Thousands of news outlets covering the swine flu outbreak are showing people in Mexico and other countries wearing cloth or paper surgical masks that are worn routinely in operating rooms by surgical personnel. Some health authorities have urged people to use them to protect themselves and reduce the chance of contracting type A H1N1 influenza.
The only problem with that strategy is that for the prevention of transmission of swine flu this type of mask is essentially worthless. Surgical masks will not block aerosolized particles as small as a droplet containing influenza virions from entering the airway. They essentially stop only spittle from a surgeon’s mouth and mucous from a surgeon’s nose from inadvertently dropping into a wound.
In order to prevent transmission of communicable respiratory diseases like swine flu,the CDC suggests that masks rated N95, N99, or N100 be used. The European equivalent is a mask rated EN 149 FFFP 3. The “95” rating means that the mask will stop 95% of particles .3 microns or larger in size (the airborne droplets containing influenza microbes are about .5 microns in size.) These masks are sold under various brand names such as the Affinity Foldable Respirator and the Particulate Respirator.
In addition to the too large pore size of a standard surgical mask, they are not form fitting to the face and allow “leakage” of aerosolized droplets around the edges. N95 masks usually have a rubberized strap that fits around the head and a rubberized border around the mask filter that allows for a snug, tight fit.
When medical personnel are fitted for N95 masks that must be worn when they are near influenza, tuberculosis and SARS patients, they typically must schedule a trip to the Occupational and Employee Health office to insure their masks are properly sized.
Although there are several commercially designed protocols, a commonly used procedure is called the Bitrex fit test. Fit tests require that the patient remove a full face beard if present to insure that there is no leakage around the edge of the mask.
N95, N99, and N100 masks are expensive (about $1.50-$10 a piece) and they are not manufactured in sufficient quantity to supply the entire population. So, many people will resort to wearing the simple the surgical masks in the hopes of gaining even a small amount of protection.
Although doing so provides little protection, in this scenario paper or cloth surgical masks should be discarded after one use and thorough handwashing with hot soap and water or an alcohol based hand lotion should be performed after disposing of the used mask.
Some experts do recommend that patients that are known to be infected should wear paper or cloth masks if the higher grade masks are not available to at least somewhat reduce projection of microbe containing droplets.