Guest Column: History is our greatest teacher in controlling the spread of COVID-19 |

Guest Column: History is our greatest teacher in controlling the spread of COVID-19

Public health actually has its “roots” in the days of cholera. Prior to John Snow’s removal of the Broad Street pump handle (and thus the founding of epidemiology) it was widely believed that disease was spread from breathing “bad air” (known as miasma). This belief led to installing city sewer systems, mandatory (government-operated) garbage removal, rodent control, and paving dirt streets (making removal of animal wastes — especially from horses — more efficient).

The relevance of Miasma to our current pandemic is centered on the now clear possibility that the COVID virus (SARS-CoV-2) is efficiently spread through aerosolized droplets from asymptomatic and symptomatic persons. This was, indeed, very much the case (and remains so) with tuberculosis. Although not given a name at the time, the primary public health strategy prior to antibiotic treatment for TB was based almost entirely on optimizing air exchange in spaces near infected people. The name for understanding this in today’s world is air exchange per hour (abbreviated as ACH). Spaces with higher levels of ACH pose much lower risks of spreading SARS-CoV-2.

In places where ACH is low (e.g., crowded factories, patient waiting rooms, shared open cubicle offices in tightly sealed, energy-efficient buildings) people have the highest risk of inhaling the virus if one or more of the others in that shared space are shedding the virus. The public health solution then is one that can be centered on environmental re-design. Known as “built environments” in the parlance of public health practice, the concept implies that existing buildings and existing public spaces should be re-thought to optimize ACH.

The history lessons from tuberculosis teach us that optimizing ACH through built environments has already been a highly successful public health strategy. Consider, for example, the design of sanatoriums that were built to control TB. These typically were constructed with ample numbers of large windows that could easily be opened to promote rapid air exchange. Even better — and highly applicable to the low rainfall and climate of the Roaring Fork Valley — is the concept of re-thinking the nature of eating and drinking establishments. Outdoor beer gardens, for example, would be an unlikely place for the aerosolized spread of the virus. In fact, ACH is an “indoor concept” — that is, the total air volume of the space is part of the equation to calculate ACH. Thus, in places that are largely outdoors, ACH is no longer even a truly applicable concept (meaning the exchange is extremely high and thus defies assessment).

Of course, what I have proposed here is only one of many public health strategies that may ultimately be applied to the control of our current pandemic. It is, however, one that can be achieved at relatively low costs, and with inversely high payoffs for our future — especially given our economic dependence on a tourist industry and our close proximity to travelers from I-70 patronizing bars and restaurants in Glenwood Springs. Once again, a bit of current investment now may prove to be the best “medicine” for the future.

Dr. Crosby can be contacted at

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