“one is far more likely to inhale aerosols than be sprayed by a droplet.”

Airborne transmission of SARS-CoV-2

Kimberly A. Prather1,*, Linsey C. Marr2,*, Robert T. Schooley3, Melissa A. McDiarmid4, Mary E. Wilson5,6, Donald K. Milton7

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Science 16 Oct 2020:
Vol. 370, Issue 6514, pp. 303-304
DOI: 10.1126/science.abf0521

There is overwhelming evidence that inhalation of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) represents a major transmission route for coronavirus disease 2019 (COVID-19). …

Viruses in droplets (larger than 100 µm) typically fall to the ground in seconds within 2 m of the source and can be sprayed like tiny cannonballs onto nearby individuals. Because of their limited travel range, physical distancing reduces exposure to these droplets. Viruses in aerosols (smaller than 100 µm) can remain suspended in the air for many seconds to hours, like smoke, and be inhaled. They are highly concentrated near an infected person, so they can infect people most easily in close proximity. But aerosols containing infectious virus (2) can also travel more than 2 m and accumulate in poorly ventilated indoor air, leading to superspreading events (3).

Individuals with COVID-19, many of whom have no symptoms, release thousands of virus-laden aerosols and far fewer droplets when breathing and talking (4–6). Thus, one is far more likely to inhale aerosols than be sprayed by a droplet (7), and so the balance of attention must be shifted to protecting against airborne transmission.

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