Published: May 08, 2007

U.S. Agency Issues Guidance for Public Face Mask Use in Pandemic

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Face masks could help when used with other measures, CDC director says

Interim guidance on whether face masks or respirators should be used for personal protection in public places during an influenza pandemic was issued by the U.S. Centers for Disease Control and Prevention (CDC) May 3.

"If used correctly, face masks and respirators may help prevent some exposures, but they should be used along with other preventive measures, such as social distancing and hand hygiene," the CDC said.

The agency qualified its guidance by noting information is limited on use of face masks and respirators to control pandemic influenza in community settings, and "it is difficult to assess their potential effectiveness in controlling influenza in these settings."

A flu pandemic is a global outbreak caused by a new flu virus that spreads around the world and puts everyone at risk. Such a virus spreads easily from person to person, mostly by close contact (less than two meters) with infected people who are coughing and sneezing.

A combination of protective actions would be needed during a pandemic, according to the guidance, including washing hands, minimizing exposure by keeping infected people away from others and treating them with anti-viral drugs, having those who care for ill family members voluntarily stay home and encouraging everyone to avoid crowded places and large gatherings.

"We know that many times people will want to wear a mask if they think they're going to be exposed to an infectious disease, and we certainly saw that in [severe acute respiratory syndrome] SARS," said CDC Director Dr. Julie Gerberding during a May 3 teleconference.

SARS is a human respiratory viral disease that was responsible for a major epidemic between November 2002 and July 2003, with more than 8,000 known cases and 774 deaths, according to the World Health Organization.

"We wish we had better science to help people prepare for that," Gerberding added, "and we are doing the kinds of research studies that are going to give us a lot better information, but those results aren't going to be available for quite a few months and possibly even a couple of years in some cases, but we didn't want to wait."

"Pandemic influenza remains a very real threat," Health and Human Services Secretary Michael Leavitt said in a statement. "We continue to look for ways to protect people and reduce the spread of disease. The guidance issued today is a good step forward in the broader, multifaceted federal effort to prepare the nation for an influenza pandemic."

The interim recommendations are based on the best judgment of public health experts who relied in part on information about the protective value of masks in health care facilities.

Face Masks and Respirators

Face masks are loose-fitting disposable masks that cover the nose and mouth. They include products labeled as surgical, dental, medical procedure, isolation and laser masks.

Face masks stop the wearer from spreading droplets and keep splashes or sprays from reaching the wearer's mouth and nose. They are not designed to protect against breathing in very small particles. Face masks should be used only once.

A respirator - an N95 or higher filtering facepiece respirator approved by the U.S. National Institute for Occupational Safety and Health - is designed to protect people from breathing in very small particles that might contain viruses.

"N95" means the filter on the respirator screens out 95 percent of particles 0.3 microns and larger that otherwise could pass through into the respiratory system. Higher numbers mean a higher percentage of particles are screened. N95 respirators, which are disposable and cannot be cleaned, should be worn only once.

N95 respirators usually are used in construction and other jobs that involve dust and small particles. Health care workers like nurses and doctors also use respirators when taking care of patients who have diseases that can spread through the air.

The filter and tightness of fit together determine a respirator's effectiveness. To be most effective, such respirators must fit tightly to the face so air is breathed through the filter material. Respirators are not designed to fit tightly on children or people with facial hair.

Because it screens out very small particles, a respirator gives a higher level of protection than a face mask.

CDC GUIDANCE

The CDC offered specific advice to reduce the risk of infection during a pandemic. Individuals should:

Avoid close contact and crowded conditions whenever possible, rather than relying on the use of masks or respirators;

In crowded settings, consider using face masks to protect noses and mouths from other people's coughs and reduce the likelihood of coughing on others; and

Use respirators when contact with an infectious person cannot be avoided, such as when caring for a sick person at home.

According to the guidance, people should consider wearing a face mask during an influenza pandemic if they are sick with the flu and think they might have close contact with other people, live with someone who has flu symptoms or will spend time in a crowded public place.

People should consider wearing a respirator during an influenza pandemic if they are well and expect to be in close contact with people who are sick with pandemic flu.

More information about masks and respirators and about community preventive measures is available at the U.S. government's pandemic flu Web site.

For more information on U.S. and international efforts to combat avian influenza, see Bird Flu (Avian Influenza).

Source: U.S. Department of State