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DANGER! CARBON MONOXIDE!
What you need to know to protect you and your family from this “silent
killer”
What is Carbon Monoxide?
It is produced by the incomplete burning of fuels like natural gas, propane,
heating oil, kerosene, coal, charcoal or wood due to inadequate air.
Improperly installed or poorly maintained appliances that run on these fuels can
create unsafe levels of CO. In enclosed spaces like your home, cottage or
vehicle, even a small amount of CO is dangerous.
Carbon monoxide (CO) is a colorless and odorless gas. Because you can’t see,
taste or smell it, it can affect you or your family before you even know it’s
there. Even at low levels of exposure, carbon monoxide can cause serious health
problems. CO is harmful because it will rapidly accumulate in the blood,
depleting the ability of blood to carry oxygen. (Exposure Guidelines for
Residential Indoor Air Quality, Health Canada, 1989).
What are the Symptoms of CO poisoning?
Exposure to CO can cause flu-like symptoms such as headaches, nausea, dizziness,
burning eyes, confusion, drowsiness and even loss of consciousness. In severe
cases, it can cause brain damage and death.
Older persons, children, people with heart or respiratory conditions and pets
may be more sensitive to it and feel the effects earlier than others.
What Causes a CO Hazard?
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Fuel-burning appliances, venting systems and chimneys that haven’t been serviced
or regularly maintained by a qualified heating contractor
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A chimney blocked by a bird or squirrel nest, snow and ice or other debris
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Improper venting of a furnace and cracked furnace heat exchangers
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Exhaust fumes seeping into your home from a car running in an attached garage
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Using fuel-burning appliances designed for the outdoors (like BBQs, lanterns,
chainsaws, lawnmowers, snow blowers) in a closed area (like a tent, recreational
vehicle, cottage, garage, workshop)
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Combustion gases spilling into a home if too much air is being consumed by a
fireplace, or exhausted by a kitchen or bathroom fan, in a tightly-sealed house.
Be aware of these Danger Signs
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You or others in your family are feeling the symptoms of CO exposure
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You notice a sharp, penetrating odor or smell of gas when your furnace or
fuel-burning appliance turns on
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The air feels stale or stuffy
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The pilot light of your gas furnace or other fuel-burning appliance goes out
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Chalky, white powder forms on the chimney/exhaust vent pipe, or soot builds up
around the exhaust vent
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Excessive moisture forms on windows and walls
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The carbon monoxide alarm sounds.
How Can I Eliminate Sources of CO in my Home?
The most important step you can take to eliminate the possibility of CO
poisoning is to ensure that CO never has an opportunity to enter your home. This
is your first line of defense. Review this list to minimize the risk of CO in
your home.
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Have a qualified technician inspect and clean fuel-burning appliances yearly,
before the cold weather sets in, to ensure they are in good working order
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Have a qualified technician inspect chimneys and vents yearly for cracks,
blockages (e.g., bird’s nests, twigs, old mortar), corrosion or holes
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Check fireplaces for closed or blocked flues
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Check with a qualified technician before enclosing heating and hot water
equipment in a smaller room, to ensure there is adequate air for proper
combustion
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If you have a powerful kitchen exhaust fan or downdraft cook top, have a
qualified technician check that its operation does not pull fumes back down the
chimney
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Never use propane or natural gas stove tops or ovens to heat your home
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Never start a vehicle in a closed garage; open the garage doors first. Pull the
car out immediately onto the driveway, then close the garage door to prevent
exhaust fumes from being drawn into the house
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Do not use a remote automobile starter when the car is in the garage; even if
the garage doors are open
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Never operate propane, natural gas or charcoal barbecue grills indoors or in an
attached garage
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Avoid the use of a kerosene space heater indoors or in a garage. If its use is
unavoidable, provide combustion air by opening a window while operating
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Never run a lawnmower, snow blower, or any gasoline-powered tool such as a
whipper-snipper or pressure washer inside a garage or house
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The use of fossil fuels for refrigeration, cooking, heat, and light inside
tents, trailers, and motor homes can be very dangerous. Be sure that all
equipment is properly vented to the outside and use electric or battery-powered
equipment where possible
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Regularly clean the clothes dryer ductwork and outside vent cover for blockages
such as lint, snow, or overgrown outdoor plants
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Reduce or eliminate the use of fondue heaters indoors
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Remove snow and ice accumulations around intake and exhaust vents for furnaces
and appliances.
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If you live close to a road with heavy traffic, outdoor carbon monoxide levels
can affect your indoor air quality, especially during rush hour. Such levels
should not set off a CO alarm, but slightly elevated CO levels might be
observable on some types of CO detectors with a digital display.
Carbon Monoxide Detectors: Is One Really Necessary?
If you take the actions above, you greatly reduce your risk of CO poisoning. But
unanticipated dangerous incidents may still occur despite your best efforts to
avoid CO. The installation of at least one CO alarm in your home is a good
safety precaution; and, in some municipalities, it is the law. A detector might
be your second line of defense, but, it is necessary. You should have one in
your home today.
There are performance differences between these detector types. However, changes
to the CO standards have resulted in all detectors, regardless of detector type,
having to undergo extensive testing. All are certified to operate under
different environments (various chemical exposures, different relative humidity,
etc.) satisfactorily if they meet the standards.
How Does a CO Detector Work?
There are three basic types of CO sensors – metal oxide, biomimetic and
electrochemical. Each is discussed in the chart below. Note, while there may be
performance differences between these technologies, all detectors are tested and
approved for their operation. The retail cost of a detector will generally
relate to the number of features included and its warranty conditions.
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Metal Oxide Semi-Conductor (MOS)
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Biomimetic
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Electrochemical
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How does it work?
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The original technology for detecting CO. Heated tin oxide reacts with CO to
determine the levels of the toxic gas. Must connect to house power.
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Gel-coated discs darken in the presence of CO. Colour change sounds an alarm.
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Chemical reaction with CO creates an electrical current, setting off an alarm.
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Features
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No need to remember to check batteries as the unit plugs in
Battery backup is available for up to 20 hours
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-less expensive technology
-can be battery operated
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-highly sensitive and accurate readings at all CO levels
-most units come with a continuous digital readout and a memory feature that
allows you to check past CO levels
-fast reset time
-most units sound an alert when sensor needs replacing
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What Features Should I Look for When Purchasing a CO Detector?
Most CO detectors are designed to give an alarm when CO levels reach a high
level in a short time. However, health agencies advise that long term, low level
exposure are also of concern, especially for the unborn and young children, the
elderly and those with a history of heart or respiratory problems (Health
Canada, 1989). Detectors that can display both high and low levels are more
expensive; but, they do provide greater accuracy and more information.
Here are some features to consider when purchasing a CO detector:
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Look for a detector that is listed with the Canadian Standards Association (CSA)
standard. The logos of the testing agency will be on the product.
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Choose a detector with a memory if you want to monitor long term low level
exposure and short term, high level exposure. Even though product standards do
not allow manufactures to display low levels of CO, these units monitor and
store this information. Peak levels, no matter what the level of concentration,
can be viewed by pressing a button.
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Battery-operated units allow detector placement in the most convenient location.
However, any battery operated device requires the user’s diligence in replacing
worn out batteries.
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Do not connect plug in units to an electrical outlet controlled by a wall
switch.
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No detectors will operate properly forever. Replace them at least every five
years, unless the manufacturer specifies a shorter or longer life.
Eventually, manufacturers may be required to print expiry dates on their CO
detectors. This will ensure you are purchasing an up-to-date product with a full
sensor life.
Where Do I Put a CO Detector?
Most manufacturers specify where you should locate their CO detector. In
general, the best place to put the detector is where you will hear it while
sleeping. CO is roughly the same weight as air and distributes evenly throughout
a room, so a detector can be placed at any height in any location, as long as
its alarm can be heard. Additional units could be installed in several other
locations around the home, such as a child’s bedroom; check the list below
before installing.
To avoid both damage to the unit and to reduce false alarms, do not install CO
detectors:
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In unheated basements, attics or garages
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In areas of high humidity
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Where they will be exposed to chemical solvents or cleaners, including hair
spray, deodorant sprays, etc.
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Near vents, flues or chimneys
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Within 2 metres (6 ft.) of corners or areas where natural air circulation is low
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Near forced – or unforced – air ventilation openings
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Within 2 metres (6 ft.) of corners or areas where natural air circulation is low
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Where they can be damaged, such as an outlet in a high traffic area
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Where directly exposed to the weather.
What Do I Do if I Hear the CO Detector Alarm?
Do not ignore the CO detector’s alarm if it sounds. Treat each alarm as serious
and respond accordingly.
CO detectors are designed to sound an alarm before a healthy adult would feel
any symptoms. Infants, the elderly and those with respiratory and heart
conditions are at particular risk and may react to even low levels of CO
poisoning (Health Canada, 1989).
Response To An Obvious Source of CO
If your detector sounds an alarm and you have an obvious source of CO, such as
an unvented kerosene heater:
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If anyone is suffering from flu-like symptoms, call 9-1-1
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Remove or turn off the source
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Ventilate the house
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Reset the alarm
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Do not re-occupy the house until the alarm ceases
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Take steps to avoid this situation in the future.
Response To An Unknown Source of CO
If your CO detector is sounding an alarm and there is no obvious source of CO:
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Evacuate the house, including pets and do a head count
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If anyone has flu-like symptoms, call 09-1-1; if there are no health problems,
call your gas utility, heating contractor or the fire department to have your
house tested
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If you live in a single family home: do not ventilate your home, turn off
fuel-burning appliances or reset your CO detector prior to someone testing your
home*
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If you live in a duplex, row house, apartment, or otherwise attached house, do
ventilate the house and turn off fuel-burning appliances. In this case, the
safety of your neighbors is more important that trying to find the CO source.
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Have a qualified service technician inspect and repair all fuel-burning
appliances, if they are identified as being the CO source
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Do not re-occupy the house unless those who tested the house inform you the
danger is over.
* Many CO alarm calls have been classified as “false alarms” because the
homeowner has ventilated the home and turned off the equipment before fire
fighters or technicians can measure the CO levels and find the source.
Symptoms of CO Poisoning
Be sure that all members of your family know the symptoms of CO poisoning:
Mild Exposure
Flu-like symptoms such as headache, running nose, sore eyes, etc.
Medium Exposure
Drowsiness, dizziness, vomiting. The sense of disorientation and confusion may
make it difficult for some victims to make rational decisions like leaving the
home or calling for assistance.
Extreme Exposure
Unconsciousness, brain damage, death
Continued Low-level Exposure to CO
While this may not lead to observable symptoms, you should still avoid such
exposure.
Testing a Carbon Monoxide Detector
Most CO detectors have a test button that should be pressed once a week to
confirm the device is in operation. Detectors with displays can be tested with a
known source of CO such as smoke from a cigarette or incense stick. Hold the CO
source about 8-10 inches away and watch the digital display respond to the
presence of even a small amount of CO. BUT, an alarm will most likely not sound
with this test.
There are CO detector test kits available, where CO detectors are sold, that
provide a vial of high level of CO (1000 ppm) and a plastic tent to house the
unit during the test. This test only proves that your detector will sound an
alarm with a very high level of CO.
What Standards Apply to CO Detectors?
The two main industry standards used in Canada are CAN/CGA-6.19. “Residential
Carbon Monoxide Detectors,” and UL2034, “Single and Multiple Station Carbon
Monoxide Detectors.” Units should bear the approval of one of these standards.
Electric powered units should also bear the CSA approval.
In general, current standards require detectors to alarm for 70 ppm within 240
minutes, 150 ppm within 50 minutes and 400 ppm within 15 minutes.
Earlier CO-detector models were designed with different standards. Recent
changes to detectors primarily address false alarms common with the older
models. Revisions to these standards do not make current carbon-monoxide
detectors obsolete.
Carbon Monoxide Concentrations
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CO concentration in parts per million (ppm)
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Effects
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0-2
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Normal conditions inside and outside Canadian houses.
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11
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Maximum tolerable indoor concentration over an eight hour period. ¹
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25
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Maximum allowable concentration for continuous exposure for healthy adults in
any eight hour period. ¹
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30
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CO detectors must not sound alarm within 30 days. ²
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70
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CO detectors must sound alarm within one to four hours. ²
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150
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CO detectors must sound alarm within 10 to 50 minutes. ²
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200
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Slight headache, fatigue, dizziness and nausea after two to three hours. CO
detector alarm must sound within 35 minutes. ³
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400
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CO detectors must sound alarm within 4 to 15 minutes. ²
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800
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Dizziness, nausea and convulsions within 45 minutes, death within 2 or 3 hours.
³
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1600
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Death within one hour. ³
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13,000
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Danger of death after one to three minutes
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¹ Exposure Guidelines for Residential Indoor Air Quality, Health Canada, 1989.
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² From CAN/CSA 6.19, Residential Carbon Monoxide Alarming Devices, 2001
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³ Carbon Monoxide Poisoning, Iowa State University of Science and Technology,
AEN-172
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Do CO Detectors Require Maintenance?
CO detectors should be maintained in accordance with the manufacturer’s
instructions. Keep your air vents clean by vacuuming them occasionally. Test the
detectors regularly. In general, units should be tested at least once a month.
CO Alarms should be replaced every seven years; or, according to manufacture’s
instructions.
Are CO Detectors Required?
The Ontario Building Code requires CO detectors in newly constructed homes with
solid fuel burning appliances such as woodstoves and fireplaces.
As of October 1, 2009, CO detectors are mandatory in all North Bay homes,
containing a fuel burning appliance and/or an attached garage. (By-law #
2009-16)
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