Smoke and fume inhalation can cause serious breathing problems, poisoning and loss of consciousness. It may happen during a fire, after exposure to vehicle exhaust, from faulty heating equipment, generators, industrial processes or other sources of harmful gases and vapours.
The danger is not always obvious. Some gases, including carbon monoxide, cannot be seen or smelled, and symptoms may initially seem mild before becoming more serious.
This guide explains how to recognise smoke or fume inhalation, what first aid to give, when to call 999, and why your own safety must always come first.
Important: never enter a smoke-filled or fume-filled area to rescue someone unless you are appropriately trained and equipped. You could quickly become another casualty.
Smoke and fume inhalation happens when a person breathes in harmful gases, particles, vapours or combustion products.
Possible sources include:
The exact effects depend on what was inhaled, how concentrated it was and how long the person was exposed.
Smoke from a fire may contain a mixture of hot gases, toxic chemicals and particles that can irritate or damage the airway and lungs.
Some fire environments can also contain carbon monoxide, which interferes with the body's ability to carry oxygen effectively.
Possible consequences include:
Symptoms vary depending on the substance and severity of exposure.
Possible warning signs include:
After a fire, additional clues can include soot around the nose or mouth, facial burns or singed facial hair.
| Step | What to do | Why it matters |
|---|---|---|
| 1. Protect yourself | Do not enter an area containing smoke, fumes or an unknown gas unless it has been made safe and you are appropriately trained and equipped. | Rescuers can be overcome very quickly by toxic gases or lack of oxygen. |
| 2. Call for emergency help | Call 999 or 112 for serious smoke or fume exposure. | The casualty may need oxygen, monitoring and hospital treatment. |
| 3. Move to fresh air if safe | Help the casualty away from the source and into fresh air only if this can be done without exposing yourself. | This stops or reduces further inhalation. |
| 4. Help them rest | Support them in a comfortable position and encourage calm, normal breathing. | Breathing may become more difficult if they panic or exert themselves. |
| 5. Monitor them | Keep checking breathing, responsiveness and overall condition while help is on the way. | Symptoms can worsen after the initial exposure. |
No, not unless you are appropriately trained and equipped.
Smoke and toxic fumes can make a rescuer unconscious very quickly. St John Ambulance guidance specifically advises against entering a fume-filled area yourself.
If someone is trapped inside:
Fire and rescue personnel have respiratory protective equipment and training for these environments.
Call 999 or 112 if:
Tell the ambulance service what substance or source may be involved if you know.
If the exposure is chemical or industrial, keep the product information or Safety Data Sheet available where possible.
If the casualty is awake and breathing:
Do not allow them to return to the contaminated area.
Breathing difficulty after smoke or fume exposure should be taken seriously.
Call 999 and keep the casualty at rest.
Possible signs of worsening breathing include:
If the person has asthma and exposure has triggered an attack, help them use their usual reliever inhaler according to their asthma plan.
See our First Aid for Asthma Attacks guide for detailed guidance.
If the casualty becomes unresponsive:
See our First Aid for an Unconscious Person guide for further information.
If someone is unresponsive and not breathing normally:
Do not delay CPR while trying to determine exactly which gas or smoke caused the collapse.
See our CPR Explained and AED & Defibrillators Explained guides.
Carbon monoxide is a poisonous gas produced when fuels do not burn completely.
Possible sources include:
Carbon monoxide cannot be reliably detected by smell or sight.
Possible symptoms include:
St John Ambulance advises calling 999 or 112 if carbon monoxide poisoning is suspected and helping the casualty into fresh air without entering the contaminated area yourself. :contentReference[oaicite:2]{index=2}
If several people in the same room or building develop headache, dizziness, nausea, confusion or weakness, consider the possibility of a shared environmental cause such as carbon monoxide or another harmful gas.
Leave the area if it is safe to do so and call emergency services.
Do not re-enter until the building has been declared safe.
A person rescued from a fire may have several injuries at the same time.
Possible concerns include:
Do not focus only on visible burns. Breathing problems can be more immediately dangerous.
See our Burns & Scalds First Aid guide for burn treatment information.
Warning signs that the airway may have been affected include:
Airway swelling can become more serious after the initial incident, so significant smoke exposure should not be dismissed simply because the person is initially able to talk.
Yes.
Some people may initially appear relatively well after inhaling smoke or fumes and then develop worsening symptoms.
Seek medical advice if someone develops:
Smoke can trigger asthma symptoms, but smoke inhalation and an asthma attack are not necessarily the same thing.
| Smoke or fume inhalation | Asthma attack |
|---|---|
| May affect anyone after exposure to harmful gases, particles or fumes. | Occurs in someone whose airways narrow because of asthma. |
| May involve toxic gases such as carbon monoxide. | Can be triggered by smoke, allergies, infection or other triggers. |
| May cause headache, confusion, nausea and unconsciousness as well as breathing symptoms. | More typically causes wheezing, coughing, chest tightness and difficulty breathing. |
| Significant exposure may require emergency assessment even in someone without asthma. | The person should follow their established asthma emergency plan and use their prescribed reliever as appropriate. |
Workplaces may contain harmful fumes from:
The first aid response may depend on the exact substance.
Where chemicals are involved:
See our COSHH & First Aid Explained guide for wider workplace planning.
Confined spaces are particularly dangerous because gases can accumulate and oxygen levels may fall.
Examples can include:
Never enter a confined space to rescue someone without the training, equipment and rescue arrangements required for that environment.
A casualty may have collapsed because the atmosphere itself is immediately dangerous to life.
Portable generators can produce carbon monoxide.
They should not be used inside homes, garages, tents, caravans or other enclosed areas where exhaust gases can build up.
If someone becomes unwell near a running generator:
Vehicle exhaust can also contain carbon monoxide and other harmful gases.
Risk increases when engines run in poorly ventilated garages, workshops, loading areas or other enclosed locations.
If a person collapses in a vehicle or enclosed area where an engine has been running, do not enter if the atmosphere may still be dangerous.
Call emergency services and follow their instructions.
Emergency oxygen may be useful after smoke or fume inhalation, but it should generally be administered by someone who is appropriately trained and using suitable equipment.
Do not delay calling 999, moving the casualty to fresh air where safe, or starting CPR while searching for oxygen equipment.
Do not give food or drink to someone who is drowsy, confused, unresponsive or struggling to breathe.
If there is a possibility of poisoning or chemical exposure, follow advice from emergency services or the relevant Safety Data Sheet rather than giving anything by mouth.
Children can be particularly vulnerable to smoke and toxic gases because of their smaller airways and body size.
After significant smoke exposure, seek urgent medical advice if a child has:
Call 999 for serious breathing difficulty or reduced responsiveness.
Older people or those with heart or lung conditions may become seriously unwell after smoke exposure more quickly than a healthy adult.
Lower the threshold for obtaining medical advice if the casualty has:
Common mistakes include:
A standard first aid kit cannot treat smoke inhalation or carbon monoxide poisoning.
The most important actions are:
A first aid kit may still be useful for associated injuries such as burns, cuts or other injuries sustained during an evacuation.
You can view our range of first aid kits for home, workplace and emergency preparedness.
| Situation | What to do |
|---|---|
| Smoke or fumes still present | Do not enter the area unless trained and equipped. Call emergency services. |
| Casualty can be reached safely | Move them into fresh air and away from the source. |
| Breathing difficulty | Call 999 and keep the casualty at rest while monitoring them. |
| Possible carbon monoxide exposure | Move to fresh air where safe and call 999 or 112. |
| Unresponsive but breathing normally | Use the recovery position where appropriate and continue monitoring breathing. |
| Not breathing normally | Call 999, begin CPR and use an AED if available. |
| Industrial chemical exposure | Identify the substance and provide the Safety Data Sheet or product information to emergency services. |
St John Ambulance provides clinically reviewed guidance on carbon monoxide poisoning and first aid emergencies involving harmful fumes.
You can read the St John Ambulance guidance on carbon monoxide poisoning for further information.
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