Cryogenic Liquid Burns
Cryogenic liquids and materials cooled to near-cryogenic temperatures (such as uninsulated plumbing conveying cryogenic liquids or tools in contact with cryogenic liquids) can cause immediate and severe thermal burns. Additionally, after an initial feeling of cold the area may become numb and the severity of the burn may not be readily apparent. Any injury from cryogenic liquids or cryogenically cooled materials must be evaluated by a medical professional as quickly as possible to assess the extent of the damage and begin care to prevent further damage and ensure the best outcome possible.
Two cryogenic liquid burns have occurred at LBNL in the past few years, and in both cases the person who was burned did not immediately recognize the injury due to the extreme cold and numbness. It can be nearly impossible to distinguish between a cold sensation that is harmless and a cold sensation that is associated with a burn.
What does a cryogenic liquid burn look and feel like?
We all know what a burn from a hot object looks and feels like. Blisters appear quickly, the area becomes red and inflamed, and the pain is immediate and obvious. But at low temperatures, all of the body’s natural responses to injury are slowed down or stopped entirely. Below about 7 degrees Celsius, tissues become numb, so there may be no pain immediately following a cryogenic liquid burn. The burned area may look pale, somewhat yellowish, and waxy. In severe cases the tissue will feel harder to the touch than it should. As the tissue warms up and the nerves being to function again, the pain of a cold burn can be severe. Rubbing the affected area or warming the injury too rapidly can also cause additional injury. It is best to seek medical treatment immediately for any suspected burn and let a professional advise on the best course of action.
First Response for Cryogen Burns
In case of skin contact:
- If the affected area is extensive, the contact with cryogen or a super-cooled surface was prolonged, skin has been torn from freezing to a cold surface, or if the victim is in distress call x7911 from any main site land line, 911 from a cell phone, or use the local emergency line from off-site locations.
- Thaw the affected area with room temperature (not hot) water.
- If it can be accomplished, dip the burn gently into a bath for 15-30 minutes rather than pouring water over it
- Do not apply dry heat
- Do not massage or rub the area to try to increase circulation
- Loosen any clothing or PPE which might reduce blood flow to the area.
- Watch for signs of shock – cold sweating; paleness; rapid breathing and pulse; or nausea with or without vomiting. If any signs appear, immediately call emergency services, take the victim to a warm place, lie them down, and elevate the feet.
- If blisters appear, the burn will require medical attention. For more severe cases, call x7911, 911 from a cell phone, or a local emergency line. Otherwise, take the victim to seek medical attention as soon as possible and report the incident to the victim’s Activity Lead and Supervisor.
- Cryogenic burns are very painful as they begin to thaw. Aim to thaw the affected area slowly so that medical attention arrives before thawing is complete.
- Infection is a serious concern with cryogenic burns. If the burn is thawed before medical attention is received, cover the area loosely with sterile dressings.
In case of eye contact with cryogen or extremely cold vapor:
- Remove the worker from the source.
- Open eyes wide to facilitate evaporation.
- Immediately call x7911 from any main site land line, 911 from a cell phone, or use the local emergency line from off-site locations.
- Flush the eyes with lukewarm but not hot water for 15 minutes to warm the tissue.
- Do not delay medical attention, as cryogen burns to the eyes can lead to permanent damage and loss of vision; have someone else call while you assist the employee.
In case of hypothermia:
Symptoms of hypothermia include: shivering, dizziness, nausea, fast breathing, confusion, lack of coordination, trouble speaking, fatigue and rapid pulse. In more severe cases, breathing may be slow and shallow and the pulse may be weak.
- If hypothermia is suspected, immediately call emergency services at x7911 from the main site, 911 from a cell phone, or use the local emergency line.
- If the area is still cold, take the victim to a warm area, remove any wet and/or cold clothes, and cover the victim with copious blankets or garments to warm them up.
- Do not move the victim more than is absolutely necessary.
- Do not give the victim anything by mouth.
- Do not apply hot water or direct heat.
- Do not apply heat to the arms or legs.
Personal Protective Equipment is a Last Line of Defense
In avoiding burns from cryogenic liquids, it is important to know the limitations of personal protective equipment. PPE, such as cryo gloves, only provide minimal protection and do not protect a wearer against a flow of cryogenic liquid, submersion in cryogenic liquid, or prolonged contact with a cryogenically cooled object. Whenever possible, it is far better to engineer out the need to have your hands anywhere near cryogenic liquids or cryogenically cooled objects. But in the cases where it is necessary to have your hands near the splash zone of a cryogenic liquid or to touch something that has been cooled to cryogenic temperatures, cryo gloves will only protect you from minimal or very short duration contact, such as picking up a hose, moving it a couple feet and setting it down, or closing a valve. It is very possible to sustain burns from cryogenically cooled objects or cryogenic liquid while wearing cryo gloves. This has happened at LBNL. The gloves cannot protect against immersion in cryogenic liquids, a gentle flow of cryogenic liquid (e.g. a leaking pipe), or from prolonged contact with cryogenically cooled objects.
Additionally, even if a cryo glove claims to be waterproof, the waterproofing is generally only a coating on the fabric of the glove, which loses effectiveness quickly over time as it rubs off and may not ever protect against liquid seeping in through the seams of the glove. It’s also important to know that if the interior of the cryo glove does get wet, the glove loses its insulative properties and becomes completely ineffective. Frost and ice buildup on cryogenic liquid handling equipment is a near certainty, so it’s a good idea to avoid handling the parts of a system that have iced over.
For examples of incidents resulting in cryogenic liquid burns, including some that have happened at LBNL, see Incidents and Lessons Learned.
Use the Right PPE for the Job
The cryogenic liquids SME performed a few small tests of liquid nitrogen splashes onto gloves and shoes of various types. A data-logging thermometer was used in conjunction with a bare-junction thermocouple taped to the inside of a finger of the glove, or taped either inside or outside of a sock on a wooden shoe insert inside of a shoe. This data is very preliminary and is presented here for illustrative purposes only.
See the PPE Selection Guide for more information on selecting good PPE for cryogenic liquid work.
