Bava Metzia 36b ~ Marshes, Miasmas and Bad Air

בבא מציעא לו, ב

אתמר פשע בה ויצאת לאגם ומתה כדרכה אביי משמיה דרבה אמר חייב... הכא חייב מ"ט דאמרינן הבלא דאגמא קטלה

It was stated: If a custodian was negligent in watching an animal, and it escaped to a marsh and died there of natural causes...Abaye said in the name of Rabbah: he is liable to pay for the animal...because we say that the foul air of the marsh killed it...

Two buffaloes gather by the waters of the Chebayesh marsh in Nassiriya, southeast of Baghdad, February, 2015. Image from here.

Two buffaloes gather by the waters of the Chebayesh marsh in Nassiriya, southeast of Baghdad, February, 2015. Image from here.

As Rashi explains, the custodian is liable because his negligence was the cause of the animal's death. 

הכא איכא למימר בפשיעה מתה. שאם היתה בבית לא מתה, ויציאתה לאגם היא פשיעת מיתתה, דשמא הבל המצוי באגם קטלה

Here you can say that it died due to negligence. For if the animal was kept at home it would not have died, but its going out to the marsh is the negligent act that resulted in its death,  for perhaps the foul air of the marsh killed it.

Today's page of  Talmud suggests that just walking in a marsh can kill you because of the poisonous air that exists there.  We’ve encountered the notion of poisonous air before in Bava Kamma (55a) where Rav Nachman suggested that a fall into a pit of less than ten tefachim was not lethal because foul air was only found at a depth of ten tefachim. According to Rav Nachman, the one who digs a pit is only liable for damages caused by foul air, rather than the trauma of the fall itself. Rav Nachman goes on to clarify that foul air may not always kill, but instead may just cause physical injury, or in his words "אין הבל למיתה ויש הבל לנזקין."

As we shall see, this notion "of bad air" was an ancient belief that lasted all the way through modern times, and the Talmud reflected a widely held theory of noxious air that came to be called the Theory of Miasmas. A miasma was a poisonous vapor or mist that caused illness or disease. Infection was thought to affect people who inhaled these bad vapors. In this way the miasma theory was used to explain the spread of contagious diseases, or the death of wandering animals.

Origins of the Miasma theory of Disease

Dana Tulodziecki, from the Department of Philosophy at Purdue University, has a nice working definition of the miasmatic theory. Here it is. 

...diseases were brought about and passed on through decomposing organic material that would disperse into the air as noxious and disease-causing odours, the miasmas. This noxious air in turn would affect potential victims, causing a variety of diseases of differing strengths. The type of disease, as well as its severity were thought to depend on the complex interplay between a number of factors, some related to the miasmas themselves (such as climate and weather, which were thought to affect miasmatic natures), some related to the potential sufferers of diseases (such as factors relating to the sturdiness of their constitutions or their values, which were thought to affect their susceptibility to various diseases), and some related to the local circumstances in which miasmas existed (such as overcrowding or bad ventilation, which were thought to compound whatever problems were already present).

The word miasma comes from the Greek μίασμα meaning pollution.  The theory dates back to Hippocrates (~460-377 BCE) who wrote about it in his classic work, On Air, Water and Places:

Whoever wishes to investigate medicine properly, should proceed thus: in the first place to consider the seasons of the year, and what effects each of them produces for they are not at all alike, but differ much from themselves in regard to their changes. Then the winds, the hot and the cold, especially such as are common to all countries, and then such as are peculiar to each locality.

And here's a word describing a disease you've heard of that means bad air. Malaria, from the Italian mal aria.

Marshes as Dangerous Places in ROman Times

In the first century BCE, the Roman writer Marcus Vitruvius Pollio (born ~80–70 BCE) had this to say about the dangers of the swamps and marshes:

The neighborhood of a marshy place must be avoided; for in such a site the morning air, uniting with the fogs that rise in the neighborhood, will reach the city with the rising sun; and these fogs and mists, charged with the exhalation of the fenny animals, will diffuse an unwholesome effluvia over the bodies of the inhabitants, and render the place pestilent.

Vitruvius (for some reason he is known by his middle name) lived about two hundred years before Rabbah (d.~330CE) and Rabbah's nephew Abaye (d.~339 CE), and here he implicated marshes with the causes of disease - because of the dangerous vapors they contain. Fast forward about 1,500 years and the great Florence Nightingale made the air a central part of her call for better conditions for the working class.

The very first cannon of nursing, the first and the last thing upon which a nurses's attention must be fixed, the first essential to the patient, without which all the rest you can do for him is as nothing, with which I had almost said you may leave all the rest alone, is this: TO KEEP THE AIR HE BREATHES AS PURE AS THE EXTERNAL AIR, WITHOUT CHILLING HIM...Again, a thing I have often seen both in private houses and institutions. A room remains uninhabited...the air is stagnant, musty, and corrupt as it can by possibility be made. It is quite ripe to breed small-pox, scarlet fever, diphtheria, or anything else you please.
From inhaling the odour of beef the butcher’s wife
obtains her obesity
— Professor H Booth The Builder, July 1844

Do Miasmas cause cholera?

The miasmatic theory became a big deal in the discussion of the causes of the terrible cholera epidemics that ravaged London in the 1850s and beyond. William Farr was a statistician of repute; he held the important sounding position of Statistical Superintendent of the General Register Office. Farr believed that the theory completely explained both the transmission of cholera and where it struck, and his model is a reminder of how scientists can get it terribly wrong. Farr the statistician thought, along with others, that rotting organic matter would give rise to miasmas. In addition, he thought that the conditions “which are so constantly found in alluvial [muddy] soils, lying on a level with or below the tidal waters” were particularly good sources for producing miasmas.  He obtained the death rates from cholera, which he believed demonstrated that “cholera was three times more fatal on the coast than in the interior of the country”.  As Tulodziecki notes, Farr found just what the miasma theory predicted: that wherever high concentrations of miasma were predicted, the mortality rate from cholera was high, and wherever the miasma theory predicted that the concentrations of miasma were lower, so was the mortality rate.  But Farr took this to the next level. Being a good scientist he developed a law that made predictions about the death rates from cholera, that related these to the elevation of the soil. Here is what he found:

[T]he mortality from cholera in London bore a certain constant relation to the elevation of the soil, as is evident when the districts are arranged by groups in the order of their altitude. We place the districts together which are not on an average 20 feet above the Thames, and find that on this bottom of the London basin the mortality was the at the average rate of 102 in 10,000: in the second group, at 20 and under 40 feet of elevation, or on the second terrace, the mortality from cholera was the rate of 65 in 10,000; in the third group, or on the third terrace 40-60 feet high, the mortality from cholera was at the rate of 34 in 10,000; in the fourth group, 60-80 feet high, the mortality from cholera was at the rate of 27 in 10,000; in the fifth group, 80-100 feet high, the mortality was at the rate of 22 in 10,000; in a district 100 feet high, the mortality was 17 in 10,000; in Hampstead, about 350 high, the mortality was 8, or deducting a stranger infected at Wandsworth, but who died there, 7 in 10,000... [b]y ascending from the bottom to the third terrace, the mortality is reduced from 102 to 34; by ascending to the sixth terrace it is reduced to 17 … It will be observed, that the number representing the mortality on the third terrace is one-third of the number 102, representing the mortality on the first, and that the mortality on the sixth terrace is one-sixth part of the mortality on the first….

Here are Farr’s original tables:

Farr, W. Report on the mortality of cholera in England, 1848-49. London, W. Clowes 1852. lxii

Farr, W. Report on the mortality of cholera in England, 1848-49. London, W. Clowes 1852. lxii

From which he developed Farr’s Law of Elevations and produced this lovely diagram to show the relationship between the death rates from cholera and the elevation.

Farr, W. Report on the mortality of cholera in England, 1848-49.  London, W. Clowes 1852. lxv.

Farr, W. Report on the mortality of cholera in England, 1848-49.  London, W. Clowes 1852. lxv.

As you might have expected, those who represented religion chimed about the causes of the terrible cholera epidemic. One of those was Henry Whitehead, who served as an assistant priest at the Church of St Luke's in Soho, located in the heart of the 1854 London cholera outbreak. It was all God's will, only this time God was acting through the medium of miasmas:

Henry Whitehead. The Cholera in Berwick Street. London, Hope & Co. 1854. p.13

Henry Whitehead. The Cholera in Berwick Street. London, Hope & Co. 1854. p.13

The Real Cause of Cholera

Scanning electron microscope image of V. Cholerae

Scanning electron microscope image of V. Cholerae

As we have noted before, the true cause of cholera is an infectious agent, called Vibrio Cholerae. If it finds its way into your intestine, its toxin will cause the cells of your gut to excrete water at a remarkable rate. The result is overwhelming dehydration, and death may follow in a matter of hours. (By the way, water-borne cholera epidemics are still common. After the 2012 Haitian earthquake over 9,000 people died from cholera. That's 9,000 people who survived the earthquake itself, only to die from drinking water that was infected with cholera. And just last week the UN announced it would pay compensation to the victims and their families, since it was United Nations peacekeepers who introduced the cholera epidemic to Haiti in 2010. Now back to the London epidemic of 1854.)  Farr had great data and a compelling theory, on par with the talmudic belief that at the bottom of a shallow pit, bad air would kill you. But Farr’s Law of Elevations is wrong. The transmission of cholera has nothing to do with the elevation of those it infects.  It is a water-borne disease, and if the water is cleaned of cholera, the disease vanishes. End of story.  

It's Hard to Be Right....

It was John Snow (not this Jon Snow) who investigated the cholera epidemic of 1854 and discovered its source was a contaminated water pump.  Snow, whose day job was anesthesiologist to Queen Victoria, had to convince a skeptical group of physicians, including those who believed in the miasmatic theory and the compelling data of miasmatist-in-chief William Farr. Although we know Snow was absolutely correct, here is the kind of opposition he encountered, from an editorial on the pages of Britain's leading medical journal The Lancet:

Why is it, then, that Dr. Snow is so singular in his opinion? Has he any facts to show in proof? No!... But Dr. Snow claims to have discovered that the law of propagation of cholera is the drinking of sewage-water. His theory, of course, displaces all other theories. Other theories attribute great efficacy in the spread of cholera to bad drainage and atmospheric impurities. Therefore,says Dr. Snow, gases from animal and vegetable decomposition are innocuous ! If this logic does not satisfy reason, it satisfies a theory; and we all know that theory is often more despotic than reason. The fact is, that the well whence Dr. Snow draws all sanitary truth is the main sewer. His specus, or den, is a drain. In riding his hobby very hard, he has fallen down through a gully-hole and has never since been able to get out again.

Wow. And you thought politics was a tough profession.  Anyway time went on and more evidence was found to support Snow and the water-borne model of cholera against Farr and the air-borne explanation.  In 1866 the snarky Lancet had a volte-face (that's a U-turn in Britain, or a flip-flop here in the US) and admitted Snow had been right all along, though it came a little late for poor Dr Snow. He had died eight years earlier.

We understand that the sisters of the late Dr. Snow are now in a position of considerable pecuniary difficulty; they are, in fact, almost if not entirely without means. The researches of Dr. Snow are among the most fruitful in modern medicine. He traced the history of cholera. We owe to him chiefly the severe induction by which the influence of the poisoning of water-supplies was proved. No greater service could have been rendered to humanity than this; it has enabled us to meet and combat the disease, where alone it is to be vanquished, in its sources or channels of propagation...Dr. Snow was a great public benefactor, and the benefits which he conferred must be fresh in the minds of all.

Why We Believed in the Miasma Theory of Disease

What explains the persistence of the theory of miasmas from at least 400 BCE, through the times of our own Talmud Bavli and on to London in the middle of the nineteenth century?  In his excellent book The Ghost Map(subtitled The story of London's most terrifying epidemic and how it changed science, cities, and the modern world) Steven Johnson has an explanation that is as compelling as any I have read. 

The perseverance of miasma theory into the nineteenth century was as much a matter of instinct as it was intellectual tradition. Again and again in the literature of miasma, the argument is inextricably linked to the author’s  visceral disgust at the smells of the city. The sense of smell is often described as the most primitive the senses, provoking powerful feelings of lust or repulsion…Modern brain-imaging technology has revealed the intimate physiological connection between the olfactory system and the brain's emotional centers. In fact, the seat of many of those emotional centers -the limbic system- was once called the rhinencephalon, literally "nose-brain" or "smell-brain." A 2003 study found that strong smells triggered activity in both the amygdala and the ventral insula…Both regions can be thought of as alarm centers of the brain; in humans, they possess the capacity to override the neocortical systems where language-based reasoning occurs…
The human brain appears to have evolved an alert system whereby a certain class of extreme smells triggers an involuntary disgust response that effectively short-circuits one’s ability to think clearly, and produces a powerful desire to avoid objects associated with that smell. It is easy to imagine the evolutionary pressures that would bring this trait into being. Once again microbes are at the center of the story. Eating meat or vegetation that has already begun the decomposition process poses a significant health risk, as does eating foods that have been contaminated with fecal matter-precisely because of the microbial life-forms that are doing the decomposing...
The trouble is that survival strategies optimized for a hunter-gatherer lifestyle play out differently in a modern city of two million people. Civilization had produced many transformations in the experience of human life: farms, wheels, books, railroads. But civilized life had another distinguishing feature: it was a lot smellier. Densely packed populations of people without modern waste-management systems produced powerfully repellent odors...
The miasmatists had plenty of science and statistics and anecdotal evidence to demonstrate that the smells of London weren't killing people.But their gut instincts - or, more like it, their amygdalas- kept telling them otherwise. All of John Snow's detailed, rigorous analysis of the water companies and the transmission routes...couldn't compete with a single whiff of the air...The miasmatist wsere unable to override the alarm system that had evolved so many aeons before.They mistook the smoke for the fire.

Abaye and Rava on Miasmas

We opened this post pointing out that it was Abaye who explained why the watchman of an animal that escaped to a marsh and died there was responsible for damages:  the miasmas of the marshes killed it and the watchman should have been, well, more watchful. However Rava, who often sparred with Abaye over points of law, disagreed, and exempted the watchman from liability. When your time is up, it's up, and the animal would have died anyway, or as Rava put it: "With respect to the Angel of Death, what does it matter to me if the animal is here or there." Jewish law, the halakha, ruled like Rava, but it is worth noting that Rava too believed in the marsh miasmas, at least according to the medieval talmudist Avraham ben David (Ra'avad, d. 1198), as quoted in the sixteenth century work Shitta Mekubetzet:

שיטה מקובצת בבא מציעא דף לו, ב 


סבירא ליה לרבא שאין האויר מזיק אלא לענין חליי הגוף אבל לענין מיתה לא מעלה ולא מוריד

Rava believed that the atmosphere causes only morbidity but not mortality...

Today we know that the air we breathe does indeed have a great impact on your health. One study from MIT estimated that there are 200,000 premature deaths in the US each year from combustion emissions. But do rotten smells, marshes and ground floor apartments cause disease? Nope. But it's taken over two thousand years to realize that.