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What Are the Signs of Carbon Monoxide Poisoning?


A total of 5,149 people died in the U.S. from 1999 to 2010 due to unintentional carbon monoxide poisoning1. That’s an average of 430 deaths per year. Why is that number so high? Carbon monoxide (CO) is a deadly and preventable killer but still we have so many deaths. Below we will take a look at statistics for known carbon monoxide poisonings, how it can be prevented and why every home should have a CO detector.

What is carbon monoxide?

Carbon monoxide is a clear but toxic, odorless, flammable gas that results when carbon does not completely combust. There is no taste, which makes it even more difficult to detect during CO leaks. The most common culprit for carbon monoxide leaks is the internal combustion engine in addition to some furnaces and ovens.

Why is carbon monoxide dangerous?

Carbon monoxide is very dangerous to those who breathe it in because it pushes out oxygen from the blood, taking its place. The CO binds to hemoglobin in the blood creating carboxyhemoglobin which stops oxygen from binding to hemoglobin. As the carbon monoxide replaces the oxygen the body’s organs receive less of the oxygen they need to function properly. As carbon monoxide builds up in the blood, the body eventually loses consciousness and the victim can suffocate to death if not removed from the source of CO.

Severe poisoning can take place as quickly as minutes; however, a small slow leak can also take place over time. If caught before the buildup of carbon monoxide becomes too severe, the poisoning can be reversed. Unfortunately though, due to the nature of CO poisoning, it is possible to recover while still suffering from permanent damage to the brain and other organs. This damage can have various effects and render a person impaired for the rest of their life.

What are symptoms of carbon monoxide poisoning?

There are a number of symptoms of CO poisoning, most of which are also symptoms of illnesses. Some of the most common symptoms include:

  • Headache
  • Nausea
  • Dizziness
  • Shortness of breath
  • Loss of muscle control
  • Loss of consciousness
  • Chest Pain
  • Fatigue
  • Flu-like symptoms
  • Confusion
  • Depression
  • Hallucinations
  • Agitation
  • Abdominal pain
  • Fainting
  • Memory difficulties

The severity of symptoms experienced by an individual varies based upon an individual’s health as well as the concentration of CO in the air. In the average person, a concentration of 35 parts per million causes a headache and dizziness in 6-8 hours of constant exposure. In more serious cases, 12,800 parts per million of CO results in unconsciousness in the victim after 2-3 breaths and death in less than three minutes.

The carbon monoxide headache

The most commonly seen symptom of CO poisoning is a headache. Victims that have experienced this symptom describe it as a continuous headache that sits at the front of the head and generates a dull pain. It’s a very distinct headache so it’s important that you leave your home immediately.

Delayed neurological manifestations

In some cases of carbon monoxide poisoning victims have been known to exhibit delayed neurological symptoms. These symptoms can be particularly troublesome and include dementia, psychosis, amnesia, difficulty speaking, cortical blindness, depression, and symptoms that mimic Parkinson’s disease. There is no set of characteristics to determine who will develop these delayed neurological symptoms and they have been seen in as many as 50% of poisoned individuals. These severe delayed symptoms can occur between 2-40 days following poisoning.

Sources of carbon monoxide

Some common sources include cigarette smoke, malfunctioning furnaces, house fires, heaters, vehicle exhaust, wood burning stoves, electric generators and equipment that uses propane. When these things are used in confined spaces they increase the concentration of carbon monoxide that is breathed in.

Preventing carbon monoxide poisoning

CO poisoning not only occurs in homes but it also occurs in numerous workplaces where particular equipment is prominent. It is important to understand how this silent killer can be prevented in both of these settings.

Carbon monoxide detectors

The primary method of prevention is a carbon monoxide detector – see our review of the best carbon monoxide detectors.

Carbon monoxide detectors are affordable and easy to use but they provide a first line of defense against potential leaks. These detectors can be purchased alone or as part of a larger home alarm package and vary in price depending upon the company that produces them. On average, a good CO detector can be purchased for $30. Within every detector is a small sensor that is triggered when any above-normal amount of CO is sensed. Dangerous levels of carbon monoxide are determined by the Underwriters Laboratories (UL) safety standards. The average level of carbon monoxide within a home that has no gas stove ranges from 0.5 to 5 parts per million, for homes with gas stoves this level is higher. These detectors are calibrated to sound an alarm when above safe levels of CO are detected by the sensor inside the housing. Depending upon the concentration of carbon monoxide in the air, the detector will sound an alarm in a few minutes or, for much lower concentrations, within an hour.

The importance of detector maintenance

Just like smoke alarms, it is important to regularly maintain CO detectors. This means that each time the clock jumps forward or rolls back, as you check your smoke alarm batteries, you should also test your batteries. It is also important to replace your detector as you feel it is necessary. Studies show that over time the sensitivity of these devices declines so it is important to pay attention to the estimated lifespan of the alarm that you select.

Routine appliance maintenance

A considerable number of carbon monoxide poisonings result from faulty furnaces, heating systems, and appliances that run on gas, oil or coal. This means that it is crucial to get these items serviced every year in order to ensure that they are not leaking carbon monoxide into the home. Routine checks will also help to ensure that your home appliances remain in good working order.

Use caution

Caution should always be used when using camping stoves, generators or charcoal grills. These items should never be used indoors or in closed spaces because they lead to a significant buildup of carbon monoxide. It is also important never to run a car while sitting immobile in the garage. Even if the garage door is open, the CO can build up and get sucked back into the house as soon as a door is cracked.

Use only regulation heaters

Heaters that have been approved by UL for indoor use should be the only heaters that are used indoors. Using any other type of heater can result in the release of carbon monoxide into a poorly ventilated area. One of the biggest mistakes that homeowner’s make when trying to use unconventional methods to heat their home is to use a gas oven to do so. Gas ovens result in a rapid buildup of CO which can quickly overcome homeowners.

Always ensure that chimneys are cleared

Not only can blocked chimneys lead to fire, but they can also lead to a buildup of carbon monoxide within the home. Since the chimney sits unused for a long period of time during the spring and summer, it is important every fall before lighting the stove or fireplace for the first time, to get a cleaning. Local chimney sweeps are generally affordable and they are certainly more affordable than death by carbon monoxide poisoning!

Use a personal carbon monoxide detector on the job if needed

In occupations where carbon monoxide exposure poses a severe threat, employers should always issue personal carbon monoxide detectors. These small versions of their larger counterparts work the same way and are often issued to firefighters, police officers, refinery workers, taxi drivers, and machine workers. If carbon monoxide above normal levels is a commonplace occurrence, employers should offer a breathing apparatus. In situations where confined spaces and high levels of CO are combined, employers are required to test employees for sufficient oxygen levels prior to entering the workspace.

Always be conscious of symptoms

If you ever experience symptoms that indicate a possibility of carbon monoxide poisoning it is important not to ignore them. If these symptoms are experienced at work, ensure that your employer is made aware of them. If these symptoms are experienced at home, consult a doctor with your concerns.

What to do if your CO detector sounds

If your carbon monoxide detector sounds your first concern should be evacuating the area. Children, the elderly and those with compromised health should be evacuated from the home first. If there are too many individuals in need of assistance to evacuate at once, make sure that windows in the home are opened to help dilute the concentration of CO in the area. Once everyone has been evacuated from the home call the fire department and also ask for medical assistance to be dispatched to your location. Ensure that emergency professionals are aware of the presence of CO in the home. Do not go back into the home until the source has been identified. It may require public service officials from utility companies to come to the area and correct gas leaks, but the fire department will be able to locate a leak and turn off its source.

Treatment for carbon monoxide poisoning

Carbon monoxide poisoning is treated through the administration of high doses of oxygen. This oxygen is applied through a facemask using an oxygen reserve bag. In cases where poisoning is extreme, individuals may be placed in a hyperbaric oxygen chamber where oxygen can be delivered in even higher doses. Victims of CO poisoning should always be kept in hospital custody and receive oxygen treatment until blood oxygen levels are safe enough for them to be released. Despite having been treated, it is important that victims do not return to the area of poisoning until the leak has been identified and resolved.


The symptoms of CO poisoning frequently mimic other illnesses and as such victims often receive other diagnoses including:

  • Flu
  • Chronic fatigue syndrome
  • Depression
  • Food poisoning
  • Viral infections
  • Cyanide poisoning
  • Opioid abuse
  • Sedative abuse
  • Stroke
  • Migraine
  • Myocardial ischaemia

If you have received one of these diagnoses but suspect carbon monoxide poisoning you should always seek a second opinion.

What are some carbon monoxide poisoning statistics?

According to the Centers for Disease Control and Prevention, carbon monoxide poisoning is more common during the fall and winter. This is due to the increased use of heaters, generators and gas furnaces.

  • Males make up three times more deaths than females from CO poisoning.
  • People 65 years and older had the highest death rates from CO poisoning.
  • The lowest death rates from CO poisoning was from people 25 years and younger.

Demographics of carbon monoxide victims

While there is no typical carbon monoxide victim, statistics show that some groups of people are more likely to report poisoning. Women rather than men report higher incidences of carbon monoxide poisoning. Researchers suggest that this is not due to an increased predisposition but rather because women are more likely to be at home for longer periods of time than men although recent trends indicate that this is not as much of the case as it once was. As with most illnesses and injuries, children, unborn children, the elderly and those with compromised respiratory function are at highest risk for serious side effects. This group is almost always the first to show signs of poisoning.

Carbon monoxide poisoning and pregnancy

Carbon monoxide exposure is of particular concern during pregnancy. Exposure to unhealthy levels of CO has been proven to cause severe adverse effects as it deprives fetal tissue of oxygen through preventing maternal oxygen from passing to the baby. In addition to oxygen deprivation in this way, carbon monoxide also crosses into the baby’s body and causes poisoning. Where CO quickly attaches to adult hemoglobin, it attaches at a much higher rate in infants. Even in cases where mothers to experience only slight side effects from carbon monoxide, infants may experience fatal poisoning.

Carbon monoxide poisoning is the leading cause of poisoning deaths

With the existing data, carbon monoxide poisoning is the leading cause of poisoning death within the United States. That fact alone is mind-blowing since the identification of CO poisoning after death can be tricky. The effects of carbon monoxide often mimic other illnesses or conditions and lead to misdiagnoses of the cause of death. Even without these misdiagnoses, carbon monoxide leads the pack in poisoning deaths.

Learn more

Check out our best smoke detectors reviews to learn about dual sensor alarms that will detect smoke and CO.

Not sold on the dangers of CO or just want to learn more about it? Check out this short segment of carbon monoxide poisoning covered by CNN.

Have you heard of any nightmare CO stories?

Source: [1] Centers for Disease Control and Prevention

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