Friday, February 28, 2014

Make a silent killer noisy with Carbon Monoxide Detector alarms


I had just purchased my personal carbon monoxide (CO) detector that I planned to attach to my belt while performing Ottawa Home Inspections.  These units are useful when going into crawl spaces, attics and basements where there is a potential for CO.


I dropped by to visit a buddy of mine at his sign shop and while we are chatting my CO detector starts to vibrate and buzz.  Odd I thought, must be a glitch, I take it outside into the fresh air and it stops. I return to the shop and a few minutes later it starts to vibrate and buzz again.  I look around and see the overhead gas heater unit and ask when that last time it was serviced ... "ah never" in the 10 years he's been renting the shop space. (unit was similar to below)

The next day I go back with my more sensitive Bacharach Snifit CO detector that takes a reading in Parts Per Million (PPM).

The reading is very high when the gas heater is running and the fan was blowing.  My buddy says he's been having headaches lately and been really tired. I suggest the heater needs to be looked ASAP as clearly it is leaking CO and he is suffering from CO poisoning based on what he said.  The next day the service contractor comes by to have a look and find that 3 out of the 4 heat exchanger tubes are cracked and leaking CO (the fan was pushing the CO into the room)

Thanks to the CO detector, probably saved him!  So I thought I do some further research, gather it and share it here.


Carbon Monoxide (CO) is a tasteless, colourless and odourless poisonous gas often referred to as ‘the silent killer’. It is produced when fuels such as natural gas, oil, wood, propane and kerosene don’t get enough air to burn up completely. Damaged or blocked venting as well as inadequate air flow can allow carbon monoxide to build up inside a home, cottage, camper or tent.

Always make sure fuel burning appliances have an adequate air supply to prevent a CO hazard.
The best way to ensure that you and your family are not exposed to the dangers of carbon monoxide is to take the necessary steps to eliminate it at the source. Make maintenance of your fuel burning appliances, equipment and venting systems an absolute priority.

  • 480 U.S. residents died between 2001 and 2003 from non-fire-related carbon-monoxide poisoning.
  • Most CO exposures occur during the winter months, especially in December (including 56 deaths, and 2,157 non-fatal exposures), and in January (including 69 deaths and 2,511 non-fatal exposures). The peak time of day for CO exposure is between 6 and 10 p.m.
  • Many experts believe that CO poisoning statistics understate the problem. Because the symptoms of CO poisoning mimic a range of common health ailments, it is likely that a large number of mild to mid-level exposures are never identified, diagnosed, or accounted for in any way in carbon monoxide statistics.
  • Out of all reported non-fire carbon-monoxide incidents, 89% or almost nine out of 10 of them take place in a home.


When CO is inhaled, it displaces the oxygen that would ordinarily bind with hemoglobin, a process the effectively suffocates the body. CO can poison slowly over a period of several hours, even in low concentrations. Sensitive organs, such as the brain, heart and lungs, suffer the most from a lack of oxygen.

High concentrations of carbon monoxide can kill in less than five minutes. At low concentrations, it will require a longer period of time to affect the body. Exceeding the EPA concentration of 9 parts per million (ppm) for more than eight hours may have adverse health affects. The limit of CO exposure for healthy workers, as prescribed by the U.S. Occupational Health and Safety Administration, is 50 ppm.
The Symptoms Of CO Poisoning

Carbon monoxide inhibits the ability of your blood to absorb oxygen. The symptoms of CO poisoning are similar to the flu and include nausea, headache, burning eyes, confusion and drowsiness. Eventually CO poisoning can lead to unconsciousness and even death. The key difference is that with CO poisoning, there is no fever and the symptoms tend to disappear when the person gets fresh air.

Infants and children absorb carbon monoxide faster than adults due to their high metabolic rates so the signs will show up more quickly in children.
These are warning signs. If they appear, it is imperative to get everyone, including pets, away from the source of the CO and to fresh air immediately and call 911 or the local fire department.

Any fuel-burning appliances which are malfunctioning or improperly installed can be a source of CO, such as:

  • furnaces;
  • stoves and ovens;
  • water heaters;
  • dryers;
  • room and space heaters;
  • fireplaces and wood stoves;
  • charcoal grills;
  • automobiles;
  • clogged chimneys or flues;
  • space heaters;
  • power tools that run on fuel;
  • gas and charcoal grills;
  • certain types of swimming pool heaters; and
  • boat engines.
Carbon monoxide detection is registered in parts per million (PPM). The Canadian Occupational Health and Safety Act threshold for CO in businesses is 25 PPM over an eight-hour period; for homes, the limit is just 9 PPM, as people are potentially exposed to CO over a longer period in a residence.  Below is a chart of carbon monoxide levels and effects:

Carbon Monoxide Concentration
ppm = parts per million

Exposure Limits and Effects
As posted by various safety and engineering organizations.
ASHRAE 62-89: – The maximum allowable concentration for continuous (24-hour) exposure. ASHRAE states the ventilation air shall meet the outdoor air standard referenced to EPA and 9 PPM.
U.S. Environmental Protection Agency: 9 PPM – This level or lower as an ambient air quality goal averaged over eight hours. This outdoor air standard is exceeded in many urban areas due to auto exhaust.
UL 2034 (Underwriters Laboratories, CO alarm detector designation): 30 PPM is the concentration required for UL 2034 listed alarms to sound when this concentration is present for 30 days minimum. This allows the sensor to clear itself. People of vulnerable health may require alarms with lower PPM concentration trigger levels. (NOTE: Alarms listed under UL 2034  may not have been able to meet this requirement.)
10 – 35
Cautionary chronic levels: 10–35 PPM is a marginal level in reference to potential or foreseeable problems in some situations. Occupants should be advised of a potential health hazard to infants and small children, elderly people and persons suffering from respiratory or heart problems. If a building has an attached auto garage, CO levels should be documented there. Accept this level as normal where un-vented appliances are in use. These levels are unacceptable when originated from vented appliances.
U.S. Environmental Protection Agency: – This level or lower as an ambient air quality goal averaged over one hour outside. Common action level: 35 PPM is a common action level where emergency responders should utilize self contained breathing apparatus if sustained occupation of the area is required. 35 PPM or less averaged over an eight-hour day within that workday is a common goal of certain states’ occupational health and safety agencies. This is also a common goal of many employers despite higher regulated concentra­tion standards and may require the measurement of several simultaneous reference locations. Max safe level for 8 hrs (OSHA). Normally no physical effects for short exposure periods.
OSHA: 50 PPM – Maximum allowable concentration for a worker’s continuous exposure in any eight-hour period. This eight-hour average requires continuous measurement and accurate reporting in the workplace. 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. NFPA FSH 8 hour exposure limit.
UL 2034: 70 PPM concentration required for UL 2034-listed CO alarms to sound when concentration is present for no more than 240 minutes (four hours) or as early as 60 minutes (one hour)
36 – 99
Foreseeable hazardous levels: 36–99 PPM is excessive. Medical alert and health consultation is advised especially if levels displayed chronic conditions. Evacuate the area. Air packs are recommended if sustained conditions and presence required. Conditions must be mitigated. Ventilation required.
100 – 199
Evacuation advisory levels: 100–200 PPM is a common building evacuation standard and is dangerous. Medical alert conditions exist. Occupant health inquiries should be conducted. Exposed occupants should have someone else transports them to seek medical help. 15-minute maximum exposure upon discovery.
UL 2034: 150-PPM concentration required for UL 2034 listed CO alarms to sound when concentration is present for no more than 50 minutes or as early as 10 minutes.
Evacuation Required! 200 PPM is universally accepted as an evacuation action level. Occupant health inquiries should be conducted. Exposed occupants should have someone else transports them to seek medical help. 15-minute maximum exposure upon discovery. Building should be ventilated and searched for additional occupants. Combustion systems should be thoroughly tested for CO production and dispersion. Max safe level for 1 hr (OSHA). NFPA FSH: Slight headache within 2 to 3 hours.
UL 2034: 400-PPM concentration required for UL 2034 listed CO alarms to sound if concentration is present for no more than 15 minutes or as early as four minutes. Frontal headache within 1 to 2 hours. Widespread headache after 3 hours. NFPA FSH: headache, nausea after 1 – 2 hours.
Headache, dizziness, nausea, convulsions within 45 minutes. Loss of consciousness within 2 hours. NFPA FSH: loss of consciousness after 1 hour.
NPFA FSH: Loss of consciousness after 1 hr exposure
Collapse and possible death within 1 hour. NFPA FSH: Headache, dizziness, nausea within 20 minutes.
Headache, dizziness within 10 minutes. Unconsciousness and danger of death within 30 minutes. NFPA FSH: Headache, nausea, dizziness after 5 – 10 minutes; collapse and unconsciousness after 30 minutes.
NFPA FSH: Head, dizziness after 2 minutes, unconsciousness and death after 10-15 minutes
NFPA FSH: Immediate physiological effects, unconsciousness and danger of death within 1 - 3 minutes.

ASHRAE: American Society of Heating, Refrigeration and Air-Conditioning Engineers OSHA: Department of Labor, Occupational Safety and Health Administration EPA: Environmental Protection Agency.

UL: Underwriters Laboratories – UL2034 is the current standard used by CO detector manufacturers.
NFPA FSH: National Fire Protection Association Fire Safety Handbook, 19th Edition.
              Chart Source:

  • Purchase and install carbon monoxide detectors with labels showing that they meet the requirements of the UL standard 2034 or  Canadian Standard Association (CSA) CAN/CGA 6.19 standard
  • Make sure appliances are installed and operated according to the manufacturer's instructions and local building codes. Have the heating system professionally inspected by a Ottawa Home Inspector and serviced by qualified HVAC company annually to ensure proper operation. The inspector should also check chimneys and flues for blockages, corrosion, partial and complete disconnections, and loose connections.
  • Never service fuel-burning appliances without the proper knowledge, skill and tools. Always refer to the owner's manual when performing minor adjustments and when servicing fuel-burning equipment.
  • Have your gas appliances serviced regularly.
  • Have you chimney inspected and cleaned every year by a W.E.T.T. certified professional
  • Never operate a portable generator or any other gasoline engine-powered tool either in or near an enclosed space, such as a garage, house or other building. Even with open doors and windows, these spaces can trap CO and allow it to quickly build to lethal levels.
  • Never use portable fuel-burning camping equipment inside a home, garage, vehicle or tent unless it is specifically designed for use in an enclosed space and provides instructions for safe use in an enclosed area.
  • Never burn charcoal inside a home, garage, vehicle or tent.
  • Never leave a car running in an attached garage, even with the garage door open.
  • Never use gas appliances, such as ranges, ovens or clothes dryers to heat your home.
  • Never operate un-vented fuel-burning appliances in any room where people are sleeping.
  • During home renovations, ensure that appliance vents and chimneys are not blocked by tarps or debris. Make sure appliances are in proper working order when renovations are complete.
  • Do not place generators in the garage or close to the home. People lose power in their homes and get so excited about using their gas-powered generator that they don't pay attention to where it is placed. The owner's manual should explain how far the generator should be from the home.
  • Clean the chimney. Open the hatch at the bottom of the chimney to remove the ashes. Hire a chimney sweep annually.
  • Check vents. Regularly inspect your home's external vents to ensure they are not obscured by debris, dirt or snow. 

  • Unlike smoke, which rises to the ceiling, CO mixes with air. If a combination smoke/carbon monoxide detector is used, it should be located on the ceiling to ensure that it will detect smoke effectively.
  • CO alarms should not be installed near fuel burning appliances.
  • When choosing a CO alarm, look for the CSA Blue Flame mark (below)

    and the reference “CSA 6.19-01” – the most up-to-date Canadian standard or  UL standard 2034  This shows that the CO alarm meet recognized standards for safety.
  • Install carbon monoxide alarms adjacent to the bedrooms in your home. If there are bedrooms on more than one floor in your home then install CO alarms on those floor as well so you can hear the alarm.
  • CO alarms should be installed as per manufacturer’s instructions. Follow the same manufacturer’s maintenance procedures as you would with smoke alarms



The Consumer Product Safety Commission recommends a detector on each floor of a residence. At a minimum, a single detector should be placed on each sleeping floor with an additional detector in the area of any major gas burning appliances such as a furnace or water heater. Installation in these areas ensures rapid detection of any potentially malfunctioning appliances and the ability to hear the alarm from all sleeping areas. In general, carbon monoxide detectors should be placed high (near the ceiling) for most effective use. Detectors should also not be placed within five feet of gas fueled appliances or near cooking or bathing areas. Consult the manufacturers installation instructions for proper placement of a detector within a given area.

Detectors come in two basic kinds: inexpensive detector strips (sometimes described as biomimetic detectors, because they supposedly mimic the way our bodies respond to carbon monoxide) that you stick on your wall and more expensive electronic alarms that run off a power outlet or battery supply. They have some things in common but work in different ways, so let's tackle them separately



  • Within 10 feet of each bedroom door and near all sleeping areas, where it can wake sleepers. The Consumer Product Safety Commission (CPSC) and Underwriters Laboratories (UL) recommend that every home have at least one carbon monoxide detector for each floor of the home, and within hearing range of each sleeping area;
  • On every floor of your home, including the basement (source: International Association of Fire Chiefs/IAFC);
  • Near or over any attached garage. Carbon monoxide detectors are affected by excessive humidity and by close proximity to gas stoves (source: City of New York);
  • Near, but not directly above, combustion appliances, such as furnaces, water heaters, and fireplaces, and in the garage (source: UL); and
  • On the ceiling in the same room as permanently installed fuel-burning appliances, and centrally located on every habitable level, and in every HVAC zone of the building (source: National Fire Protection Association 720). This rule applies to commercial buildings.


No carbon monoxide (CO) or smoke alarm, no matter how advanced the technology, can work if the batteries are dead, so remembering to change the batteries in your alarms is a very important safety procedure in your home.

Batteries need to be replaced once every year. A good habit to establish is to change the batteries every fall when you change your clocks.


You should follow the manufacturer's instructions. Using a test button tests whether the circuitry is operating correctly, not the accuracy of the sensor. Alarms have a recommended replacement age, which can be obtained from the product literature or from the manufacturer. Some have the expiration date on a label on the unit.

Another recommendation is to test the CO alarm frequently, at least once a month and when clocks are adjusted for daylight saving time, and replace dead batteries when necessary


Like most things, carbon monoxide (CO) detectors wear out with age. They have to be replaced in order to ensure maximum effectiveness and safety for your family. Please check the manufacturer’s instructions for information on when your particular carbon monoxide detector should be replaced.
Typically every 7 years , 10 years for smoke alarms.


Never ignore an alarming CO alarm! It is warning you of a potentially deadly hazard.

The best advice is to stay calm. Some situations resulting in activation of a carbon monoxide detector are not life threatening and do not require calling 911 or the fire department. To determine the need to call 911 or the fire department, ask the following questions of everyone in the household:
"Does anyone feel ill? Is anyone experiencing the 'flu-like' symptoms of headache, nausea or dizziness?"
If the answer to the above by anyone in the household is true, evacuate the household to a safe location and have someone call 911 or the fire department. Failure to evacuate immediately may result in prolonged exposure and worsening effects from possible carbon monoxide gas. The best initial treatment for carbon monoxide gas exposure is fresh air.
If the answer to the above by everyone in the household is no, the likelihood of a serious exposure is greatly diminished and one probably does not need to call 911 or the fire department. Instead, turn off any gas burning appliances or equipment, ventilate the area and attempt to reset the alarm. If the alarm will not reset or resounds, call a qualified heating and ventilating (HVAC) service contractor to inspect your system for possible problems. If at any time during this process someone begins to feel ill with the symptoms described above evacuate the household to a safe location and have someone call 911 or the fire department.


CO alarms are available for boats and recreational vehicles and should be used. The Recreation Vehicle Industry Association (RVIA) requires CO alarms in motor homes and in trailers.


In North America, some national, state and local municipalities require installation of CO detectors in new and existing homes, as well as commercial businesses, among them: Illinois, Massachusetts, Minnesota, New Jersey, Vermont and New York City, and the Canadian province of Ontario. Installers are encouraged to check with their local municipality to determine what specific requirements have been enacted in their jurisdiction.

In Ontario:

Under the new Hawkins-Gignac Act (Bill 77), homes or apartments built before Aug. 6, 2011 — when the Ontario Building Code was amended — don’t have to have hardwired carbon monoxide detectors installed. The new bill would require a battery-operated or plug-in detector for those residences.
The new law applies to homes with a gas appliance or attached garage. The new CO detector law, similar to the requirement for smoke alarms, is to be enforced by local fire departments under the Fire Prevention and Protection Act.
In summary, carbon monoxide is a dangerous poison that can be created by various household appliances. CO detectors must be placed strategically throughout the home or business in order to alert occupants of high levels of the gas.


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