Burn (injury)

In medicine, a burn is a type of injury to the skin caused by heat, electricity, chemicals, or radiation (an example of the latter is sunburn).
Immediate first aid for burns consists of immersing the injured area in cool clean water to cool the injured tissues.
There are in modern vernacular terminology three degrees of burns.

• First-degree burns are usually limited to redness and pain at the site
• Second-degree burns additionally have blistering of the skin
• Third-degree burns additionally have charring of the skin or eschar formation. An eschar is a scab that has separated from the unaffected part of the body. These are painless because at this stage the nerve endings are burnt away.

A newer classification of "Superficial Thickness", "Partial Thickness" (which is divided into superficial and deep categories) and "Full Thickness" relates more precisely to the epidermis, dermis and subcutaneous layers of skin and is used to guide treatment and predict outcome.
Burns that injure the tissues underlying the skin, such as the muscles or bones, are characterized as "fourth-degree burns". (In classical medical literature there were six degrees; with fourth-degree burns the skin is irretrievably lost, in fifth-degree burns the muscle is irretrievably lost, in sixth-degree burns the bone is charred). Serious burns, especially if they cover large areas of the body, can cause death; any hint of burn injury to the lungs, for example through smoke inhalation, is a medical emergency.
Chemical burns are usually caused by chemical compounds, such as sodium hydroxide (lye), silver nitrate, and more serious compounds (such as sulfuric acid). Note that most chemicals (but not all) that can cause moderate to severe chemical burns are strong acids or bases. Nitric acid is possibly one of the worst burn-causing chemicals, as an oxidizer. Most chemicals that can cause moderate to severe chemical burns are called caustic.
Electrical burns are generally symptoms of electrocution, being struck by lightning, being defibrillated or cardioverted without conductive gel, etc. The internal injuries sustained may be disproportionate to the size of the "burns" seen - as these are only the entry and exit wounds of the electrical current.
Survival and outcome (scars, contractures, complications) of severe burn injuries is remarkably improved if the patient is treated in a specialized burn center/unit rather than a hospital.
In cases of murder, burning might also be used to eliminate the evidence (body) or make features unidentifiable.

Scald

Scalding is a specific type of burning that is caused by non-solid hot material: liquid and/or steam, usually water and vapour, sometimes oil (especially for cooks). It is usually regional and usually does not cause death. However, deaths have occurred in more unusual circumstances, such as when people have accidentally broken a steam pipe.