NFPA Journal®, January/February 2008
By Jennifer Flynn
Carbon monoxide (CO), also known as the “silent killer”, is a colorless, odorless, poisonous gas that results from the incomplete burning of common fuels such as natural or liquefied petroleum (LP) gas, oil, wood, or coal. When CO is inhaled, it enters the blood stream and reduces the ability of the blood to carry oxygen to vital organs, such as the heart and brain.
Fire departments are often called to assist when people suspect that carbon monoxide might be present. Some of these calls are reported after a CO alarm sounds. Some may be in response to symptoms of CO poisoning.
In 2005, U.S. fire departments responded to an estimated 61,100 non-fire CO incidents in which carbon monoxide was found, or an average of seven such calls per hour. The number of incidents increased 18 percent from 51,700 incidents reported in 2003.
In the home, heating and cooking equipment that burn fuel are potential sources of carbon monoxide, which is why installation codes and standards for fueled equipment emphasize arrangements for adjusting venting. Vehicles or generators running in an attached garage can also produce dangerous levels of carbon monoxide.
For example, in March 2004, a carbon monoxide leak from a gas furnace left two families suffering the effects of CO poisoning. The leak began in one family’s basement, spread throughout the house and into a neighbor’s home. The leak resulted in the CO poisoning and death of a 14 year-old-girl, who lived in the home where the leak originated. Another seven individuals were treated for CO poisoning, including two women, ages 40 and 19 years old, and two males, age 20 and 4 years old, who lived with the 14-year-old girl, and a 24-year-old woman and two boys, ages 3 years old and 1 month, who lived next door. These seven victims were treated for CO poisoning and survived the incident.
In 2005, three children were taken to the hospital and treated for CO poisoning when exhaust fumes from a power generator leaked into the house through a crack in a door for several hours. The children included a 7-year-old boy and two girls, ages 4 and 11. According to the Consumer Product Safety Commission (CPSC), the amount of exhaust from one generator is equivalent to that of hundreds of idling cars. The three children were lucky they were removed from the area and treated early enough that they did not die.
Another little boy was not so lucky. On Christmas Eve, 2004, a generator had been running in 2008the basement of the family’s home. That night the 3-year-old was found unresponsive with a CO level above 500 parts per million (ppm). (The Environmental Protection Agency lists the level of CO in air as 3 ppm.) The boy had suffered CO poisoning, cardiac arrest, and died. A 35-year-old neighbor of the boy had gone into the house to help and suffered a headache, nausea, and vomiting and was treated at the hospital for CO poisoning.
The dangers of CO exposure
The dangers of CO exposure depend on a number of variables, including the victim’s health and activity level. Infants, pregnant women, and people with physical conditions that limit their body’s ability to use oxygen (i.e., emphysema, asthma, heart disease) can be more severely affected by lower concentrations of CO than healthy adults would be.
CO poisoning can be confused with flu symptoms, food poisoning and other illnesses. Some symptoms include shortness of breath, nausea, dizziness, light headedness, or headaches. High levels of CO can be fatal, causing death within minutes. Although most CO poisoning happens during a single incident, it is possible to suffer from chronic CO poisoning when a person is exposed to low levels of CO over weeks or months and experiences symptoms over that time.
Even single-incident CO exposures can have long-term health consequences, such as cardiovascular manifestations, neurological dysfunction, or brain damage, occuring days to weeks after the exposure. In 14 percent to 40 percent of serious initial CO poisonings, the individual exposed still faces the prospect of delayed neurologic dysfunction.
According to the Centers for Disease Control and Prevention (CDC), an estimated 15,200 people were treated annually during 2001-2003 in emergency departments for nonfatal, unintentional, non-fire-related CO exposure. During 2001-2002, the CDC estimates 480 people died, on average, each year from unintentional non-fire related carbon monoxide exposure.
The CPSC is a federal regulatory agency that works to reduce the risk of injuries and deaths that result specifically from consumer products. According to them, 166 unintentional non-fire carbon monoxide poisoning deaths were associated with consumer products on average, annually from 2002-2004 . This was a 34 percent increase in unintentional non-fire carbon monoxide poisoning deaths from 1999-2000, in which an average of 124 deaths were reported annually.
Of the CO non-fire deaths related to consumer products in 2003 and 2004, 47 percent were associated with the use of heating systems, most often gas heating systems. Another 35 percent of the CO deaths were associated with engine-driven tools. The CPSC reports that 73 percent of CO deaths occurred in the home, while deaths in tents, campers, and other temporary shelters accounted for an estimated 14 percent of deaths during 2003-2004.
The CPSC examined carbon monoxide incidents associated specifically with engine-driven generators and other engine-driven tools that occurred between 1990 and 2004. During these 15 years, generators resulted in 264 CO potential exposure deaths and were the leading engine-driven consumer products involved in CO exposure incidents.
NFPA 720 and State legislation
The applicable NFPA standard is NFPA 720, Standard for the Installation of Carbon Monoxide (CO) Warning Equipment in Dwelling Units. The 2005 edition of the code covers the selection, application, installation, location, testing, and maintenance of CO warning equipment within dwelling units that contain fuel-burning appliances or fireplaces, or have attached garages. The purpose of the standard is to provide a warning of the presence of CO in sufficient time to allow occupants to either escape or take other appropriate action.
According to NFPA 720, a CO alarm or detector must be centrally located outside each separate sleeping area in the immediate vicinity of the bedrooms. Each alarm or detector should be located on the wall, ceiling, or other location as specified in the installation instructions that accompany the unit.
As of 2007, 15 states and more than 40 other authorities having jurisdiction require some form of carbon monoxide detection. Texas, for example, only requires CO detectors in day care and group homes, while Oklahoma only requires detectors in child care facilities. Many states only require carbon monoxide detectors in newly constructed buildings. Of the 15 states that have adopted requirements for carbon monoxide detection, ten require the installation of carbon monoxide detectors in occupancies not covered by the standard, which only applies to dwelling units.
The NFPA Technical Committee on Carbon Monoxide Detection has expanded the scope and requirement of NFPA 720 to cover all occupancies — not just dwelling units. The newly revised version of NFPA 720 will require CO alarms or detectors outside each separate sleeping area and on every level within the dwelling unit. It will also cover, for the first time, buildings and structures other than dwelling units. The standard is being voted on and should go into effect in 2008.
Reducing CO deaths and injuries
NFPA urges individuals to follow these steps to ensure safety in and around their home.
Install CO alarms (listed by an independent testing laboratory) inside to provide early warning of accumulating CO. CO alarms should be installed in a central location outside each separate sleeping area. If bedrooms are spaced apart, each area will need a CO alarm.
Call your local fire department’s non-emergency number to find out what number to call if the CO alarm sounds. 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).
If your CO alarm sounds, immediately move to a fresh air location and call for help. Remain at the fresh air location until emergency personnel say it is okay. If the audible trouble signal sounds, check for low batteries or other trouble indicators.
Test CO alarms at least once a month and replace CO alarms according to the manufacturer’s instructions. CO alarms are not substitutes for smoke alarms. Know the difference between the sound of your smoke alarms and CO alarms.
Have fuel-burning heating equipment (fireplaces, furnaces, water heaters, wood and coal stoves, space or portable heaters) and chimneys inspected by a professional every year before cold weather arrives.
When purchasing new heating and cooking equipment, select products tested and labeled by an independent testing laboratory. When using a fireplace, open the fl ue for adequate ventilation. Never use your oven to heat your home.
If you need to warm 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.
During and after a snowstorm, make sure vents for the dryer, furnace, stove, and fireplace are clear of snow build-up.
When camping, remember to use battery-powered lights in tents, trailers, and motor homes.
A generator should be placed well away from the house because carbon monoxide can get pulled into the house through vents or open windows.
Jennifer Flynn is a Research Analyst with the NFPA’s Fire Analysis and Research Division. She can be reached at firstname.lastname@example.org.