What are the Dangers of Smoke Inhalation?

Updated: Apr 21

[1] Although we likely consider burns and fire-related injuries as the biggest cause of deaths in a fire, smoke inhalation kills more people [2] on average per year.

Remember the last time you sat too close to a campfire or barbeque, and you started to cough, and your eyes were red, dry, and itchy? This is an example of acute (immediate) smoke irritation. This cleared quickly, generally when you were away from the fire, and you probably did not suffer any longer-term effects. Unfortunately, in emergency situations, escape can be delayed, and symptoms can worsen from over-exposure. Prolonged exposure can be evidenced by soot around the nostrils and the mouth, particularly in the inner edge of the lips and the roof of the mouth. However, more worrying is the serious damage that occurs deeper inside the body.

Shed burning with large smoky flames in the black of night.

What is Smoke?

Smoke can be thought of as a by-product that is the result of incomplete combustion. It can be made up of ‘tiny particles of either partially oxidized or fully oxidized or unreacted fuel particles,’[3] of which many can be toxic or harmful to health as the chemical process of combustion removes oxygen from the air: leaving nothing but smoke and carbon dioxide to inhale. Generally, the darker and thicker the smoke, the more toxic chemicals it produces and the more it should be avoided, if possible.

The components of smoke that stem from fires can differ depending on the fuel being burnt but can contain a large proportion of similar particles and chemicals. These go on to affect airway patency, deliver acute (immediate) symptoms that fade, and even long-term symptoms that can be life-changing. Smokes commonly contain carbon monoxide (CO), Carbon Dioxide (CO²), and particulate matter-sometimes referred to as soot.

Smoke Inhalation Injuries (SII)

Smoke and air in a fire can reach a temperature range of between 100-1,500°C, climbing from floor to ceiling, which can rapidly rise during fire events such as a flashover, causing unimaginable damage to the body, particularly in the respiratory tracts and organs. Smoke Inhalation Injuries (SII) can be assessed using a bronchoscopy[4] which allows medical professionals to examine your tongue, epiglottis, larynx (voice box), trachea (windpipe), bronchus, and lungs to assess damage and devise a treatment plan.[5]

Without early detection and treatment, SII can be a major cause of mortality in burn patients, or in the best-case scenario at least indicate an extended stay in intensive care and requiring ventilation due to the increased possibility of developing pneumonia.[6]

Doctor figure holding a chest x-ray, front and side views.

Carbon Monoxide (CO) and Carbon Dioxide (CO²)

Carbon monoxide and carbon dioxide are produced when fuels such as wood, gas, or oil do not burn completely. As the fire continues, oxygen is used up and carbon dioxide is released. Some of these carbon atoms do not join with other carbon atoms as the chemical combustion process continues and these leftover particles join with oxygen atoms found in the air. This forms carbon monoxide- which has only one carbon atom, and one oxygen atom (CO). This differs from carbon dioxide, which has one carbon atom and two oxygen, hence CO². If a fire does not have enough oxygen, from a lack of fresh ventilation for example, or there is a build-up of carbon dioxide (which is released from the outset of the combustion reaction), it will cease combusting, the fuel stops burning properly, and carbon monoxide is released.

Carbon monoxide will be recognisable to most due to carbon monoxide poisoning, which is only commonly assimilated with faulty boilers or central heating systems, or cookers, but can also occur from prolonged exposure to fire. Carbon monoxide poisoning occurs after CO ‘enters your bloodstream and mixes with haemoglobin (the part of red blood cells that carry oxygen around your body) to form carboxyhaemoglobin. When this happens, the blood is no longer able to carry oxygen, and this lack of oxygen causes the body's cells and tissue to fail and die.’[7]

Symptoms can range from tension-style headaches, nausea and vomiting, dizziness, and difficulty breathing, to neurological changes, for example struggling to concentrate and remember, plus mood and personality changes, seizures, tachycardia, loss of consciousness, and even death [8] if exposure to CO continues. CO² exposure comes with the same side effects as carbon monoxide poisoning but is required to be inhaled in much higher concentrations before effects can be noticed; unlike CO which can be deadly from as little as 3-4% concentration range.

Reddish flames and particles on a black background

Particulate Matter or Soot.[9]

When items are burned, particles of the charred items are taken up into the air, where they can rise and eventually resettle, or they can be breathed into the body.

This particulate matter can be of differing sizes and very fine particles, measuring only 2.5 microns or smaller in size, can have devastating consequences on the health of people who breathe them in. Exposure to such fine particles can cause ‘short-term health effects such as eye, nose, throat and lung irritation, coughing, sneezing, runny nose and shortness of breath.’[10]

Prolonged exposure can affect lung capabilities and can worsen lung and heart conditions such as asthma or heart disease. ‘Scientific studies have linked increases in daily PM2.5 exposure with increased respiratory and cardiovascular hospital admissions, emergency department visits and deaths, [and that long term exposure can result in] increased rates of chronic bronchitis, reduced lung function and increased mortality from lung cancer and heart disease.’[11]

The Risks are Clear

As explored above, exposure to the components of smoke can be extremely dangerous, even if only for a short while, and long-term exposure can create vast increases in the risks to your short- and long-term health, potentially even resulting in death.

The best way to avoid long-term damage due to the inhalation of smoke is, of course, to completely avoid exposure to fire. Secondary measures such as rapid evacuation, getting outside into the well-ventilated spaces, moving low and close to the ground, covering the mouth and nose with a damp cloth to create a barrier for smoke and smoke particles, seeking medical assistance and being vigilant for the symptoms of smoke inhalation after the event.

Many large-scale atrium buildings are now being designed with layouts and features that funnel the smoke out, with the assistance of smoke curtains guiding the smoke to the smoke vents above, to prevent damage to the main centre point of the building and allows for escape routes to be kept clear of smoke. If your workplace is at greater risk of fire and smoke generation, you can consider active fire protection measures such as mechanical smoke extraction systems that contain smoke vents, dampers, and fan and motor assemblies, or less invasive active measures such as a mix of smoke, and fire curtains with reduced smoke leakage, which can be fitted into open-plan offices with minimal structural impact.


[1] Image taken from Unsplash.com, courtesy of Stephen Radford.

[2] PMC: US National Library of Medicine, National Institutes of Health, ‘Inhalation injury as a prognostic factor for mortality in burn patients,’ written by R.H. El- Helbawy and F.M. Ghareeb, <https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3230152/> 20.10.2021

[3] FireFighter Insider.com, ‘Black Smoke: What Does It Mean And What Causes It?,’ <https://firefighterinsider.com/black-smoke-what-does-it-mean-and-what-causes-it/ > 20.10.2021

[4] A bronchoscopy- ‘“an examination of the breathing passages of your lungs. […] It is carried out with a thin tube-like instrument at its tip, called a bronchoscopy…” usually inserted in the nose or mouth.’ Information taken from NHS, Oxford University Hospitals, ‘Oxford Centre for Respiratory Medicine Bronchoscopy Information for Patients,’ <https://www.ouh.nhs.uk/patient-guide/leaflets/files/12354Pbronchoscopy.pdf > 25.10.2021

[5] Image from Pexels.com, courtesy of Anna Schvets.

[6] Egyptian Journal of Chest Diseases and Tuberculosis, ‘Role of fibreoptic bronchoscopy in management of smoke inhalation lung injury,’ Mohamed Amin, Hany Shaarawy and Esam Gad El-Rab, July 2015, <https://www.sciencedirect.com/science/article/pii/S0422763815200908 > 25.10.2021

[7] NHS.uk, ‘Carbon Monoxide Poisoning,’ <https://www.nhs.uk/conditions/carbon-monoxide-poisoning/> 22.10.2021

[8] Paraphrased from above.

[9] Image from Pexels.com, courtesy of Igor Haritanovich.

[10] New York State, Department for Health, ‘Fine Particles (PM 2.5) Questions and Answers,’ <https://health.ny.gov/environmental/indoors/air/pmq_a.htm> 20.10.2021

[11] See above.

Cover image from Pexels.com, courtesy of Pixabay

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