Posted on: May 16, 2020 at 3:23 pm

A black light experiment done in Japan has made its way around the world even faster than COVID-19. The video shows just how quickly a virus can spread in certain settings, and why personal hygiene is crucial to preventing the spread of disease.


Black Light Video Experiment

The video was produced by the public broadcasting organization NHK in partnership with health experts. The purpose is to show that without proper hygiene measures in place, by the restaurant and its patrons, one infected person can spread a disease extremely quickly. (1, 2)

In the video, 10 people come to a buffet-style restaurant, similar to one you would find at a restaurant, on a cruise, or at a resort. One of those people is selected to be “infected”. They are given a solution to rub on their hands that can only be seen under black lights; this is to simulate that person coughing into their hands. (1, 2)


The diners then go about the buffet as they normally would, without considering that someone amongst them may have an illness. (1, 2)

Read: Can’t Find Any Hand Sanitizer? Here’s How To Make Your Own

After 30 minutes, black lights are turned on to illuminate everywhere that the virus spread and the results are quite shocking. The virus can be found nearly everywhere (1, 2):

  • Participants hands, faces, and clothing
  • Tongs, ladles, and utensils
  • Handles of pitchers and lids
  • Cups, dishware, and cutlery
  • Tables and chairs
  • Food

Not a single participant was without the “virus” on their hands.


The experiment was then done a second time, this time with proper safety measures in place. These measures include (1, 2):

  • The changing and cleaning of communal utensils and dishware more frequently
  • Face masks and gloves worn by food workers
  • More frequent handwashing – diners were encouraged to wash their hands frequently before, during, and after the meal

After 30 minutes, the black light was turned on again. This time, none of the participants had the fluorescent substance on their hands or faces. (1, 2)

Read: Photos show why hand sanitizer doesn’t work as well as soap and water to remove germs

Drawbacks of the Experiment

The purpose of the experiment was to demonstrate how impactful washing your hands can be to stop the spread of an infection such as COVID-19. (1, 2)

“What the video demonstrated, is that it will spread to surfaces and to people very efficiently,” John Nicholls, clinical professor of pathology at Hong Kong University, told CNN, “and I think it really highlights the need of what people have been saying about hand hygiene to stop the spread of disease.” (1)

While all of this is true, Nicholls and other experts remind us that it is an artificial experiment. The amount of fluorescent liquid on the “infected” person’s hands was far more than the number of germs that would appear on your hands if you were to cough or sneeze into them. (1, 2)

Experts insist that the video shows the possibility of how the coronavirus may have spread in places like the Diamond Cruise ship, but it is not real proof that that is what happened in that specific situation. (1, 2)

The Bottom Line

This video is meant to be an educational tool to show people how powerful simple acts of hygiene, such as proper handwashing, can be to prevent the spread of colds and flu, and of course future pandemics. (1, 2)

If we all do our part we can help to keep our planet happier and healthier.

Keep Reading: Should You Disinfect Your Groceries To Prevent COVID-19?

Julie Hambleton
Nutrition and Fitness Enthusiast
Julie Hambleton is a fitness and nutrition expert and co-founder of The Taste Archives along with her twin sister Brittany Hambleton.

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