curated by Marilyn M. Singleton, M.D., J.D.

Transmission of SARS-CoV-2

Note: A COVID-19 (SARS-CoV-2) particle is 0.125 micrometers (μm); influenza virus size is 0.08 – 0.12 μm; a human hair is about 150 μm.

*1 nm = 0.001 micron; 1000 nm = 1 micron; Micrometer (μm) is the preferred name for micron (an older term)

1 meter is = 1,000,000,000 nm or 1,000,000 microns

Droplets

• Virus is transmitted through respiratory droplets produced when an infected person coughs, sneezes or talks. Larger respiratory droplets (>5 μm) remain in the air for only a short time and travel only short distances, generally <1 meter. They fall to the ground quickly.https://www.thelancet.com/journals/lanres/article/PIIS2213-2600(20)30245-9/fulltext
  • This idea guides the CDC’s advice to maintain at least a 6-foot distance.
• Virus-laden small (<5 μm) aerosolized droplets can remain in the air for at least 3 hours and travel long distances.https://www.nejm.org/doi/pdf/10.1056/NEJMc2004973?articleTools=true

Air currents

• In air conditioned environment these…