How is COVID-19 transmitted? 

COVID-19 is transmitted largely by the airborne route on tiny particles called aerosols, not by contact or much larger droplets as originally thought.

 

This means it can linger in room air for hours and can travel under doors, along corridors, and occasionally even through ventilation shafts. Think cigarette smoke. 

Increasing room ventilation reduces the amount of germs in the air and makes catching COVID-19 less likely. The CO₂ level in room air can be used to indicate how well ventilated it is.

Watch the very short videos in the Tweets below to see how airborne germs spread like a mist or smoke: 

This short report features Professor JL Jimenez of the University of Colorado on the role of aerosols in transmission and the use of CO2 monitoring to assess indoor air quality:

This four-minute video by Professor Shelly Miller of the University of Colorado provides an excellent summary of how respiratory infections are transmitted through the air and is well worth watching:

Why surfaces and contact are not the major mechanism of spread, Part 1: 

For more detailed information, this academic review paper by some of the world’s leading scientists provides an excellent summary of the knowledge at the end of 2020. Click on the image to open the paper in a new window:

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Professor Nancy Baxter, Head of Melbourne School of Population & Global Health gives a summary of each of the myths in the article in this excellent Twitter thread:

The last word on this matter of airborne transmission, which all sensible authorities now agree is the most significant method of transmission, goes to Professor Baxter: 

Why surfaces and contact are not the major mechanism of spread, Part 2: