by Samhita Vitta on  August 10, 2020 at 2:02 PM Health Watch
  • Easy and cost-effective way to determine the efficiency of masks in preventing the spread of viral droplets
  • Fitted N95 masks most effective compared to other masks
  • Valved N95 masks not so efficient in protecting people around
  • Neck Fleece is the worst effective as it breaks down larger particles

Masks play an important role in preventing the spread of COVID-19. Every type of mask is generally considered effective in blocking the viral droplets.

Most of the efficiency testing of masks are done on N95 masks and surgical masks but not on loose-fitting masks most people are using during the pandemic.
Efficiency of Different Masks in Protecting People Against COVID-19

A group of scientists from the Duke University test 14 different types of masks and face coverings for their efficiency.

They used a quick, easy and cost-effective method to determine the effectiveness of the wide range of masks.

Experimental Setup

Fischer and his team devised an inexpensive laser experiment. It was mainly used to test how various types of masks block tiny droplets which may contain viral particles when people speak.

The experimental setup consisted of a lens which turns an optical laser into a sheet of light.

The light sheet is shone through a dark enclosure which is made up of duct tape and cardboard sheets. It reveals droplets when it passes through it.

A mobile phone camera filmed the results.

People taking part in the experiment would speak towards the sheet of light. They would say a phrase 'Stay healthy, people' while wearing the 14 different types of face coverings and masks.

An algorithm was used to count the droplets noticed in the video to figure out the efficiency of the mask.

Experiment Results

Fischer confirmed that small droplets get expelled when people speak, and some face coverings performed better than the other in blocking these expelled particles.

The mask that prevented the most amounts of droplets is N95 masks.

N95 masks were followed by surgical masks and polypropylene masks in reducing the amounts of droplets.

Other masks such as cotton masks, knitted masks showed an ability to block droplets.

The valved N95 mask did not perform as well as the fitted N95 mask due to its exhaust valve.

The valves are closed when breathing, but they are open when people are speaking. Thus, valved N95 masks are effective in protecting the wearer from the outside environment. However, it does a bad job of protecting others.

Bandanas were among the least effective options.

Neck fleece was found to be the worst, and it is worse than not wearing any face covering.

The number of droplets increased in the speaker with a neck fleece. The researchers believe the material of neck fleece breaks down large droplets into smaller ones.

Smaller droplets are easily carried away by air currents, making it dangerous for people nearby.


The researchers emphasize the easy, low-cost testing method to detect the efficiency of the masks.

Every mask is almost equal in protecting against COVID-19. Wearing a mask is vital to prevent the spread of the virus.

Source: Medindia

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