Ebullism is the formation of
gas bubble
Bubble, Bubbles or The Bubble may refer to:
Common uses
* Bubble (physics), a globule of one substance in another, usually gas in a liquid
** Soap bubble
* Economic bubble, a situation where asset prices are much higher than underlying fund ...
s in
bodily fluids
Body fluids, bodily fluids, or biofluids, sometimes body liquids, are liquids within the human body. In lean healthy adult men, the total body water is about 60% (60–67%) of the total body weight; it is usually slightly lower in women (52-55%). ...
due to reduced environmental pressure, for example at high
altitude
Altitude or height (also sometimes known as depth) is a distance measurement, usually in the vertical or "up" direction, between a reference datum and a point or object. The exact definition and reference datum varies according to the context ...
. It occurs because a system of liquid and gas at equilibrium will see a net conversion of liquid to gas as pressure lowers; for example, liquids reach their boiling point at lower temperatures when the pressure on them is lowered.
Symptoms
Symptoms of ebullism include bubbles in the membranes of the mouth and eyes, swelling of the
skin
Skin is the layer of usually soft, flexible outer tissue covering the body of a vertebrate animal, with three main functions: protection, regulation, and sensation.
Other animal coverings, such as the arthropod exoskeleton, have different ...
, and bubbles in the blood. Blood circulation and breathing may be impaired or stopped. The
brain
A brain is an organ (biology), organ that serves as the center of the nervous system in all vertebrate and most invertebrate animals. It is located in the head, usually close to the sensory organs for senses such as Visual perception, vision. I ...
tissue may be
starved
''Starved'' is an American television sitcom that aired for one season on FX for seven episodes in 2005. The series was about four friends who each suffer from eating disorders, who met at a "shame-based" support group called Belt Tighteners. I ...
of
oxygen
Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements ...
because of blockage of
arteries
An artery (plural arteries) () is a blood vessel in humans and most animals that takes blood away from the heart to one or more parts of the body (tissues, lungs, brain etc.). Most arteries carry oxygenated blood; the two exceptions are the pu ...
, and the
lungs
The lungs are the primary organs of the respiratory system in humans and most other animals, including some snails and a small number of fish. In mammals and most other vertebrates, two lungs are located near the backbone on either si ...
may swell and
hemorrhage
Bleeding, hemorrhage, haemorrhage or blood loss, is blood escaping from the circulatory system from damaged blood vessels. Bleeding can occur internally, or externally either through a natural opening such as the mouth, nose, ear, urethra, v ...
. Death results unless recompression is rapid enough to reduce the bubbles before tissue damage occurs.
In 1960,
Joseph Kittinger
Joseph William Kittinger II (July 27, 1928 – December 9, 2022) served as a United States Air Force (USAF) officer from 1950 to 1978. He was a fighter pilot who earned Command Pilot status and retired as a colonel. He held the world record for ...
experienced localised ebullism during a ascent in a
helium
Helium (from el, ἥλιος, helios, lit=sun) is a chemical element with the symbol He and atomic number 2. It is a colorless, odorless, tasteless, non-toxic, inert, monatomic gas and the first in the noble gas group in the periodic ta ...
-driven gondola.
His right-hand glove failed to pressurise and his hand expanded to roughly twice its normal volume
accompanied by disabling pain. His hand took about three hours to recover after his return to the ground.
Tissue samples from the remains of the crew of
Space Shuttle STS-107 ''Columbia'' revealed evidence of ebullism. Given the level of tissue damage, the crew could not have regained consciousness even with re-pressurization.
Mechanism
In the atmospheric pressure present at
sea level
Mean sea level (MSL, often shortened to sea level) is an average surface level of one or more among Earth's coastal bodies of water from which heights such as elevation may be measured. The global MSL is a type of vertical datuma standardis ...
, water boils at . At an altitude of , it boils at only , the normal
body temperature
Thermoregulation is the ability of an organism to keep its body temperature within certain boundaries, even when the surrounding temperature is very different. A thermoconforming organism, by contrast, simply adopts the surrounding temperatur ...
of humans. This altitude is known as ''
Armstrong's Line.''
[Davis, Jeffrey R., Johnson, Robert, and Stepanek,Jan, ''Fundamentals of Aerospace Medicine'', 4th Edition (2008), p. 252.] In practice bodily fluids do not boil off at this altitude. This is because the skin and outer organs have enough strength to withstand this pressure, thus pressure inside the body would be significantly higher—however, nitrogen bubbles are starting to form, creating a hazard.
Prevention
To prevent ebullism, a pure oxygen (O
2) atmosphere was used in early space flights to eliminate nitrogen in the blood. There are major fire hazards associated with using pure O
2 as a breathing gas, which was central to the death of three astronauts in a fire during a ground test with
Apollo 1
Apollo 1, initially designated AS-204, was intended to be the first crewed mission of the Apollo program, the American undertaking to land the first man on the Moon. It was planned to launch on February 21, 1967, as the first low Earth orbit ...
.
Nonetheless, NASA continued to use a nominally pure oxygen atmosphere throughout the Apollo Program but switched to air for the follow-on Space Transport System "Space Shuttle". Russian cosmonauts used pure oxygen before changing to a higher-pressure
nitrox
Nitrox refers to any breathing gas, gas mixture composed (excepting trace gases) of nitrogen and oxygen. This includes atmospheric air, which is approximately 78% nitrogen, 21% oxygen, and 1% other gases, primarily argon. In the usual applicatio ...
mixture, leading to incompatibility problems in 1975 on the Apollo-Soyuz Test Project.
Space suits are often pressurized to several
psi lower than stations' capsules or shuttles and since they still use pure O
2, an acclimation period is common in the airlock to remove nitrogen and other gases from the bloodstream.
Etymology
The term "space ebullism" was introduced by Captain Julian E. Ward in his paper "The True Nature of the Boiling of Body Fluids in Space", published in Aviation Medicine in October 1956.
It was suggested "because the word ebullism does not connote the addition of heat to produce vapor." It comes from Latin ebullire, meaning "to bubble out, or to boil up."
See also
*
*
References
{{Space medicine
Medical terminology
Space medicine