PREPUBUCATIQN
COPY
NIOSH •CDPHE • CPSC • OSHA • EPA
SEPTEMBER 1996
Preventing Carbon Monoxide Poisoning
from Small Gasoline-Powered
and Tools
U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES
Public Health S«rvlc«
Centers for Disease Control and Prevention
National Institute for Occupational Safety and Health
-------
-------
DISCLAIMER
Mention of any company or product does not constitute endorsement by the National
Institute for Occupational Safety and Health, the Colorado Department of Public Health
and Environment, the Consumer Product Safety Commission, the Occupational Safety
and Health Administration, or the U.S. Environmental Protection Agency.
This document is in the public domain and may be freely copied or reprinted.
Copies of this and other documents are available from
Publications Dissemination, EID
National Institute for Occupational Safety and Health
4676 Columbia Parkway
Cincinnati, OH 45226-1998
Fax number (513) 533-8573
Telephone number: 1-800-3S-NIOSH (1-800-356-4674)
E-mail: pubstaft@niodst1.em.cdc.gov
To receive other information about occupational safety and health problems, call
1-800-35-NIOSH (1-800-356-4674), or visit the NIOSH Home Page on the
World Wide Web at http^/www.cdc.gov/niosh/homepage.html
DHHS (NIOSH) Publication No. 96-118
ii • , - ' ' • ' ' ' •/'•'''•.•••-••'
-------
-------
PREFACE
This ALERT is the joint product of a combined effort among the following agencies:
• The National Institute for Occupational Safety and Health (NIOSH)
• The Colorado Department of Public Health and Environment (CDPHE)
• The U.S. Consumer Product Safety Commission (CPSC)
• The Occupational Safety and Health Administration (OSHA)
• The U.S. Environmental Protection Agency (EPA)
\ ' • ' . --•-'•_
Each agency has a unique role in protecting either workers/consumers or the general
public from health and safety hazards. Because of their common interest in prevention
of carbon monoxide (CO.) poisonings resulting from widespread use of small gasoline-
powered engines and tools in enclosed or confined spaces, the agencies elected to work
together to produce a joint document to address this problem and provide recommen-
dations for prevention. Such a combined effort avoids duplication and confusion from
multiple documents and promotes efficient use of government resources.
iii
-------
ACKNOWLEDGMENTS
Principal contributors to the development of this joint ALERT include:
• Janet J. Ehlers, Jane B. McCammon, Dennis O'Brien, G. Scott Earnest,
R. Leroy Mickelsen, Mary L. Woebkenberg, and Jerome P. Flesch (NIOSH)
• Allison Hawkes and Lyle McKenzie (CDPHE)
* • Elizabeth Leland (CPSCJ
• Edward Stein (OSHA)
• Richard Leukroth and John Girman (EPA)
Iv
-------
NIOSH • CDPHE • CPSC • OSHA • EPA
'! • ALERT
Preventing Carbon Monoxide Poisoning from
Small Gasoline-Powered Engines and Tools
WARNING!
Indoor use of gasoline-powered engines and tools is risky business.
Many people using gasoline-powered tools such as high-pressure washers, concrete
cutting saws (walk-behind/hand-held), power trowels, floor buffers, welders, pumps, com-
pressors, and generators in buildings or semi-enclosed spaces have been poisoned by
carbon monoxide (CO). CO can rapidly accumulate, even in areas that appear to be well
ventilated, and build up to dangerous and fatal concentrations within minutes. Examples
of such poisonings include the following:
A farm owner died of cd poisoning
while using an 11-horsepower gasoline-
powered pressure washer to clean his
bam. He had worked about 30 minutes
before being overcome.
A municipal employee at ah indoor water
treatment plant lost consciousness while
trying to exit a 59,000-cubic-fopt room
where he had been working with an
8-horsepower, gasoline-powered pump.
Doors adjacent to the work area were
open while he worked. His hpspital
diagnosis was CO poisoning.
Five workers were treated for CO poi-
soning after using two 8-horse-power
gasoline-powered, pressure washers in
a poorly ventilated underground parking
garage.
f
A plumber used. a gasoline-powered
concrete saw in a basement with open
doors and windows and a cooling fan.
He experienced a severe headache
and dizziness and began to act in a
paranoid manner. His symptoms were
related to CO poisoning.
These examples show a range of effects caused by CO poisoning in a variety of work
settings with exposures that occurred over different time periods and with different types
of ventilation. Workers in areas with closed doors and windows were incapacitated within
minutes. Opening doors and windows or operating fans does NOT guarantee safety. CO
is a dangerous poison. Operating gasoline-powered engines and tools indoors is RISKY
BUSINESS, : -
Please distribute copies to users.
-------
RECOMMENDATIONS
It is not widely known that small gasoline-powered engines and tools present a serious
health hazard. They produce high concentrations of carbon monoxide, a poisonous gas
that can cause illness, permanent neurological damage, and death. Because it is
colorless, odorless and nonirritating, CO can overcome exposed persons without warn-
ing. Often there is little time before a person experiences symptoms that inhibit their
ability to seek safety. Prior use of equipment without incident has sometimes given users
a false sense of safety; such users have been poisoned on subsequent occasions.
Recommendations for preventing CO poisoning are provided below for employers
equipment users, tool rental agencies, and tool manufacturers.
All Employers and Equipment Users:
• Do NOT allow the use of or operate
gasoline-powered engines or tools
Inside buildings or in partially enclosed
areas unless gasoline engines can be
located outside away from air intakes.
Use of gasoline-powered tools indoors
where CO from the engine can accumu-
late can be fatal.-
An exception to this rule might be an
emergency rescue situation where other
options are not available, and then only
when equipment operators, assisting
personnel and the victim are provided
with supplied-air respirators.
• Learn to recognize the. symptoms and
signs of CO overexposure: headache,
nausea, weakness, dizziness, visual
disturbances, changes in personality,
and loss of consciousness. Any of these
symptoms and signs can occur within
minutes of usage.
• Always place the pump and power unit
of high-pressure washers outdoors so
. that engine exhaust is not drawn in-
doors where the work is being done.
Run only the high-pressure wash line
inside.
• Consider the use of tools powered by
electricity or compressed air if they are .
available and can be used safely. For
example, electric-powered tools present
an electrocution hazard and require
specific precautions for safety.
• If compressed air is used, place the
gasoline-powered compressor out-
doors away from air intakes so that
engine exhaust is not drawn indoors
where the work is being done.
• Where potential sources of CO exist,
use personal CO monitors equipped
with audible alarms to warn workers
when CO concentrations are too high.
Employers Should Also:
« Conduct a workplace survey to identify all
potential sources of CO exposure.
• Educate workers about the sources and
conditions that may result in CO poison-
ing as well as the symptoms and control
of CO exposure.
• Always substitute less hazardous
equipment whenever possible, or use
equipment that allows for the placement of
-------
gasoline-powered engines outdoors at
a safe distance from air entering the
building. .•
• Monitor employee CO exposure to de-
termine the extent of the hazard.
Equipment Users Should Also:
• Substitute less hazardous equipment
whenever possible. Use electric tools or
tools with engines that are separate
from the tool for placement outdoors.
• Leam to recognize the warning symp-
toms of CO poisoning.
• If you have any symptoms, immediately
turn off equipment and go outdoors or
to a place with uncontaminated air.
• Call 911 or another local emergency
number for medical attention or assis-
tance if symptoms occur. Do NOT drive
a motor vehicle—get someone else to
drive you to a health care facility.
• Not return to the work area until the tool
has been deactivated and measured
CO concentrations are below accepted
guidelines and standards.
I - - V
• Watch coworkers for the signs of CO
toxicity.
Tool Rental Agencies Should:
• Put warning labels on gasoline-powered
tools—for example: WARNING
—CARBON MONOXIDE PRODUCED
DURING USE CAN KILL—DO NOT
USE INDOORS OR IN OTHER SHEL-
TERED AREAS.
t
Tell renters that gasoline-powered tools
should NOT be used indoors and ex-
plain why.
Recommend safer tools for intended
use, if available.
Have portable, audible .CO monitors for
rent and encourage the use of them.
Provide renters with educational mate-
rials like this information sheet.
Tool Manufacturers Should:
• Design tools that can be used safely
indoors.
• Provide warning labels for existing and
new gasoline-powered equipment—for
example: WARNING—CARBON
MONOXIDE PRODUCED DURING
USE CAN KILL—DO NOT USE IN-
DOORS OR IN OTHER SHELTERED
AREAS.
• Provide recommendations on equip-
ment maintenance to reduce CO
emissions.
• Recommend the use of portable, audi-
ble CO monitors with small gasoline-
powered engines.
-------
FOR MORE INFORMATION
For additional information, see ALERT: Preventing Carbon Monoxide Poisoning from
Small Gasoline-Powered Engines and Tools [DHHS (NIOSH) Publication No 96-118]
Single copies of the Alert are available free from the following:
"' / •
Publications Dissemination, EID
National Institute for Occupational Safety and Health
4676 Columbia Parkway
Cincinnati, OH 45226
Fax number: (513) 533-8573
Phone number: 1-800-35-NIOSH (1-800-356-4674)
E-mail: pubstaft@rtiosdt1.em.cdc.gov
This Alert is the joint product of a combined effort among the following agencies:
• The National Institute for Occupational Safety and Health (NIOSH)
• The Colorado Department of Public Health and Environment (CDPHE)
* The U*S* Consumer Product Safety Commission (CPSC)
• The Occupational Safety and Health Administration (OSHA)
• The U.S. Environmental Protection Agency (EPA)
DHHS (NIOSH) Publication No. 96-118a
-------
NIOSH • CDPHE • CPSC • OSHA • EPA -'•-!
\ ALERT!
Preventing Carbon Monoxide Poisoning from
Small Gasoline-Powered Engines and Tools
WARNING!
Do not use equipment and tools powered by gasoline engines inside
buildings or other partially enclosed spaces unless the gasoline engine can
be placed outdoors away from air intakes.
Hundreds of people performing many different tasks have been poisoned because small
gasoline-powered engines and tools produced hazardous concentrations of carbon
monoxide (CO) even in relatively open buildings:
• In December"! 992, a farm owner found his 12-year-old son unconscious near the
door of a swine farrowing building (birthing barn) in Iowa. The boy had been
working alone, using an 11 -horsepower, gasoline-powered pressure washer for
about 1/2 hour to clean the building. '
• In January 1993, a 33-year-old farm owner in Iowa died of carbon monoxide
poisoning while using an 11 -horsepower, gasoline-powered pressure washer to
clean his swine farrowing barn. He had worked about Vz hour before being
overcome. ' ,
• In January 1993, a 60-year-old drywall finisher in Colorado collapsed and fell from
the scaffold on which he was standing. He was using a small gasoline-powered
compressor to apply a textured surface to a cathedral ceiling in a house. Although
he landed on a balcony below, escaping further injury, he was confused and
unable to identify an escape route from the building. He was rescued by coworkers
who saw him beckoning for help at the patio door.
• In February 1993, a 30-year-old plumber in Colorado developed a severe head-
ache and dizziness, and began to demonstrate paranoid behavior which was later
diagnosed as CO poisoning. He had worked for 2 to 3 hours using a gasoline-
powered concrete cutter to access pipes in a basement. He and his supervi-
sor anticipated possible problems related to the exhaust from this equipment and
had set up what they considered to be adequate ventilation (opened doors and
windows, placed cooling fans near the cutter and farther down the hall).
Carbon Monoxide Poisoning
-------
• In June 1994, five workers in Washington, D.C., who experienced dizziness,
confusion, headaches, and nervousness were treated for CO poisoning after
using two 8-horsepower, gasoline-powered pressure washers for 4 hours in an
empty, poorly ventilated, underground parking garage. When one of the five
workers collapsed at the worksite, coworkers carried him outside, remained with
him for a short time and then, unaware of the hazard, re-entered the hazardous
worksite. Only after a second worker collapsed did workers recognize the hazard,
evacuate the environment, and seek help.
• In October 1994, a 37-year-old municipal employee at an indoor water treatment
facility in Colorado lost consciousness while trying to exit a 59,000 cubic foot room
where he had been working with an 8-horsepower, gasoline-powered water pump
for4 hours.
• In December 1994, a previously healthy 59-year-old owner/operator of a flooring
installation business in Colorado experienced headache and dizziness after
working for 2!& hours in the stairwell of a building containing a gasoline-powered
generator supplying power to the construction site. He left the building and rested
in his car. Upon returning to the stairwell, he collapsed in a grand mal seizure
related to CO poisoning.
These are examples of the many situations in which people have been poisoned because
they did not recognize the danger of using small gasoline-powered engines indoors.
These poisoninqs can occur quickly, even in the presence of what many would consider
"adequate ventilation" and in areas that many would define as relatively open spaces
such as parking garages.
HEALTH EFFECTS
CO is a lethal poison that is produced when fuels such as gasoline are burned. It is one
of many chemicals found in engine exhaust, and can rapidly accumulate even in areas
that might appear to be well ventilated. Because CO is colorless, tasteless, odorless,
and nonirritating, it can overcome the exposed person without warning. It produces
weakness and confusion, depriving the person of the ability to seek safety.
"\
CO poisons primarily by tightly binding to hemoglobin in the blood (forming carbox^-
hemoglobin), replacing oxygen, and reducing the oxygen-carrying capacity of the blood.
CO may also poison by binding to tissues and cells of the human body and interfering
with their normal function. Persons with pre-existing heart disease are at increased risk.
Fetuses of pregnant women are also at increased risk—especially when mothers are
exposed to high CO levels. Recognizing early warning signs of CO poisoning is
sometimes difficult because early symptoms of CO exposure (headache, dizziness, and
nausea) are nonspecific and may be mistaken for symptoms of other illnesses such as
colds, flu, or food poisoning. Confusion and weakness can inhibit a person's ability to
escape the hazardous environment.
Carbon Monoxide Poisoning
-------
The severity of symptoms of CO exposure is influenced by three main factors- (1) the
concentration of CO in the environment; (2) how long the exposure lasts; and (3) work
load and breathing rate. In general, assuming that users of gasoline-powered engines
are engaged in at least a moderate level of activity, exposure to CO concentrations of
80-100 parts per million (ppm) for 1 to 2 hours can result in decreased exercise tolerance
and, in persons who are at risk, may bring on chest pain and cause irregular heartbeat
[EPA 1991 a]. Symptoms associated with CO exposure concentrations of 100 to 200 ppm
include headache, nausea, and mental impairment. More serious central nervous system
effects, coma, and death are associated with CO exposure concentrations of 700 ppm
or greater for an hour or more [llano and Raffin 1990; Forbes et al. 1945]. Symptoms of
nervous system effects include staggering, confusion, changes in personality, and
muscle aches. These symptoms may continue or.occur for several days to several weeks
after the exposure stops and the poisoned person has apparently recovered. Victims of
CO poisoning should be immediately removed from the exposure site and given 100%
oxygen. Hyperbaric chambers provide oxygen under pressure and are sometimes
necessary in cases of serious CO poisoning.
CURRENT STANDARDS AND RECOMMENDED GUIDELINES
Organizations set standards of make recommendations for exposure to hazardous
substances based on assumptions inherent to their regulatory oversight or authority
Differences in the stated values reflect variations in the place, duration, characteristics
of the population, or proposed use.
Workplace/Industry .
the current Occupational Safety and Health Administration (OSHA) permissible expo-
sure limit (PEL) for carbon monoxide is 50 ppm as an 8-hr time-weighted average (TWA)
[29 CFR 1910.1000*]. The NIOSH recommended exposure limit (REL) for CO is 35 ppm
TWA and a ceiling limit (CL) of 200 ppm [NIOSH 1992]. The NIOSH recommended
immediately dangerous to. life and health concentration (1DLH) for CO is 1,200 ppm.
The IDLH is the concentration which could result in death or irreversible health effects,
or prevent escape from the contaminated environment within 30 minutes. The American
Conference of Governmental Industrial Hygienists (ACGIH) has adopted a threshold limit
value (TLV) for CO of 25 ppm TWA [ACGIH 1992a].
Ambient Air/Residential Settings
The U.S. Environmental Protection Agency (EPA) has established an ambient (outdoor)
CO air quality Federal standard off 9 ppm for an 8-hr exposure and 25 ppm for short-term
(1-hr) exposure [EPA 1991 a]. The Consumer Product Safety Commission (CPSC) staff
recommends that long-term exposures to CO in indoor environments be limited to
less than 15 ppm as an 8-hr TWA and 25 ppm for 1 hr, but product-specific recommen-
dations for CO may vary depending on expected usage patterns and exposure.
•Coda of Federal Regulations. See CFR in references.
Carbon Monoxide Poisonfna
,3
-------
DATA SUMMARIZING CO POISONINGS
Illness related to CO exposure is probably underestimated because workers with mild
symptoms may go untreated or medical providers may not recognize their symptoms as
CO poisoning. In addition, persons may not recognize the cause of their symptoms
unless coworkers and other persons become ill at the same time.
Two surveys assessing individuals' beliefs,' knowledge, and risk perceptions regarding
CO suggest that many people are unaware of the hazards associated with CO. In 1993,
NIOSH assessed flood victims' risk perceptions associated with CO poisoning from using
equipment powered by small engines (e.g., gasoline-powered pressure washers indoors
to cleanup flood-related debris) [Greife et al. 1995]. Many of the 4.16 respondents (26%)
incorrectly believed that with only a window open, the use of a gasoline-powered engine
indoors would be safe. A majority of respondents (54%) and 92% of respondents
between the ages 12 and 20, incorrectly believed that it was safe to operate a gasoline-
powered engine indoors with windows and doors open and an exhaust fan running. In a
second survey, during follow-up investigations of nonfatal, unintentional CO poisoning
in residential settings in Connecticut between November 1993 and March 1994, inves-
tigators interviewed 36 victims or their adult representatives [CDC 1995b]. Many of the
victims of CO poisoning (poisoning was related to heating systems, .gas appliances, and
fireplaces) still demonstrated a lack of knowledge about prevention strategies. When
asked to list prevention methods, 14% were unable to list any method, 44% listed
appropriate maintenance of appliances, 30% listed the use of a CO detector, and 14%
listed proper ventilation. .
Reports from a number of sources show CO poisoning from the use of gasoline-powered
tools indoors happens frequently:
• OHNAC: The NIOSH-sponsored Occupational Health Nurses in Agricultural
Communities (OHNAC) Surveillance Program identified 18 cases of CO poisoning
related to the use of small engines; 17 cases occurred in less than 3 years
[CDC 1993; Ehlers 1994]. Although only one case was a fatality, at least three
cases could have been fatal had the victims not been found by coworkers or family
members, removed from the hazardous environment, and taken for medical
care. At least four were overcome in about Vz hour. Persons working in open
environments (e.g., doors and windows open and exhaust fans operating) began
developing symptoms in as little as 1 hour of constant work or as much as 7 hours
of intermittent exposure. All interviewed persons reported being unaware that they
could be poisoned in a short time and that CO can attain hazardous levels inside
buildings with windows and doors open. Several victims, although appearing
obviously confused and ill to family members at the worksite, were unaware of
their impaired condition and sought medical help only at the Insistence of family
members. Seven of the 18 incidents occurred among Iowa farmers using pressure
washers to clean animal housing between January 1992 and March 1994. Of the
other 11 cases, 7 occurred while using pressure washers to clean animal housing
Carbon Monoxide Poisoning
-------
elsewhere or in other years, and 4 occurred while using gasoline-powered
pressure washers or concrete saws to clean up after floods.
Colorado Department of Public Health and Environment (CDPHE): In Colorado,
40% (135) of all work-related, CO poisonings reported to CDPHE since 1985
have been related to the use of gasoline-powered equipment [CDPHE 1996].
Other sources of exposure associated with reported occupational poisonings in
Colorado include automobile exhaust (25% of poisonings) and furnaces (12%).
Seventeen of the 135 workers poisoned by gasoline-powered equipment lost
consciousness during their exposure to emissions and two workers died. The
135 poisonings were primarily caused by concrete cutting saws (28 workers),
power trowels (15 workers), high pressure washers (14 workers), compressors
(10 workers), welding equipment (9 workers), and floor buffers (9 workers). Other
equipment causing poisonings included jackhammers, pumps, carpet cleaners,
and paint sprayers. Information about where the 135 poisoned workers were using
gasoline-pbwered equipment was available in 115 incidences; 110 of these 115
(96%) poisonings occurred indoors.
George Washington University (GWU): Seven worker poisonings related to the
emissions from gasoline-powered tools used indoors have also been identified
by the GWU Emergency Department Surveillance Project. Five of these poison-
ings occurred in June 1994 and were discussed above (workers using a pressure
washer in an empty underground parking garage) [CDC 1995a]. Two additional
workers were poisoned while using gasoline-powered saws.
California: A study of all death certificates in the State of California during the
10-year period from 1979-88 showed 444 deaths due to unintentional carbon
monoxide poisoning [CDHS 1993]. Of these deaths, 23 (5%) were caused, by
small engine exhaust.
• National Estimates: There is no complete U.S. database for this problem.
According to the U.S. Bureau of Labor Statistics (BLS) there were hearty 900
work-related CO poisonings resulting in death or illness in private industry in the
United States in 1992 (32 deaths and 867 nonfatal poisonings) [BLS 1992a,b].
CPSC estimates that in 1992, the latest year for which data are available, there
were 212 carbon monoxide deaths associated with the use of household fuel-
burning appliances. Thirteen of these deaths were reported to have involved the
use of gasoline-powered appliances [NCHS/CPSC1992]. In 1994, the latest year
for which data are available, CPSC estimates that 3,900 carbon monoxide injury
incidents occurred where an average of two to three persons per incident were
treated in hospital emergency rooms. Of these 3,900 incidents, approximately
400 incidents were associated with the use of gasoline-powered appliances
[CPSC 1994]. ;
Carbon Monoxide Polsonfna - 5
-------
ENVIRONMENTAL MEASUREMENTS AND MODELING DOCUMENT
RAPID CO BUILDUP
Three of the above groups measured CO concentrations after the CO poisoning incidents
in the same or similar exposure situations to estimate how quickly dangerous CO
concentrations developed. A fourth group modeled the time to reach dangerous CO
concentrations. .
• OHNAC: NIOSH measured the generation of CO by a gasoline-powered pressure
(GPP) washer using a 5.5 horsepower (hp) engine under environmental condi-
tions comparable to those experienced by the farmers using pressure washers
described in this report [Venable et al. 1995]. A 5.5 hp GPP washer was operated-
inside a double-car garaoe, 8,360 ft3 building (range in cases: 3,420 ft3 to 10,080 ft3)
using two ventilation scenarios. In the first or "worst case" scenario, .all doors,
windows and vents were closed; breathing zone concentrations of CO reached
200 ppm in 5 minutes, 1,200 ppm (IDLH value) within 15 minutes and continued
to increase above 1,500 ppm in 19 minutes. In the second or "best case" scenario,
the two double-car garage doo.rs and one window were all left open and the
vent unsealed; breathing zone concentrations of CO reached 200 ppm within
3 minutes and peaked at 658 ppm within 12 minutes. The results from the
simulations indicate that acutely toxic concentrations of CO greater than 200 ppm
(NIOSH ceiling) can be quickly generated within 3 to 5 minutes near a pressure
washer operated indoors, even when passive ventilation is provided and IDLH
concentrations of 1,200 ppm can be generated rapidly in enclosed spaces.
• CDPHE: The Colorado Department of Public Health and Environment measured
or recreated exposures in four poisonings related to the use of gasoline-powered
tools indoors [CDPHE 1996].
First, CDPHE attempted to estimate the CO exposure of the drywall texturizer
discussed earlier by sampling the air at another construction site where he was
doing similar work. On the day of. the air sampling, the gasoline-powered com-
pressor was placed just outside the garage door. Because of the way that the
equipment was designed and oriented, exhaust from the engine on the compres-
sor went directly into the house when the garage door was open. As is usual for
this operation, all windows and external doors in the home had been closed and
sealed with tape and paper to protect the surfaces from the texturing material and
maintain the proper conditions for drying. The concentration of CO at the tailpipe
of the compressor engine was substantially greater than 1,000 ppm (this
was the upper limit of the testing equipment). Within the first 20 minutes of
•the operation, CO concentrations.as high as 410 ppm were measured in the
basement of the home, and as high as 322 ppm where the worker was standing.
CDPHE asked the worker to open the windows and external doors on the upper
floor of the duplex because of concerns about this concentration of exposure. CO
Carbon Monoxide Poisoning
-------
concentrations within the house dropped to approximately 30 ppm when that was
done, but this is not the way the process is usually carried out.
In response to the second incident, another GO poisoning related to the use of
an 8-horsepower pressure washer in a 30,000 cubic foot room of a municipal
construction project, CDPHE asked to run the_same pressure washer in the same
room a few days later; There was no mechanical ventilation in this room because
the facility was not yet operational. The pressure washer was placed approxi-
mately 15 feet from one comer of the room (the same place the worker had placed
it on the day of the poisoning). The power unit was an integral part of the
washer. Again, the CO concentration atthe engine exhaust pipe was greaierthan
1,000 ppm, the highest Concentration CDPHE could measure at the time. CDPHE
measured CO concentrations as high as 450 ppm at several locations in the
room within 20 minutes of activation of the washer engine, and 546 ppm
approximately 50 minutes after the washer engine was activated. The test was
then terminated. '
In a third incident, CDPHE asked the managers of the enclosed municipal water
.treatment plant to recreate the exposure situation encountered by the worker
mentioned before who was using the 8-horsepower pump in the 59,000 cubic foot
room (48 x 88 x 14 feet). This room was only partially enclosed so that employees
could observe operations in the room from the level above. Outside air was
introduced into the area through a forced-air heating system that was running on
the day of the poisoning and on the day of air sampling. External doors to the
treatment plant were opened on both days as well. Ten minutes after the pump
engine was started, CO concentrations as high as 395 ppm were measured within
7 feet of the pump, near where the employee was standing for much of the time
on the day of the poisoning. CO concentrations 25 feet from the water pump rose
to as high as 193 ppm during the 20-minute test. CDPHE returned to the room
one hour after the water pump was stopped and measured 40 ppm of CO.
Finally, in January 1996, two Colorado workers were poisoned as a result of
operating a gasolinerpowered, 5-horsepower, walk-behind concrete saw during
a remodeling project. The machine was three years old and used 2 to 3 times per
year. The workers operated the saw for about an hour and a half inside what had
previously been two bathrooms (the dividing wall had been removed, the area of
the room was 2,332 cubic feet). The workers were cutting a hole in the floor to
allow access to pipes below the floor. The two doors to the room were open and
the bathroom ventilation system was operating when these poisonings occurred.
The day after the poisonings occurred, the work in this bathroom was continued
with two differences. A cooling fan was used this time in an effort to better move
CO from the room, and the saw was operated for shorter periods of time (the
periods of operation were not clearly defined but were thought to be fifteen to
thirty minutes in duration). CDPHE recreated the second day's operating condi-
tions to measure CO concentrations in the room. The NIOSH ceiling limit of
200 ppm was exceeded within the first minute of operation. Within five minutes
Carbon Monoxide Poisoning 7
-------
of operation, the CO concentration within the room reached 842 ppm, at which
point the demonstration was discontinued (See Figure 1).
• GWU: In the poisoning incident where five workers were using pressure washers
in an underground garage, the Fire Department measured 648 pprn CO one hour
afterthe washers had been turned off (washers had been running forthree hours).
• NIOSH: NIOSH engineers modeled the time required for a gasoline-powered,
5 horsepower, 4-cycle engine to reach the 200 ppm (ceiling) and 1,200 ppm
immediately dangerous to life and health (IDLH) CO concentration for room sizes
of 1,000 to 100,000 ft3 and general ventilation rates of 1 to 20 air changes per
hour (ACH) [ACGIH 1992b]. The CO generation rate used in the model was
670 grams/hp-hr based on data from a 1991 EPA study [EPA 1991 b]. Ideal mixing
was assumed. Under .actual conditions, if mixing were poor, hazardous concen-
trations could develop more quickly. In the small 1,000 ft3 roorri, the ceiling
concentration of 200 ppm was reached in approximately 0.1 minute, and the IDLH
was reached in less than 1 minute at all air flow rates. In the medium 10,000 ft3
room, the IDLH was reached in approximately 7 minutes for 1 air change per hour
and approximately 10 minutes for 5 air changes per hour. These models demon-
strate that for rooms up to 10,000 ft3, the NIOSH ceiling limit of 200 ppm was
exceeded in less than 2 minutes even with general ventilation rates as high as
20 air changes per hour. In no case would it be possible to operate an engine for
8 hours without exceeding the NIOSH REL of 35 ppm. (See Figures 2 through 4).
CO Concentration versus time
(2,332 cubic foot room)
ENGINE STOPPED, (842 ppm)
Ceiling = 200 ppm
ENGINE STARTED
4 6 8 10 12 14
Time (minutes)
Figure 1. Actual CO concentration measured inside a 2,332 ft3 bathroom with a gasoline-powered 5 hp
concrete saw operating (doors open, cooling fan, and ventilation running).
8
Carbon Monoxide Poison'ma
-------
CO Concentration versus time
(I,pOO cubic foot room)
2,000
— 1ACH
-t-5ACH
-*-10 ACH
^-15 ACH
-*- 20 ACH
0.4 0.6 0.8
Time (minutes)
Figure 2. Calculated CO concentration generated by a 5 hp, 4-cycle gasoline-powered engine in a 1,000 ft3
room with various air changes per hour (ACH).
CO Concentration versus time
. (10,000 cubic foot room)
3,000
ACH
ACH
* 10 ACH
;"-15 ACH
^20 ACH
2 4
8 10 12 14 16 18
Time (minutes),
Figure 3. Calculated CO concentration generated by 5 hp, 4-cycie gasoline-powered engine in a 10,000 ft?
room with various air changes per hour (ACH).
Carbon Monoxide Poisoning
-------
CO Concentration versus time
(100,000 cubic foot room)
700
5 10 15 20 25 30 35 40 45 50
Time (minutes)
Figure 4. Calculated CO concentration generated by a 5 hp, 4-cyde gasoline-powered engine in a 100,000 ft?
room with various air changes per hour (ACH).
RECOMMENDATIONS
It is not widely known that small gasoline-powered engines and tools present a serious
health hazard. They produce high concentrations of carbon monoxide, a poisonous gas
that can cause illness, permanent neurological damage, and death. Because it is
colorless, odorless and nonirritating, CO can overcome exposed persons without warn-
ing. Often there is little time before a person experiences symptoms that inhibit their
ability to seek safety. Prior use of equipment without incident has sometimes given users
a false sense of safety; such.users have been poisoned on subsequent occasions.
Recommendations for preventing CO poisoning are provided below for employers,
equipment users, tool rental agencies, and tool manufacturers.
All Employers and Equipment Users:
• DO NOT allow the use of or operate gasoline-powered engines or tools inside
buildings or in partially-enclosed areas unless gasoline engines can be located
outside away from air intakes. Use of gasoline-powered tools indoors where CO
from the engine can accumulate can be fatal.
• An exception to this rule might be an emergency rescue situation where other
options are not available, and then only when equipment operators, assisting
personnel and the victim are provided with supplied-air respirators.
10
Carbon Monoxide Poisoning
-------
• Learn to recognize the signs and symptoms of CO overexposure: headache,
nausea, weakness, dizziness, visual disturbances, changes in personality, and
loss of consciousness. Any of these sighs and symptoms can occur within minutes
of usage.
• Always place the pump and power unit of high-pressure washers outdoors so that
engine exhaust is not drawn indoors where the work is being done. Run only the
high-pressure wash line inside.
^ • Consider the use of tools powered by electricity or compressed air if they are
available and can be used safely. For example, electric-powered tools present an
electrocution hazard,and require specific precautions for safety.
• If compressed air is used, place the gasoline-powered compressor outdoors away
from air intakes so that engine exhaust is not drawn indoors where the work is
being done. '
• Where potential sources of CO exist, use personal CO monitors equipped with
audible alarms to warn workers when CO concentrations ar,e too high. More
information on GO monitors is contained in the appendix.
Employers Should Also:
• Conduct a workplace survey to identify all potential sources of CO exposure.
••• Educate workers about the sources and conditions that may result in CO poison-
ing as well as the symptoms and control of CO exposure.
• Always substitute less hazardous equipment if possible. Use equipment that
allows for the placements gasoline-powered engines outdoors at a safe distance
from air entering the building.
• Monitor employee CO exposure to determine the extent of the hazard.
, "\
. .,...» ' • . • -..-._ • v
Equipment Users Should Also: .
• Substitute less hazardous equipment whenever possible. Use electric tools or
tools with engines that are separate from the tool for placement outdoors.
• Learn to recognize the warning symptoms of CO poisoning.
• If you have any symptoms, immediately turn off equipment and go outdoors or to
a place with uncontaminated air.
• ' • . . ••; ; ' y .- • - ,' .''.-.
Carbon Monoxide PoJsonfna 11
-------
• Call 911 or another local emergency number for medical attention or assistance
if symptoms occur. Do NOT drive a motor vehicle—get someone else to drive vou
to a health care facility.
• Not return to the work area until the tool has been deactivated and measured CO
concentrations are below accepted guidelines and standards.
• Watch coworkers for the signs of CO toxicity.
Tool Rental Agencies Should:
• Put warning labels on gasoline-powered tools—for example: WARNING-
CARBON MONOXIDE PRODUCED DURING USE CAN KILL—DO NOT USE
INDOORS OR IN OTHER SHELTERED AREAS.
• Tell renters that the tool should NOT be used indoors and why.
• Recommend safer tools for intended use, if available.
• Have portable, audible CO monitors for rent and encourage the use of them.
• Provide renters with educational materials like this information sheet.
•
Tool Manufacturers Should:
* * . • '
• Design tools that can be used safely indoors.
• Provide warning labels for existing and new gasoline-powered equipment—for
example: (WARNING—CARBON MONOXIDE PRODUCED DURING USE CAN
KILL—DO NOT USE INDOORS OR IN OTHER SHELTERED AREAS).
• Provide recommendations on equipment maintenance to reduce CO emissions.
• Recommend the use of portable, audible CO monitors with small gasoline-
powered engines.
DISTRIBUTION
NIOSH, CDPHE, CPSC, OSHA, and EPA request that the information in this ALERT be
brought to the attention of (1) aH employers and workers who use small gasoline-powered
engines and tools in their jobs and trades (e.g., building, construction, agriculture, and
maintenance and cleaning operations), (2) tool rental agencies and equipment sellers
and users, (3) tool manufacturers, and (41 editors of appropriate trade journals.
12 Carbon Monoxide Poisoning
-------
REFERENCES
ACGIH [1992a], 1992-1993 threshold limit values for chemical substances and physical
agents and biological exposure indices. Cincinnati, OH: American Conference of Gov-
ernmental Industrial Hygienists.
ACGIH [1992b]. Industrial ventilation—a manual of recommended practice. 21st ed^
Cincinnati, OH: American Conference of Governmental Industrial Hygienists Committee
on industrial ventilation, pp. 2-1 to 2-16. '
BLS [1992a]. Census of fatal occupational injuries. Washington, DC: U S Department
of Labor, Bureau of Labor Statistics. Unpublished data.
BLS [1992b]. Survey of occupational injuries and illnesses. Washington DC- U S
Department of Labor* Bureau of Labor Statistics. Unpublished data.
CDC (Centers for Disease Control and Prevention) [1993]. Unintentional carbon monox-
ide poisoning from indoor use of pressure washers—Iowa, January 1992-January 1993.
CDC (Centers for Disease Control and Prevention) [1995a]. Carbon monoxide poisoning
, from use of gasoline-fueled powered washers \n an underground parking garage-
District of Columbia, 1994. MMWR 44(18):356-357,363-364. • <
CDC (Centers for Disease Control and Prevention) [1995b]. Unintentional carbon mon-
oxide poisonings in residential settings—Connecticut, November 1993-March 1994
MMWR 44(41 ):765-767.
CDHS [1993]. Causes of unintentional deaths from carbon monoxide poisonings in
California. Sacramento, CA: California Health Services Department.
CDPHE [1996]. .Occupational carbon monoxide poisonings in Colorado. Denver, CO:
Colorado Department of Public Health and Environment. Unpublished data.
' • , . ' , \
CFR. Code of Federal Regulations. Washington, DC: U.S. Government Printing Office!
Office of the Federal Register.
CPSC [1994]; National electronic injury surveillance system. Washington, DC: Consumer
Product Safety Commission.
Ehlers J [1994]. Carbon monoxide poisoning among Iowa farmers while using gasoline-
powered washers—a case series. Cincinnati, OH: U.S. Department of Health and Human
Services, Public Health Service, Centers for Disease Control and Prevention, National
Institute for Occupational Safety and Health. Unpublished report.
Carbon Monoxide Poisoning 13
-------
EPA [1991 a]. Air quality criteria for carbon monoxide. Washington, DC: U S Environ-
mental Protection Agency, Office of Research and Development. Publication No
EPA-600/8-90/045F.
EPA [1991b]. Nonroad engine and .vehicle emission study—report. Washington. DC:
U.S. Environmental Protection Agency, Office of Air and Radiation. Publication No EPA
21A-2001. . • ~
Forbes WH, Sargent F, Foughton FJW [1945]. The rate of CO uptake by normal man
Am J Physiol 143:594-608. .
Greife A, Goldenhar LM, Freund E, Stock A, Hornung R, Cormon C, Halperin W [1995].
Risk perception of carbon monoxide poisoning from gasoline-powered engines among
midwest flood victims. Cincinnati, OH: U.S. Department of Health and Human Services,
Public Health Service, Centers for Disease Control and Prevention, National Institute for
Occupational Safety and Health. Unpublished report.
llano A, Raffin T [1990]. Management of carbon monoxide poisoning. Chest 97:165-9.
NCHS/CPSC [1992]. Death certificate file. Atlanta, GA: U.S. Department of Health and
Human Services, Public Health Service, Centers for Disease Control and Prevention,
National Center for Health Statistics, and Consumer Product Safety Commission.
NIOSH [1992]. NIOSH recommendations for occupational safety and health. Compendium
of policy documents and statements. Cincinnati, OH: U.S. Department of Health and
Human Services, Public Health Service, Centers for Disease Control and Prevention
National Institute for Occupational Safety and Health, DHHS (NIOSH) Publication No.
92-100.
Venable H, Wallingford K, Roberts D, Booher D £1995]. Simulated carbon monoxide
exposure in an enclosed structure from a gasoline-powered pressure v/asher. Appl
Occup Environ Hyg 70(7):581-584.
Carbon Monoxide Poisoning
-------
APPENDIX
Carbon Monoxide Monitors and Detectors
Detectors for carbon monoxide (CO) are manufactured and marketed for use in either
the home or occupational industrial settings/The detectors for home use are devices
which will sound an alarm before CO levels in the home become hazardous. There is an
Underwnters Laboratories, Inc. performance standard (UL 2034) for residential CO
detectors. Detectors currently available on the market are battery-powered, plug-in or
hard-wired. Some models incorporate a visual display of the parts per million (ppm) level
of CO present in the home. For more information on CO detectors for home use call the
Consumer Product Safety Commission Hotline at 1-800-638-2772.
CO detectors for use in residential settings are not designed for use in typical workplace
settings. Monitoring requirements in an occupational setting are differentfrom monitoring
in the home. In the workplace it is frequently necessary to monitor a worker's exposure
to carbon monoxide over an entire work shift and determine the time-weighted average
concentration of the exposure. It may also be necessary to have carbon monoxide
monitors with alarm capabilities in the workplace. Carbon monoxide in the workplace can
be detected using detector tubes, direct-reading passive badges, dosimeter tubes and
direct-reading instruments. These badges, tubes, and instruments operate on a variety
of pnnciples including colorimetric reaction, potentiomejry, coutometry, infrared spec-
trometry, fluorescence, thermal conductivity, and heat of combustion. The direct-reading
instruments are frequently equipped with audio and or visual alarms and may be used
for area and cr personal exposure monitoring. Some have microprocessors and memory
for stonng CO concentration readings taken during the day. It is significant to note that
some of the devices mentioned for workplace CO monitoring are not capable of
monitonng time-weighted averages, and not ail are equipped with alarms. The appropri-
ate monitor must be chosen on an application-by-application basis. For more information
on the availability of workplace CO monitors or their application, call the National Institute
for Occupational Safety and Health at 1 -800-35-NIOSH (1 -800-356-4674) ^
Carbon Monoxide Poisoning 15
-------
National Institute for Occupational Safety and Health
Colorado Department of Public Health and Environment
U.S. Consumer Product Safety Commission
Occupational Safety and Health Administration
U.S. Environment Protection Agency
DHHS (NIOSH) Publication No. 96-118
------- |