Q: Do Surgical Masks STOP Swine Flu?

A: Probably not.

----
As the swine flu outbreak deepens, panicked citizens of North America are donning face masks. In Mexico City's downtown square, the Zócalo, for example, the army handed out face masks, and customs officials on U.S. borders are wearing protective personal gear, such as gloves and masks. (Click here for images.)

But do surgical masks offer effective protection against viruses? In 2003, Jon Cohen wrote that the SARS virus, which is just 100 nanometers in size, can easily pass through such barriers. And there's every reason to believe that swine flu, at 80 to 120 nanometers, can, too. The original article is reprinted below.

{snip}

The University of Cincinnati's Sergey Grinshpun has studied N-95 respirators and says it all comes down to "collection efficiency." N-95s made by different manufacturers have different collection efficiencies below the .3 cutoff. In other words, one company's mask, if properly fitted, might filter out 92 percent of coronaviruses, while another might catch only 50 percent.

"It seems to offer better protection than nothing," Grinshpun says. And he notes that viruses often travel on top of larger carrier molecules—like globs of mucus—making it easier to filter them. That's why CDC Director Julie Gerberding last week noted that covering your face with a T-shirt might help if you come in close contact with an infected person.

To efficiently protect yourself from coronaviruses, you would need to wear a full-faced mask with a high-efficiency particle air filter. But such HEPA filter masks cause what Grinshpun calls "quite a discomfort" in short order.

view link