Protective effects of surgical masks, face shields, combination of both

Editor's Note

In this study from Wayne State University School of Medicine, Detroit, researchers found that surgical masks alone surpassed protection by face shields, and a combination of both was similar to surgical masks alone.

Researchers simulated human speaking to examine the transmission of aerosols using blood agar plates (simulating an exposed person) at 6 inches and 6 feet from the source.

Among their findings:

• When face shields were used alone, significant numbers of bacterial colonies grew on the blood agar plates.
• When surgical masks were used alone, minimal colony forming units grew on the blood agar plates at both distances.
• When face shields were used in combination with surgical masks, there was no significant improvement compared to surgical masks alone.

The researchers noted that their findings were similar to what has been found in other related studies.