face shields

Face Shields Don’t Adequately Protect Against COVID-19, Study Reveals

If wearing a face shield makes you feel safe and protected from airborne pathogens such as those from COVID-19, think again. A study published in the American Journal of Infection Control suggests surgical masks are far more effective than face shields, and in fact, face shields provide little more than eye protection.


According to the World Health Organization (WHO), the COVID-19 virus has infected more than 136 million people worldwide, resulting in nearly three million deaths. Evidence suggests the virus is spread by expelling droplets through coughing or sneezing. A study by the United States National Academy of Science found that even breathing or talking could release tiny particles (bioaerosols) that carry the virus. 

The Study

Researchers at the Detroit Medical Center and Wayne State University School of Medicine conducted a study to compare the efficacy of surgical masks versus face shields in preventing bioaerosol transmission. The study, which tested 17 different scenarios, created bioaerosols using a fan connected to a nebulizer to simulate a human source expelling droplets. Petri plates (simulating an exposed person) were placed at certain distances from the source to detect transmitted aerosols. Key findings from the study revealed:

  • Significant bacterial numbers were found when face shields were used alone.
  • Minimal bacteria particles were found when masks were used alone.
  • No significant improvement was noted when masks and face shields were used together.

The study was limited in that actual humans weren’t used, but according to researchers,
“the results presented here probably represent best case experiments.”

Results: Masks Offer Best Protection

The study determined “Professionals working in high-risk settings with exposure to aerosols and droplets, such as dentists, would benefit from the use of face shields, or perhaps goggles, which this experiment could not simulate, as added eye protection. The shields would also protect the mask surface from contamination, prolonging the life of the mask.”

“Face shields alone, including use in source control, were not effective in preventing the transmission of aerosols generated by the nebulizer.” Researchers concluded. “Surgical masks provided good protection from nebulized bacteria.”

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