What are the risks and effects of carbon monoxide? Carbon Monoxide is the most prevalent cause of accidental poisoning deaths, and poisoning related injuries around the world.

Essential facts

Carbon monoxide is highly dangerous, as it is undetectable to human senses and highly poisonous, killing within minutes or hours depending on the concentration in the air. It’s silence and difficult-to-sense properties have gained it the ominous title ‘The Silent Killer.’

Carbon monoxide is so dangerous because it is absorbed into the body simply through breathing. As it enters the lungs it attaches itself to hemoglobin in the blood preventing your blood from absorbing oxygen. In effect this starves the body and its organs of oxygen, suffocating you from the inside out.

In 2010 The World Health Organization outlined its grave concern that carbon monoxide exposure is an under-publicized health concern. It reported that carbon monoxide is the leading cause of accidental poisonings in homes, with exposure resulting in severe cardiovascular and neurobehavioral effects, and even death.

The figures:

  • According to The Gas Safety Trust, each year in the UK alone around 50 people die from the effects of carbon monoxide poisoning; with on average 4,000 more going to accident and emergency departments due to the effects of the gas.
  • According to the NHS (2014), 200 of these cases are hospitalized. Due to the silent nature and opaque symptoms often confused with a common cold it is believed these numbers are massively under representative of the real figures.
  • Corgi research reveals that shockingly, 1 in 10 of us have suffered carbon monoxide poisoning (Source: CORGI HomePlan, 2015).
  • Research by the ‘Carbon Monoxide Is Alarmed’ campaign found that almost two-thirds of people in Great Britain are putting themselves at risk because they don’t have a carbon monoxide alarm.

It is believed many more people than officially reported die through strokes and respiratory illness exasperated by inhaling low levels of carbon monoxide over prolonged periods. Still more are left with permanent damage and invalidity. Pregnant women and their babies are, particularly at risk. CO risk is very real in the modern world, and the potential scale of this risk is cause for concern.

Symptoms of Carbon Monoxide Poisoning

Being aware of the symptoms could save your life and the lives of those you are responsible for. Carbon monoxide symptoms are similar to those of fatigue, headache, nausea, dizziness, sore throat, dry cough flu, viral infections, food poisoning or even a hangover. Because of this, it’s common for people to mistake the symptoms of carbon monoxide poisoning for something else. This is also why it’s believed cases are hugely under-reported.

The Department of Health’s statistics suggests the most common symptoms of carbon monoxide poisoning are headache (90%), nausea and vomiting (50%), vertigo (50%), confusion/changes in consciousness (30%), and weakness (20%).

Early symptoms to low levels of carbon monoxide exposure can be a reduction in your concentration levels, being unnaturally tired, uncoordinated, and having a mild headache. With prolonged or higher levels of exposure the symptoms of carbon monoxide poisoning get more pronounced and may include:

  • Severe headache
  • Nausea
  • Vomiting
  • Dizziness
  • Exhaustion
  • blurred vision
  • memory loss and confusion
  • changes in personality and behavior
  • loss of muscle control and coordination
  • impaired hearing
  • impaired vision

Other factors like diet, stress and the environment can impact the severity of all of these symptoms. To help identify a link to carbon monoxide, you can:

  • Spot if symptoms only occur when you are at home and diminish when you are away from home.
  • Check if other people and pets in your household are experiencing similar symptoms at a similar time.
  • Compare symptoms to other members in the dwelling and the rate at which the symptom might be progressing.

More severe poisoning can result in a fast and irregular heart rate, hyperventilation, confusion, drowsiness and difficulty breathing. It can take weeks for these symptoms to show and often symptoms can get worse before they get better. For some people, exposure can leave them with permanent and irreversible damage to vital organs.

Long term effects include:

  • Exhaustion and fatigue
  • Reduced muscle coordination and balance
  • Tremors
  • Difficulties controlling bladder
  • Sickness and dizziness
  • Headaches
  • Confusion
  • Irregular heartbeat
  • Sensitivity to light
  • High pitch noise in-ear and difficulty hearing
  • Increased sensitivity to foods

Babies and children are more at risk than adults because they tend to breathe twice as fast, inhaling twice as much carbon monoxide, and because their organs are still developing they are at a higher risk of organ damage. Unborn babies are at the highest risk of carbon monoxide poisoning, because fetal hemoglobin blends easier with carbon, raising the fetus’s carbon monoxide concentration levels to be higher than the pregnant mother.

Many cases of carbon monoxide poisoning can often be missed. Proving its existence in the body involves testing the blood to see if carbon monoxide is still present. It can be flushed from the body with oxygen or hyperbaric treatment. High or prolonged exposure to carbon monoxide poisoning can have long-lasting effects and cannot be reversed, severely affecting health and quality of life.

Ultimately, prolonged or severe levels of exposure cause unconsciousness, brain damage, coma, and death if medical assistance is not received in time.

Unlike in other countries, in the UK we do not routinely check for the preset of carbon monoxide in the corpse. Again, leading experts believe that cases of fatal poisoning are under-reported and mistaken for other causes of death.

Carbon Monoxide Levels – Effect on Health Explained

The levels of carbon monoxide detected, are typically described as the concentration of carbon monoxide molecules in the air and is recorded in parts per million (ppm).

The amount of carbon monoxide the blood absorbs, depends mainly on two factors, the concentration of carbon monoxide in the air and the length of time of exposure. Adverse health effects of carbon monoxide can be reduced by periods of breathing fresh air. The extent of recovery from the symptoms depends on the number and length of those periods. The table below outlines the typical effects of consistent exposure to different concentration levels of carbon monoxide in the air:

Parts per Million Time of Exposure Response
50 NA Threshold limit, no apparent toxic symptoms. Safety level as specified by the Health and Safety Executive for a maximum of 30 minutes.
100 Several hours No symptoms for long periods
200 2-3 hours Possible headache
400 1-2 hours Frontal headache and nausea within 1-2 hours becoming widespread within 3 hours
800 45 minutes Headache, dizziness and nausea
800 2 hours Dizziness, nausea, convulsions within 45 minutes, insensible, collapse and possible unconsciousness with in 2 hours.
1600 20 minutes Headache, dizziness and nausea
1600 2 hours Collapse, unconsciousness, possible death
3200 5-10 minutes Headache and dizziness
3200 10-15 minutes Unconsciousness and possible death
6400 1-2 minutes Headache and dizziness
6400 0-15 minutes Unconsciousness and possible death
12800 Immediate Unconsciousness
12800 1-3 minutes Danger of death

Many carbon monoxide detectors have screens showing the reading of carbon monoxide concentration levels. Anything below 35ppm is considered safe for exposure over an 8-hour period. Anything over 400ppm is considered extremely dangerous.