CDC officials are recommending that anyone entering the hospital room of a patient with suspected or confirmed H1N1 influenza, or anyone in close proximity to someone with undiagnosed flu-like symptoms, should wear a fit-tested N95 respirator or greater.

Covering the mouth and nose, the N95 is the most common disposable particulate respirator. It filters at least 95 percent of airborne particles.

CDC cannot mandate the use of N95s but the Occupational Safety and Health Administration can.

Trouble is, there may not be enough N95s to go around this flu season. That's why the American Hospital Association (AHA) wants the CDC to temper its recommendation with practicality.

Supply Limited

If all health care personnel who come into even casual contact with actual or suspected H1N1 flu patients wear N95 respirators, "we'll get through winter and run out of them," says James Bentley, PhD, senior vice president for Strategic Policy Planning for the AHA.

"Either we get a surge of flu patients and a diminished workforce to care for them if we're stretching out the masks, or we use them up rapidly and no one has the masks. We want a balanced approach. Use them for people most at risk and allow flexibility for others."

Nurses taking vital signs, for example, or food service workers and housekeepers "will be fine with medical/surgical masks," Bentley says, noting med/surg masks protected Canadian caregivers during the SARS epidemic a few years ago.

A Canadian study published online in the Journal of the American Medical Association Oct. 1 backs up his premise. Researchers at McMaster University randomly assigned surgical masks and respirators to 446 nurses in eight Ontario hospitals as they cared for patients with feverish respiratory illness during the 2008-2009 flu season. It turned out 50 nurses given masks caught the flu as did 48 assigned N95 respirators. "In routine healthcare settings, particularly where the availability of N95 respirators is limited, surgical masks appear to be non-inferior to N95 respirators for protecting healthcare workers against influenza," the authors said.

"Flu is a cool-weather disease," he says. "You would expect it to taper off by next spring. Despite all the publicity, H1N1 so far has followed a variant of the traditional pattern of flu. We have to get to spring and hopefully still have masks for people who really need them."

Conservative Approach

CDC officials, however, are leaning toward a more conservative approach, since recent studies show respirable flu particles are prevalent in emergency departments and hospital treatment areas. 

"N95 face pieces provide large and small particle protection beyond what surgical masks provide," says Roland Berry Ann, deputy director of the National Personal Protective Technology Lab at the National Institute for Occupational Safety and Health (NIOSH), the branch of CDC charged with protecting healthcare workers.

What's more, he said, the N95 filtering face piece "is the bottom rung of respiratory protection we certify." Other respirators, such as full-face respirators and powered air purifying respirators with blowers and hoods, offer more protection - for more money.

Asked how many N95s are available as the nation moves into flu season, Berry Ann says NIOSH can only estimate, since many manufacturers use distribution systems that keep no record of their total sales.

"We have received reports of some places finding difficulty getting them when ordered," he says. "Manufactures have reported they are working at full capacity but we recognize there are some local and regional supply problems and inventory problems."

Complicating matters, hospitals tend to shy away from buying unfamiliar-name brands of N95s made in undeveloped countries, especially in these litigious times. "I think people in the health business have gotten skittish of manufacturers in undeveloped countries, where you don't know if the quality control process or the materials used are as good," Bentley says.

Reusable N95s?

So would it make sense, given a possible short supply, to reuse N95s? As of now, N95s are indicated for one-time use only. Were they reusable, the problem of short supply would all but vanish.

Can N95s be worn more than once? Would any lingering influenza virus die after a week or so? Unfortunately, no one knows. "The length of time the virus can remain viable is variable with the environment in which it is stored," Berry Ann says. "More research needs to be done before knowledge is definitive on this. Some recent research out of CDC suggests H1N1 virus can remain viable for up to a week at least."

According to www.flu.gov, H1N1 can live on a surface for 2 to 8 hours.

How about microwaving them? "In the microwave, N95s shrivel and don't fit anymore. It kills the virus but deforms the respirator," he said. Steam heat, however, shows promise in preserving a mask's fitting performance - but more research is needed.

You may extend an N95's life in one way, however. As long as you don't touch it or remove it, a respirator continues to protect even as it becomes contaminated. "So you can wear it beyond one patient exposure, rather than taking it off after each patient encounter, if you had multiple, cohorted H1N1 patients," Berry Ann says. "That is not something we recommend on a normal basis because of the risk of transmission from a contaminated respirator. If no replacement respirators are available, that is something that could be done if infection control practices are followed."

Michael Gibbons is a senior associate editor at ADVANCE.