Microdroplets and the Coronavirus

Japanese scientists discover another method of transmission

Although the number of daily cases of the coronavirus in the United States has begun their presumptive decline, it is still important to continue following strict quarantine guidelines until the problem is contained; the Centers for Disease Control and Prevention (CDC) advises maintaining at least six feet of social distancing to help flatten the curve of COVID-19. However, new studies raise the possibility that social distancing recommendations may not be enough to prevent the spread of COVID-19 among individuals. 

This study raises concerns about current self-isolation guidelines, helps to understand the astonishingly swift spread of COVID-19 across the globe, and stresses the need for adequate protective equipment for healthcare workers.

In March 2020, a team of Japanese scientists conducted a breakthrough study on an undiscovered transmission route for the coronavirus, which helps explain the unusually rapid spread of the virus across the planet. Prior to this study, there were two known main routes of virus transmission: contact with contaminated surfaces and droplets admitted in sneezes and coughs (2). With recommended precautions and guidelines like social distancing, these two routes of transmission can be pretty easily avoided.
However, microdroplet infection can spread much more easily than both surface contact with the virus and air contact through someone’s cough or sneeze. This newfound method of transmission, which can result when you are having a conversation with someone or are simply close to each other, can occur even with strict social distancing. 

The research team used high-sensitivity cameras to capture film of the microdroplets based on when someone sneezed, coughed, and talked at different volumes. The microdroplets found were one ten-thousandth of a millimeter in size, which is invisible to the naked eye (3). When someone speaks, coughs, or sneezes, the large particles emitted typically drop to the ground in under one minute. However, microdroplets can remain in the air for up to 20 minutes in enclosed spaces; researchers estimate that a single cough or sneeze could generate up to 100,000 microdroplets (4). This means that even if someone is not concurrently in the same room as someone who is infected, the other person runs the risk of being infected if that person was in the room within twenty minutes prior. The study ran simulations with 10 people in an enclosed space, and after 20 minutes, the microdroplets were seen to have completely spread across the room— easily inhalable by anyone standing near. 

Microdroplets linger in enclosed spaces for up to 20 minutes after being emitted.

Although most schools worldwide are already closed, this information nevertheless shows that anyone shopping, eating in restaurants, or around others in an enclosed space is in jeopardy. Most importantly, this raises the need to supply healthcare workers with adequate equipment like masks to protect themselves. 

Scientists from the study have conclusive advice. According to Tateda Kazuhiro of the Japanese Association for Infectious Diseases, creating airflow by opening two windows in an enclosed space is vital to lessen the chances of virus spreading (5).

Scientist Tateda Kazuhiro of the Japanese Association for Infectious Diseases.

What does this mean for our current social distancing guidelines? They work, but still not effectively enough. The most effective way to prevent the spread of the coronavirus is to self-quarantine. This means that going on walks and runs, and running errands are more dangerous than previously suspected, and avoiding conversation and wearing a mask is ever important for everyone’s safety.

– Lucas Liu


  1. Retrieved April 14, 2020, from https://www.worldometers.info/coronavirus/country/us/
  2. Young, J. (2020, March 30). Japanese Scientists Find New Coronavirus Transmission Route in Breakthrough Study. CCN. Retrieved April 16, 2020, from https://www.ccn.com/japan-scientists-find-new-transmission-route-of-coronavirus-in-breakthrough-study/
  3. Accessed Cade, D. (2020, April 3). Scientists Use High-Sensitivity Camera to Capture ‘Microdroplets’ that May Transmit Virus. PetaPixel. Retrieved April 16, 2020, from https://petapixel.com/2020/04/03/scientists-use-high-sensitivity-camera-to-capture-microdroplets-that-may-transmit-virus/
  4. Broom, D. (2020, April 14). This Japanese experiment shows how easily coronavirus can spread – and what you can do about it. World Economic Forum. Retrieved April 16, 2020, from https://www.weforum.org/agenda/2020/04/coronavirus-microdroplets-talking-breathing-spread-covid-19/
  5. (2020, March 31). Reducing risk of microdroplet infection. NHK World-Japan. Retrieved April 17, 2020, from https://www3.nhk.or.jp/nhkworld/en/news/ataglance/845/.


  1. https://boygeniusreport.files.wordpress.com/2020/03/coronavirus-covid-19-transmission-japan-micro-droplets.jpg?quality=98&strip=all&w=834
  2. https://imagevars.gulfnews.com/2020/03/31/Talking-to-someone_17130a280c4_original-ratio.jpg

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