IOM assesses reuse of masks in flu pandemic

Apr 28, 2006 (CIDRAP News) – There is no practical way to clean disposable medical masks and N95 respirators to allow them to safely be reused if supplies run short in an influenza pandemic, a panel of experts at the Institute of Medicine (IOM) has concluded.

However, that doesn't mean a mask or respirator can't be used more than once by the same person, provided it's still in reasonable condition, the committee said. At the same time, the panel cautioned that little is known about the effectiveness of the devices or about how flu viruses spread.

On the assumption that supplies may run short in a flu pandemic, the US Department of Health and Human Services (HHS) asked the IOM in January to assess the possibility of reuse of disposable masks and N95 respirators.

Medical masks fit loosely over the nose and mouth and are mainly meant for use by healthcare workers and patients to prevent them from spreading pathogens by sneezing and coughing, the IOM noted in a news release about the report.

N95 respirators, in contrast, are used in both medical and industrial settings to protect wearers from inhaling harmful microscopic particles, the IOM said. They are designed to fit snugly around the mouth and nose. When properly fitted, they should filter out 95% of aerosol particles.

The committee stressed that neither type of device has been tested for its ability to protect people from flu viruses.

The IOM said the committee found disposable masks and respirators "do not lend themselves to reuse because they work by trapping harmful particles inside the mesh of fibers of which they are made. This hazardous buildup cannot be cleaned out or disinfected without damaging the fibers or other components of the device such as the straps or nose clip."

Further, the panel couldn't identify any simple changes in the devices that would permit reuse, or any changes that would eliminate the need to test the fit of respirators to ensure that they work, the IOM said.

But that doesn't necessarily rule out reuse of a respirator or mask by the same person, the report says.

A person who wants to reuse an N95 respirator should wear a medical mask or a clear plastic face shield over it to protect it from surface contamination, the committee said. The user should store the respirator carefully between uses and should wash his or her hands before and after handling it and the device used to shield it.

As for masks, manufacturers told the committee that several models can be used repeatedly by the same person until they become damaged, moist, dirty, or hard to breathe through, the report says. It says this is acceptable for infected patients in particular, since reuse is unlikely to increase their risk of contamination.

The report also notes that there are respirators with replaceable filter cartridges, and these can be reused by one or more wearers. Though they cost more than disposable respirators, they are worth considering as an alternative, in the panel's judgment.

The IOM says that little is known about the effectiveness of masks and respirators or even about how flu viruses spread.

"Even the best respirator or surgical mask will do little to protect a person who uses it incorrectly, and we know relatively little about how effective these devices will be against flu even when they are used correctly," said Donald S. Burke, professor of international health and epidemiology at Johns Hopkins University in Baltimore and co-chair of the IOM committee.

The IOM release says it is not known whether flu viruses "disperse as aerosolized particles released in the breath of infected people, spread on larger droplets projected through coughing and sneezing, or are contracted through physical contact with contaminated people and surfaces."

The committee calls for HHS to sponsor research on how well masks, respirators, and other filtering materials protect against flu viruses. In addition, methods should be developed to decontaminate masks and respirators without damaging them, the IOM says.

See also:

Apr 27 IOM news release

Table of contents for IOM report "Reusability of Facemasks During an Influenza Pandemic: Facing the Flu"
http://www.nap.edu/catalog.php?record_id=11637

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