There’s Something In the Air…But Is It a Virus? Part 1
The COVID-19 pandemic has, almost inevitably, exposed important differences in writing about the history of disease. Is this a narrative driven by a desire to win an argument in the present or is it intended to reconstruct the thinking of the past in its own terms?
The former is a version of what historians often describe as ‘Whig History,’ a story of the inevitability of progress, culminating in the current state of affairs. We have marched towards a greater degree of enlightenment, usually through the individual efforts of Great Men, and occasionally Great Women. It has many similarities to the idea of a ‘Creation Myth,’ a term used mainly by anthropologists to describe the stories that social groups tell about how the world came to take the form that it does and to justify their place in it. The past is constructed as a precursor to a present, which necessarily follows from it and is legitimized by it.
Alternatively, historians can set out to reconstruct the past on its own terms. How did people at the time make sense of what was happening around them? What chances and contingencies led to one outcome rather than another? In the case of disease, what theories were circulating and why were some preferred to others? What counted as an explanation or as evidence by contemporary standards? Historians try to insert themselves in time and space much as a sociologist or anthropologist might do in participant observation of the present.
This clash is particularly evident in the disputes about airborne transmission of the SARS-Cov-2 virus. There has been a debate for the last 50 years or so among physicists who work on air about the nature and size of the particles involved in respiratory infection. Broadly speaking, this can be characterized as ‘aerosols’ versus ‘droplets’. The aerosol faction argue, largely from experimental evidence, that virions, the actual infective particles of virus, are attached to small, light pieces of exhaled matter that can hang around in the air for considerable periods of time and drift over distances of several meters. The droplet faction, with some support from direct measures as well as experiments, argue that virions are mostly attached to larger pieces of exhaled matter, particularly water droplets, which remain close to the infected person and fall rapidly to the ground.
Neither faction takes much account of the evidence from human challenge studies that it is quite difficult to infect people, even when putting virus directly up their noses; of the evidence that this virus does not survive well outside the body and is rapidly inactivated when exhaled; and of the evidence that humans have well-established preferences about social distancing that may well impact on viral evolution and selection for transmissibility.
The implications for policy are quite different. The droplet faction favor relatively simple and cheap personal interventions like masks and greater distancing, despite the lack of robust evidence to support either. The aerosol faction see clouds of infective particles everywhere and call for major capital works in most non-domestic contexts to extract and filter air to clinical standards. Again, there is a lack of robust evidence but much talk of an approach to clean air paralleling that of providing clean water. This faction has had better links to clinical medicine, largely through their involvement in the design of hospital ventilation systems, and have been more embedded in the scientific advice processes in both the UK and the US. However, politicians have hesitated about the cost implications of their policies.
One way in which the aerosol faction have tried to consolidate their position is by arguing that they are the legitimate heirs to past work that has been inappropriately dismissed. The droplet faction are anxious not to be seen as miasmatists, continuing a discredited 18th and 19th-century approach that focussed on ‘bad air.’ The aerosol faction argue that this theory was largely correct, even if poorly expressed, and reach even further back to the place of air in Ancient Greek and Roman medicine.
A key text for this is a manuscript, Airs, Waters, Places, which forms part of a collection known as the Hippocratic Corpus, written by various authors well after the time of Hippocrates himself. A useful test of any historical writing on early medicine is the degree to which it attributes views to Hippocrates as an individual. Almost nothing reliable is known about his own life, thinking and practices, as opposed to the legacy of the Hippocratic School, reflected in the documents that form the Corpus. The historic Hippocrates has become an iconic figure in the creation myths of medicine.
Airs, Waters, Places proposes a causal connection between the physical, mental and moral nature of a population and the environment into which they are born. ‘Environment’ in this context includes climate, season, food, water and soil type. In modern terms, it is mostly about the physical geography of a place and the life-style that it supports. This influence was felt well into the 20th century when annual reports to local government by the chiefs of their public health departments would still contain references to climatic conditions during the year. These data have now become an important source for research on climate change.
The place where people were born shaped their constitution and likely future health. It might also favour particular diseases, which would present risks to settlers or travelers, who had been born elsewhere. Bad air was a matter of topography, where emanations from damp soils, marshes, bogs and the like were not dispersed by cleansing winds. There is nothing in this tradition about indoor air or human interventions. Health might be improved by moving to a location more compatible with the patient’s constitution or by avoiding places that were incompatible with the balance of humours in their body.
As various social historians of medicine have observed, ancient medicine could identify problems that are defined with more precision by modern epidemiology. Oral traditions accumulated reports of, for example, the health risks of swamps long before mosquitoes were found to be a disease vector. But this is not in any sense a precursor to the medicine of our own time. The Hippocratic tradition considered air as part of a complex set of interactions. There was no notion of ‘bad stuff in air’ that could be cleansed so much as ‘bad air’ that was a hazard for those not accustomed to it from birth.
Claiming ancient medicine as a legitimator of a contemporary position is one way to develop a creation myth. It invokes symbols that still carry prestige in the Western world, where a knowledge of Ancient Latin and Greek language and culture is associated with the education of some elite groups.
Although the term ‘miasma’ is used in the Hippocratic Corpus, it is relatively uncommon. Miasmatic theory as a specific practice, which does take account of indoor conditions, emerged much later and becomes most influential in the nineteenth century. I plan to discuss this in a future post.
