CNN – “…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…Researchers tested 14 commonly available masks including a professionally fitted N95 mask, usually reserved for health care workers. First the test was performed with a speaker talking without wearing a mask. Then they did it again while a speaker was wearing a mask. Each mask was tested 10 times. The most effective mask was the fitted N95. Three-layer surgical masks and cotton masks, which many people have been making at home, also performed well…”