Smoke inhalation and carbon monoxide poisoning first aid¶

Smoke inhalation is the leading cause of death in indoor structure fires, claiming far more lives than external flame burns. When household materials, plastics, furniture foam, and fuel burn in an enclosed space, they release superheated gases that scorch the upper airway alongside lethal concentrations of invisible toxic gases like carbon monoxide (CO) and hydrogen cyanide (HCN). Immediate rescue into fresh air, monitoring for rapid airway swelling, and rapid transport for medical oxygen therapy are critical to saving a victim's life.

Do this now¶

1. Protect yourself and verify scene safety: Never enter a burning building, smoke-filled room, or enclosed space (such as a garage or basement with a running generator) without self-contained breathing apparatus. Hold your breath and stay low only if extracting someone immediately visible from an unburned doorway.
2. Move the person into fresh outdoor air immediately: Carry or drag the victim at least 15 to 30 meters (50 to 100 feet) away from the smoke source or indoor structure into open, circulating outdoor air.
3. Call emergency medical services: Call your local emergency number (911 in the United States and Canada, 112 across the European Union, 999 in the United Kingdom) or consult our directory of emergency numbers. Report suspected smoke inhalation or carbon monoxide poisoning so paramedics bring high-flow oxygen and advanced airway equipment.
4. Check breathing and position the victim:
5. If conscious and breathing: Help the person sit upright or semi-upright (at a 45-degree angle). Sitting upright reduces swelling in the throat and makes breathing easier.
6. If unconscious but breathing: Place the person on their side in the recovery position so their tongue does not block the throat and any vomit or mucus drains safely out of the mouth.
7. If unresponsive and not breathing normally: Begin CPR immediately with chest compressions and rescue breaths.
8. Loosen tight clothing and keep the person still: Unbutton collars, ties, belts, and jackets around the neck and chest. Keep the victim completely at rest; physical exertion increases oxygen demand and accelerates the circulation of carbon monoxide and cyanide to the heart and brain.
9. Watch for sudden airway closure: Listen closely for a raspy, hoarse voice, noisy high-pitched breathing (stridor), or difficulty swallowing, which signal that throat tissues are blistering and swelling shut from heat.

flowchart TD
    Start["Victim Exposed to Smoke or Carbon Monoxide"] --> Safe{"1. Is the Scene Safe for You to Enter?"}
    Safe -->|No: Heavy Smoke or Fire| Wait["Stay Outside, Call Emergency Services, Wait for Firefighters"]
    Safe -->|Yes: Safe to Reach| FreshAir["2. Move Victim Immediately to Fresh Outdoor Air"]
    FreshAir --> Call["3. Call Emergency Services: Request High-Flow Oxygen"]
    Call --> Check{"4. Is the Victim Conscious and Breathing?"}
    Check -->|Conscious and Breathing| Upright["Sit Victim Upright at 45 Degrees, Loosen Collar, Keep Calm and Still"]
    Check -->|Unconscious, Breathing Normally| Recovery["Place in Side Recovery Position, Monitor Airway for Swelling"]
    Check -->|Not Breathing or Only Gasping| CPR["Begin CPR Immediately: 30 Compressions to 2 Rescue Breaths"]
    Upright --> Hospital["5. Mandatory Hospital Evaluation for Airway Burns and Delayed Lung Edema"]
    Recovery --> Hospital
    CPR --> Hospital

The three lethal mechanisms of smoke inhalation¶

Understanding how smoke injures the human body explains why someone who walks out of a fire looking unharmed can collapse into respiratory arrest 30 minutes later. Smoke inhalation attacks the body through three distinct mechanisms at the same time.

Recognizing upper airway thermal burns (impending airway closure)¶

Dry air conducts heat poorly, so most thermal heat from a fire is absorbed by the moist tissues of the mouth, throat, and voice box before reaching the deep lungs (unless the person inhaled live steam, which burns all the way down into the lungs). When the delicate tissues of the throat and larynx are scorched by hot gases, they react just like a severe skin burn: they blister and swell rapidly with fluid.

Because the adult windpipe at the vocal cords is only a narrow opening, swelling over the first 30 minutes to 4 hours after a fire can completely seal the airway shut. Look and listen for these urgent red flags:

• Facial and nasal signs: Burns around the lips, nose, or eyebrows, or singed nasal hairs inside the nostrils.
• Carbonaceous (black) sputum: Soot coating the tongue, gums, or roof of the mouth, or the victim spitting up gray or black-flecked saliva.
• Voice changes: A newly hoarse, muffled, or raspy voice, or pain when speaking or swallowing saliva.
• Stridor: A harsh, high-pitched squeaking or whistling sound heard when the person breathes in. Stridor is a life-threatening medical emergency indicating that the airway is already narrowed by more than 70 percent.

Carbon monoxide (CO) and hydrogen cyanide (HCN) toxicity¶

Modern homes and vehicles are filled with synthetic polymers, polyurethane foam mattresses, nylon carpets, upholstery, and plastics. When these materials burn or smolder, they produce two invisible, deadly cellular poisons: carbon monoxide and hydrogen cyanide (often called the "toxic twins" of smoke inhalation).

How carbon monoxide starves the body of oxygen¶

Carbon monoxide is an odorless, colorless, tasteless gas produced by any incomplete combustion of carbon fuels (wood, coal, gasoline, natural gas, propane, charcoal, and household structures). When inhaled:

1. Carbon monoxide binds to hemoglobin in red blood cells with an affinity 200 to 250 times stronger than oxygen, forming carboxyhemoglobin (COHb).
2. This prevents red blood cells from carrying oxygen from the lungs to the rest of the body, and prevents the remaining oxygen molecules from releasing into starving brain and heart tissues.
3. Simultaneously, hydrogen cyanide enters the cells directly and shuts down the mitochondria (the cellular powerhouses), preventing cells from using any oxygen that does arrive.

Symptoms of carbon monoxide poisoning by severity¶

Also note that the classic textbook sign of "cherry-red skin and lips" is almost never seen in living victims; it typically appears only after death. Living victims of carbon monoxide poisoning usually look pale, sweaty, or bluish-gray (cyanotic).

Step-by-step first aid while waiting for paramedics¶

Once the victim is out of the hazardous environment and in fresh air, follow these specific care steps until emergency medical personnel take over:

1. Optimize positioning for breathing¶

• Conscious patients: Help the person sit upright at a 45-to-90-degree angle, leaning slightly forward with their hands resting on their knees or a table (the tripod position) if they feel short of breath. Keeping the head elevated above the heart uses gravity to slow down fluid swelling in the upper throat and vocal cords.
• Unconscious, breathing patients: Roll the person onto their side in the recovery position. Carbon monoxide and cyanide frequently trigger severe nausea and vomiting; lying flat on the back while unconscious causes fatal aspiration of vomit into the lungs.

2. Treat external burns and preserve body heat¶

• If the victim's clothing is still smoldering or hot, douse it with cool running water and remove any clothing that is not melted or stuck to the skin (see our burns first aid guide).
• Once any burning has stopped, wrap the victim in clean, dry blankets. Both carbon monoxide poisoning and thermal burns disrupt the body's temperature regulation, and shivering increases oxygen consumption by up to 400 percent.

3. Administer emergency oxygen if trained and equipped¶

In normal outside air (21% oxygen), it takes 4 to 6 hours for the human body to eliminate half of the carbon monoxide bound to its blood cells.

• Breathing 100% high-flow medical oxygen through a tight-fitting non-rebreather mask (delivered by firefighters or paramedics) cuts that half-life down to 60 to 90 minutes.
• In severe cases (such as coma, seizures, cardiac ischemia, very high blood CO levels, or carbon monoxide exposure in a pregnant woman where fetal hemoglobin binds CO tightly), hospitals use hyperbaric oxygen therapy (HBOT) inside a pressurized chamber at 2.5 to 3 atmospheres, reducing the elimination time to 20 to 30 minutes and preventing delayed brain damage.

4. Perform CPR with rescue breaths if needed¶

If the victim is unresponsive and not breathing or only gasping, start CPR immediately. Unlike sudden cardiac arrest from a primary heart rhythm problem (where hands-only CPR is effective for the first few minutes), arrest from smoke inhalation or carbon monoxide is an asphyxial arrest where the blood is completely depleted of oxygen. Providing 30 chest compressions followed by 2 full rescue breaths delivers fresh oxygen into the victim's lungs. Looking after your own safety: the minuscule amount of carbon monoxide exhaled from a victim's lungs during mouth-to-mouth resuscitation poses no toxicity hazard to the rescuer.

Delayed pulmonary edema: the 24 to 48 hour danger window¶

Every person exposed to significant smoke inside an enclosed space must be evaluated at a hospital emergency department, even if they feel fine after breathing fresh air for 15 minutes.

Toxic gases in smoke (such as phosgene from burning plastics, hydrochloric acid, and nitrogen oxides) dissolve slowly into the moisture lining the deep air sacs (alveoli) of the lungs. Over 12 to 48 hours after the fire, this chemical damage breaks down the capillary membranes in the lungs, causing fluid from the bloodstream to leak into the air sacs. This condition is called delayed non-cardiogenic pulmonary edema (or acute respiratory distress syndrome).

Watch any smoke-exposed person closely for 48 hours and return to the emergency room immediately if they develop:

• New or worsening shortness of breath while resting or walking across a room.
• A persistent cough that begins producing frothy, pink, or blood-tinged sputum.
• Wheezing, crackling sounds in the chest, or inability to lie flat in bed without gasping for air.
• Delayed neurological signs (such as memory loss, confusion, personality changes, or unsteady walking), which can emerge days to weeks after carbon monoxide poisoning if not treated with adequate oxygen.

Frequently asked questions¶

Can a fingertip pulse oximeter detect carbon monoxide poisoning?¶

No, standard fingertip pulse oximeters cannot tell the difference between hemoglobin carrying oxygen and hemoglobin poisoned with carbon monoxide, so they will show a falsely normal reading of 98 to 100 percent even during life-threatening carbon monoxide poisoning.

How long after smoke inhalation can lung symptoms appear?¶

While upper throat swelling from heat typically develops within 30 minutes to 4 hours, chemical injury to the deep lung tissue can cause delayed fluid buildup (pulmonary edema) and severe breathing difficulty 12 to 48 hours after the initial smoke exposure.

Is it safe to give mouth-to-mouth rescue breaths to someone with carbon monoxide poisoning?¶

Yes, once the victim has been moved out of the contaminated room into fresh outdoor air, the trace amount of carbon monoxide or smoke gases remaining in their exhaled breath is far too diluted to harm a rescuer performing mouth-to-mouth resuscitation.

Why shouldn't you give water to someone who inhaled hot smoke?¶

Hot smoke scorches the delicate tissues of the voice box and throat, causing rapid blistering and swelling that can cause choking, vocal cord spasm, or vomiting during emergency medical intubation if the person swallows liquids.

Related guides¶

• Burns and scalds first aid
• CPR and AED step-by-step guide
• Carbon monoxide leaks and alarms
• House fire escape and survival
• Emergency numbers by country