What is carbon monoxide?

Carbon monoxide (CO) is a poisonous,

colorless, odorless, and tasteless gas. Although it

has no detectable odor, CO is often mixed with

other gases that do have an odor. So, you can

inhale carbon monoxide right along with gases that

you can smell and not even know that CO is

present.

CO is a common industrial hazard resulting

from the incomplete burning of natural gas and

any other material containing carbon such as

gasoline, kerosene, oil, propane, coal, or wood.

Forges, blast furnaces and coke ovens produce

CO, but one of the most common sources of

exposure in the workplace is the internal

combustion engine.

How does CO harm you?

Carbon monoxide is harmful when breathed

because it displaces oxygen in the blood and

deprives the heart, brain, and other vital organs

of oxygen. Large amounts of CO can overcome

you in minutes without warning—causing you to

lose consciousness and suffocate.

Besides tightness across the chest, initial

symptoms of CO poisoning may include

headache, fatigue, dizziness, drowsiness, or

nausea. Sudden chest pain may occur in people

with angina. During prolonged or high exposures,

symptoms may worsen and include vomiting,

confusion, and collapse in addition to loss of

consciousness and muscle weakness. Symptoms

vary widely from person to person. CO poisoning

may occur sooner in those most susceptible: young

children, elderly people, people with lung or heart

disease, people at high altitudes, or those who

already have elevated CO blood levels, such as

smokers. Also, CO poisoning poses a special risk

to fetuses.

CO poisoning can be reversed if caught in

time. But even if you recover, acute poisoning

may result in permanent damage to the parts of

your body that require a lot of oxygen such as the

heart and brain. Significant reproductive risk is

also linked to CO.

Who is at risk?

You may be exposed to harmful levels of CO in

boiler rooms, breweries, warehouses, petroleum

refineries, pulp and paper production, and steel

production; around docks, blast furnaces, or

coke ovens; or in one of the following

occupations:

■ Welder

■ Garage mechanic

■ Firefighter

■ Carbon-black maker

■ Organic chemical

synthesizer

■ Metal oxide reducer

■ Longshore worker

■ Diesel engine operator

■ Forklift operator

■ Marine terminal worker

■ Toll booth or tunnel

attendant

■ Customs inspector

■ Police officer

■ Taxi driver.

What can you do if you suspect

someone has been poisoned?

When you suspect CO poisoning, promptly

taking the following actions can save lives:

■ Move the victim immediately to fresh air

in an open area.

■ Call 911 or another local emergency number

for medical attention or assistance.

■ Administer 100-percent oxygen using a

tight-fitting mask if the victim is breathing.

■ Administer cardiopulmonary resuscitation

if the victim has stopped breathing.

Warning: You may be exposed to fatal levels

of CO poisoning in a rescue attempt. Rescuers

should be skilled at performing recovery

operations and using recovery equipment.

Employers should make sure that rescuers are

not exposed to dangerous CO levels when

performing rescue operations.

How can employers help prevent

CO poisoning?

To reduce the chances of CO poisoning in your

workplace, you should take the following actions:

■ Install an effective ventilation system that

will remove CO from work areas.

■ Maintain equipment and appliances (e.g., water

heaters, space heaters, cooking ranges) that

can produce CO in good working order to

promote their safe operation and to reduce

CO formation.

■ Consider switching from gasoline-powered

equipment to equipment powered by electricity,

batteries, or compressed air if it can be used

safely.

■ Prohibit the use of gasoline-powered engines

or tools in poorly ventilated areas.
U.S. Department of Labor

Occupational Safety and Health Administration

2002

■ Provide personal CO monitors with audible

alarms if potential exposure to CO exists.

■ Test air regularly in areas where CO may be

present, including confined spaces. See

Title 29 of the Code of Federal Regulations

(CFR) 1910.146.

■ Install CO monitors with audible alarms.

■ Use a full-facepiece pressure-demand selfcontained breathing apparatus (SCBA)

certified by the National Institute for

Occupational Safety and Health (NIOSH), or a

combination full-facepiece pressure demand

supplied-air respirator with auxiliary selfcontained air supply in areas with high CO

concentrations, i.e., those immediately

dangerous to life and health atmospheres.

(See 29 CFR 1910.134.)

■ Use respirators with appropriate canisters for

short periods under certain circumstances

where CO levels are not exceedingly high.

■ Educate workers about the sources and

conditions that may result in CO poisoning

as well as the symptoms and control of CO

exposure.

In addition, if your employees are working in

confined spaces where the presence of CO is

suspected, you must ensure that workers test for

oxygen sufficiency before entering.

What can employees do to help

prevent CO poisoning?

Employees should do the following to reduce

the chances of CO poisoning in the workplace:

■ Report any situation to your employer that

might cause CO to accumulate.

■ Be alert to ventilation problems—especially in

enclosed areas where gases of burning fuels

may be released.

■ Report promptly complaints of dizziness,

drowsiness, or nausea.

■ Avoid overexertion if you suspect CO poisoning

and leave the contaminated area.

■ Tell your doctor that you may have been

exposed to CO if you get sick.

■ Avoid the use of gas-powered engines, such as

those in powered washers as well as heaters

and forklifts, while working in enclosed spaces.

What are the OSHA standards for

CO exposure?

■ The OSHA PEL is 50 parts per million (ppm).

OSHA standards prohibit worker exposure to

more than 50 parts of the gas per million parts

of air averaged during an 8-hour time period.

■ The 8-hour PEL for CO in maritime operations

is also 50 ppm. Maritime workers, however,

must be removed from exposure if the CO

concentration in the atmosphere exceeds

100 ppm. The peak CO level for employees

engaged in Ro-Ro operations (roll-on roll-off

operations during cargo loading and unloading)

is 200 ppm.

How can you get more information

on safety and health?

OSHA has various publications, standards,

technical assistance, and compliance tools to help

you, and offers extensive assistance through

workplace consultation, voluntary protection

programs, grants, strategic partnerships, state

plans, training, and education. OSHA’s Safety

and Health Program Management Guidelines

(Federal Register 54:3904-3916, January 26,

1989) detail elements critical to the development

of a successful safety and health management

system. This and other information are available

on OSHA’s website.

■ For one free copy of OSHA publications, send

a self-addressed mailing lable to OSHA

Publications Office, P.O. Box 37535,

Washington, DC 20013-7535; or send a

request to our fax at (202) 693-2498, or call

us at (202) 693-1888.

■ To order OSHA publications online at

www.osha.gov, go to Publications and

follow the instructions for ordering.

■ To file a complaint by phone, report an

emergency, or get OSHA advice, assistance, or

products, contact your nearest OSHA office

under the “U.S. Department of Labor” listing

in your phone book, or call toll-free at

(800) 321-OSHA (6742). The teletypewriter

(TTY) number is (877) 889-5627.

■ To file a complaint online or obtain more

information on OSHA federal and state

programs, visit OSHA’s website.

This is one in a series of informational fact sheets highlighting OSHA programs, policies, or standards. It does not impose

any new compliance requirements or carry the force of legal opinion. For compliance requirements of OSHA standards or

regulations, refer to Title 29 of the Code of Federal Regulations. This information will be made available to sensory-impaired

individuals upon request. Voice phone: (202) 693-1999. See also OSHA’s website at www.osha.gov.