Researchers created a test to determine which masks are the least effective

(CNN) - Schools are reopening, amusement parks are welcoming back visitors, and outdoor dining is the new way to eat out. But despite the signs that life is returning back to normal, the coronavirus pandemic has gone nowhere.

That's why a group of researchers at Duke University created a simple technique to analyze the effectiveness of various types of masks which have become a critical component in stopping the spread of the virus.

The quest began when a professor at Duke's School of Medicine was assisting a local group buy masks in bulk to distribute to community members in need. The professor wanted to make sure the group purchased masks that were actually effective.

In the study published Friday, researchers with Duke's physics department demonstrated the use of a simple method that uses a laser beam and cell phone to evaluate the efficiency of masks by studying the transmission of respiratory droplets during regular speech.

"We use a black box, a laser, and a camera," Martin Fischer, one of the authors of the study, told CNN. "The laser beam is expanded vertically to form a thin sheet of light, which we shine through slits on the left and right of the box."

In the front of the box is a hole where a speaker can talk into it. A cell phone camera is placed on the back of the box to record light that is scattered in all directions by the respiratory droplets that cut through the laser beam when they talk.
A simple computer algorithm then counts the droplets seen in the video.