사용자:Nike787/미아즈마

19세기 당시 콜레라 전염병을 그린 작품. 독을 품은 공기가 질병을 퍼트린다는 당시의 인식을 보여주고 있다.

미아즈마(Miasma)란 폐기된 의료 학설중 하나로서, 콜레라, 클라미디아, 흑사병 등 질병의 발병원인이 ‘미아즈마’(고대 그리스어: μίασμα, "오염")라 불리는 ‘나쁜 공기’에 있다는 주장이다. 학계에서 완전히 폐기되던 1880년까지 정설로 널리 받아들여졌었다. 미아스마라고 표기되기도 하며 영어권에서는 ‘나쁜 공기’(bad air), ‘밤 공기’(night air)로도 불렸으며, 한자 문화권에서는 장기(瘴氣)라는 표현이 사용되었다.

개요

물질이 부패하며 발생하는 미아즈마로 인하여 전염병이 돈다는 주장으로, 주로 전염병과 관련하여서만 사용된 학설이지만, 19세기 초반의 일부 학자들은 이 학설을 이용하여 다른 주장(음식의 냄새만 맡고도 살이 찔 수 있다는 등)을 펼치기도 했다.

물질이 부패하여 악취가 나는 곳은 주로 병원균이 번식하고 전염병이 창궐하기 때문에 당시에는 정설로 취급되며 매우 신빙성 있는 학설로 받아들여졌지만, 세균의 존재를 몰랐던 당시에 질병 원인을 병원균이 아닌 악취로 규정하였기 때문에 근본적으로 잘못된 이론이다.

공식적으로 폐기되는 19세기 말까지 고대 유럽과 중국에서 널리 정설로 받아들여졌다. 1880년 이후 이 학설은 미생물 이론(특정 질병의 발병 원인은 특정한 미생물에 있다는 이론)으로 대체되며 완전히 학계에서 폐기되고 만다. 한편 질병을 막기 위해 악취를 제거해야 한다는 기존의 인식 탓에 나라에서 도시 환경미화에 노력을 기울이는 등 긍정적인 효과도 있었다.

어원

‘미아즈마’(고대 그리스어: μίασμα)라는 말의 어원은 “오염”이라는 의미의 고대 그리스어에서 유래하였다. 중세 이탈리아어로 “나쁜 공기”라는 의미를 가진 말라리아와도 어원의 유사성이 있다.

폐기 전 세간의 인식

1613년 크라쿠프에서 발간된 책으로, 이른바 “나쁜 공기”의 예방에 관한 내용을 담고 있다.

해당 시대 사람들은 미아즈마라는 독성을 머금은 수증기라고 믿었으며 질병을 일으키는 성분이 작게 분해되어 습기의 형태를 띤다고 생각했다. 당시 학계에서는 질병은 그러한 수증기가 발생되는 환경, 즉 오염된 물이나 악취가 나는 공기, 더러운 위생 상태와 같은 조건에서 발생하는 것으로 보았는데, 유해여부는 악취의 유무를 통해 판별하였으며, 사람에서 사람으로 직접 전염되는 것이 아니라 같은 미아즈마 수증기의 영향권에 있다면 전염된다고 믿었다.

1850년대 당시 학계에서는 런던과 파리에서 유행하던 콜레라의 원인으로 미아즈마를 꼽았다. 미아즈마 학설의 신봉자였던 윌리엄 파(William Farr)는 콜레라가 공기를 통해 전염되며 템즈강 유역에 엄청난 ‘미아즈마’가 있다고 주장했다. 당시 템즈강 유역은 생활하수가 그대로 흘러들어가며 위생이 나쁜 탓에 악취가 심하였으므로 아예 틀린 주장은 아니었다. 콜레라 창궐 당시 세간에 널리 받아들여지고 있었던 미아즈마 학설은, ‘콜레라는 물을 통해 전염된다’는 존 스노의 주장이 나오자 그 빛을 잃게 된다. 콜레라는 물로만 전염되는 것은 아니었지만 역학조사를 통한 존 스노의 주장은 기존의 미아즈마 학설보다 훨씬 근거있는 주장이었고, 결과적으로 이 주장은 일부 사실로 밝혀지고 미아즈마 학설은 학계에서 점차 의심받기 시작한다. 존 스노는 이 업적으로 훗날 ‘역학의 아버지’로 불리게 된다. 미아즈마 학설 탓에 악취만 제거하면 된다는 인식을 가지던 당시 런던에서는 인분과 오물이 그대로 템즈강으로 유입되게 하는 등 악취제거 위주의 잘못된 전염병 대처를 하였고 결국 런던 소호 지역은 물론 콜레라 발병 지역 전역에서 콜레라 대처가 늦고 말았다.

크림 전쟁의 유명한 간호사 플로렌스 나이팅게일 역시 당시 정설처럼 받아들여지던 미아즈마 학설의 신봉자였으며 이에 따라 병원 내의 냄새제거와 위생개선에 대단히 힘썼다. 나이팅게일은 저서 《노동자 계층 간호 참고서》(Notes on Nursing for the Labouring Classes, 1860년)에서 환자가 실내에서도 바깥 공기와 같은 신선한 공기를 마실 수 있도록 실내환경을 유지할 것을 권장하였다. 나이팅게일의 이러한 노력은 비록 잘못된 학설을 근거로 시행한 것들이지만 결과적으로 병원 내 청결 유지와 위생개선, 원내감염 예방에 큰 도움이 되었고 이같은 노력은 현대의 병원에서도 계속되고 있는 것이다.

19세기 초 유럽 지역에서는 경고문 등에서 ‘유해한 안개’(unhealthy fog)라 표현되며 위험한 것으로 간주되었는데, 당시에는 안개가 생기면 해당 지역에 미아즈마가 존재한다는 것을 강하게 시사한다고 보았다. 미아즈마는 안개나 연기처럼 기류에 의해 이동하며 바람을 통해 확산되며, 단순히 공기중을 떠다니는 것이 아니라 공기 자체를 바꾸어버린다고 생각했다. 마치 사람이 질병에 감염되듯이 대기환경 자체가 감염된다고 믿은 것이다. 당시의 많은 사람들이 미아즈마가 대기 환경과 공기의 성질 자체를 완전히 변화시키는 신비로운 존재라고 생각했다.

19세기 이후

발효병 이론과 밤공기

발효병 이론(Zymotic Theory)에 따라 당대에는 "미아즈마"는 토양에서 올라와서 질병을 퍼트린다고 생각했다. 미아즈마는 썩어가는 초목과 더러운 물(늪, 슾지, 도시의 빈민가 등)에서부터 비롯된다고 믿었다. 당대의 일반적인 사람들, 특히 허약하거나 병약한 사람들은 밤공기(night air, 미아즈마의 이명)를 마시는 걸 꺼려 가급적 밖에 나가지 않았고 집 문을 닫아놓았다. 발효병 이론의 영향으로 차가운 공기는 병을 옮긴다는 속설이 있어 대중들은 찬 공기도 두려워했다. 밤 공기에 대한 공포는 난방시설과 환기장치의 발달과 함께 서서히 사라졌고, 말라리아의 확산에는 모기가 직접적인 영향을 미친다는 것이 알려지며 이러한 인식 전환에 기여했다.

전염론과 미아즈마론

19세기 이전만 해도 서구권에서는 밤공기(night air)는 유해한 것으로 보았다. 19세기가 지나는 동안, 의학계에서는 질병확산의 원인에 대한 견해가 전염론과 미아즈마론 두 가지로 나뉘게 된다. 전염론자(Contagionist)들은 질병이 신체적 접촉을 통해 전염된다고 주장하였고, 미아즈마론자들은 질병은 미아즈마의 형태로 공기중에 존재하여 신체적 접촉 없이도 전염이 가능하다고 주장하였다. 대표적인 미아즈마론자는 토머스 사우스우드 스미스와 플로렌스 나이팅게일이었다. 결과적으로, 전염론과 미아즈마론 둘 다 완전히 틀린 학설은 아니었다. 현재의 세균 이론으로 밝혀진 바로는, 질병에 따라 다르지만 직접적인 접촉으로 인한 전염과 공기중 전염 둘 다 가능하다.

각주

Influence on sanitary engineering reforms

In the early nineteenth century, the living conditions of industrialized cities in Britain were increasingly unsanitary. Population was moving in much faster than the infrastructure could support. For example, the population of Manchester doubled within a single decade, leading to overcrowding and a great increase in waste accumulation. The theory of miasma disease made sense to the sanitary reformers of the mid-19th century. Miasma explained why cholera and other diseases were epidemic in places where the water was undrained and very foul-smelling. As sanitary reform’s engineering leader, London’s Edwin Chadwick, asserted that "all smell is disease", and he proposed that a change in the fundamental structure of sanitation systems was in order to combat increasing urban mortality rates. Chadwick asserted that the problem of epidemics of cholera and typhoid was directly related to urbanization, and he proposed that new, independent sewer systems should be connected to homes. Chadwick supported his proposal with reports from the London Statistical Society which showed dramatic increases in both morbidity and mortality rates since the beginning of urbanization in the early nineteenth century. Though Chadwick proposed reform on the basis of miasma theory, his proposals still contributed to sanitation improvements, such as preventing the reflux of noxious air from sewers back into houses by separate drainage systems in the sanitation designs, which incidentally led to decreased episodes of cholera and thus helped to support the theory.

The miasma theory was consistent with the observations that disease was associated with poor sanitation (and hence foul odours) and that sanitary improvements reduced disease; it was not consistent with the observations of microbiology however which led to the later germ theory of disease. The introduction of medical bacteriology in the 1870s and 1880s provided a challenge to the miasma theory, though consensus was not reached immediately; concerns over sewer gas, which was a major component of the miasma theory developed by Galen and brought to prominence by the Great Stink, led to continuing proponents of the theory who observed that sewers enclosed the refuse of the human bowel, which medical science had discovered could teem with typhoid, cholera, and other microbes.

The work of John Snow is notable for helping to make the connection between cholera and typhoid epidemics and contaminated water sources, which contributed to the eventual demise of miasma theory. During the cholera epidemic of 1854, Snow traced high mortality rates among the citizens of Soho to a water pump in Broad Street. Snow convinced the local government to remove the pump handle, which resulted in a marked decrease in cases of cholera in the area. In 1857, Snow submitted a paper to the British Medical Journal which attributed high numbers of cholera cases to water sources that were contaminated with human waste. Snow used statistical data to show that citizens who received their water from upstream sources were considerably less likely to develop cholera than those who received their water from downstream sources. Though his research supported his hypothesis that contaminated water, not foul air, was the source of cholera epidemics, a review committee concluded that Snow’s findings were not significant enough to warrant change, and they were summarily dismissed. Additionally, other interests intervened in the process of reform. Many water companies and civic authorities pumped water directly from contaminated sources such as the Thames to public wells, and the idea of changing sources or implementing filtration techniques was an unattractive economic prospect. In the face of such economic interests, reform was slow to be adopted.

Even though later disproven by the influence of bacteria and the discovery of viruses, the miasma theory helped make the connection between poor sanitation and disease. This caused public health reforms and encouraged cleanliness, which in Britain led to the legislation of Parliament which approved the Public Health Acts of 1848 and 1858 and the Local Government Act of 1858. The latter of these confers the power of instating investigations into the health and sanitary regulations of any town or place, upon the petition of residents or death rates exceeding the norm. Early medical and sanitary engineering reformers included Henry Austin, Joseph Bazalgette, Edwin Chadwick, Frank Forster, Thomas Hawksley, William Haywood, Henry Letheby, Robert Rawlinson, Sir John Simon and Thomas Wicksteed. These and later British regulatory improvements were reported in the United States as early as 1865.

Particularly notable to nineteenth century sanitation reform is the work of Joseph Bazalgette, chief engineer to London’s Metropolitan Board of Works. Encouraged by the Great Stink, Parliament sanctioned Bazalgette to design and construct a comprehensive system of sewers which intercepted London’s sewage and diverted it away from its water supply. The system helped purify London’s water supply and saved the city from epidemics. In 1866, the last of the three great British cholera epidemics took hold in a small area of Whitechapel. However, the area was not yet connected to Bazalgette’s system, and the confined area of the epidemic in London acted as testament to the efficiency of the system’s design.

Years later, the influence of these sanitary reforms on Britain was described by Sir Richard Rogers:

London was the first city to create a complex civic administration which could coordinate modern urban services, from public transport to housing, clean water to education. London's County Council was acknowledged as the most progressive metropolitan government in the world. Fifty years earlier, London had been the worst slum city of the industrialized world: over-crowded, congested, polluted and ridden with disease...

The miasma theory did contribute to containing disease in urban settlements, but did not allow for a suitable approach to safe excreta reuse in agriculture to be adopted. It was one of the causes for abandoning the prevailing practice of collecting human excreta from urban settlements and reusing them in the surrounding farmland (nowadays referred to as the ecosan approach of "closing the loop" when done in a safe manner). Such resource recovery schemes were common in many European cities until the 19th century before the arrival of sewer-based sanitation systems.

Throughout the nineteenth century public health, sanitation and the influence of miasma became the main reasons for the controversial practice of cremation. The miasma theory stated that infectious diseases were spread by noxious gases emitted from decaying organic matter, which included decaying corpses. This public health argument for cremation faded along with the miasma theory.

From miasma to germ theory

Although the connection between germ and disease was proposed quite early, it was not until the late-1800s that the germ theory was generally accepted. The miasmatic theory was challenged by John Snow, suggesting that there was some means by which the disease was spread via a poison or morbid material (orig: materies morbi) in the water. He suggested this before and in response to an epidemic on Broad Street in central London in 1854. Because of the miasmatic theory's predominance among Italian scientists, the discovery in the same year by Filippo Pacini of the bacillus that caused the disease was completely ignored.

It was not until 1876 that Robert Koch proved that the bacterium Bacillus anthracis caused anthrax, which brought a definitive end to Miasma Theory.

In 1846, the Nuisances Removal and Diseases Prevention Act was passed to identify whether the transmission of Cholera is by air or by water. The bill was used to encourage the owner to clean their dwelling and connect them to sewers.

Some years later in 1855, John Snow made a testimony against the Amendment to this bill that regularized air pollution of some industries. He claimed that:

That is possible; but I believe that the poison of the cholera is either swallowed in water, or got directly from some other person in the family, or in the room; I believe it is quite an exception for it to be conveyed in the air; though if the matter gets dry it may be wafted a short distance.

At the same year, William Farr, who was then the major supporter of the Miasma Theory, issued a report to criticize the germ theory. Farr and the Committee wrote that:

After careful inquiry, we see no reason to adopt this belief. We do not feel it established that the water was contaminated in the manner alleged; nor is there before us any sufficient evidence to show whether inhabitants of that district, drinking from that well, suffered in proportion more than other inhabitants of the district who drank from other sources.

The more formal experiments on the relationship between germ and disease were conducted by Louis Pasteur between 1860 and 1864. He discovered the pathology of the puerperal fever and the pyogenic vibrio in the blood, and suggested using boric acid to kill these microorganisms before and after confinement.

By 1866, eight years after the death of John Snow, William Farr publicly acknowledged that the miasma theory on the transmission of cholera was wrong, by his statistical justification on the death rate.

See also

• Germ theory of disease

Further reading

• Beasley, Brett (2015년 9월 30일). “Bad Air: Pollution, Sin, and Science Fiction in William Delisle Hay’s The Doom of the Great City (1880)”. 《The Public Domain Review》 5 (18). 
• Sterner, Carl S. (2007). “A Brief History of Miasmic Theory” (PDF). 《Bulletin of the History of Medicine》 22 (1948): 747. 
• Thorsheim, Peter (2006). 《Inventing Pollution: Coal, Smoke, and Culture in Britain since 1800》. Ohio University Press. ISBN 0-8214-1681-2. 

External links

• Prevailing theories before the germ theory
• Cholera theories
• Term definition

jawp

瘴気（しょうき）は、古代から19世紀まで、ある種の病気（現在は感染症に分類されるもの）を引き起こすと考えられた「悪い空気」。気体または霧のようなエアロゾル状物質と考えられた。瘴気で起こると考えられた代表的な病気はマラリアで、この名は古いイタリア語で「悪い空気」という意味の mal aria から来ている。

ミアスマ、ミアズマ (μίασμα, miasma) ともいい、これはギリシア語で「不純物」「汚染」「穢れ」を意味する。漢字の「瘴」は、マラリアなど熱帯性の熱病とそれを生む風土を意味する。

歴史

古くは、古代ギリシアのヒポクラテスが唱えている。彼によると、病気は「悪い土地」「悪い水」「悪い空気」などにより発生する。「悪い空気」、つまり瘴気は、「悪い水」、つまり沼地や湿地から発生し、人間がこれを吸うと体液のバランスを崩し病気になる。また、こうして病気になった人間も瘴気を発し、周囲の人間を感染させる。

瘴気説は、病気の原因は呪いや祟りだとするような考えよりは、物理的な外因を想定している分、かなり前進している。マラリアを媒介する蚊は「悪い水」で繁殖するため、「悪い水」の近くにいるとマラリアに罹りやすいというのは事実であり、それから推論・一般化した考えだとみなすこともできる。中国でも遅くとも唐代には、「悪い水」が瘴（マラリア）の原因らしいと認識されていたようである（韓愈「好収我骨瘴江辺」など）。

17世紀イギリスのトーマス・シーデナムは、瘴気が起こす病気として天然痘、赤痢、敗血症、ペストなどを挙げた。また彼は、瘴気は地球内部から発生すると主張した。

19世紀イギリスのエドウィン・チャドウィックは、瘴気説を根拠に下水道の整備を訴えた。また、19世紀アメリカのジョン・ゴーリーは、空気中の瘴気を除去するために、氷冷式エアコンを発明し病院に導入した。「悪い水」や「悪い空気」が病気の原因だという考えは原因と結果だけ見ればそう間違ってはおらず、公衆衛生においては一定の成果を上げたといえる。

否定する考え方

一方、古代ローマのヴァロは、瘴気とは気体ではなく微小な動物だと主張した。これはマラリア媒介蚊のことだと解釈すれば、真実を言い当てていた。しかしこの考えは瘴気説の主流とはならなかった。

16世紀イタリアのジローラモ・フラカストロは、病気が伝染する原因は、微小な生物である「contagium vivim（生きた接触体）」との接触（コンタギオン、コンタジョン）だと唱えた。彼の主張は、「contagium vivim」の正体が未知であることを除けば、現在の病原体に対する理解と変わらないものであった。その後、1674年にアントニ・ファン・レーウェンフックが微生物を発見すると、微生物こそが「contagium vivim」ではないかという推測が現れた。ルイ・パストゥールは細菌による発酵と腐敗を研究した結果、「contagium vivim」の正体は細菌だとする説を主張した。

1876年、ロベルト・コッホが、炭疽症の病原体と推測されていた炭疽菌が実際に病原体であることを、実験で証明した。その後も次々と感染症の病原体が発見され、瘴気は否定された。

瘴気が原因と考えられた主な病気

• インフルエンザ
• コレラ
• 赤痢
• 天然痘
• 敗血症
• ペスト
• マラリア
• ハンセン病（らい病）

現代の「瘴気」

ホメオパシーでは、瘴気 (miasma) から派生した概念であるマヤズム (miasm、カナ表記は英語式発音「マイアズム」の転訛。希にミアズマとも) があらゆる病気の原因だと考える。ただしマヤズムは人間に内在する病因とされており、外から作用する病因である瘴気からは大きく意味を変えている。