Dry Ice and Liquid Nitrogen Confined-Space Asphyxiation: Vehicle and Cooler Survival¶

Solid carbon dioxide (dry ice, at -78.5 degrees Celsius [-109.3 degrees Fahrenheit]) and cryogenic liquid nitrogen (\(\text{LN}_2\), at -195.8 degrees Celsius [-320.4 degrees Fahrenheit]) are widely used by consumers, delivery drivers, restaurants, hospitals, and laboratories to freeze food during power outages, ship frozen groceries or biological samples, create theatrical party fog, and flash-freeze desserts. Because both substances turn directly from a condensed phase into an invisible, odorless gas as they warm up, expanding in volume by 550-fold to 845-fold for dry ice and 696-fold for liquid nitrogen, placing even a small styrofoam cooler of dry ice or a venting liquid nitrogen dewar inside a closed passenger car, delivery van, unventilated walk-in cooler, small basement bathroom, or elevator cab creates a rapidly fatal confined-space asphyxiation chamber. Even worse, the two gases kill through completely different physiological mechanisms: sublimating dry ice causes acute hypercapnic carbon dioxide (\(\text{CO}_2\)) toxicity (which remains deadly even if plenty of oxygen is still present), whereas boiling liquid nitrogen causes silent normocapnic hypoxic asphyxiation (where the victim feels zero shortness of breath or air hunger before losing consciousness in two breaths). If anyone becomes dizzy, breathless, or unconscious near dry ice or liquid nitrogen, call your local emergency number immediately (911 in the United States and Canada, 112 across the European Union, 999 in the United Kingdom) or consult our directory of emergency numbers. For medical resuscitation and related gas emergencies, read our guides on carbon dioxide, dry ice sublimation, liquid nitrogen, and asphyxiation first aid, confined space asphyxiation: manholes, silos, and tanks, and compressed gas cylinder valve shear, rocketing tank, and cryogenic leaks.

Do this now¶

1. If you are driving a car or van carrying dry ice or liquid nitrogen and feel sudden shortness of breath, rapid heartbeat, headache, or dizziness, roll down ALL windows immediately, switch the dashboard A/C to Fresh Outside Air (NEVER Recirculate), pull over safely, and step out of the vehicle. Even 2.3 to 9 kilograms (5 to 20 pounds) of dry ice placed inside a closed sedan cabin or SUV cargo area (or inside a trunk that vents into the cabin through the rear parcel shelf) can push cabin \(\text{CO}_2\) concentrations past the 30,000 to 50,000 parts per million (3% to 5%) danger threshold within 15 to 40 minutes if the windows are up and the climate control is set to recirculate.
2. If you see someone lying unconscious inside a walk-in cooler, freezer, small storage room, elevator, or closed vehicle containing dry ice or a spilled cryogenic dewar, DO NOT walk in and close the door behind you. Hold your breath, prop the walk-in cooler or vehicle doors 100 percent wide open first so cross-ventilation flushes the dense gas pocket out along the floor, and only drag the victim out if you can reach them within 5 seconds from the open doorway while holding your breath. If the room is filled with a thick white cryogenic fog from a large liquid nitrogen spill or compressed \(\text{CO}_2\) line leak, wait outside for firefighters wearing Self-Contained Breathing Apparatus (SCBA).
3. Never ride inside an elevator cab alongside a liquid nitrogen dewar, a pressurized cryogenic cylinder, or a large cart of dry ice. Send the cryogenic dewar or dry ice cart up or down the elevator unaccompanied, using lobby signs or a partner on the destination floor to receive it. If the elevator stalls between floors during a power outage while you are locked inside the small \(4\text{-cubic-meter}\) (\(140\text{-cubic-foot}\)) cab with a venting liquid nitrogen tank, the boiling nitrogen will displace the cab's oxygen below the 10-percent survival threshold in minutes.
4. Never store dry ice inside an airtight glass jar, screw-top plastic bottle, sealed metal container, or latched airtight cooler, and never store dry ice inside a working walk-in cooler or airtight chest freezer. Because 1 kilogram (2.2 pounds) of solid dry ice sublimates into 541 liters (19.1 cubic feet) of \(\text{CO}_2\) gas, sealing dry ice inside a rigid container without a gas-relief vent builds pressures exceeding 5,000 kilopascals (725 psi), causing a violent dry-ice bomb explosion that shatters hands and eyes or blows the door off a freezer.
5. Once an unconscious dry-ice or liquid-nitrogen victim is dragged into fresh outdoor air, check for breathing and start rescue breathing and CPR immediately. Because asphyxiation from \(\text{CO}_2\) or \(\text{N}_2\) stops breathing before the heart stops beating, immediate rescue breaths (mouth-to-mouth or bag-valve-mask with 100% oxygen) rapidly flush the displaced gas out of the alveoli and frequently restore a spontaneous pulse if started within 3 to 5 minutes.
6. Treat any cryogenic skin or eye contact (-78.5°C dry ice or -196°C liquid nitrogen) as a deep frostbite injury, warm the frozen skin in a 37°C to 39°C (98.6°F to 102.2°F) water bath and NEVER rub the frozen tissue. Never touch dry ice with bare skin (use insulated leather or cryogenic gloves) and never swallow or serve beverages or "dragon's breath" snacks containing un-evaporated liquid nitrogen or solid dry ice fragments, which freeze and perforate the esophagus and stomach on contact.

Decision tree: dry ice and liquid nitrogen confined-space emergencies¶

flowchart TD
    Start["Cryogenic or Sublimating Gas Emergency: Dry Ice (CO2) or Liquid Nitrogen (LN2)"] --> Location{"Where is the exposure or spill occurring?"}

    Location -->|"1. INSIDE A MOVING OR PARKED VEHICLE: Transporting Dry Ice or LN2 Dewar"| CarAction["IMMEDIATE VEHICLE VENTILATION: 1. Roll ALL 4 windows completely down immediately 2. Switch HVAC to Fresh Outside Air (turn OFF Recirculation) and fan to MAX 3. Pull off the road, park, and exit the vehicle into fresh air 4. Move dry ice/dewar to open pickup bed or separate trunk with windows cracked"]

    Location -->|"2. WALK-IN COOLER, FREEZER, OR SMALL ROOM: Spilled Dewar or Stored Dry Ice"| RoomCheck{"Is a person collapsed inside the room?"}

    RoomCheck -->|"No: Spill or sublimating blocks only"| VentRoom["UNOCCUPIED SPILL PROTOCOL: 1. Do NOT enter the walk-in cooler or closed room 2. Prop the exterior door 100% open using a heavy wedge from outside 3. Turn on building exhaust fans and rope off the doorway 4. Wait 30+ minutes or verify O2 >= 19.5% and CO2 < 0.5% with gas meter"]

    RoomCheck -->|"Yes: Worker or bystander unconscious on floor"| RescueTriage{"Can you pull them out from the threshold in < 5 seconds?"}

    RescueTriage -->|"Yes: Victim is right at the open doorway"| FastDrag["THRESHOLD HOLD-BREATH EXTRICATION: 1. Wedge door wide open so it cannot swing shut behind you 2. Take a deep breath in fresh air, hold breath, grab victim's ankles/collar, and drag out 3. Start rescue breaths + CPR immediately in fresh air"]

    RescueTriage -->|"No: Deep inside room or dense white fog"| CallSCBA["WAIT FOR SCBA FIRE RESCUE: 1. NEVER enter a nitrogen-fogged room without Self-Contained Breathing Apparatus 2. Prop door wide open from outside and direct a portable fan into the doorway 3. Call 911 / 112 / 999 for immediate Fire-Rescue SCBA extraction"]

    Location -->|"3. DIRECT SKIN, EYE, OR GI INGESTION: Touching Dry Ice or Swallowing LN2"| CryoBurn["CRYOGENIC INJURY TRIAGE: 1. Skin: Flush or immerse frozen skin in 37 C to 39 C (98.6 F to 102.2 F) warm water (never rub) 2. If dry ice/metal is frozen to skin, pour lukewarm water over junction to release (never rip dry) 3. Ingestion: Call 911 immediately for gastric perforation triage; do NOT induce vomiting"]

The gas-expansion math: why 5 kilograms (11 pounds) of dry ice turns a car into a hazard zone¶

Many people transport dry ice inside the passenger cabin or SUV cargo space of their car without realizing how fast solid \(\text{CO}_2\) sublimates into gas, or that carbon dioxide is an active chemical toxin to the central nervous system, not merely a simple oxygen displacer.

1. Sublimation rate and cabin volume calculation¶

• Expansion ratio: One kilogram (\(2.2\text{ pounds}\)) of solid dry ice has a volume of roughly \(0.64\text{ liters}\), but when it sublimates into \(\text{CO}_2\) gas at \(20°C\) (\(68°F\)) and atmospheric pressure, it expands to 541 liters (19.1 cubic feet) of pure \(\text{CO}_2\) gas (an expansion ratio of roughly 845-to-1 by volume).
• Sublimation rate in a warm car: Inside a standard styrofoam cooler or paper bag placed in a \(22°C\) (\(72°F\)) car cabin, dry ice sublimates at roughly 1% to 3% per hour when sitting still, and up to 5% to 10% per hour when exposed to warm airflow, loose packaging, or broken pellets (such as dry-ice blasting pellets or loose ice-cream packing blocks).
• The 3,000-Liter Passenger Cabin: A standard compact or midsize sedan has an interior air volume of roughly 2,800 to 3,200 liters (100 to 113 cubic feet).
• To raise the \(\text{CO}_2\) concentration inside that 3,000-liter car cabin from normal outdoor air (\(0.04\%\text{ or }400\text{ ppm}\)) to the OSHA Immediately Dangerous to Life or Health (IDLH) threshold of 4% (40,000 ppm) requires only 120 liters of \(\text{CO}_2\) gas.
• **120 liters of \(\text{CO}_2\) gas is produced by the sublimation of just 220 grams (0.48 pounds / 7.7 ounces) of dry ice **
• If a driver places a 10-kilogram (22-pound) box of dry ice pellets or blocks inside a car with the windows closed and the dashboard air conditioner set to "MAX A/C / Recirculate", just 2.2 percent of that dry ice sublimating over 20 to 30 minutes pushes the cabin past 4% \(\text{CO}_2\), while 500 grams (1.1 pounds) sublimating pushes the cabin past 9% to 10% \(\text{CO}_2\), a concentration that causes convulsions, coma, and death in minutes (as has occurred in multiple documented fatalities involving ice-cream delivery drivers and family members sleeping or driving in cars with dry ice).

2. Why trunk storage still vents into the passenger cabin¶

Many drivers assume that putting dry ice inside the closed trunk (boot) of a 4-door sedan completely isolates the gas from the passengers in the front and back seats. Automotive aerodynamics engineers design passenger cars so that fresh air enters through the front cowl vents, flows through the passenger cabin, passes through the rear package-shelf vents into the trunk, and exits through rubber flapper valves hidden behind the rear bumper. When the car is parked, idling, or driving with the HVAC on Recirculate, sublimating \(\text{CO}_2\) pressurizes the trunk and diffuses forward through the fold-down rear seat backs directly into the passenger cabin.

Comparison of Dry Ice (\(\text{CO}_2\)) vs Liquid Nitrogen (\(\text{LN}_2\)) vs Carbon Monoxide (\(\text{CO}\))¶

How to transport dry ice and liquid nitrogen safely in a vehicle¶

Whenever you must transport dry ice or a liquid nitrogen dewar by road, follow these strict compressed-gas and hazardous-materials safety rules (aligned with DOT PHMSA, Compressed Gas Association [CGA] Pamphlet P-12, and UK HSE / BCGA CP30):

1. Best vehicle choice: Transport dry ice or liquid nitrogen inside the open bed of a pickup truck or inside a cargo van fitted with an airtight steel bulkhead partition separating the cargo bay from the driver's cab and equipped with a roof rotary ventilator.
2. If you must use a passenger car, SUV, or minivan:
3. Never transport a liquid nitrogen dewar inside a passenger car cabin if any cargo vehicle is available; if forced in an emergency, secure the dewar upright with seatbelts/straps so it cannot tip over and dump liquid nitrogen onto the floor carpet during hard braking.
4. Keep at least two windows (one front, one opposite rear) rolled down at least 5 centimeters (2 inches) for the entire trip, regardless of rain or cold weather.
5. Set the vehicle climate control to FRESH OUTSIDE AIR (disable the Recirculate button) and set the blower fan to Medium or High so positive outside air pressure continuously flushes the cabin from front to back.
6. Never sit inside a parked, non-moving car containing dry ice or liquid nitrogen, even for 5 minutes while waiting in a parking lot.
7. When arriving at your destination: Open all vehicle doors and let the trunk/cargo bay air out for 60 seconds before leaning your head inside the deep cargo well to lift out a heavy cooler.

Walk-in coolers, basement freezers, and laboratory cryogenic spills¶

Walk-in restaurant refrigerators, supermarket meat lockers, hospital cold rooms, and brewery fermentation cellars are non-ventilated sealed insulated boxes. When a power outage strikes a restaurant or grocery store, managers often purchase 50 to 200 kilograms (110 to 440 pounds) of dry ice blocks and stack them on the shelves inside the closed walk-in cooler to keep food from spoiling.

1. The Walk-In Cooler Death Trap¶

• A standard \(2.4\text{-by-}3.0\text{-by-}2.4\text{-meter}\) (\(8\text{-by-}10\text{-by-}8\text{-foot}\)) walk-in cooler has an internal volume of 17,280 liters (640 cubic feet) and has zero fresh-air intake vents (its evaporator fans only recirculate the trapped air inside the box).
• Placing 25 kilograms (55 pounds) of dry ice inside that closed walk-in cooler overnight generates 13,500 liters of pure \(\text{CO}_2\) gas, turning the lower 1.5 meters (5 feet) of the walk-in cooler into a 50% to 70% \(\text{CO}_2\) gas chamber.
• The next morning, an employee opens the heavy walk-in door, steps inside to grab a tray of food, lets the spring-loaded door click shut behind them, inhales two breaths of 50% \(\text{CO}_2\), and collapses onto the floor, where the \(\text{CO}_2\) concentration is highest, dying within 3 minutes unless someone outside sees them through a window.

2. Mandatory Safety Protocol for Using Dry Ice in Walk-In Coolers or Freezers:¶

1. Place a large, high-visibility DANGER - DRY ICE (\(\text{CO}_2\)) ASPHYXIATION HAZARD - DO NOT ENTER WITHOUT VENTILATING sign taped directly across the outside door handle and latch of any walk-in cooler or room containing dry ice.
2. Never enter a walk-in cooler that has held dry ice overnight until you have propped the main door 100 percent wide open with a heavy wedge and blown fresh air inside with a box fan for at least 15 to 20 minutes.
3. Never allow the spring-loaded door of a walk-in cooler to close while you are inside if any dry ice, liquid nitrogen, or compressed \(\text{CO}_2\) beer/soda fountain cylinders are stored inside the box.
4. Check the interior glow-in-the-dark Emergency Door Release Plunger before using any walk-in cooler so you can push the latch open from the inside even in total darkness.

First aid for cryogenic burns, skin adhesion, and culinary liquid nitrogen ingestion¶

1. Cryogenic skin and eye contact (-78.5°C Dry Ice or -196°C Liquid Nitrogen)¶

• Why brief liquid nitrogen splashes roll off skin (The Leidenfrost Effect), and why wet clothing is catastrophic: When a few drops of \(-196°C\) (\(-320°F\)) liquid nitrogen splash onto bare, warm, dry skin, the liquid droplets instantly boil on contact, creating a microscopic cushion of nitrogen gas vapor beneath the droplet (the Leidenfrost effect) that insulates the skin for 1 to 2 seconds as the droplets roll off harmlessly. However, if liquid nitrogen splashes onto cotton clothing, canvas shoes, watchbands, or inside the cuff of a safety glove, the fabric absorbs and holds the liquid nitrogen directly against the skin for 10 to 60 seconds, freezing the skin, subcutaneous fat, and tendons solid to the bone.
• Step-by-step Cryogenic Burn First Aid:
• If liquid nitrogen has soaked into a glove, sock, or sleeve: Pull the loose garment off immediately if it is not yet frozen to the skin. If the clothing or a piece of dry ice/cold metal is frozen solid to the skin, DO NOT pull or rip it off dry, ripping it off tears away the entire frozen epidermis. Instead, pour lukewarm tap water (\(37°C\text{ to }39°C\) [\(98.6°F\text{ to }102.2°F\)]) over the stuck object until the ice bond melts and releases cleanly.
• Rapidly rewarm the frozen skin in a \(37°C\text{ to }39°C\) (\(98.6°F\text{ to }102.2°F\)) circulating water bath for 15 to 30 minutes until the pale, hard, waxy skin turns pink/red and pliable. Never use hot water above \(42°C\) (\(108°F\)), never use dry radiant heat (like a space heater), and never rub or massage frozen skin (rubbing grinds internal ice crystals against cell membranes).
• Wrap loosely in dry sterile gauze (placing gauze pads between affected fingers or toes), do not pop clear blisters, give oral ibuprofen if conscious, and seek medical care.
• If liquid nitrogen splashes into the eyes: Flush the open eye immediately with copious lukewarm water or sterile saline for 15 minutes, cover both eyes loosely with a sterile patch without pressure, and get emergency ophthalmological care.

2. Culinary "Dragon's Breath" / Liquid Nitrogen Cocktail Ingestion (Gastric Barotrauma)¶

Bars, fairs, and novelty ice-cream shops sometimes use liquid nitrogen or solid dry ice to create smoking cocktails or cereal puffs ("Dragon's Breath"). Both the US Food and Drug Administration (FDA) and food safety agencies worldwide warn that all liquid nitrogen and solid dry ice must 100 percent evaporate or sublimate BEFORE the food or drink is handed to a consumer. - What happens if a person swallows even 5 to 10 milliliters (1 to 2 teaspoons) of liquid nitrogen or a chunk of dry ice: 1. It causes immediate full-thickness cryogenic necrosis of the mouth, pharynx, esophagus, and stomach wall. 2. Inside the warm \(37°C\) (\(98.6°F\)) stomach, 10 milliliters of liquid nitrogen instantly boils into 7 liters (1.85 gallons) of pressurized nitrogen gas faster than the esophageal sphincter can belch it out. The stomach inflates like a balloon and explodes (gastric barotrauma / stomach perforation), dumping gas and stomach acid into the peritoneal cavity (tension pneumoperitoneum), which pushes up on the diaphragm and causes respiratory and cardiac arrest. - Immediate First Aid: Call 911 / 112 / 999 immediately for emergency surgical transport. Never induce vomiting and do not force the patient to drink large volumes of water into a perforated stomach; keep the patient sitting semi-upright to ease breathing until paramedics arrive.

Regional emergency numbers and agency protocols¶

• United States: Call 911 immediately for any confined-space collapse, vehicle \(\text{CO}_2\) toxicity, or cryogenic ingestion, and tell the dispatcher specifically that carbon dioxide (dry ice) or liquid nitrogen asphyxiation is involved so firefighters bring 4-gas / \(\text{CO}_2\) monitors and SCBA. For non-life-threatening exposure questions, call Poison Control at 1-800-222-1222. Workplace limits are regulated by OSHA (29 CFR 1910.1000: \(\text{CO}_2\) 8-hour PEL = 5,000 ppm; NIOSH STEL = 30,000 ppm; IDLH = 40,000 ppm [4%]; minimum safe oxygen = 19.5%).
• Canada: Call 911 for emergency rescue, or 1-844-POISON-X (1-844-764-7669) for poison centers. Transport of dry ice and liquid nitrogen is regulated under Transport Canada TDG (Transportation of Dangerous Goods: UN1845 Carbon Dioxide, Solid; UN1977 Nitrogen, Refrigerated Liquid).
• United Kingdom: Call 999 or 112. Regulated by the Health and Safety Executive (HSE) (EH40 Workplace Exposure Limits: \(\text{CO}_2\) 8-hr LTEL = 5,000 ppm, 15-min STEL = 15,000 ppm) and the British Compressed Gases Association (BCGA) Codes of Practice (CP26 for Bulk Liquid Nitrogen, CP30 for Safe Use of Liquid Nitrogen Dewars, and GN11 for Reduced Oxygen Atmospheres).
• European Union: Call 112 across all EU member states. Governed by the European Industrial Gases Association (EIGA) safety standards (EIGA Doc 44: Hazards of Inert Gases and Oxygen Depletion and EIGA Doc 67: Safe Handling of Carbon Dioxide Containers and Dry Ice).
• Australia and New Zealand: Call 000 in Australia (Poisons Information 13 11 26) or 111 in New Zealand (National Poisons Centre 0800 764 766). Regulated by Safe Work Australia and AS 5034 (Installation and use of inert gases for beverage dispensing and cellars).

Frequently asked questions¶

Does a standard household carbon monoxide (CO) detector alarm when dry ice fills a room with carbon dioxide (CO2)?¶

No. A carbon monoxide ($\text{CO}$) detector and a carbon dioxide ($\text{CO}_2$) monitor are two completely different instruments with zero cross-sensitivity. Standard household and workplace $\text{CO}$ alarms use an electrochemical fuel cell that reacts only to carbon monoxide ($\text{CO}$, from burning fuel or exhaust). Even if sublimating dry ice fills a room or walk-in cooler with a lethal 10% (100,000 ppm) concentration of carbon dioxide ($\text{CO}_2$) or boiling liquid nitrogen drops the oxygen level to 5%, a standard carbon monoxide detector will read 0 ppm and will never sound an alarm. Restaurants, breweries, and labs must install dedicated infrared $\text{CO}_2$ monitors and electrochemical Oxygen ($\text{O}_2$) depletion alarms mounted at both breathing height and 30 centimeters (12 inches) above the floor.

Why is 8% carbon dioxide (CO2) fatal in minutes even if the room still contains 19% oxygen?¶

Unlike nitrogen, helium, or argon, which are physiologically inert gases that only cause harm when they push the oxygen percentage below 16% to 19.5%, carbon dioxide ($\text{CO}_2$) is an active metabolic waste product that your body must continuously dump out of your lungs to keep your blood pH at $7.40$. When the air you inhale already contains 5% to 8% $\text{CO}_2$, the concentration gradient across your alveoli reverses: your lungs can no longer exhale $\text{CO}_2$, and inhaled $\text{CO}_2$ dissolves into your bloodstream to form carbonic acid ($\text{H}_2\text{CO}_3$). Within minutes, arterial blood pH plummets below $7.0$ (**profound acute respiratory acidosis**), causing cerebral vasodilation, elevated intracranial pressure, cardiac arrhythmias, coma, and respiratory arrest, even if the room air still contains 19% oxygen.

Can I wear a cartridge respirator or an N95 dust mask to rescue someone who collapsed in a walk-in cooler filled with dry ice or liquid nitrogen?¶

Never enter an oxygen-deficient or high-$\text{CO}_2$ space wearing an N95 mask, a half-face organic-vapor respirator, or a gas mask. Air-purifying respirators only filter particulates or trace chemical vapors out of ambient air; they do not supply oxygen and cannot scrub out 50,000 ppm of $\text{CO}_2$. Entering a nitrogen-displaced or $\text{CO}_2$-flooded walk-in cooler wearing a filter mask will kill you in the exact same two breaths as entering with a bare face. Only a positive-pressure **Self-Contained Breathing Apparatus (SCBA)** with its own compressed air tank or a supplied-air airline respirator provides breathable air.

Is the white cloud of fog above liquid nitrogen or dry ice the actual gas itself?¶

The visible white fog rolling off a bowl of dry ice or a liquid nitrogen spill is not $\text{CO}_2$ or $\text{N}_2$ gas, both carbon dioxide and nitrogen gas are 100 percent invisible and colorless. The white cloud is simply normal water vapor humidity in the room air that has condensed into microscopic water droplets (clouds) after being chilled by the cold invisible gas. Crucially, as the $\text{CO}_2$ or $\text{N}_2$ gas warms up past the dew point of the room, **the white fog disappears completely while the invisible asphyxiating gas remains trapped in the room or car**. Never assume a space is safe to breathe just because the visible white fog has cleared.

What first aid should I give someone who just breathed concentrated CO2 from a dry-ice cooler and is hyperventilating with a pounding headache?¶

Move the person immediately into fresh outdoor air away from the vehicle or building, and have them sit upright in a comfortable position. Because inhaled $\text{CO}_2$ triggers intense stimulation of the brainstem respiratory center, the person will breathe rapidly and deeply for 5 to 15 minutes as their lungs blow off the excess dissolved $\text{CO}_2$ and restore normal blood pH. Reassure them, loosen tight collars, administer supplemental oxygen if available, and call 911 / 112 / 999 if they experienced any brief loss of consciousness, chest pain, persistent confusion, or visual disturbances. Taking a hands-on CPR and first aid course from the Red Cross, St John Ambulance, or a local provider prepares you to respond to asphyxial emergencies.

Related guides¶

• Carbon dioxide, dry ice sublimation, liquid nitrogen, and asphyxiation first aid
• Confined space asphyxiation: manholes, silos, and tanks
• Compressed gas cylinder valve shear, rocketing tank, and cryogenic leaks
• Hypothermia and frostbite emergency first aid

Sources and official guidance¶

• Occupational Safety and Health Administration (OSHA) and National Institute for Occupational Safety and Health (NIOSH): Hazard Alert: Preventing Fatalities from Carbon Dioxide (Dry Ice) and Liquid Nitrogen Asphyxiation in Confined Spaces, Walk-In Coolers, and Delivery Vehicles.
• Compressed Gas Association (CGA) and European Industrial Gases Association (EIGA): CGA Pamphlet P-12 (Safe Handling of Cryogenic Liquids), CGA G-6.1 (Carbon Dioxide / Dry Ice Safety), and EIGA Doc 44 (Hazards of Inert Gases and Oxygen Depletion).
• United Kingdom Health and Safety Executive (HSE) and British Compressed Gases Association (BCGA): BCGA Code of Practice CP30 (The Safe Use of Liquid Nitrogen Dewars up to 500 Litres) and GN11 (Reduced Oxygen Atmospheres in Cellars and Coolers).
• United States Food and Drug Administration (FDA): Safety Alert on Adding Liquid Nitrogen and Dry Ice to Foods and Beverages at the Point of Sale (Gastric Barotrauma and Cryogenic Perforation).
• Centers for Disease Control and Prevention (CDC / MMWR): Epidemiological Case Reports of Fatal Carbon Dioxide Intoxication During Vehicular Transport and Storage of Dry Ice.