How Did We Get Here: What Are Droplets and Aerosols and How Far Do They Go? A Historical Perspective on the Transmission of Respiratory Infectious Diseases

17 Pages Posted: 28 Apr 2021

See all articles by Katherine Randall

Katherine Randall

Virginia Tech

E. Thomas Ewing

Department of History

Linsey Marr

Virginia Tech

Jose Jimenez

University of Colorado

L. Bourouiba

Massachusetts Institute of Technology

Date Written: April 15, 2021

Abstract

The COVID-19 pandemic has exposed major gaps in our understanding of the transmission of viruses through the air. These gaps slowed recognition of airborne transmission of the disease, contributed to muddled public health policies, and impeded clear messaging on how best to slow transmission of COVID-19. In particular, current recommendations have been based on four tenets: 1) respiratory disease transmission routes can be viewed mostly in a binary manner of "droplets" versus "aerosols"; 2) this dichotomy depends on droplet size alone; 3) the cutoff size between these routes of transmission is 5 μm; and 4) there is a dichotomy in the distance at which transmission by each route is relevant. Yet, a relationship between these assertions is not supported by current scientific knowledge. Here, we revisit the historical foundation of these notions, and how they became entangled from the 1800s to today, with a complex interplay among various fields of science and medicine. This journey into the past highlights potential solutions for better collaboration and integration of scientific results into practice for building a more resilient society with more sound, far-sighted, and effective public health policies.

Note: Funding Statement: KR - none; ETE - National Endowment for the Humanities Grant HG-229283-15 (ended 2019) and Grant FV-256881-17 (ended 2018); LCM - National Institute of Allergy and Infectious Diseases Center of Excellence in Influenza Research and Surveillance (HHSN272201400007C) and the NSF National Nanotechnology Coordinated Infrastructure (ECCS 1542100 and ECCS 2025151); JLJ - none; LB - Smith Family Foundation, the Burroughs Wellcome Fund, the Wellcome Trust, the National Science Foundation, the Massachusetts Institute of Technology (MIT) Policy Lab, the MIT Ferry, Reed, and Edgerton Funds

Declaration of Interests: The authors declare no competing interests.

Keywords: COVID-19, aerosols, droplets, transmission, history

Suggested Citation

Randall, Katherine and Ewing, E. Thomas and Marr, Linsey and Jimenez, Jose and Bourouiba, Lydia, How Did We Get Here: What Are Droplets and Aerosols and How Far Do They Go? A Historical Perspective on the Transmission of Respiratory Infectious Diseases (April 15, 2021). Available at SSRN: https://ssrn.com/abstract=3829873

Katherine Randall

Virginia Tech ( email )

Blacksburg, VA 24061
United States

E. Thomas Ewing

Department of History ( email )

United States

Linsey Marr (Contact Author)

Virginia Tech ( email )

250 Drillfield Drive
Blacksburg, VA 24061
United States

Jose Jimenez

University of Colorado ( email )

1070 Edinboro Drive
Boulder, CO 80309
United States

Lydia Bourouiba

Massachusetts Institute of Technology ( email )

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