How Effective Are Different Face Masks for H1N1?
No Difference Between N95 Respirator and Surgical Mask
Nov 2, 2009
A study presented early in 2009 indicated that respirators provided better protection from spreading H1N1 virus disease (swine flu). But at the October 2009 meeting of the Infectious Disease Society of America, the original investigators retracted their conclusions, indicating they did not use a satisfactory statistical approach, according to Michael Smith, of MedPage Today (an online healthcare newsletter).
That retraction was in line with other studies that showed no difference between the two approaches, surgical masks and respirators.
What Are N95 Respirators?
Respirators are devices that improve breathing. The term covers a broad range of devices. Gas masks are respirators. So are machines that force air into the lungs. In connection with H1N1, they are usually special fiber cup-shaped masks that fit over the nose and mouth. They clean the air breathed by filtering out ultra-small particles. Air-floating ultra-small particles may contain viruses such as the H1N1 virus. Filtering them out of inspired air helps blocks the transmission of H1N1 disease.
N95 means the type mask has been shown to catch or filter 95% of aerosol particles 0.3 microns in diameter. This is about the size of virus-containing particles expelled during a cough or sneeze. Such particles can hang in the air for a period of time.
Respirators can be used in surgery to keep operators from contaminating the open wound. But for this comparison, a “surgical mask” means the traditional soft fiber handkerchief-like device often seen in old movies and TV shows.
Because they may provide a tighter seal around the nose and mouth, many feel respirators are more efficient. They should not be used by people with significant facial hair that may interrupt the seal, nor by children for whom a proper fit may not be obtained.
Value of Respirators and Surgical Masks
Respirators and masks are generally not recommended for people not at high risk from H1N1. They might be useful, according to the US CDC (Atlanta) in people whose occupation might expose them to those with flu-like disease. They are recommended for health care workers who might be exposed to those with flu-like disease. Health care workers could include family members who tend to patients in the home.
They also will be given to patients with flu-like disease who seek or receive care to reduce their risk of infecting nearby people.
How Are Respirators Used?
A close fit is essential. Usually there is a metal strip that can be bent to secure the respirator around the top of the nose. There should be no air leaks around the respirator. Most respirators are disposable—they should be discarded after use. They should never be shared.
How Are Surgical Masks Used?
A close fit is also essential. The nose must be covered. (TV shows in which the actors wearing masks expose their noses are a joke; do not do that.)
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