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Talk:Ghost

Semi-protected edit request
Under `Terminology' - add in the origin of `haint' (Appalachian English) since the term `haint' redirects to the page. — Preceding unsigned comment added by 107.116.93.20 (talk) 19:04, 15 November 2023 (UTC)

Native American/Aboriginal views?
Can someone do a section on it?

Ted 2607:FEA8:4A2:4100:9133:C026:7F1C:5813 (talk) 18:55, 20 March 2023 (UTC)

For "See also" section
" List of ghost films " (from wikipedia)

Ted 2607:FEA8:4A2:4100:9133:C026:7F1C:5813 (talk) 19:05, 20 March 2023 (UTC)

Scientific Consensus is vague
The paragraph saying "scientific consensus" says ghost aren't real is a vague appeal to Authority. It is a vague authority referring a fluff piece. A more responsible phrasing would place ghosts existence as outside the purview of science. I understand amateur ghost hunters may edit this page often enough to be frustrating but we should strive to avoid logical fallicies. A reasonable voice (talk) 15:35, 12 May 2023 (UTC)
 * The change you're attempting to make is significant. Altering The overwhelming consensus of science is that there is no proof that ghosts exist to The existence of ghosts is impossible to falsify, equivalent to a *shrug emoji*, will require more than your opinion. Novemberjazz 15:39, 12 May 2023 (UTC)
 * I don't quite understand. Are you saying that the opinion stated should be stronger? Why do you believe that this revision can not be made. Nonetheless, i don't believe i have made a substantial change to the content so let me  know what type of source you believe a rewording requires and i will acquire it. I believe that this edit needs to be made, but as a new Wikipedia contributor I am happy to listen to whatever clerical steps I may have missed or etiquette I should follow for edit. If you feel my rewording needs work, I am happy to hear what you believe a rewording should have. A reasonable voice (talk) 16:00, 12 May 2023 (UTC)
 * It is a vague authority referring a fluff piece. What "fluff piece" are you referring to? Do you mean Philosophy of Science: From Problem to Theory, by Mario Bunge? Surely you jest. - LuckyLouie (talk) 17:41, 12 May 2023 (UTC)
 * My apologies, I mixed the source with this https://www.livescience.com/26697-are-ghosts-real.html  article used later. Still, an article defining the philosophy of science is not much better. That means that the current phrasing itself verges on original research, unless the source specifically mentions ghosts.  A reasonable voice (talk) 22:59, 12 May 2023 (UTC)
 * No, there isn't any original research here. The citation to the treatise by Mario Bunge directly supports the philosophy of science perspective (ghosts resist falsification so whether they exist or not is moot), but since Wikipedia is a general purpose encyclopedia, ending the discussion there would not be useful since there are perennial surges of pop culture claims and public interest and we have many reliable sources to address them. Evidence, or lack of it, that could support the existence of ghosts and the supernatural has not been seriously entertained within mainstream scientific circles since the Victorian era, so contemporary authors like Benjamin Radford and Joe Nickell are used on Wikipedia to reflect the majority scientific view. In this instance, the citation to livescience.com is merely a convenience; the authors are widely accepted WP:FRIND sources in their own right, often employed to comment on WP:FRINGE topics. I can appreciate your desire to avoid logical fallacies and such, but I don't believe we are in danger of perpetuating any in the present article. Of course you are encouraged to discuss here on the Talk page, but bear in mind any changes to the article need to be agreed to by WP:CONSENSUS. - LuckyLouie (talk) 18:55, 13 May 2023 (UTC)
 * This seems like a fine justification to not add any information saying ghosts are real based on science. However, my concern is much simpler. The phrase "The overwhelming consensus of science is that there is no proof that ghosts exist" is not supported or related to the statement "Ghosts themselves are not falsifiable". I have two concerns, the first, this sentence is really a way to get as saying "ghosts aren't real, 'science' proves it" without technically saying it. This is really strongly implying to the laymen that science can indeed prove a negative or make any statements at all about ghosts, when it can't. The second, the specific (and so far unsourced) claim of consensus is meant to imply that science is not a method of creating replicalible models of the world (most often connected to a loose network of individual researchers and research group) but rather an vague god like objective truth. It is this mischaracterization that is harmful, it is an appeal to a vague authority. It didn't even have the decency to be connected to the philosophers you mentioned in your reply. When I have time i will rewrite a sample to make sure your concerns that the public is taking Ghost Hunting a little too seriously (not that is the purpose of an enclyopedia) without implying an appeal to vague authority. However, I don't agree that this phrasing is helpful, logically supported by the source, or good for layman's explanation. I also want to point out that this isn't an article about ghost hunting, this is an article about a cultural phenomenon that ghost hunting is connected to. A strong rebuttal of ghost hunting as pseudoscience belongs in the lead of that article, not in a general article of interest to a much much broader section of the population.  A reasonable voice (talk) 21:07, 13 May 2023 (UTC)
 * Also, the paper referenced explicitly say that it isn’t saying that ghosts don’t exist or litigating whether there’s evidence for them. It specifies that the sole reason ghosts aren’t a valid scientific concept is because they’re outside any scientific system. It’s (explicitly) not about evidential claims vis-à-vis ghosts. 2605:B100:519:44B4:D095:801D:F709:D564 (talk) 22:20, 14 July 2024 (UTC)

Semi-protected edit request on 10 May 2024
The citation for Friedrich Nietzsche’s usage of ghost under the METAPHOR section of the wiki page for “Ghost” can be found in the gay science, book five, aphorism 365 of the Walter Kaufmann translation. The current citation is not a direct citation. 174.236.225.8 (talk) 03:16, 10 May 2024 (UTC)
 * Red question icon with gradient background.svg Not done: it's not clear what changes you want to be made. Please mention the specific changes in a "change X to Y" format and provide a reliable source if appropriate. Charliehdb (talk) 10:14, 10 May 2024 (UTC)
 * Change citation “[145] Quoted in Gary Gutting ed., The Cambridge Companion to Foucault (2003) p. 235” for Nietzsche’s metaphorical usage of ghost to aphorism 365 of the Gay Science, book five, written by Friedrich Nietzsche and translated by Walter Kaufmann. 2600:1700:8400:F230:790A:39D:BDA9:C466 (talk) 15:46, 10 May 2024 (UTC)

title: Talk:Ghost


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Stole (vestment)

The stole is a liturgical vestment of various Christian denominations, which symbolizes priestly authority; in Protestant denominations which do not have priests but use stoles as a liturgical vestment, however, it symbolizes being a member of the ordained. It consists of a band of colored cloth, usually of silk, about seven and a half to nine feet long and three to four inches wide, whose ends may be straight or may broaden out in the shape of a spade or bell. The center of the stole is worn around the back of the neck and the two ends hang down parallel to each other in front, either attached to each other or hanging loose. The stole is almost always decorated in some way, usually with two crosses, or sometimes another significant religious design. It is often decorated with contrasting galloons (ornamental trim) and fringe is usually applied to the ends of the stole following. A piece of white linen or lace may be stitched onto the back of the collar as a sweat guard, which can be replaced more cheaply than the stole itself.

Etymology and history

The word stole derives via the Latin stola, from the Greek στολή (stolē), "garment", originally "array" or "equipment".

The stole was originally a kind of shawl that covered the shoulders and fell down in front of the body; on women they were often very large. After being adopted by the Church of Rome around the seventh century (the stole having also been adopted in other locales prior to this), the stole gradually became narrower and started to feature more ornate designs, developing into a mark of dignity. Nowadays, the stole is usually wider and can be made from a wide variety of material.

There are many theories as to the "ancestry" of the stole. Some say it came from the tallit (Jewish prayer mantle), because it is very similar to the present usage (as in the minister puts it on when he or she leads in prayer) but this theory is no longer regarded much today. More popular is the theory that the stole originated from a kind of liturgical napkin called an orarium (cf. orarion) very similar to the sudarium. In fact, in many places the stole is called the orarium. Therefore, it is linked to the napkin used by Christ in washing the feet of his disciples, and is a fitting symbol of the yoke of Christ, the yoke of service.

The most likely origin for the stole, however, is to be connected with the scarf of office among Imperial officials in the Roman Empire. As members of the clergy became members of the Roman administration (see Constantine I and Christianity) they were granted certain honors, one specifically being a designator of rank within the imperial (and ecclesiastical) hierarchy. The various configurations of the stole (including the pallium or the omophorion) grew out of this usage. The original intent, then was to designate a person as belonging to a particular organization and to denote their rank within their group, a function which the stole continues to perform today. Thus, unlike other liturgical garments which were originally worn by every cleric or layman, the stole was a garment which was specifically restricted to particular classes of people based on occupation.

Stoles were already used in pre-Roman Italic religion. In the Umbrian Iguvine Tablets, a stole was used by an officiating priest during offering rituals. It was worn on the shoulder during a sacrifice, and then placed on an offering cake:

''While you are slaying it, wear a stole on your right shoulder. When you have slain it, place (the stole) upon the mefa cake. While you are presenting it, wear the stole on your right shoulder. Present grain-offerings and sacrifice with mead.'' (ibid, pg. 164)

Symbolism and color

Together with the cincture and the now mostly defunct maniple, the stole symbolizes the bonds and fetters with which Jesus was bound during his Passion; it is usually ornamented with a cross. Another version is that the stole denotes the duty to spread the Word of God. In the Catholic Church's Latin liturgical rites, the priests' stole represents priestly authority, while the diaconal stole (which is diagonally and conjoined at the side) represents service. In the Eastern Orthodox Church the symbolism is the same, though it also symbolizes particularly the anointing with oil which accompanies ordination, and which flows down the body as the stole does.

The stole worn for the celebration of the Holy Mass and the Liturgy of the Hours matches the liturgical color of the day.

Roman Catholic
In the Latin Catholic tradition the stole is the vestment that marks recipients of Holy Orders. It is conferred at the ordination of a deacon, by which one becomes a member of the clergy after the suppression of the tonsure and minor orders after the Second Vatican Council.

A bishop or other priest wears the stole around his neck with the ends hanging down in front, while the deacon places it over his left shoulder and ties it cross-wise at his right side, similar to a sash.

Before the reform of the liturgy after the Second Vatican Council, priests who were not bishops were required to cross the stole over the breast (as pictured below), but only at Mass or at other functions at which a chasuble or cope was worn. It is now often worn hanging straight down without being crossed across the breast. The General Instruction of the Roman Missal, which is the liturgical law for the Roman Catholic Church concerning the Mass, no longer makes explicit that a Priest must cross his stole. It states, "the stole is worn by the Priest around his neck and hanging down in front of his chest..." (GIRM §340). Unless there is a law promulgated by a particular diocese or other ordinary, it is left to the priest to interpret what this means. On solemn occasions, the Pope wears, as part of his choir dress, a special stole of state highly decorated and bearing his personal coat of arms.

For the celebration of the Mass, the principal celebrant as well as concelebrants wear the stole over the alb but under the chasuble. Likewise, the deacon wears the stole over the alb but under the dalmatic. The stole is also worn over the surplice or alb for the distribution and reception of Holy Communion.

The priest or deacon who presides in paraliturgical celebrations, such as the Stations of the Cross, usually wears the stole over the surplice (or alb), and always under the cope.

In Catholic practice, the vesting prayer for the stole is: "Redde mihi, Domine, obsecro, stolam immortalitatis, quam perdidi in prævaricatione primi parentis: et, quamvis indignus accedo ad tuum sacrum mysterium, merear tamen gaudium sempiternum. Amen. ('Restore to me, O Lord, the robe of immortality, which was lost in the transgression of our first parents, and, inasmuch as I approach your Sacred Mysteries in an unworthy manner, nevertheless, may I be made deserving of eternal blessedness.')"

Protestant
In Protestant churches, the stole is most often seen as the symbol of ordination and the office of the ministry of Word and Sacrament. Stoles are often given by the congregation (sometimes hand-made or decorated) as a love gift at ordination or at other life milestones. Generally, Protestant clergy wear the stole in the same manner as Catholic priests—around the back of the neck with the ends hanging down the front (though not crossed). Stoles are commonly worn by ordained ministers in Anglican, Lutheran, and Methodist denominations. In less liturgical Protestant denominations, such as the Presbyterian, United Church of Christ, Christian Church (Disciples of Christ), and Unitarian Universalist, clergy traditionally wore either a pulpit robe (with a preaching scarf) or simply a suit during church services, but the wearing of stoles by clergy has increased since the mid-1970s.

Anglican

During the English Reformation, the stole, along with most other sacramental vestments, were removed from the Church of England. The Oxford Movement began an interest in pre-Reformation worship, and eventually the stole (along with other vestments) were revived among Anglo-Catholic clergy. Though today, it is not uncommon for a Low Church priest to wear a stole with choir dress, stricter ones may still object to its use, and wear the tippet instead. This re-introduction of the stole continued to cause concern even in the 20th century. During the 1950s, the Bishop of London, William Wand, and the Bishop of Oxford, Kenneth Kirk, refused to ordain any candidate to the priesthood who would not wear a stole. Many candidates objected to wearing it because of their theological and traditional allegiances. Finally, Geoffrey Fisher, Archbishop of Canterbury, had to resolve the matter, and instructed that all bishops must not refuse ordination simply because the candidate was unwilling to wear the stole. Today, there is less controversy. When a stole is used in a deacon's ordination, it may be conferred on him or her and worn over the shoulder. At ordination to the priesthood, the newly ordained priest then wears the stole around his or her neck, hanging down in front, either straight down or less commonly crossed across the front of the body and secured with the cincture.

Lutheran
In the Evangelical Lutheran Church in America (ELCA), both Ministers of Word and Sacrament (pastors) and Ministers of Word and Service (deacons) are entitled to wear the stole as both orders are ordained, though many deacons choose not to do so. ELCA pastors generally wear the stole hanging straight down while deacons wear them over one shoulder as in the Anglican and Roman traditions.

In the Lutheran Church–Missouri Synod (LCMS) and the Independent Evangelical-Lutheran Church (Germany), only pastors wear the stole, as there is only the one order of ordination, that of pastor, in these Lutheran traditions. (The office of bishop for Episcopal polity and president for Congregational Polity is not a separate order of ordination.)

However, certain Lutheran churches, such as the Evangelical Lutheran Church of Finland and the Church of Sweden, practice the three-fold ministry of holy orders (in that the orders of deacon, priest, and bishop are separate ordinations). In such churches, wearing a deacon's stole when assisting in a liturgy is an official rule, and different rubrics exist for the use of the stole by priests and bishops. Ordained clergy of the Church of Sweden follow the use described for Anglican deacons and priests in this article, except the practice of wearing the stole hanging straight down is reserved for bishops (priests wear it crossed over the chest except over a surplice, when no cincture is worn).

Methodist
In the United Methodist Church, ordained deacons wear a stole around the shoulder as in the Anglican and Roman traditions. An ordained elder wears the stole in the same fashion as an Anglican or Roman Catholic priest, with the role of elder being the Methodist equivalent, among other Protestant denominations, to that office. The English word "priest" is in fact derived from the Greek word presbyter, which means "elder".

Byzantine practice
In The Byzantine Rite practice of the Eastern Orthodox and Greek Catholic churches, the stole worn by a deacon is called an orarion, while that worn by a priest or bishop is called an epitrachelion (a bishop additionally wears an omophorion), all similar in meaning and use to the Western stole. In Greek Orthodox practice, the deacon wears a double orarion, meaning it comes over the left arm and under the right. Minor clerics (and in Greek and Melkite traditions the altar servers as well) wear an orarion wrapped around their waist, crossed in back, and then either crossed again in front and tucked under the belted section or not crossed and tucked in (see explanation of subdeacon below).

The priest's epitrachelion consists of a long strip of cloth, hung around the neck with the two strips fastened together in front, either by buttons or by stitching. The epitrachelion comes down in front almost to the hem of his robes, and is symbolic of the priest's "anointing" (Septuagint: Psalm 132:2; KJV: Psalm 133:2). Traditionally—though not necessarily—the epitrachelion will have seven crosses on it: six in the front (three on each side) and one on the back of the collar. The priest traditionally blesses the cross on the collar and kisses it before he puts it on, and kisses it again when he takes it off. When he is vesting for the Divine Liturgy, he says the following prayer before putting on the epitrachelion:

"Blessed is God, Who poureth out His grace upon His priests, like the oil of myrrh upon the head, which runneth down upon the beard, upon the beard of Aaron: which runneth down to the fringe of his raiment. (Cf. Psalm 132:2, LXX)"

In the Russian Orthodox tradition, the priest may say a special blessing and sprinkle the epitrachelion with holy water before it is worn for the first time. A priest is not permitted to celebrate even the simplest service, even the Daily Office, unless he is wearing the epitrachelion (and in some traditions the epimanikia, or "cuffs", as well). When a member of the faithful goes to Confession, the priest places the edge of his epitrachelion over the head of the penitent as he confesses his sins. After the absolution, the penitent will often kiss the priest's hand and then one of the crosses on the edge of the epitrachelion. At an Orthodox wedding, the priest will have the bridal couple hold the edge of his epitrachelion as he leads them in a procession three times around the Gospel Book, symbolizing the pilgrimage of life.

The protodeacon or archdeacon wears the orarion "doubled", i.e., over the left shoulder, under the right arm, and passing again over the left shoulder. The two ends hang down, one in the front and one in the back, coming down almost to the hem of his sticharion (dalmatic).

A deacon wears an orarion which simply passes over the left shoulder, the two ends of which hang straight down, one in the front and one in the back, coming down almost to the hem of his sticharion. This is only common in the most traditional Orthodox churches. In many Eastern traditions, the stole is always worn "doubled" unless the deacon in question is wearing only his exorasson (outer cassock) and then it is essentially folded and worn over the left shoulder.

The subdeacon wears his orarion over both shoulders, crossed in the back and the front. Those acting as subdeacons (i.e., vested and serving as subdeacons but without having been ordained) wear their orarion crossed only in the back, to show that they do not bear holy orders.

Oriental Orthodox

In the Oriental Orthodox Churches, the priestly stole is very similar to the epitrachelion described above; however, instead of a long narrow strip of fabric that is wrapped around the neck and fastened together, it is often cut out of a single broad piece of cloth that has a hole cut in it for the head to pass through. Sometimes, depending upon the liturgical Rite, it also extends farther down the back.

British monarch
The British monarch, although not in holy orders, is anointed with the oil of chrism and invested with a stole during the coronation rite. This stole, made of gold silk, is officially named the Stole Royal or Armilla, and is one of several coronation robes kept overnight in the Jerusalem Chamber of Westminster Abbey before the day of the coronation. The coronation (which is always in the context of a Eucharist) is an official liturgy of the Church of England; the Archbishop of Canterbury has responsibility for the ceremony and is almost always its presider.

Mandaean
A stole is used in the Mandaean religion by the priests during rituals.

Unitarian Universalist
Historically, Unitarian and Universalist ministers wore street clothes, formal morning coats, or academic gowns while leading worship; stoles were rare.

A key moment in the acceptance of stoles by Unitarian Universalist clergy was the formation in the late 1960s of the Congregation of Abraxas, a short-lived effort to "draw upon the world's traditions of awe, repentance, thanksgiving, and service, and to renew those forms for the liberal religious communities." Vern Barnet, an Abraxas founder, states that "our success has been mainly in modeling for our colleagues the wearing of stoles or other vestments" and notes the wearing by Eugene Pickett, president of the Unitarian Universalist Association, of a stole given him by the Congregation of Abraxas at a General Assembly in the mid-1970s.

At about the same time, the increased number of women entered Unitarian Universalist ministry may have been a factor in the rising popularity of stoles. So may the increase in the number of former Catholic and Orthodox people who became UUs in the course of the 20th century.

Today, a stole/scarf/tippet is worn by many Unitarian Universalist ministers during weekly worship services as a symbol of ordained ministry. Other participants in the service may also wear stoles. Unitarian Universalist stoles often are adorned with the Unitarian Universalist Flaming Chalice and come in a wide range of colors.

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/

title: Stole (vestment)


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Pass (military)

A pass is permission to be away from one's military unit for a limited period of time. Time away on a pass is not counted against leave, the annual allotment of days off from duty.

Types of passes

 * Normal off-duty hours — granted to personnel to allow them to go off their military installation whenever they are not required to be on duty, subject to recall at any time as needed, and revocable at the unit's discretion.
 * Regular pass — granted to allow personnel to be away for a designated period of time only. May be granted to those, such as trainees, not eligible for a normal off-duty hours pass.
 * Three-day pass — the longest continuous pass granted allows a serviceman or servicewoman to be away for 72 consecutive hours. Often granted in recognition of special achievement or as a reward, especially as a way of granting a three-day weekend.

By country variations
In the RAF, a "Permanent Pass" known as Form 557 would be issued to servicemen of good standing and six-months service allowing them to leave the quarters after duty until midnight and no further than eight miles (or as otherwise restricted on the form). It could be endorsed with permission to wear plain clothes.

title: Pass (military)


text:
User:AndreasB

Well, if you're looking for me, I'm not logged in here very often anymore. Though I started out here, I'm mostly on the German Wikipedia.

User talk:AndreasB de:Benutzer:AndreasB

title: User:AndreasB


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Carbon monoxide poisoning

Carbon monoxide poisoning typically occurs from breathing in carbon monoxide (CO) at excessive levels. Symptoms are often described as "flu-like" and commonly include headache, dizziness, weakness, vomiting, chest pain, and confusion. Large exposures can result in loss of consciousness, arrhythmias, seizures, or death. The classically described "cherry red skin" rarely occurs. Long-term complications may include chronic fatigue, trouble with memory, and movement problems.

CO is a colorless and odorless gas which is initially non-irritating. It is produced during incomplete burning of organic matter. This can occur from motor vehicles, heaters, or cooking equipment that run on carbon-based fuels. Carbon monoxide primarily causes adverse effects by combining with hemoglobin to form carboxyhemoglobin (symbol COHb or HbCO) preventing the blood from carrying oxygen and expelling carbon dioxide as carbaminohemoglobin. Additionally, many other hemoproteins such as myoglobin, Cytochrome P450, and mitochondrial cytochrome oxidase are affected, along with other metallic and non-metallic cellular targets.

Diagnosis is typically based on a HbCO level of more than 3% among nonsmokers and more than 10% among smokers. The biological threshold for carboxyhemoglobin tolerance is typically accepted to be 15% COHb, meaning toxicity is consistently observed at levels in excess of this concentration. The FDA has previously set a threshold of 14% COHb in certain clinical trials evaluating the therapeutic potential of carbon monoxide. In general, 30% COHb is considered severe carbon monoxide poisoning. The highest reported non-fatal carboxyhemoglobin level was 73% COHb.

Efforts to prevent poisoning include carbon monoxide detectors, proper venting of gas appliances, keeping chimneys clean, and keeping exhaust systems of vehicles in good repair. Treatment of poisoning generally consists of giving 100% oxygen along with supportive care. This procedure is often carried out until symptoms are absent and the HbCO level is less than 3%/10%.

Carbon monoxide poisoning is relatively common, resulting in more than 20,000 emergency room visits a year in the United States. It is the most common type of fatal poisoning in many countries. In the United States, non-fire related cases result in more than 400 deaths a year. Poisonings occur more often in the winter, particularly from the use of portable generators during power outages. The toxic effects of CO have been known since ancient history. The discovery that hemoglobin is affected by CO emerged with an investigation by James Watt and Thomas Beddoes into the therapeutic potential of hydrocarbonate in 1793, and later confirmed by Claude Bernard between 1846 and 1857.

Background
Carbon monoxide is not toxic to all forms of life, and the toxicity is a classical dose-dependent example of hormesis. Small amounts of carbon monoxide are naturally produced through many enzymatic and non-enzymatic reactions across phylogenetic kingdoms where it can serve as an important neurotransmitter (subcategorized as a gasotransmitter) and a potential therapeutic agent. In the case of prokaryotes, some bacteria produce, consume and respond to carbon monoxide whereas certain other microbes are susceptible to its toxicity. Currently, there are no known adverse effects on photosynthesizing plants.

The harmful effects of carbon monoxide are generally considered to be due to tightly binding with the prosthetic heme moiety of hemoproteins that results in interference with cellular operations, for example: carbon monoxide binds with hemoglobin to form carboxyhemoglobin which affects gas exchange and cellular respiration. Inhaling excessive concentrations of the gas can lead to hypoxic injury, nervous system damage, and even death.

As pioneered by Esther Killick, different species and different people across diverse demographics may have different carbon monoxide tolerance levels. The carbon monoxide tolerance level for any person is altered by several factors, including genetics (hemoglobin mutations), behavior such as activity level, rate of ventilation, a pre-existing cerebral or cardiovascular disease, cardiac output, anemia, sickle cell disease and other hematological disorders, geography and barometric pressure, and metabolic rate.

Physiology
Carbon monoxide is produced naturally by many physiologically relevant enzymatic and non-enzymatic reactions best exemplified by heme oxygenase catalyzing the biotransformation of heme (an iron protoporphyrin) into biliverdin and eventually bilirubin. Aside from physiological signaling, most carbon monoxide is stored as carboxyhemoglobin at non-toxic levels below 3% HbCO.

Therapeutics
Small amounts of CO are beneficial and enzymes exist that produce it at times of oxidative stress. A variety of drugs are being developed to introduce small amounts of CO, these drugs are commonly called carbon monoxide-releasing molecules. Historically, the therapeutic potential of factitious airs, notably carbon monoxide as hydrocarbonate, was investigated by Thomas Beddoes, James Watt, Tiberius Cavallo, James Lind, Humphry Davy, and others in many labs such as the Pneumatic Institution.

Signs and symptoms
On average, exposures at 100 ppm or greater is dangerous to human health. The WHO recommended levels of indoor CO exposure in 24 hours is 4 mg/m3. Acute exposure should not exceed 10 mg/m3 in 8 hours, 35 mg/m3 in one hour and 100 mg/m3 in 15 minutes.

Acute poisoning
The main manifestations of carbon monoxide poisoning develop in the organ systems most dependent on oxygen use, the central nervous system and the heart. The initial symptoms of acute carbon monoxide poisoning include headache, nausea, malaise, and fatigue. These symptoms are often mistaken for a virus such as influenza or other illnesses such as food poisoning or gastroenteritis. Headache is the most common symptom of acute carbon monoxide poisoning; it is often described as dull, frontal, and continuous. Increasing exposure produces cardiac abnormalities including fast heart rate, low blood pressure, and cardiac arrhythmia; central nervous system symptoms include delirium, hallucinations, dizziness, unsteady gait, confusion, seizures, central nervous system depression, unconsciousness, respiratory arrest, and death. Less common symptoms of acute carbon monoxide poisoning include myocardial ischemia, atrial fibrillation, pneumonia, pulmonary edema, high blood sugar, lactic acidosis, muscle necrosis, acute kidney failure, skin lesions, and visual and auditory problems. Carbon monoxide exposure may lead to a significantly shorter life span due to heart damage.

One of the major concerns following acute carbon monoxide poisoning is the severe delayed neurological manifestations that may occur. Problems may include difficulty with higher intellectual functions, short-term memory loss, dementia, amnesia, psychosis, irritability, a strange gait, speech disturbances, Parkinson's disease-like syndromes, cortical blindness, and a depressed mood. Depression may occur in those who did not have pre-existing depression. These delayed neurological sequelae may occur in up to 50% of poisoned people after 2 to 40 days. It is difficult to predict who will develop delayed sequelae; however, advanced age, loss of consciousness while poisoned, and initial neurological abnormalities may increase the chance of developing delayed symptoms.

Chronic poisoning
Chronic exposure to relatively low levels of carbon monoxide may cause persistent headaches, lightheadedness, depression, confusion, memory loss, nausea, hearing disorders and vomiting. It is unknown whether low-level chronic exposure may cause permanent neurological damage. Typically, upon removal from exposure to carbon monoxide, symptoms usually resolve themselves, unless there has been an episode of severe acute poisoning. However, one case noted permanent memory loss and learning problems after a three-year exposure to relatively low levels of carbon monoxide from a faulty furnace.

Chronic exposure may worsen cardiovascular symptoms in some people. Chronic carbon monoxide exposure might increase the risk of developing atherosclerosis. Long-term exposures to carbon monoxide present the greatest risk to persons with coronary heart disease and in females who are pregnant.

In experimental animals, carbon monoxide appears to worsen noise-induced hearing loss at noise exposure conditions that would have limited effects on hearing otherwise. In humans, hearing loss has been reported following carbon monoxide poisoning. Unlike the findings in animal studies, noise exposure was not a necessary factor for the auditory problems to occur.

Fatal poisoning
One classic sign of carbon monoxide poisoning is more often seen in the dead rather than the living – people have been described as looking red-cheeked and healthy. However, since this "cherry-red" appearance is more common in the dead, it is not considered a useful diagnostic sign in clinical medicine. In autopsy examinations, the appearance of carbon monoxide poisoning is notable because unembalmed dead persons are normally bluish and pale, whereas dead carbon-monoxide poisoned people may appear unusually lifelike in coloration. The colorant effect of carbon monoxide in such postmortem circumstances is thus analogous to its use as a red colorant in the commercial meat-packing industry.

Epidemiology
The true number of cases of carbon monoxide poisoning is unknown, since many non-lethal exposures go undetected. From the available data, carbon monoxide poisoning is the most common cause of injury and death due to poisoning worldwide. Poisoning is typically more common during the winter months. This is due to increased domestic use of gas furnaces, gas or kerosene space heaters, and kitchen stoves during the winter months, which if faulty and/or used without adequate ventilation, may produce excessive carbon monoxide. Carbon monoxide detection and poisoning also increases during power outages, when electric heating and cooking appliances become inoperative and residents may temporarily resort to fuel-burning space heaters, stoves, and grills (some of which are safe only for outdoor use but nonetheless are errantly burned indoors).

It has been estimated that more than 40,000 people per year seek medical attention for carbon monoxide poisoning in the United States. 95% of carbon monoxide poisoning deaths in Australia are due to gas space heaters. In many industrialized countries, carbon monoxide is the cause of more than 50% of fatal poisonings. In the United States, approximately 200 people die each year from carbon monoxide poisoning associated with home fuel-burning heating equipment. Carbon monoxide poisoning contributes to the approximately 5,613 smoke inhalation deaths each year in the United States. The CDC reports, "Each year, more than 500 Americans die from unintentional carbon monoxide poisoning, and more than 2,000 commit suicide by intentionally poisoning themselves." For the 10-year period from 1979 to 1988, 56,133 deaths from carbon monoxide poisoning occurred in the United States, with 25,889 of those being suicides, leaving 30,244 unintentional deaths. A report from New Zealand showed that 206 people died from carbon monoxide poisoning in the years of 2001 and 2002. In total carbon monoxide poisoning was responsible for 43.9% of deaths by poisoning in that country. In South Korea, 1,950 people had been poisoned by carbon monoxide with 254 deaths from 2001 through 2003. A report from Jerusalem showed 3.53 per 100,000 people were poisoned annually from 2001 through 2006. In Hubei, China, 218 deaths from poisoning were reported over a 10-year period with 16.5% being from carbon monoxide exposure.

Causes
Carbon monoxide is a product of combustion of organic matter under conditions of restricted oxygen supply, which prevents complete oxidation to carbon dioxide (CO2). Sources of carbon monoxide include cigarette smoke, house fires, faulty furnaces, heaters, wood-burning stoves, internal combustion vehicle exhaust, electrical generators, propane-fueled equipment such as portable stoves, and gasoline-powered tools such as leaf blowers, lawn mowers, high-pressure washers, concrete cutting saws, power trowels, and welders. Exposure typically occurs when equipment is used in buildings or semi-enclosed spaces.

Riding in the back of pickup trucks has led to poisoning in children. Idling automobiles with the exhaust pipe blocked by snow has led to the poisoning of car occupants. Any perforation between the exhaust manifold and shroud can result in exhaust gases reaching the cabin. Generators and propulsion engines on boats, especially houseboats, has resulted in fatal carbon monoxide exposures.

Poisoning may also occur following the use of a self-contained underwater breathing apparatus (SCUBA) due to faulty diving air compressors.

In caves carbon monoxide can build up in enclosed chambers due to the presence of decomposing organic matter. In coal mines incomplete combustion may occur during explosions resulting in the production of afterdamp. The gas is up to 3% CO and may be fatal after just a single breath. Following an explosion in a colliery, adjacent interconnected mines may become dangerous due to the afterdamp leaking from mine to mine. Such an incident followed the Trimdon Grange explosion which killed men in the Kelloe mine.

Another source of poisoning is exposure to the organic solvent dichloromethane, also known as methylene chloride, found in some paint strippers, as the metabolism of dichloromethane produces carbon monoxide. In November 2019, an EPA ban on dichloromethane in paint strippers for consumer use took effect in the United States.

Detectors
Prevention remains a vital public health issue, requiring public education on the safe operation of appliances, heaters, fireplaces, and internal-combustion engines, as well as increased emphasis on the installation of carbon monoxide detectors. Carbon monoxide is tasteless, odourless, and colourless, and therefore can not be detected by visual cues or smell.

The United States Consumer Product Safety Commission has stated, "carbon monoxide detectors are as important to home safety as smoke detectors are," and recommends each home have at least one carbon monoxide detector, and preferably one on each level of the building. These devices, which are relatively inexpensive and widely available, are either battery- or AC-powered, with or without battery backup. In buildings, carbon monoxide detectors are usually installed around heaters and other equipment. If a relatively high level of carbon monoxide is detected, the device sounds an alarm, giving people the chance to evacuate and ventilate the building. Unlike smoke detectors, carbon monoxide detectors do not need to be placed near ceiling level.

The use of carbon monoxide detectors has been standardized in many areas. In the US, NFPA 720–2009, the carbon monoxide detector guidelines published by the National Fire Protection Association, mandates the placement of carbon monoxide detectors/alarms on every level of the residence, including the basement, in addition to outside sleeping areas. In new homes, AC-powered detectors must have battery backup and be interconnected to ensure early warning of occupants at all levels. NFPA 720-2009 is the first national carbon monoxide standard to address devices in non-residential buildings. These guidelines, which now pertain to schools, healthcare centers, nursing homes, and other non-residential buildings, include three main points:
 * 1. A secondary power supply (battery backup) must operate all carbon monoxide notification appliances for at least 12 hours,
 * 2. Detectors must be on the ceiling in the same room as permanently installed fuel-burning appliances, and
 * 3. Detectors must be located on every habitable level and in every HVAC zone of the building.

Gas organizations will often recommend getting gas appliances serviced at least once a year.

Legal requirements
The NFPA standard is not necessarily enforced by law. As of April 2006, the US state of Massachusetts requires detectors to be present in all residences with potential CO sources, regardless of building age and whether they are owner-occupied or rented. This is enforced by municipal inspectors and was inspired by the death of 7-year-old Nicole Garofalo in 2005 due to snow blocking a home heating vent. Other jurisdictions may have no requirement or only mandate detectors for new construction or at time of sale.

World Health Organization recommendations
The following guideline values (ppm values rounded) and periods of time-weighted average exposures have been determined in such a way that the carboxyhemoglobin (COHb) level of 2.5% is not exceeded, even when a normal subject engages in light or moderate exercise:
 * 100 mg/m3 (87 ppm) for 15 min
 * 60 mg/m3 (52 ppm) for 30 min
 * 30 mg/m3 (26 ppm) for 1 h
 * 10 mg/m3 (9 ppm) for 8 h
 * 7 mg/m3 (6 ppm) for 24 h (for indoor air quality, so as not to exceed 2% COHb for chronic exposure)

Diagnosis
As many symptoms of carbon monoxide poisoning also occur with many other types of poisonings and infections (such as the flu), the diagnosis is often difficult. A history of potential carbon monoxide exposure, such as being exposed to a residential fire, may suggest poisoning, but the diagnosis is confirmed by measuring the levels of carbon monoxide in the blood. This can be determined by measuring the amount of carboxyhemoglobin compared to the amount of hemoglobin in the blood.

The ratio of carboxyhemoglobin to hemoglobin molecules in an average person may be up to 5%, although cigarette smokers who smoke two packs per day may have levels up to 9%. In symptomatic poisoned people they are often in the 10–30% range, while persons who die may have postmortem blood levels of 30–90%.

As people may continue to experience significant symptoms of CO poisoning long after their blood carboxyhemoglobin concentration has returned to normal, presenting to examination with a normal carboxyhemoglobin level (which may happen in late states of poisoning) does not rule out poisoning.

Measuring
Carbon monoxide may be quantitated in blood using spectrophotometric methods or chromatographic techniques in order to confirm a diagnosis of poisoning in a person or to assist in the forensic investigation of a case of fatal exposure.

A CO-oximeter can be used to determine carboxyhemoglobin levels. Pulse CO-oximeters estimate carboxyhemoglobin with a non-invasive finger clip similar to a pulse oximeter. These devices function by passing various wavelengths of light through the fingertip and measuring the light absorption of the different types of hemoglobin in the capillaries. The use of a regular pulse oximeter is not effective in the diagnosis of carbon monoxide poisoning as these devices may be unable to distinguish carboxyhemoglobin from oxyhemoglobin. Breath CO monitoring offers an alternative to pulse CO-oximetry. Carboxyhemoglobin levels have been shown to have a strong correlation with breath CO concentration. However, many of these devices require the user to inhale deeply and hold their breath to allow the CO in the blood to escape into the lung before the measurement can be made. As this is not possible in people who are unresponsive, these devices may not appropriate for use in on-scene emergency care detection of CO poisoning.

Differential diagnosis
There are many conditions to be considered in the differential diagnosis of carbon monoxide poisoning. The earliest symptoms, especially from low level exposures, are often non-specific and readily confused with other illnesses, typically flu-like viral syndromes, depression, chronic fatigue syndrome, chest pain, and migraine or other headaches. Carbon monoxide has been called a "great mimicker" due to the presentation of poisoning being diverse and nonspecific. Other conditions included in the differential diagnosis include acute respiratory distress syndrome, altitude sickness, lactic acidosis, diabetic ketoacidosis, meningitis, methemoglobinemia, or opioid or toxic alcohol poisoning.

Treatment
Initial treatment for carbon monoxide poisoning is to immediately remove the person from the exposure without endangering further people. Those who are unconscious may require CPR on site. Administering oxygen via non-rebreather mask shortens the half-life of carbon monoxide from 320 minutes, when breathing normal air, to only 80 minutes. Oxygen hastens the dissociation of carbon monoxide from carboxyhemoglobin, thus turning it back into hemoglobin. Due to the possible severe effects in the baby, pregnant women are treated with oxygen for longer periods of time than non-pregnant people.

Hyperbaric oxygen
Hyperbaric oxygen is also used in the treatment of carbon monoxide poisoning, as it may hasten dissociation of CO from carboxyhemoglobin and cytochrome oxidase to a greater extent than normal oxygen. Hyperbaric oxygen at three times atmospheric pressure reduces the half life of carbon monoxide to 23 minutes, compared to 80 minutes for oxygen at regular atmospheric pressure. It may also enhance oxygen transport to the tissues by plasma, partially bypassing the normal transfer through hemoglobin. However, it is controversial whether hyperbaric oxygen actually offers any extra benefits over normal high flow oxygen, in terms of increased survival or improved long-term outcomes. There have been randomized controlled trials in which the two treatment options have been compared;     of the six performed, four found hyperbaric oxygen improved outcome and two found no benefit for hyperbaric oxygen. Some of these trials have been criticized for apparent flaws in their implementation. A review of all the literature concluded that the role of hyperbaric oxygen is unclear and the available evidence neither confirms nor denies a medically meaningful benefit. The authors suggested a large, well designed, externally audited, multicentre trial to compare normal oxygen with hyperbaric oxygen. While hyperbaric oxygen therapy is used for severe poisonings, the benefit over standard oxygen delivery is unclear.

Other
Further treatment for other complications such as seizure, hypotension, cardiac abnormalities, pulmonary edema, and acidosis may be required. Hypotension requires treatment with intravenous fluids; vasopressors may be required to treat myocardial depression. Cardiac dysrhythmias are treated with standard advanced cardiac life support protocols. If severe, metabolic acidosis is treated with sodium bicarbonate. Treatment with sodium bicarbonate is controversial as acidosis may increase tissue oxygen availability. Treatment of acidosis may only need to consist of oxygen therapy. The delayed development of neuropsychiatric impairment is one of the most serious complications of carbon monoxide poisoning. Brain damage is confirmed following MRI or CAT scans. Extensive follow up and supportive treatment is often required for delayed neurological damage. Outcomes are often difficult to predict following poisoning, especially people who have symptoms of cardiac arrest, coma, metabolic acidosis, or have high carboxyhemoglobin levels. One study reported that approximately 30% of people with severe carbon monoxide poisoning will have a fatal outcome. It has been reported that electroconvulsive therapy (ECT) may increase the likelihood of delayed neuropsychiatric sequelae (DNS) after carbon monoxide (CO) poisoning. A device that also provides some carbon dioxide to stimulate faster breathing (sold under the brand name ClearMate) may also be used.

Pathophysiology
The precise mechanisms by which the effects of carbon monoxide are induced upon bodily systems are complex and not yet fully understood. Known mechanisms include carbon monoxide binding to hemoglobin, myoglobin and mitochondrial cytochrome c oxidase and restricting oxygen supply, and carbon monoxide causing brain lipid peroxidation.

Hemoglobin
Carbon monoxide has a higher diffusion coefficient compared to oxygen, and the main enzyme in the human body that produces carbon monoxide is heme oxygenase, which is located in nearly all cells and platelets. Most endogenously produced CO is stored bound to hemoglobin as carboxyhemoglobin. The simplistic understanding for the mechanism of carbon monoxide toxicity is based on excess carboxyhemoglobin decreasing the oxygen-delivery capacity of the blood to tissues throughout the body. In humans, the affinity between hemoglobin and carbon monoxide is approximately 240 times stronger than the affinity between hemoglobin and oxygen. However, certain mutations such as the Hb-Kirklareli mutation has a relative 80,000 times greater affinity for carbon monoxide than oxygen resulting in systemic carboxyhemoglobin reaching a sustained level of 16% COHb.

Hemoglobin is a tetramer with four prosthetic heme groups to serve as oxygen binding sites. The average red blood cell contains 250 million hemoglobin molecules, therefore 1 billion heme sites capable of binding gas. The binding of carbon monoxide at any one of these sites increases the oxygen affinity of the remaining three sites, which causes the hemoglobin molecule to retain oxygen that would otherwise be delivered to the tissue; therefore carbon monoxide binding at any site may be as dangerous as carbon monoxide binding to all sites. Delivery of oxygen is largely driven by the Bohr effect and Haldane effect. To provide a simplified synopsis of the molecular mechanism of systemic gas exchange in layman's terms, upon inhalation of air it was widely thought oxygen binding to any of the heme sites triggers a conformational change in the globin/protein unit of hemoglobin which then enables the binding of additional oxygen to each of the other vacant heme sites. Upon arrival to the cell/tissues, oxygen release into the tissue is driven by "acidification" of the local pH (meaning a relatively higher concentration of 'acidic' protons/hydrogen ions) caused by an increase in the biotransformation of carbon dioxide waste into carbonic acid via carbonic anhydrase. In other words, oxygenated arterial blood arrives at cells in the "hemoglobin R-state" which has deprotonated/unionized amino acid residues (regarding nitrogen/amines) due to the less-acidic arterial pH environment (arterial blood averages pH 7.407 whereas venous blood is slightly more acidic at pH 7.371). The "T-state" of hemoglobin is deoxygenated in venous blood partially due to protonation/ionization caused by the acidic environment hence causing a conformation unsuited for oxygen-binding (in other words, oxygen is 'ejected' upon arrival to the cell because acid "attacks" the amines of hemoglobin causing ionization/protonation of the amine residues resulting in a conformation change unsuited for retaining oxygen). Furthermore, the mechanism for formation of carbaminohemoglobin generates additional 'acidic' hydrogen ions that may further stabilize the protonated/ionized deoxygenated hemoglobin. Upon return of venous blood into the lung and subsequent exhalation of carbon dioxide, the blood is "de-acidified" (see also: hyperventilation) allowing for the deprotonation/unionization of hemoglobin to then re-enable oxygen-binding as part of the transition to arterial blood (note this process is complex due to involvement of chemoreceptors and other physiological functionalities). Carbon monoxide is not 'ejected' due to acid, therefore carbon monoxide poisoning disturbs this physiological process hence the venous blood of poisoning patients is bright red akin to arterial blood since the carbonyl/carbon monoxide is retained. Hemoglobin is dark in deoxygenated venous blood, but it has a bright red color when carrying blood in oxygenated arterial blood and when converted into carboxyhemoglobin in both arterial and venous blood, so poisoned cadavers and even commercial meats treated with carbon monoxide acquire an unnatural lively reddish hue.

At toxic concentrations, carbon monoxide as carboxyhemoglobin significantly interferes with respiration and gas exchange by simultaneously inhibiting acquisition and delivery of oxygen to cells and preventing formation of carbaminohemoglobin which accounts for approximately 30% of carbon dioxide exportation. Therefore, a patient with carbon monoxide poisoning may experience severe hypoxia and acidosis (potentially both respiratory acidosis and metabolic acidosis) in addition to the toxicities of excess carbon monoxide inhibiting numerous hemoproteins, metallic and non-metallic targets which affect cellular machinery.

Myoglobin
Carbon monoxide also binds to the hemeprotein myoglobin. It has a high affinity for myoglobin, about 60 times greater than that of oxygen. Carbon monoxide bound to myoglobin may impair its ability to utilize oxygen. This causes reduced cardiac output and hypotension, which may result in brain ischemia. A delayed return of symptoms have been reported. This results following a recurrence of increased carboxyhemoglobin levels; this effect may be due to a late release of carbon monoxide from myoglobin, which subsequently binds to hemoglobin.

Cytochrome oxidase
Another mechanism involves effects on the mitochondrial respiratory enzyme chain that is responsible for effective tissue utilization of oxygen. Carbon monoxide binds to cytochrome oxidase with less affinity than oxygen, so it is possible that it requires significant intracellular hypoxia before binding. This binding interferes with aerobic metabolism and efficient adenosine triphosphate synthesis. Cells respond by switching to anaerobic metabolism, causing anoxia, lactic acidosis, and eventual cell death. The rate of dissociation between carbon monoxide and cytochrome oxidase is slow, causing a relatively prolonged impairment of oxidative metabolism.

Central nervous system effects
The mechanism that is thought to have a significant influence on delayed effects involves formed blood cells and chemical mediators, which cause brain lipid peroxidation (degradation of unsaturated fatty acids). Carbon monoxide causes endothelial cell and platelet release of nitric oxide, and the formation of oxygen free radicals including peroxynitrite. In the brain this causes further mitochondrial dysfunction, capillary leakage, leukocyte sequestration, and apoptosis. The result of these effects is lipid peroxidation, which causes delayed reversible demyelination of white matter in the central nervous system known as Grinker myelinopathy, which can lead to edema and necrosis within the brain. This brain damage occurs mainly during the recovery period. This may result in cognitive defects, especially affecting memory and learning, and movement disorders. These disorders are typically related to damage to the cerebral white matter and basal ganglia. Hallmark pathological changes following poisoning are bilateral necrosis of the white matter, globus pallidus, cerebellum, hippocampus and the cerebral cortex.

Pregnancy
Carbon monoxide poisoning in pregnant women may cause severe adverse fetal effects. Poisoning causes fetal tissue hypoxia by decreasing the release of maternal oxygen to the fetus. Carbon monoxide also crosses the placenta and combines with fetal hemoglobin, causing more direct fetal tissue hypoxia. Additionally, fetal hemoglobin has a 10 to 15% higher affinity for carbon monoxide than adult hemoglobin, causing more severe poisoning in the fetus than in the adult. Elimination of carbon monoxide is slower in the fetus, leading to an accumulation of the toxic chemical. The level of fetal morbidity and mortality in acute carbon monoxide poisoning is significant, so despite mild maternal poisoning or following maternal recovery, severe fetal poisoning or death may still occur.

History
Humans have maintained a complex relationship with carbon monoxide since first learning to control fire circa 800,000 BC. Primitive cavemen probably discovered the toxicity of carbon monoxide upon introducing fire into their dwellings. The early development of metallurgy and smelting technologies emerging circa 6,000 BC through the Bronze Age likewise plagued humankind with carbon monoxide exposure. Apart from the toxicity of carbon monoxide, indigenous Native Americans may have experienced the neuroactive properties of carbon monoxide through shamanistic fireside rituals.

Early civilizations developed mythological tales to explain the origin of fire, such as Vulcan, Pkharmat, and Prometheus from Greek mythology who shared fire with humans. Aristotle (384–322 BC) first recorded that burning coals produced toxic fumes. Greek physician Galen (129–199 AD) speculated that there was a change in the composition of the air that caused harm when inhaled, and symptoms of CO poisoning appeared in Cassius Iatrosophista's Quaestiones Medicae et Problemata Naturalia circa 130 AD. Julian the Apostate, Caelius Aurelianus, and several others similarly documented early knowledge of the toxicity symptoms of carbon monoxide poisoning as caused by coal fumes in the ancient era.

Documented cases by Livy and Cicero allude to carbon monoxide being used as a method of suicide in ancient Rome. Emperor Lucius Verus used smoke to execute prisoners. Many deaths have been linked to carbon monoxide poisoning including Emperor Jovian, Empress Fausta, and Seneca. The most high-profile death by carbon monoxide poisoning may possibly have been Cleopatra or Edgar Allan Poe.

In the fifteenth century, coal miners believed sudden death was caused by evil spirits; carbon monoxide poisoning has been linked to supernatural and paranormal experiences, witchcraft, etc. throughout the following centuries including in the modern present day exemplified by Carrie Poppy's investigations.

Georg Ernst Stahl mentioned carbonarii halitus in 1697 in reference to toxic vapors thought to be carbon monoxide. Friedrich Hoffmann conducted the first modern scientific investigation into carbon monoxide poisoning from coal in 1716, notably rejecting villagers attributing death to demonic superstition. Herman Boerhaave conducted the first scientific experiments on the effect of carbon monoxide (coal fumes) on animals in the 1730s. Joseph Priestley is credited with first synthesizing carbon monoxide in 1772 which he had called heavy inflammable air, and Carl Wilhelm Scheele isolated carbon monoxide from coal in 1773 suggesting it to be the toxic entity.

The dose-dependent risk of carbon monoxide poisoning as hydrocarbonate was investigated in the late 1790s by Thomas Beddoes, James Watt, Tiberius Cavallo, James Lind, Humphry Davy, and many others in the context of inhalation of factitious airs, much of which occurred at the Pneumatic Institution.

William Cruickshank discovered carbon monoxide as a molecule containing one carbon and one oxygen atom in 1800, thereby initiating the modern era of research exclusively focused on carbon monoxide. The mechanism for toxicity was first suggested by James Watt in 1793, followed by Adrien Chenot in 1854 and finally demonstrated by Claude Bernard after 1846 as published in 1857 and also independently published by Felix Hoppe-Seyler in the same year.

The first controlled clinical trial studying the toxicity of carbon monoxide occurred in 1973.

Historical detection
Carbon monoxide poisoning has plagued coal miners for many centuries. In the context of mining, carbon monoxide is widely known as whitedamp. John Scott Haldane identified carbon monoxide as the lethal constituent of afterdamp, the gas created by combustion, after examining many bodies of miners killed in pit explosions. By 1911, Haldane introduced the use of small animals for miners to detect dangerous levels of carbon monoxide underground, either white mice or canaries which have little tolerance for carbon monoxide thereby offering an early warning, i.e. canary in a coal mine. The canary in British pits was replaced in 1986 by the electronic gas detector.

The first qualitative analytical method to detect carboxyhemoglobin emerged in 1858 with a colorimetric method developed by Felix Hoppe-Seyler, and the first quantitative analysis method emerged in 1880 with Josef von Fodor.

Historical treatment
The use of oxygen emerged with anecdotal reports such as Humphry Davy having been treated with oxygen in 1799 upon inhaling three quarts of hydrocarbonate (water gas). Samuel Witter developed an oxygen inhalation protocol in response to carbon monoxide poisoning in 1814. Similarly, an oxygen inhalation protocol was recommend for malaria (literally translated to "bad air") in 1830 based on malaria symptoms aligning with carbon monoxide poisoning. Other oxygen protocols emerged in the late 1800s. The use of hyperbaric oxygen in rats following poisoning was studied by Haldane in 1895 while its use in humans began in the 1960s.

Incidents
The worst accidental mass poisoning from carbon monoxide was the Balvano train disaster which occurred on 3 March 1944 in Italy, when a freight train with many illegal passengers stalled in a tunnel, leading to the death of over 500 people.

Over 50 people are suspected to have died from smoke inhalation as a result of the Branch Davidian Massacre during the Waco siege in 1993.

Weaponization
In ancient history, Hannibal executed Roman prisoners with coal fumes during the Second Punic War.

The extermination of stray dogs by a carbon monoxide gas chamber was described in 1874. In 1884, an article appeared in Scientific American describing the use of a carbon monoxide gas chamber for slaughterhouse operations as well as euthanizing a variety of animals.

As part of the Holocaust during World War II, the Nazis used gas vans at Chelmno extermination camp and elsewhere to murder an estimated 700,000 or more people by carbon monoxide poisoning. This method was also used in the gas chambers of several death camps such as Treblinka, Sobibor, and Belzec. Gassing with carbon monoxide started in Action T4. The gas was supplied by IG Farben in pressurized cylinders and fed by tubes into the gas chambers built at various mental hospitals, such as Hartheim Euthanasia Centre. Exhaust fumes from tank engines, for example, were used to supply the gas to the chambers.

title: Carbon monoxide poisoning


text:
Gook

Gook ( or ) is a derogatory term for people of East and Southeast Asian descent. Its origin is unclear, but it may have originated among U.S. Marines during the Philippine–American War (1899–1913). Historically, U.S. military personnel used the word “to refer to any dark-skinned foreigner, especially a non-European or non-American.” The earliest published example is dated 1920 and notes that U.S. Marines then in Haiti used the term to refer to Haitians. It was widely used in Asia in both the Korean and Vietnamese Wars.

Etymology
The Oxford English Dictionary states that the origin of the word is unknown. An earlier usage of gook, recorded in a slang dictionary published in 1893, defined gook as "a low prostitute".

The earliest use of the word in the English language comes from the name of a traditional Cornish Bonnet.

The usage for Koreans possibly comes from the Korean word "국" (guk), meaning "country", "한국" (hanguk), meaning "Korea", or "미국" (miguk), meaning "America". U.S. soldiers in the Korean War might have heard locals saying miguk (미국), referring to Americans, and misinterpreted this as "Me gook."

Historical use
The origin of gook is unclear, but it may have originated among U.S. Marines during the Philippine–American War (1899–1913), where the similar term goo-goo was also used to refer to Filipinos. The Marines who occupied Nicaragua in 1912 took to calling the natives gooks. In 1920, it was reported that U.S. Marines in Haiti used the term to refer to Haitians. Historically, U.S. military personnel used the word to refer to non-Americans of various races.

During World War II, U.S. troops fighting on the Pacific Front occasionally referred to the natives of Pacific Islands as gooks. The term appears in the 1943 film Guadalcanal Diary, when one of the characters of the film refers to the titular setting as "gook island".

When U.S. troops were stationed on the Korean Peninsula at the outbreak of the Korean War, so prevalent was the use of the word gook during the first few months of the war that U.S. General Douglas MacArthur banned its use, for fear that Asians would become alienated to the United Nations Command because of the insult. In spite of MacArthur’s early prohibition, the term was nonetheless used by U.S. troops during the conflict, and U.S. postwar occupation troops in South Korea continued to call the Koreans "gooks".

The term was also used by non-American troops during the Korean War as well. The posthumous Victoria Cross citation for British Army major Kenneth Muir, who was killed in action at the Battle of Hill 282, stated that his last words were "The Gooks will never drive the Argylls off this hill."

In modern U.S. usage, "gook" refers particularly to communist soldiers during the Vietnam War and has also been used towards all Vietnamese and at other times to all Southeast Asians in general. It is considered to be highly offensive. In a highly publicized incident, Senator John McCain used the word during the 2000 presidential campaign to refer to his North Vietnamese captors when he was a prisoner of war: "I hate the gooks. I will hate them as long as I live… I was referring to my prison guards and I will continue to refer to them in language that might offend." A few days later, however, he apologized to the Vietnamese community at large.

title: Gook


text:
Reionization

In the fields of Big Bang theory and cosmology, reionization is the process that caused electrically neutral atoms in the universe to reionize after the lapse of the "dark ages".

Reionization is the second of two major phase transitions of gas in the universe (the first is recombination). While the majority of baryonic matter in the universe is in the form of hydrogen and helium, reionization usually refers strictly to the reionization of hydrogen, the element.

It is believed that the primordial helium also experienced the same phase of reionization changes, but at different points in the history of the universe. This is usually referred to as helium reionization.

Background

The first phase change of hydrogen in the universe was recombination, which occurred at a redshift z = 1089 (379,000 years after the Big Bang), due to the cooling of the universe to the point where the rate of recombination of electrons and protons to form neutral hydrogen was higher than the reionization rate. The universe was opaque before the recombination, due to the scattering of photons (of all wavelengths) off free electrons (and free protons, to a significantly lesser extent), but it became increasingly transparent as more electrons and protons combined to form neutral hydrogen atoms. While the electrons of neutral hydrogen can absorb photons of some wavelengths by rising to an excited state, a universe full of neutral hydrogen will be relatively opaque only at those absorbed wavelengths, but transparent throughout most of the spectrum. The Dark Ages of the universe start at that point, because there were no light sources other than the gradually redshifting cosmic microwave background radiation.

The second phase change occurred once gas clouds started to condense in the early universe that were energetic enough to re-ionize neutral hydrogen. As these objects formed and radiated energy, the universe reverted from being composed of neutral atoms, to once again being an ionized plasma. This occurred between 150 million and one billion years after the Big Bang (at a redshift 20 > z > 6). At that time, however, matter had been diffused by the expansion of the universe, and the scattering interactions of photons and electrons were much less frequent than before electron-proton recombination. Thus, the universe was full of low density ionized hydrogen and remained transparent, as is the case today.

Detection methods
Looking back so far in the history of the universe presents some observational challenges. There are, however, a few observational methods for studying reionization.

Quasars and the Gunn-Peterson trough
One means of studying reionization uses the spectra of distant quasars. Quasars release an extraordinary amount of energy, being among the brightest objects in the universe. As a result, some quasars are detectable from as long ago as the epoch of reionization. Quasars also happen to have relatively uniform spectral features, regardless of their position in the sky or distance from the Earth. Thus it can be inferred that any major differences between quasar spectra will be caused by the interaction of their emission with atoms along the line of sight. For wavelengths of light at the energies of one of the Lyman transitions of hydrogen, the scattering cross-section is large, meaning that even for low levels of neutral hydrogen in the intergalactic medium (IGM), absorption at those wavelengths is highly likely.

For nearby objects in the universe, spectral absorption lines are very sharp, as only photons with energies just sufficient to cause an atomic transition can cause that transition. However, the distances between quasars and the telescopes which detect them are large, which means that the expansion of the universe causes light to undergo noticeable redshifting. This means that as light from the quasar travels through the IGM and is redshifted, wavelengths which had been below the Lyman Alpha limit are stretched, and will in effect begin to fill in the Lyman absorption band. This means that instead of showing sharp spectral absorption lines, a quasar's light which has traveled through a large, spread out region of neutral hydrogen will show a Gunn-Peterson trough.

The redshifting for a particular quasar provides temporal information about reionization. Since an object's redshift corresponds to the time at which it emitted the light, it is possible to determine when reionization ended. Quasars below a certain redshift (closer in space and time) do not show the Gunn-Peterson trough (though they may show the Lyman-alpha forest), while quasars emitting light prior to reionization will feature a Gunn-Peterson trough. In 2001, four quasars were detected by the Sloan Digital Sky Survey with redshifts ranging from z = 5.82 to z = 6.28. While the quasars above z = 6 showed a Gunn-Peterson trough, indicating that the IGM was still at least partly neutral, the ones below did not, meaning the hydrogen was ionized. As reionization is expected to occur over relatively short timescales, the results suggest that the universe was approaching the end of reionization at z = 6. This, in turn, suggests that the universe must still have been almost entirely neutral at z > 10. On the other hand, long absorption troughs persisting down to z < 5.5 in the Lyman-alpha and Lyman-beta forests suggest that reionization potentially extends later than z = 6.

CMB anisotropy and polarization
The anisotropy of the cosmic microwave background on different angular scales can also be used to study reionization. Photons undergo scattering when there are free electrons present, in a process known as Thomson scattering. However, as the universe expands, the density of free electrons will decrease, and scattering will occur less frequently. In the period during and after reionization, but before significant expansion had occurred to sufficiently lower the electron density, the light that composes the CMB will experience observable Thomson scattering. This scattering will leave its mark on the CMB anisotropy map, introducing secondary anisotropies (anisotropies introduced after recombination). The overall effect is to erase anisotropies that occur on smaller scales. While anisotropies on small scales are erased, polarization anisotropies are actually introduced because of reionization. By looking at the CMB anisotropies observed, and comparing with what they would look like had reionization not taken place, the electron column density at the time of reionization can be determined. With this, the age of the universe when reionization occurred can then be calculated.

The Wilkinson Microwave Anisotropy Probe allowed that comparison to be made. The initial observations, released in 2003, suggested that reionization took place from 30 > z > 11. This redshift range was in clear disagreement with the results from studying quasar spectra. However, the three year WMAP data returned a different result, with reionization beginning at z = 11 and the universe ionized by z = 7. This is in much better agreement with the quasar data.

Results in 2018 from Planck mission, yield an instantaneous reionization redshift of z = 7.68 ± 0.79.

The parameter usually quoted here is τ, the "optical depth to reionization," or alternatively, zre, the redshift of reionization, assuming it was an instantaneous event. While this is unlikely to be physical, since reionization was very likely not instantaneous, zre provides an estimate of the mean redshift of reionization.

21-cm line
Even with the quasar data roughly in agreement with the CMB anisotropy data, there are still a number of questions, especially concerning the energy sources of reionization and the effects on, and role of, structure formation during reionization. The 21-cm line in hydrogen is potentially a means of studying this period, as well as the "dark ages" that preceded reionization. The 21-cm line occurs in neutral hydrogen, due to differences in energy between the spin triplet and spin singlet states of the electron and proton. This transition is forbidden, meaning it occurs extremely rarely. The transition is also highly temperature dependent, meaning that as objects form in the "dark ages" and emit Lyman-alpha photons that are absorbed and re-emitted by surrounding neutral hydrogen, it will produce a 21-cm line signal in that hydrogen through Wouthuysen-Field coupling. By studying 21-cm line emission, it will be possible to learn more about the early structures that formed. Observations from the Experiment to Detect the Global Epoch of Reionization Signature (EDGES) points to a signal from this era, although follow-up observations will be needed to confirm it. Several other projects hope to make headway in this area in the near future, such as the Precision Array for Probing the Epoch of Reionization (PAPER), Low Frequency Array (LOFAR), Murchison Widefield Array (MWA), Giant Metrewave Radio Telescope (GMRT), Mapper of the IGM Spin Temperature (MIST), the Dark Ages Radio Explorer (DARE) mission, and the Large-Aperture Experiment to Detect the Dark Ages (LEDA).

Energy sources
While observations have come in which narrow the window during which the epoch of reionization could have taken place, it is still uncertain which objects provided the photons that reionized the IGM. To ionize neutral hydrogen, an energy larger than 13.6 eV is required, which corresponds to photons with a wavelength of 91.2 nm or shorter. This is in the ultraviolet part of the electromagnetic spectrum, which means that the primary candidates are all sources which produce a significant amount of energy in the ultraviolet and above. How numerous the source is must also be considered, as well as the longevity, as protons and electrons will recombine if energy is not continuously provided to keep them apart. Altogether, the critical parameter for any source considered can be summarized as its "emission rate of hydrogen-ionizing photons per unit cosmological volume." With these constraints, it is expected that quasars and first generation stars and galaxies were the main sources of energy.

Dwarf galaxies
Dwarf galaxies are currently considered to be the primary source of ionizing photons during the epoch of reionization. For most scenarios, this would require the log-slope of the UV galaxy luminosity function, often denoted α, to be steeper than it is today, approaching α = -2. With the advent of the James Webb Space Telescope (JWST), constraints on the UV luminosity function at the Epoch of Reionization have become commonplace, allowing for better constraints on the faint, low-mass population of galaxies.

In 2014, two separate studies identified two Green Pea galaxies (GPs) to be likely Lyman Continuum (LyC)-emitting candidates. Compact dwarf star-forming galaxies like the GPs are considered excellent low-redshift analogs of high-redshift Lyman-alpha and LyC emitters (LAEs and LCEs, respectively). At that time, only two other LCEs were known: Haro 11 and Tololo-1247-232. Finding local LyC emitters has thus become crucial to the theories about the early universe and the epoch of reionization.

Subsequently, motivated, a series of surveys have been conducted using Hubble Space Telescope 's Cosmic Origins Spectrograph (HST/COS) to measure the LyC directly. These efforts culminated in the Low-redshift Lyman Continuum Survey, a large HST/COS program which nearly tripled the number of direct measurements of the LyC from dwarf galaxies. To date, at least 50 LCEs have been confirmed using HST/COS with LyC escape fractions anywhere from ≈ 0 to 88%. The results from the Low-redshift Lyman Continuum Survey have provided the empirical foundation necessary to identify and understand LCEs at the Epoch of Reionization. With new observations from JWST, populations of LCEs are now being studied at cosmological redshifts greater than 6, allowing for the first time a detailed and direct assessment of the origins of cosmic Reionization. Combining these large samples of galaxies with new constraints on the UV luminosity function indicates that dwarf galaxies overwhelmingly contribute to Reionization.

Quasars
Quasars, a class of active galactic nuclei (AGN), were considered a good candidate source because they are highly efficient at converting mass to energy, and emit a great deal of light above the threshold for ionizing hydrogen. It is unknown, however, how many quasars existed prior to reionization. Only the brightest of quasars present during reionization can be detected, which means there is no direct information about dimmer quasars that existed. However, by looking at the more easily observed quasars in the nearby universe, and assuming that the luminosity function (number of quasars as a function of luminosity) during reionization will be approximately the same as it is today, it is possible to make estimates of the quasar populations at earlier times. Such studies have found that quasars do not exist in high enough numbers to reionize the IGM alone, saying that "only if the ionizing background is dominated by low-luminosity AGNs can the quasar luminosity function provide enough ionizing photons."

Population III stars
Population III stars were the earliest stars, which had no elements more massive than hydrogen or helium. During Big Bang nucleosynthesis, the only elements that formed aside from hydrogen and helium were trace amounts of lithium. Yet quasar spectra have revealed the presence of heavy elements in the intergalactic medium at an early era. Supernova explosions produce such heavy elements, so hot, large, Population III stars which will form supernovae are a possible mechanism for reionization. While they have not been directly observed, they are consistent according to models using numerical simulation and current observations. A gravitationally lensed galaxy also provides indirect evidence of Population III stars. Even without direct observations of Population III stars, they are a compelling source. They are more efficient and effective ionizers than Population II stars, as they emit more ionizing photons, and are capable of reionizing hydrogen on their own in some reionization models with reasonable initial mass functions. As a consequence, Population III stars are currently considered the most likely energy source to initiate the reionization of the universe, though other sources are likely to have taken over and driven reionization to completion.

In June 2015, astronomers reported evidence for Population III stars in the Cosmos Redshift 7 galaxy at $z = 6.60$. Such stars are likely to have existed in the very early universe (i.e., at high redshift), and may have started the production of chemical elements heavier than hydrogen that are needed for the later formation of planets and life as we know it.

title: Reionization