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| Fire Rescue
Carbon
Monoxide |
Carbon
Monoxide Risks at Home
In the past
decade, people have become more aware of the risk
of carbon monoxide (or CO) poisoning in the home.
The nonprofit National Fire Protection Association
(NFPA) prepared this fact sheet to help people protect
themselves and their families against CO poisoning.
What is carbon monoxide?
Carbon monoxide (CO) is an invisible, odorless, colorless
gas created when fossil fuels (such as gasoline, wood,
coal, propane, oil, and methane) burn incompletely.
In the home, heating and cooking equipment are possible
sources of CO. Vehicles or generators running in an
attached garage could also produce dangerous levels
of CO.
However, consumers can protect themselves against
CO poisoning by installing CO alarms inside their
homes; by properly installing, using, venting, and
maintaining heating and cooking equipment; and by
being cautious with vehicles or generators in attached
garages.
What is the effect of exposure to CO?
CO is poisonous and can kill cells of the body. CO
also replaces oxygen in the bloodstream, leading to
suffocation. Mild effects feel like the flu, while
severe effects include difficulty breathing and even
death.
Just how sick people get from CO exposure varies greatly
from person to person, depending on age, overall health,
concentration of exposure (measured in parts per million),
and length of exposure. Higher concentrations are
dangerous even for a short time.
When blood carries CO rather than oxygen, the CO-carrying
cells are called carboxyhemoglobin (COHb), in contrast
to normal oxygen-carrying hemoglobin. The percentage
of the blood that is carboxyhemoglobin -- also called
carboxyhemoglobin saturation -- measure show badly
a person is affected by CO. A doctor can measure COHb
in the blood but cannot measure CO in the body directly.
The more CO in the body, the higher the COHb, and
the sicker the person will be.
What is your risk of CO poisoning?
Deaths from unintentional poisoning by gas or vapors,
chiefly CO -- about 600 in 1996, according to the
National Safety Council -- are fairly rare, and the
number has been declining somewhat steadily, down
more than half since the early 1980s. Of all the unintentional
gas and vapor poisoning deaths in the U.S., more than
one-third involve motor vehicle exhaust gas, and more
than one fourth involve heating or cooking equipment.
The total reflects more than CO-related deaths; it
also reflects deaths resulting from other gases, such
as natural gas leaks from pipelines.*
Deaths from unintentional CO poisoning have dropped
sharply in recent years, thanks to lower CO emissions
from automobiles and safer heating and cooking appliances.
Deaths from "smoke inhalation" (largely
CO) in fires and suicides involving CO are far more
common causes of gas-related suffocation deaths.
According to the U.S. Consumer Product Safety Commission,
164 CO-related non-fire deaths were attributed to
heating and cooking equipment in 1994.** The specific
types of equipment were:
* Gas-fueled space heaters (70 deaths)
* Gas-fueled furnaces (48 deaths)
* Charcoal grills (15 deaths)
* Gas-fueled ranges (9 deaths)
* Liquid-fueled heaters (9 deaths)
* Gas-fueled water heaters (7 deaths)
* Solid-fueled heaters (6 deaths)
As with fire deaths, the risk of unintentional CO
death is highest for the very young (ages 4 or under)
and the very old (ages 75 or above).
*National Safety Council's Accident Facts, 1981-97.
** The latest year for which statistics are available
at this level of detail.
How can you protect yourself from CO poisoning?
Install CO alarms inside your home to provide early
warning of accumulating CO. However, a CO alarm is
no substitute for safe practices. The best defenses
against CO poisoning are safe use of vehicles (particularly
in attached garages) and proper installation, use,
venting and maintenance of household cooking and heating
equipment.
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Carbon
Monoxide Safety and Tips
What
to do if your CO alarm sounds
Have everyone leave the building right away. Leave
doors open as you go. Shut down heating and cooking
equipment.
Use a neighbor's telephone to report the CO alarm
warning, following the instructions you received from
the fire department when you bought the alarm.
Be on the lookout for any symptoms of CO poisoning.
Call a qualified technician to inspect all equipment.
Get immediate medical attention if anyone shows signs
of CO poisoning.
Safety
checklist
-
CO alarms are not substitutes for smoke alarms.
Smoke alarms react to fire by-products, before
CO alarms would sound. Smoke alarms give earlier
warning of a fire, providing more time to escape.
-
To guard against smoke and fire, be sure that
your home has working smoke alarms on every level
and in or near all sleeping areas.
-
Know the difference between the sound of the smoke
alarms and the sound of the CO alarms. Have a
home escape plan for any home emergency and practice
the plan with all members of the household regularly,
at least twice a year.
Safety Tips
If you need to warm up a vehicle, remove it from
the garage immediately after starting it. Do not
run a vehicle, generator, or other fueled engine
or motor indoors, even if garage doors are open.
CO from a running vehicle or generator inside an
attached garage can get inside the house, even with
the garage door open. Normal circulation does not
provide enough fresh air to reliably prevent dangerous
accumulations inside.
If you have any symptoms of CO poisoning, have your
vehicle inspected for exhaust leaks.
Have fuel-burning household heating equipment (fireplaces,
furnaces, water heaters, wood stoves, and space
or portable heaters) checked every year before cold
weather sets in.
All chimneys and chimney connectors should be evaluated
by a qualified technician to verify proper installation,
and check for cracks, blockages, or leaks. Make
needed repairs before using the equipment.
Before enclosing central heating equipment in a
smaller room, check with your fuel supplier to ensure
that air for proper combustion is provided. NFPA
54, National Fuel Gas Code, provides requirements
for openings to allow sufficient air for the proper
combustion of gas.
When using a fireplace, open the flue for adequate
ventilation.
Open a window slightly whenever using a kerosene
or gas heater. (Kerosene heaters are illegal in
many states. Always check with local authorities
before buying or using one.)
Only refuel outside, after the device has cooled.
Only use barbecue grills -- which can produce CO
-- outside. Never use them in the home or garage.
When purchasing new heating and cooking equipment,
select factory-built products approved by an independent
testing laboratory. Do not accept damaged equipment.
Hire a qualified technician (usually employed by
the local oil or gas company) to install the equipment.
Ask about -- and insist that the technician follow
-- applicable fire safety and local building codes.
When purchasing an existing home, have a qualified
technician evaluate the integrity of the heating
and cooking systems, as well as the sealed spaces
between the garage and house.
When camping, remember to use battery-powered heaters
and flashlights in tents, trailers, and motor homes.
Using fossil fuels inside these structures is extremely
dangerous. NFPA 501, Standard on Recreational Vehicles,
requires the installation of CO detectors in recreational
vehicles.
Boat operators should be aware that CO is emitted
from any boat's exhaust. When your boat is moored
or anchored alongside others', be aware of the effect
your exhaust may have on those vessels and vice
versa. The trim of the boat, as well as side curtains,
can contribute to increased concentrations of CO
by altering the airflow. Fuel burning appliances
located in accommodation spaces need to be properly
ventilated and maintained.
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Carbon
Monoxide Alarms
What are CO alarms?
Household CO alarms measure how much CO has accumulated.
Currently, CO alarms sound when the concentration
of CO in the air corresponds to 10% COHb level in
the blood. Since 10% COHb is at the very low end of
CO poisoning, the alarm may sound before people feel
particularly sick. Most CO alarms now have silence/reset
buttons and must be immune to elevated ambient levels
such as those found in urban areas.
Do I need a CO alarm?
NFPA 720, Recommended Practice for the Installation
of Household Carbon Monoxide (CO) Warning Equipment,
1998 Edition, recommends installing a CO alarm in
households containing a fuel-burning appliance, fireplace,
or in those having an attached garage.
What causes CO nuisance alarms?
Pollution and atmospheric conditions in some areas
cause low levels of CO to be present for long periods
of time. In fact, these "background" conditions
may increase CO to over the 10% COHb equivalency level,
causing older CO alarms to sound even though conditions
inside the home are not truly hazardous. However,
newer alarms have been designed to reduce sensitivities
to compensate for these background conditions. Treat
all CO alarm warning sounds as real, until it has
been verified that there is no threat from equipment
inside the dwelling.
If you buy CO alarms:
- Select alarms listed by a qualified, independent
testing laboratory.
- Follow recommendations of NFPA 720 and manufacturer's
recommendations for placement in your home.
- Install CO alarms in a central location outside
each separate sleeping area in the immediate vicinity
of the bedrooms. Each alarm should be installed
on the wall, ceiling, or other location as specified
by the manufacturer's instructions that accompany
the unit.
- Call your local fire department's non-emergency
telephone number. Tell the operator that you have
purchased a CO alarm and ask what number to call
if the CO alarm sounds. Clearly post that number
by your telephone(s). Make sure everyone in the
household knows the difference between the fire
emergency and CO emergency numbers (if there is
a difference).
- Test CO alarms at least once a month, following
the manufacturer's instructions.
- Replace CO alarms according to the manufacturer's
instructions, usually about every two to five years.
- Be aware that battery-powered CO alarms may have
unique battery packs designed to last approximately
two years, compared to batteries used in smoke alarms,
which require yearly replacement.
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