Will a Mask Protect You From SARS?

SARS, severe acute respiratory syndrome, is a new disease on a planet that surely didn't need one—and a threat to public health worldwide, as well as the economy. At this moment China still apparently faces the most serious danger. If you happen to be in the face-mask business, however, SARS would be good for your economy. In TV footage from Hong Kong, Beijing, and other cities fighting outbreaks of SARS, everybody in camera range casual pedestrians along with hospital workers—seems to be wearing a face mask. Should you lay in a supply of masks, and if so, which ones? Should you wear a mask on your next plane flight?

Actually, you don't need a supply of masks, and you almost certainly would not benefit from wearing one on your next plane trip. The widely available masks made of paper, gauze, and cotton are essentially worthless as protection against disease. They can keep you from inhaling large particles such as wood dust from carpentry, but they won’t filter viruses or bacteria. A cotton mask will give you about as much protection as holding a hanky over your face. (In fact, holding a hanky, tissue, or hand over your face and mouth when you sneeze may help protect others from catching your cold.) Viruses and bacteria are tiny and can pass through any ordinary weave.

One type of mask, the N-95, is effective, since it was designed for hospital wear when infection control is needed. Made of synthetic fibers such as polyester and polypropylene, these masks will filter out any particle measuring 0.3 microns or larger 95% of the time (hence the name). To get some idea how small a micron is, keep in mind that the average human hair is about 100 microns in diameter. The virus that is thought to cause SARS, a member of the coronavirus family, is smaller than 0.3 microns, unfortunately. The rhinovirus (the leading cause of the common cold) is even smaller. However, viruses may travel in clumps or on larger particles, so the N-95 will capture some if not all of them. Health authorities recommend the N-95 (along with gowns, gloves, and facial shields) for health-care workers. They aren't perfect, but they help. They cost anywhere from $1 to $4 apiece retail and are disposable.

Masking the problem

These masks really make sense only in health-care settings, especially when dealing with a respiratory ailment such as SARS. A proper fit is essential—gaps around the edges would render the N-95 ineffective. Health-care workers get fitted individually. You could improve the fit by taping the mask to your face, but masks of any kind are generally uncomfortable, and taping would only make matters worse and possibly irritate your skin. Of course, if you were caring for someone with SARS, you would be advised to wear an N-95 mask when in the same room with the patient, and the patient would undoubtedly have to wear a mask to protect others, at least to some extent.

Thus, the masks you see pedestrians and airline passengers wearing on TV and in photos are chiefly emblematic they make the wearer feel safer, but they don’t really do much.

How can you protect yourself against SARS?

No one, as yet, has a definitive answer. Here are some things to keep in mind:

• Don't stock up on masks or wear one until or unless there is a SARS epidemic in your area and health authorities instruct you to do so.

• Though it's not completely clear how the SARS virus travels, your best defense against catching SARS, the flu, or a cold is not a mask, but frequent hand washing with soap and water. It is likely that the virus, like cold viruses, can also be picked up on the hands and thus be spread from one object to another. But you don't need an antibacterial soap, plain soap is fine. Antibacterial agents don't work against viruses anyway. If you're in a car or anywhere a sink is not readily available, you might carry alcohol gel or wipes.

• Finally, do heed the warnings of the CDC and World Health Organization. Don't travel to quarantined areas in infected cities unless you have a very compelling reason for doing so. For further information see the website.

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