shift to post-shift. For 

 example, if an employee’s pre-shift level was 1% COHb and his/her post-shift level was 8%, then the 

 employee had a cross-shift increase of 7% COHb. 

Table 8. Exhaled Breath CO Monitoring: Post-shift %COHb in Non-smoking Lake Havasu City, Arizona 

Municipal Employees by Date 

Post-shift %COHb 5/23/2003 

N=11

5/24/2003 

N=19

5/25/2003 

N=21

5/26/2003 

N=12

< 3.5 4 (36%) 0 7 (33%) 10 (83%) 

3.5 - 5 2 (18%) 5 (26%) 4 (19%) 2 (17%) 

> 5 - 10 5 (45%) 12 (63%) 6 (29%) 0 

> 10 - 15 0 2 (11%) 4 (19%) 0 

Total > BEI (3.5% COHb) 7 (64%) 19 (100%) 14 (67%) 2 (17%) 

Mean post-shift %COHb - non-smokers 4.23 6.67 6.03 2.05 

Mean post-shift %COHb - smokers 7.04 6.74 8.15 5.0 
Health Hazard Evaluation Report No. 2002-0393-2928 Page 25 

Table 9. Reported Post-shift Symptoms by Lake Havasu City, Arizona Municipal Employees 

Symptoms reported post-shift 5/23/2003 

N=17

5/24/2003 

N=24

5/25/2003 

N=25

5/26/2003 

N=14

Headache 11 (65%) 15 (63%) 11 (44%) 3 (21%) 

Fatigue or weakness 2 (12%) 5 (21%) 3 (12%) 0 

Visual disturbances 3 (18%) 3 (13%) 3 (12%) 0 

Dizziness 3 (18%) 2 (8%) 3 (12%) 0 

Nausea or vomiting 0 0 1 (4%) 1 (7%) 

Drowsiness 1 (6%) 0 0 0 

Chest pain 1 (6%) 0 0 0 

Loss of muscle coordination 0 0 0 0 

# reporting 1 or more symptom 12 (71%) 16 (67%) 13 (52%) 3 (21%) 

# reporting 2 or more symptoms 4 (24%) 5 (21%) 5 (20%) 1 (7%) 

# with symptoms of moderate or 

greater severity* 

5 (29%) 10 (42%) 6 (24%) 0 

* = Severity of post-shift symptoms was assessed by participant choosing either mild, moderate, or a lot for 

each symptom reported. 

Table 10. Post-shift %COHb and Symptoms Among Non-smoking Lake Havasu City, Arizona Municipal 

Employees 

Non-smoking employees reporting one or Post-shift %COHb

more symptom by date: < 3.5% > 3.5-5% > 5-10% > 10%

5/23/2003 

7 of 11 non-smokers reported symptoms 

3 of 4 

(75%) 

1 of 2 

(50%) 

3 of 5 

(60%) 

0 

5/24/2003 

14 of 19 non-smokers reported symptoms 

0 4 of 5 

(80%) 

9 of 12 

(75%) 

1 of 2 

(50%) 

5/25/2003 

11 of 21 non-smokers reported symptoms 

4 of 7 

(57%) 

1 of 4 

(25%) 

3 of 6 

(50%) 

3 of 4 

(75%) 

5/26/2003 

3 of 12 non-smokers reported symptoms 

2 of 10 

(20%) 

1 of 2 

(50%) 

0 0 

Total non-smoker post-shift %COHb 

measurements over weekend = 63 

9 of 21 

(43%) 

7 of 13 

(54%) 

15 of 23 

(65%) 

4 of 6 

(67%) 
Page 26 Health Hazard Evaluation Report No. 2002-0393-2928 

FIGURES

May 23, 2003 

Figures 1-2 (L to R). Real-time CO Concentration Readings and Estimated %COHb Levels on May 23, 2003 at Lake Havasu, Arizona 

HETA 2002-0393, Lake Havasu, ID 101

Police, in channel, on Boat #2079

0

100200300400500600700800900

1000

10:45

11:15

11:45

12:15

12:45

13:15

13:45

14:15

14:45

15:15

15:45

16:15

16:45

17:15

17:45

18:15

18:45

Time (hr:min)

Concentration

(parts per million)

0.0%1.5%3.0%4.5%6.0%7.5%9.0%10.5%12.0%13.5%15.0%

CO (ppm) % COHb

HETA 2002-0393, Lake H

Police, in channel, on B

0

100200300400500600700800900

1000

10:45

11:15

11:45

12:15

12:45

13:15

13:45

14:15

14:45

1

Time (hr:m

Concentration

(parts per million)

CO (ppm) 
Health Hazard Evaluation Report No. 2002-0393-2928 Page 27 

Figures 3-6 (L to R). Real-time CO Concentration Readings and Estimated %COHb Levels on May 23, 2003 at Lake Havasu, Arizona 

HETA 2002-0393, Lake Havasu, ID 103

Police, East and West Channel,

on gas-powered golf cart & quad and foot patrol

0

100200300400500600700800900

1000

10:45

11:30

12:15

13:00

13:45

14:30

15:15

16:00

16:45

17:30

18:15

19:00

Time (hr:min)

Concentration

(parts per million)

0.0%1.5%3.0%4.5%6.0%7.5%9.0%10.5%12.0%13.5%15.0%

CO (ppm) % COHb

HETA 2002-0393, Lake H

Police, East Channel, on gas-p

0

100200300400500600700800900

1000

11:00

11:30

12:00

12:30

13:00

13:30

14:00

14:30

15:00

15

Time (hr:m

Concentration

(parts per million)

CO (ppm) 

HETA 2002-0393, Lake Havasu, ID 105

Police, East Channel, on gas-powered golf cart

0

100200300400500600700800900

1000

10:45

11:15

11:45

12:15

12:45

13:15

13:45

14:15

14:45

15:15

15:45

16:15

16:45

17:15

17:45

18:15

18:45

19:15

Time (hr:min)

Concentration

(parts per mill oi n)

0.0%1.5%3.0%4.5%6.0%7.5%9.0%10.5%12.0%13.5%15.0%

CO (ppm) % COHb

HETA 2002-0393, Lake H

EMS/fire, East Channel, on gas-

0

100200300400500600700800900

1000

11:00

11:30

12:00

12:30

13:00

13:30

14:00

14:30

15:00

1

Time (hr:m

Concentration

(parts per million)

CO (ppm) 
Page 28 Health Hazard Evaluation Report No. 2002-0393-2928 

Figures 7-10 (L to R). Real-time CO Concentration Readings and Estimated %COHb Levels on May 23, 2003 at Lake Havasu, Arizona 

HETA 2002-0393, Lake Havasu, ID 107

Police, West Channel, on gas-powered quad

0

100200300400500600700800900

1000

11:00

11:30

12:00

12:30

13:00

13:30

14:00

14:30

15:00

15:30

16:00

16:30

17:00

17:30

18:00

18:30

19:00

Time (hr:min)

Concentration

(parts per million)

0.0%1.5%3.0%4.5%6.0%7.5%9.0%10.5%12.0%13.5%15.0%

CO (ppm) % COHb

HETA 2002-0393, Lake H

Police, West Channel, on el

0

100200300400500600700800900

1000

11:00

11:30

12:00

12:30

13:00

13:30

14:00

14:30

15:00

1

Time (hr:m

Concentration

(parts per million)

CO (ppm) 

HETA 2002-0393, Lake Havasu, ID 109

Police, East Channel, Booking Station

0

100200300400500600700800900

1000

11:00

11:30

12:00

12:30

13:00

13:30

14:00

14:30

15:00

15:30

16:00

16:30

17:00

17:30

18:00

18:30

19:00

19:30

Time (hr:min)

Concentration

(parts per million)

0.0%1.5%3.0%4.5%6.0%7.5%9.0%10.5%12.0%13.5%15.0%

CO (ppm) % COHb

HETA 2002-0393, Lake H

EMS/fire, West Channel, on e

0

100200300400500600700800900

1000

11:00

11:30

12:00

12:30

13:00

13:30

14:00

14:30

15:00

15:30

Time (hr:m

Concentration

(parts per million)

CO (ppm) 
Health Hazard Evaluation Report No. 2002-0393-2928 Page 29 

Figures 11-14 (L to R). Real-time CO Concentration Readings and Estimated %COHb Levels on May 23, 2003 at Lake Havasu, Arizona 

HETA 2002-0393, Lake Havasu, ID 111

Police, East Channel, on gas-powered quad

0

100200300400500600700800900

1000

11:00

11:30

12:00

12:30

13:00

13:30

14:00

14:30

15:00

15:30

16:00

16:30

17:00

17:30

18:00

18:30

19:00

19:30

Time (hr:min)

Concentration

(parts per million)

0.0%1.5%3.0%4.5%6.0%7.5%9.0%10.5%12.0%13.5%15.0%

CO (ppm) % COHb

HETA 2002-0393, Lake H

EMS/Fire, East Channel, on e

0

100200300400500600700800900

1000

11:00

11:30

12:00

12:30

13:00

13:30

14:00

14:30

15:00

1

Time (hr:m

Concentration

(parts per million)

CO (ppm) 

HETA 2002-0393, Lake Havasu, ID 114

Police, West Channel, Booking Station

0

100200300400500600700800900

1000

14:00

14:30

15:00

15:30

16:00

16:30

17:00

17:30

18:00

18:30

19:00

19:30

Time (hr:min)

Concentration

(parts per million)

0.0%1.5%3.0%4.5%6.0%7.5%9.0%10.5%12.0%13.5%15.0%

CO (ppm) % COHb

HETA 2002-0393, Lake H

Police, in channel, on B

0

100200300400500600700800900

1000

13:00

13:30

14:00

14:30

15:00

15:30

16:00

16:30

Time (hr:m

Concentration

(parts per million)

CO (ppm) 
Page 30 Health Hazard Evaluation Report No. 2002-0393-2928 

Figures 15-16 (L to R). Real-time CO Concentration Readings and Estimated %COHb Levels on May 23, 2003 at Lake Havasu, Arizona 

HETA 2002-0393, Lake Havasu

GA, West Channel, Booking Station

0

100200300400500600700800900

1000

12:45

13:15

13:45

14:15

14:45

15:15

15:45

16:15

16:45

17:15

17:45

18:15

18:45

19:15

19:45

20:15

Time (hr:min)

Concentrat oi n

(parts per mill oi n)

HETA 2002-0393, Lak

GA, West Channel, by Pum

0

100200300400500600700800900

1000

13:45

15:00

16:15

17:30

18:45

20:00

21:15

22:30

23:45

Time (hr:

Concentration

(parts per mill oi n)
Health Hazard Evaluation Report No. 2002-0393-2928 Page 31 

May 24, 2003 Figures 17-20 (L to R). Real-time CO Concentration Readings and Estimated %COHb Levels on May 24, 2003 at Lake Havasu, Arizona 

HETA 2002-0393, Lake Havasu, ID 101

Police, in channel, on Boat #2196

0

100200300400500600700800900

1000

9:59

10:45

11:30

12:15

13:00

13:45

14:30

15:15

16:00

16:45

17:31

18:16

19:01

19:46

20:31

Time (hr:min)

Concentration

(parts per million)

0.0%1.5%3.0%4.5%6.0%7.5%9.0%10.5%12.0%13.5%15.0%

CO (ppm) % COHb

Peak 1056 ppm Peak 1090 ppm

HETA 2002-0393, Lake H

Police, East and West Channel, on g

quad and electric g

0

100200300400500600700800900

1000

10:45

11:30

12:15

13:00

13:45

14:30

15:15

Time (hr:m

Concentration

(parts per million)

CO (ppm) 

HETA 2002-0393, Lake Havasu, ID 105

Police, East Channel, on gas-powered golf cart

0

100200300400500600700800900

1000

10:45

11:15

11:45

12:15

12:45

13:15

13:45

14:15

14:45

15:15

15:45

16:15

16:45

17:15

17:45

18:15

18:45

Time (hr:min)

Concentration

(parts per million)

0.0%1.5%3.0%4.5%6.0%7.5%9.0%10.5%12.0%13.5%15.0%

CO (ppm) % COHb

HETA 2002-0393, Lake H

EMS/fire, in Thompson Bay & C

0

100200300400500600700800900

1000

10:00

10:40

11:20

12:00

12:40

13:20

14:00

14:40

Time (hr:m

Concentration

(parts per million)

CO (ppm) 

No CO data 
Page 32 Health Hazard Evaluation Report No. 2002-0393-2928 

Figures 21-24 (L to R). Real-time CO Concentration Readings and Estimated %COHb Levels on May 24, 2003 at Lake Havasu, Arizona 

HETA 2002-0393, Lake Havasu, ID 107

Police, East Channel, on gas-powered quad and golf cart,

on electric golf cart, and on foot patrol

0

100200300400500600700800900

1000

9:45

10:30

11:15

12:00

12:45

13:30

14:15

15:00

15:45

16:30

17:15

18:00

18:45

19:30

Time (hr:min)

Concentration

(parts per million)

0.0%1.5%3.0%4.5%6.0%7.5%9.0%10.5%12.0%13.5%15.0%

CO (ppm) % COHb

No CO Data

HETA 2002-0393, Lake H

Police, West Channel, on el

0

100200300400500600700800900

1000

9:45

10:30

11:15

12:00

12:45

13:30

14:15

15:00

Time (hr:m

Concentration

(parts per million)

CO (ppm) 

HETA 2002-0393, Lake Havasu, ID 109

Police, East Channel, Booking Station

0

100200300400500600700800900

1000

10:00

10:45

11:30

12:15

13:00

13:45

14:30

15:15

16:00

16:45

17:30

18:15

19:00

Time (hr:min)

Concentration

(parts per million)

0.0%1.5%3.0%4.5%6.0%7.5%9.0%10.5%12.0%13.5%15.0%

CO (ppm) % COHb

HETA 2002-0393, Lake H

Police, West Channel, Boo

on Boat #W2

0

100200300400500600700800900

1000

9:45

10:30

11:15

12:00

12:45

13:30

14:15

15:00

15:45

Time (hr:m

Concentration

(parts per million)

CO (ppm) 
Health Hazard Evaluation Report No. 2002-0393-2928 Page 33 

Figures 25-28 (L to R). Real-time CO Concentration Readings and Estimated %COHb Levels on May 24, 2003 at Lake Havasu, Arizona 

HETA 2002-0393, Lake Havasu, ID 120

Police, West Channel, on gas-powered golf cart

0

100200300400500600700800900

1000

9:30

10:15

11:00

11:45

12:30

13:15

14:00

14:45

15:30

16:15

17:00

17:45

18:30

19:15

20:00

20:45

Time (hr:min)

Concentration

(parts per million)

0.0%1.5%3.0%4.5%6.0%7.5%9.0%10.5%12.0%13.5%15.0%

CO (ppm) % COHb

HETA 2002-0393, Lake H

Police, West Channel, on gas

0

100200300400500600700800900

1000

9:45

10:30

11:15

12:00

12:45

13:30

14:15

15:00

15

Time (hr:m

Concentration

(parts per million)

CO (ppm) 

HETA 2002-0393, Lake Havasu, ID 122

Police, West channel on gas-powered quad,

in channel on Boat #2196

0

100200300400500600700800900

1000

10:00

10:45

11:30

12:15

13:00

13:45

14:30

15:15

16:00

16:45

17:30

18:15

19:00

19:45

20:30

21:15

Time (hr:min)

Concentration

(parts per million)

0.0%1.5%3.0%4.5%6.0%7.5%9.0%10.5%12.0%13.5%15.0%

CO (ppm) % COHb

HETA 2002-0393, Lake H

Police, West Channel, on gas-p

0

100200300400500600700800900

1000

10:00

10:45

11:30

12:15

13:00

13:45

14:30

15:15

Time (hr:m

Concentration

(parts per million)

CO (ppm) 
Page 34 Health Hazard Evaluation Report No. 2002-0393-2928 

Figures 29-32 (L to R). Real-time CO Concentration Readings and Estimated %COHb Levels on May 24, 2003 at Lake Havasu, Arizona 

HETA 2002-0393, Lake H

Police, in channel, on B

0

100200300400500600700800900

1000

9:00

9:45

10:30

11:15

12:00

12:45

13:30

1

Time (hr:

Concentration

(parts per million)

P

No COHb D

HETA 2002-0393, Lake Havasu, ID 124

Police, West Channel, on electric golf cart

0

100200300400500600700800900

1000

10:30

11:15

12:00

12:45

13:30

14:15

15:00

15:45

16:30

17:15

18:00

18:45

19:30

20:15

Time (hr:min)

Concentration

(parts per million)

0.0%1.5%3.0%4.5%6.0%7.5%9.0%10.5%12.0%13.5%15.0%

CO (ppm) % COHb

HETA 2002-0393, Lake H

Police, West Channel, on gas-p

0

100200300400500600700800900

1000

10:30

11:15

12:00

12:45

13:30

14:15

15:00

15:45

Time (hr:m

Concentration

(parts per million)

CO (ppm) 

HETA 2002-0393, Lake Havasu, ID 127

Police, in channel, on Boat #2079

0

100200300400500600700800900

1000

9:00

9:45

10:30

11:15

12:00

12:45

13:30

14:15

15:00

15:45

16:30

17:15

18:00

18:45

Time (hr:min)

Concentration

(parts per million)

0.0%1.5%3.0%4.5%6.0%7.5%9.0%10.5%12.0%13.5%15.0%

CO (ppm) % COHb

Peak 1118 ppm

No post-shift COHb
Health Hazard Evaluation Report No. 2002-0393-2928 Page 35 

Figures 33-35 (L to R). Real-time CO Concentration Readings and Estimated %COHb Levels on May 24, 2003 at Lake Havasu, Arizona 

HETA 2002-0393, Lake Havasu, ID 129

Police, East Channel, on gas-powered quad

0

100200300400500600700800900

1000

10:30

11:15

12:00

12:45

13:30

14:15

15:00

15:45

16:30

17:15

18:00

18:45

Time (hr:min)

Concentration

(parts per million)

0.0%1.5%3.0%4.5%6.0%7.5%9.0%10.5%12.0%13.5%15.0%

CO (ppm) % COHb

HETA 2002-0393, Lake H

Police, in channel on B

West Channel Booking 

0

100200300400500600700800900

1000

10:30

11:15

12:00

12:45

13:30

14:15

15:00

15:45

Time (hr:m

Concentration

(parts per million)

CO (ppm) 

Peak 1015 pp

HETA 2002-0393, Lake Havasu, ID 131

EMS/fire, West Channel, on electric golf cart

0

100200300400500600700800900

1000

9:30

10:15

11:00

11:45

12:30

13:15

14:00

14:45

15:30

16:15

17:00

17:45

18:30

19:15

20:00

Time (hr:min)

Concentration

(parts per million)

0.0%1.5%3.0%4.5%6.0%7.5%9.0%10.5%12.0%13.5%15.0%

CO (ppm) % COHb

HETA 2002-0393, Lake H

EMS/fire, West Channel, on e

0

100200300400500600700800900

1000

9:45

10:30

11:15

12:00

12:45

13:30

14:15

15:00

Time (hr:m

Concentration

(parts per million)

CO (ppm) 
Page 36 Health Hazard Evaluation Report No. 2002-0393-2928 

Figures 36-39 (L to R). Real-time CO Concentration Readings and Estimated %COHb Levels on May 24, 2003 at Lake Havasu, Arizona 

HETA 2002-0393, Lak

GA, West channel, on Pa

0

100200300400500600700800900

1000

12:45

13:15

13:45

14:15

14:45

15:15

15:45

16:15

16:45

Time (hr:

Concentration

(parts per million)

HETA 2002-0393, Lake Havasu, ID 133

EMS/fire, in channel, on the fire boat

0

100200300400500600700800900

1000

10:00

10:45

11:30

12:15

13:00

13:45

14:30

15:15

16:00

16:45

17:30

18:15

19:00

Time (hr:min)

Concentration

(parts per million)

0.0%1.5%3.0%4.5%6.0%7.5%9.0%10.5%12.0%13.5%15.0%

CO (ppm) % COHb

Peak 1224 ppm

HETA 2002-0393, Lake H

EMS/fire, East Channel, on e

0

100200300400500600700800900

1000

10:00

10:45

11:30

12:15

13:00

13:45

14:30

15:15

1

Time (hr:m

Concentration

(parts per million)

CO (ppm) 

HETA 2002-0393, Lake Havasu, ID 137

EMS/fire, in channel, on Boat #777

0

100200300400500600700800900

1000

10:00

10:45

11:30

12:15

13:00

13:45

14:30

15:15

16:00

16:45

17:30

18:15

19:00

Time (hr:min)

Concentration

(parts per million)

0.0%1.5%3.0%4.5%6.0%7.5%9.0%10.5%12.0%13.5%15.0%

CO (ppm) % COHb

Peak 1084 ppm
Health Hazard Evaluation Report No. 2002-0393-2928 Page 37 

Figures 40-41 (L to R). Real-time CO Concentration Readings and Estimated %COHb Levels on May 24, 2003 at Lake Havasu, Arizona 

HETA 2002-0393, Lake Havasu

GA, in channel, Boat #1297

0

100200300400500600700800900

1000

12:30

13:00

13:30

14:00

14:30

15:00

15:30

16:00

16:30

17:00

17:30

18:00

18:30

19:00

19:30

Time (hr:min)

Concentration

(parts per million)

Peak 1179 ppm

Peak 1107 ppm

Peak 1160 ppm

HETA 2002-0393, Lak

GA, West Channel, by Pum

0

100200300400500600700800900

1000

13:45

15:00

16:15

17:30

18:45

20:00

21:15

22:30

23:45

Time (hr:

Concentration

(parts per million)
Page 38 Health Hazard Evaluation Report No. 2002-0393-2928 

May 25, 2003 Figures 42-45 (L to R). Real-time CO Concentration Readings and Estimated %COHb Levels on May 25, 2003 at Lake Havasu, Ari

HETA 2002-0393, Lake Havasu, ID 101

Police, in channel, on Boat #2196

0

100200300400500600700800900

1000

9:30

10:15

11:00

11:45

12:30

13:15

14:00

14:45

15:30

16:15

17:00

17:45

18:30

19:15

20:00

20:45

Time (hr:min)

Concentration

(parts per million)

0.0%1.5%3.0%4.5%6.0%7.5%9.0%10.5%12.0%13.5%15.0%

CO (ppm) % COHb

HETA 2002-0393, Lake H

Police, East and West Channel, on g

cart and electric go

0

100200300400500600700800900

1000

9:00

9:45

10:30

11:15

12:00

12:45

13:30

14:15

1

Time (hr:m

Concentrat oi n

(parts per million)

CO (ppm) 

HETA 2002-0393, Lake Havasu, ID 104

Police, East Channel, on gas-powered golf cart

0

100200300400500600700800900

1000

9:45

10:30

11:15

12:00

12:45

13:30

14:15

15:00

15:45

16:30

17:15

18:00

18:45

19:30

Time (hr:min)

Concentration

(parts per million)

0.0%1.5%3.0%4.5%6.0%7.5%9.0%10.5%12.0%13.5%15.0%

CO (ppm) % COHb

HETA 2002-0393, Lake H

Police, East Channel, on gas-

0

100200300400500600700800900

1000

10:15

11:00

11:45

12:30

13:15

14:00

14:45

Time (hr:m

Concentration

(parts per million)

CO (ppm) 
Health Hazard Evaluation Report No. 2002-0393-2928 Page 39 

Figures 46-49 (L to R). Real-time CO Concentration Readings and Estimated %COHb Levels on May 25, 2003 at Lake Havasu, Ari

HETA 2002-0393, Lake Havasu, ID 107

Police, East Channel, on gas-powered quad & golf cart,

on electric golf cart, and on foot patrol

0

100200300400500600700800900

1000

9:30

10:15

11:00

11:45

12:30

13:15

14:00

14:45

15:30

16:15

17:00

17:45

18:30

19:15

20:00

Time (hr:min)

Concentration

(parts per million)

0.0%1.5%3.0%4.5%6.0%7.5%9.0%10.5%12.0%13.5%15.0%

CO (ppm) % COHb

HETA 2002-0393, Lake H

Police, East Channel, Boo

0

100200300400500600700800900

1000

9:00

9:45

10:30

11:15

12:00

12:45

13:30

14:15

15:00

Time (hr:m

Concentration

(parts per million)

CO (ppm) 

HETA 2002-0393, Lake Havasu, ID 114

Police, West Channel, Booking Station,

on Boat #2196, gas-powered golf cart

0

100200300400500600700800900

1000

9:45

10:30

11:15

12:00

12:45

13:30

14:15

15:00

15:45

16:30

17:15

18:00

18:45

19:30

20:15

Time (hr:min)

Concentration

(parts per million)

0.0%1.5%3.0%4.5%6.0%7.5%9.0%10.5%12.0%13.5%15.0%

CO (ppm) % COHb

No CO data

HETA 2002-0393, Lake H

EMS/Fire, West Channel, on 

0

100200300400500600700800900

1000

9:30

10:15

11:00

11:45

12:30

13:15

14:00

14:4

Time (hr:m

Concentration

(parts per million)

CO (ppm) 
Page 40 Health Hazard Evaluation Report No. 2002-0393-2928 

Figures 50-53 (L to R). Real-time CO Concentration Readings and Estimated %COHb Levels on May 25, 2003 at Lake Havasu, Arizona 

HETA 2002-0393, Lake Havasu, ID 120

Police, West Channel, on gas-powered golf cart

0

100200300400500600700800900

1000

9:30

10:15

11:00

11:45

12:30

13:15

14:00

14:45

15:30

16:15

17:00

17:45

18:30

19:15

20:00

20:45

Time (hr:min)

Concentration

(parts per million)

0.0%1.5%3.0%4.5%6.0%7.5%9.0%10.5%12.0%13.5%15.0%

CO (ppm) % COHb

No CO Data No CO Data

HETA 2002-0393, Lake H

Police, West Channel, on gas

0

100200300400500600700800900

1000

9:45

10:30

11:15

12:00

12:45

13:30

14:15

15:00

1

Time (hr:m

Concentration

(parts per million)

CO (ppm) 

HETA 2002-0393, Lake Havasu, ID 122

Police, West Channel on gas-powered quad,

in channel on Boat #2196

0

100200300400500600700800900

1000

9:30

10:15

11:00

11:45

12:30

13:15

14:00

14:45

15:30

16:15

17:00

17:45

18:30

19:15

20:00

20:45

Time (hr:min)

Concentration

(parts per million)

0.0%1.5%3.0%4.5%6.0%7.5%9.0%10.5%12.0%13.5%15.0%

CO (ppm) % COHb

HETA 2002-0393, Lake H

Police, West Channel, on gas-p

0

100200300400500600700800900

1000

9:30

10:15

11:00

11:45

12:30

13:15

14:00

14:45

1

Time (hr:m

Concentration

(parts per million)

CO (ppm) 
Health Hazard Evaluation Report No. 2002-0393-2928 Page 41 

Figures 54-57 (L to R). Real-time CO Concentration Readings and Estimated %COHb Levels on May 25, 2003 at Lake Havasu, Arizona 

HETA 2002-0393, Lake Havasu, ID 124

Police, West Channel, on electric golf cart

0

100200300400500600700800900

1000

9:45

10:30

11:15

12:00

12:45

13:30

14:15

15:00

15:45

16:30

17:15

18:00

18:45

19:30

20:15

Time (hr:min)

Concentration

(parts per million)

0.0%1.5%3.0%4.5%6.0%7.5%9.0%10.5%12.0%13.5%15.0%

CO (ppm) % COHb

HETA 2002-0393, Lake H

Police, East Channel, on gas-powe

0

100200300400500600700800900

1000

9:30

10:15

11:00

11:45

12:30

13:15

14:00

14:45

Time (hr:m

Concentration

(parts per million)

CO (ppm) 

HETA 2002-0393, Lake Havasu, ID 126

Police, West Channel, on gas-powered golf cart,

in channel on boat

0

100200300400500600700800900

1000

10:00

10:45

11:30

12:15

13:00

13:45

14:30

15:15

16:00

16:45

17:30

18:15

19:00

19:45

20:30

Time (hr:min)

Concentration

(parts per million)

0.0%1.5%3.0%4.5%6.0%7.5%9.0%10.5%12.0%13.5%15.0%

CO (ppm) % COHb

HETA 2002-0393, Lake H

Police, in channel, on B

0

100200300400500600700800900

1000

9:00

9:45

10:30

11:15

12:00

12:45

13:30

14

Time (hr:m

Concentration

(parts per million)

CO (ppm) 
Page 42 Health Hazard Evaluation Report No. 2002-0393-2928 

Figures 58-61 (L to R). Real-time CO Concentration Readings and Estimated %COHb Levels on May 25, 2003 at Lake Havasu, Arizona 

HETA 2002-0393, Lake Havasu, ID 128

Police, in channel, on Boat #2079

0

100200300400500600700800900

1000

9:00

9:45

10:30

11:15

12:00

12:45

13:30

14:15

15:00

15:45

16:30

17:15

18:00

18:45

Time (hr:min)

Concentration

(parts per million) No COHb Data

HETA 2002-0393, Lake H

Police, East Channel on gas-

in channel on Boat 

0

100200300400500600700800900

1000

9:15

10:00

10:45

11:30

12:15

13:00

13:45

14:30

Time (hr:m

Concentration

(parts per million)

CO (ppm) 

HETA 2002-0393, Lake Havasu, ID 130

Police, in channel on Boat #2196,

West Channel Booking Station

0

100200300400500600700800900

1000

9:30

10:15

11:00

11:45

12:30

13:15

14:00

14:45

15:30

16:15

17:00

17:45

18:30

19:15

20:00

20:45

Time (hr:min)

Concentration

(parts per million)

0.0%1.5%3.0%4.5%6.0%7.5%9.0%10.5%12.0%13.5%15.0%

CO (ppm) % COHb

HETA 2002-0393, Lake H

EMS/fire, West Channel, ele

0

100200300400500600700800900

1000

10:00

10:45

11:30

12:15

13:00

13:45

14:30

Time (hr:m

Concentration

(parts per million)

CO (ppm) 
Health Hazard Evaluation Report No. 2002-0393-2928 Page 43 

Figures 62-65 (L to R). Real-time CO Concentration Readings and Estimated %COHb Levels on May 25, 2003 at Lake Havasu, Arizona 

HETA 2002-0393, Lake Havasu, ID 133

EMS/fire, on the lake, on fire boat

0

100200300400500600700800900

1000

9:15

10:00

10:45

11:30

12:15

13:00

13:45

14:30

15:15

16:00

16:45

17:30

18:15

19:00

19:45

Time (hr:min)

Concentration

(parts per million)

0.0%1.5%3.0%4.5%6.0%7.5%9.0%10.5%12.0%13.5%15.0%

CO (ppm) % COHb

HETA 2002-0393, Lake H

EMS/fire, West Channel, on e

0

100200300400500600700800900

1000

10:00

10:45

11:30

12:15

13:00

13:45

14:30

Time (hr:m

Concentration

(parts per million)

CO (ppm) 

HETA 2002-0393, Lake Havasu, ID 140

EMS/fire, Thompson Bay, on fire boat

0

100200300400500600700800900

1000

9:15

10:00

10:45

11:30

12:15

13:00

13:45

14:30

15:15

16:00

16:45

17:30

18:15

19:00

19:45

Time (hr:min)

Concentration

(parts per million)

0.0%1.5%3.0%4.5%6.0%7.5%9.0%10.5%12.0%13.5%15.0%

CO (ppm) % COHb

HETA 2002-0393, Lake H

EMS/fire, Thompson Bay, 

0

100200300400500600700800900

1000

9:15

10:00

10:45

11:30

12:15

13:00

13:45

14:30

1

Time (hr:m

Concentration

(parts per million)

CO (ppm) 
Page 44 Health Hazard Evaluation Report No. 2002-0393-2928 

Figures 66-68 (L to R). Real-time CO Concentration Readings and Estimated %COHb Levels on May 25, 2003 at Lake Havasu, Arizona 

HETA 2002-0393, Lak

GA, in channel, Boat 

0

100200300400500600700800900

1000

10:45

11:30

12:15

13:00

13:45

14:30

15:15

16

Time (hr:

Concentration

(parts per million)

Peak 1053 ppm

HETA 2002-0393, Lake Havasu, ID 142

EMS/fire, East Channel, on electric golf cart

0

100200300400500600700800900

1000

9:45

10:30

11:15

12:00

12:45

13:30

14:15

15:00

15:45

16:30

17:15

18:00

18:45

19:30

Time (hr:min)

Concentration

(parts per million)

0.0%1.5%3.0%4.5%6.0%7.5%9.0%10.5%12.0%13.5%15.0%

CO (ppm) % COHb
Health Hazard Evaluation Report No. 2002-0393-2928 Page 45 

May 26, 2003 Figures 69-72 (L to R). Real-time CO Concentration Readings and Estimated %COHb Levels on May 26, 2003 at Lake Havasu, Arizona 

HETA 2002-0393, Lake Havasu, ID 104

Police, East Channel, on gas-powered golf cart

0

100200300400500600700800900

1000

9:30

9:45

10:00

10:15

10:30

10:45

11:00

11:15

11:30

11:45

12:00

12:15

12:30

12:45

13:00

13:15

13:30

13:45

14:00

Time (hr:min)

Concentration

(parts per million)

0.0%1.5%3.0%4.5%6.0%7.5%9.0%10.5%12.0%13.5%15.0%

CO (ppm) % COHb

HETA 2002-0393, Lake H

Police, East Channel, on gas-p

0

100200300400500600700800900

1000

9:45

10:00

10:15

10:30

10:45

11:00

11:15

11:30

11:45

12:00

Time (hr:m

Concentration

(parts per million)

CO (ppm) 

HETA 2002-0393, Lake Havasu, ID 107

Police, in channel, on Boat #2196

0

100200300400500600700800900

1000

9:15

9:45

10:15

10:45

11:15

11:45

12:15

12:45

13:15

13:45

14:15

14:45

15:15

15:45

16:15

Time (hr:min)

Concentration

(parts per million)

0.0%1.5%3.0%4.5%6.0%7.5%9.0%10.5%12.0%13.5%15.0%

CO (ppm) % COHb

CO monitor off at 16:39

Post shift @ 14:03

HETA 2002-0393, Lake H

Police, East Channel, Boo

0

100200300400500600700800900

1000

9:15

9:45

10:15

10:45

11:15

11:45

12:15

Time (hr:m

Concentration

(parts per million)

CO (ppm) 
Page 46 Health Hazard Evaluation Report No. 2002-0393-2928 

Figures 73-76 (L to R). Real-time CO Concentration Readings and Estimated %COHb Levels on May 26, 2003 at Lake Havasu, Arizona 

HETA 2002-0393, Lake Havasu, ID 114

Police, West Channel, Booking Station,

on Boat #2196

0

100200300400500600700800900

1000

9:30

10:00

10:30

11:00

11:30

12:00

12:30

13:00

13:30

14:00

14:30

15:00

15:30

Time (hr:min)

Concentration

(parts per million)

0.0%1.5%3.0%4.5%6.0%7.5%9.0%10.5%12.0%13.5%15.0%

CO (ppm) % COHb

HETA 2002-0393, Lake H

Police, West Channel, ot

0

100200300400500600700800900

1000

9:45

10:00

10:15

10:30

10:45

11:00

11:15

11:30

11:45

12:00

12

Time (hr:m

Concentration

(parts per million)

CO (ppm) 

HETA 2002-0393, Lake Havasu, ID 121

Police, West Channel, on gas-powered quad

0

100200300400500600700800900

1000

9:45

10:15

10:45

11:15

11:45

12:15

12:45

13:15

13:45

14:15

14:45

15:15

Time (hr:min)

Concentration

(parts per million)

0.0%1.5%3.0%4.5%6.0%7.5%9.0%10.5%12.0%13.5%15.0%

CO (ppm) % COHb

HETA 2002-0393, Lake H

Police, in channel, on B

0

100200300400500600700800900

1000

9:45

10:15

10:45

11:15

11:45

12:15

12:45

Time (hr:m

Concentration

(parts per million)

CO (ppm) 
Health Hazard Evaluation Report No. 2002-0393-2928 Page 47 

Figures 77-80 (L to R). Real-time CO Concentration Readings and Estimated %COHb Levels on May 26, 2003 at Lake Havasu, Arizona 

HETA 2002-0393, Lake Havasu, ID 123

Police, West Channel, on gas-powered golf cart

0

100200300400500600700800900

1000

9:15

9:45

10:15

10:45

11:15

11:45

12:15

12:45

13:15

13:45

14:15

14:45

15:15

Time (hr:min)

Concentration

(parts per million)

0.0%1.5%3.0%4.5%6.0%7.5%9.0%10.5%12.0%13.5%15.0%

CO (ppm) % COHb

HETA 2002-0393, Lake H

Police, West Channel, on gas

0

100200300400500600700800900

1000

9:45

10:15

10:45

11:15

11:45

12:15

12:4

Time (hr:m

Concentration

(parts per million)

CO (ppm) 

HETA 2002-0393, Lake Havasu, ID 125

Police, East Channel, on gas-powered quad

0

100200300400500600700800900

1000

9:15

9:45

10:15

10:45

11:15

11:45

12:15

12:45

13:15

13:45

Time (hr:min)

Concentration

(parts per million)

0.0%1.5%3.0%4.5%6.0%7.5%9.0%10.5%12.0%13.5%15.0%

CO (ppm) % COHb

HETA 2002-0393, Lake H

Police, West Channel, on gas-p

0

100200300400500600700800900

1000

9:45

10:15

10:45

11:15

11:45

12:15

12:45

Time (hr:m

Concentration

(parts per million)

CO (ppm) 
Page 48 Health Hazard Evaluation Report No. 2002-0393-2928 

Figures 81-84 (L to R). Real-time CO Concentration Readings and Estimated %COHb Levels on May 26, 2003 at Lake Havasu, Arizona 

HETA 2002-0393, Lake H

Police, in channel, on B

0

100200300400500600700800900

1000

9:00

9:30

10:00

10:30

11:00

11:30

12:0

Time (hr:

Concentration

(parts per million) No COHb Dat

HETA 2002-0393, Lak

GA, East Channel Bookin

0

100200300400500600700800900

1000

11:30

11:45

12:00

12:15

12:30

12:45

13:00

13:1

Time (hr:

Concentration

(parts per million)

HETA 2002-0393, Lake Havasu, ID 127

Police, in channel, on Boat #2079

0

100200300400500600700800900

1000

9:00

9:30

10:00

10:30

11:00

11:30

12:00

12:30

13:00

13:30

14:00

14:30

Time (hr:min)

Concentration

(parts per million)

0.0%1.5%3.0%4.5%6.0%7.5%9.0%10.5%12.0%13.5%15.0%

CO (ppm) % COHb

HETA 2002-0393, Lake Havasu, ID 129

Police, East Channel, on gas-powered quad

0

100200300400500600700800900

1000

9:30

9:45

10:00

10:15

10:30

10:45

11:00

11:15

11:30

11:45

12:00

12:15

12:30

12:45

13:00

13:15

13:30

13:45

14:00

Time (hr:min)

Concentration

(parts per million)

0.0%1.5%3.0%4.5%6.0%7.5%9.0%10.5%12.0%13.5%15.0%

CO (ppm) % COHb
Health Hazard Evaluation Report No. 2002-0393-2928 Page 49 

Figure 85. Real-time CO Concentration Readings and Estimated %COHb Levels on May 26, 2003 at Lake Havasu, Arizona 

HETA 2002-0393, Lake Havasu

GA, West Channel Booking Station

0

100200300400500600700800900

1000

11:00

11:15

11:30

11:45

12:00

12:15

12:30

12:45

13:00

13:15

13:30

13:45

14:00

14:15

14:30

Time (hr:min)

Concentration

(parts per million)
Page 50 Health Hazard Evaluation Report No. 2002-0393-2928 

APPENDICES

Appendix A. 2002 Labor Day Weekend Interim Report 
Health Hazard Evaluation Report No. 2002-0393-2928 Page 51 

Appendix A. 2002 Labor Day Weekend Interim Report 
Page 52 Health Hazard Evaluation Report No. 2002-0393-2928 

Appendix A. 2002 Labor Day Weekend Interim Report 
Health Hazard Evaluation Report No. 2002-0393-2928 Page 53 

Appendix A. 2002 Labor Day Weekend Interim Report 
Page 54 Health Hazard Evaluation Report No. 2002-0393-2928 

Appendix A. 2002 Labor Day Weekend Interim Report 
Health Hazard Evaluation Report No. 2002-0393-2928 Page 55 

Appendix A. 2002 Labor Day Weekend Interim Report 
Page 56 Health Hazard Evaluation Report No. 2002-0393-2928 

Appendix A. 2002 Labor Day Weekend Interim Report 
Health Hazard Evaluation Report No. 2002-0393-2928 Page 57 

Appendix A. 2002 Labor Day Weekend Interim Report 
Page 58 Health Hazard Evaluation Report No. 2002-0393-2928 

Appendix A. 2002 Labor Day Weekend Interim Report 
Health Hazard Evaluation Report No. 2002-0393-2928 Page 59 

Appendix A. 2002 Labor Day Weekend Interim Report 
Page 60 Health Hazard Evaluation Report No. 2002-0393-2928 

Appendix B. AZ Department of Health Services CO Study 
Health Hazard Evaluation Report No. 2002-0393-2928 Page 61 

Appendix B. AZ Department of Health Services CO Study 
Page 62 Health Hazard Evaluation Report No. 2002-0393-2928 

Appendix B. AZ Department of Health Services CO Study 
Health Hazard Evaluation Report No. 2002-0393-2928 Page 63 

Appendix B. AZ Department of Health Services CO Study 
Page 64 Health Hazard Evaluation Report No. 2002-0393-2928 

Appendix B. AZ Department of Health Services CO Study 
Health Hazard Evaluation Report No. 2002-0393-2928 Page 65 

Appendix B. AZ Department of Health Services CO Study 
Page 66 Health Hazard Evaluation Report No. 2002-0393-2928 

Appendix B. AZ Department of Health Services CO Study 
Health Hazard Evaluation Report No. 2002-0393-2928 Page 67 

Appendix B. AZ Department of Health Services CO Study 
Page 68 Health Hazard Evaluation Report No. 2002-0393-2928 

Appendix C. Volatile Organic Compounds 
Health Hazard Evaluation Report No. 2002-0393-2928 Page 69 

Appendix C. Volatile Organic Compounds 
Page 70 Health Hazard Evaluation Report No. 2002-0393-2928 

Appendix C. Volatile Organic Compounds 
Health Hazard Evaluation Report No. 2002-0393-2928 Page 71 

Appendix C. Volatile Organic Compounds 
Page 72 Health Hazard Evaluation Report No. 2002-0393-2928 

Appendix C. Volatile Organic Compounds 
Health Hazard Evaluation Report No. 2002-0393-2928 Page 73 

Appendix C. Volatile Organic Compounds 
Page 74 Health Hazard Evaluation Report No. 2002-0393-2928 

Appendix C. Volatile Organic Compounds 
Health Hazard Evaluation Report No. 2002-0393-2928 Page 75 

Appendix C. Volatile Organic Compounds 
Page 76 Health Hazard Evaluation Report No. 2002-0393-2928 

Appendix C. Volatile Organic Compounds 
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