Masking Our Ignorance
Click here for a printer-friendly version of this page
What is the best use of masks and the best mask to use? San Francisco is one of the cities in 1918 that made mask wearing compulsory. Citing a slogan the Italian Supreme Command had printed on every gas mask—“Who leaves this mask behind, dies”—the San Francisco mayor threatened to arrest anyone unmasked.2674 Within 36 hours, the SFPD had hauled in 175 “mask-slackers.”2675
The main mode of influenza virus transmission is coughed and exhaled respiratory droplets of virus-laden mucus and saliva. Conversational speech alone can produce thousands of these tiny droplets,2676 which tend to settle out of the air within minutes, extending a few feet into the person’s immediate environment.2677 Infection occurs when one of these droplets lands on the surface of another person’s eye, in his mouth, or up her nose, or is planted in one of these three places with contaminated hands.2678 Wearing a mask may help in two ways: by thwarting droplet contact with mucus membranes and by reminding the mask wearer not to touch his or her face.2679
There is also a concern about inhaled fecal droplets aerosolized by toilet flushing. Live virus has been isolated from the diarrhea of a child dying from H5N1, raising the possibility that virus could be spread from human to human via a fecal-oral route as well. Experiments using fluorescent-stained water have demonstrated that not only are toilet seats significantly contaminated, but a flume of aerosolized toilet water—reaching the standing height of a child—is created when a toilet is flushed. Good bathroom hygiene should include lowering the toilet lid before flushing.2680
During a pandemic crisis, if we are forced to venture out for any reason, wearing masks in public restrooms, and in all crowded public areas, may be prudent. There are essentially only two economical options—surgical masks and N95 masks. The “N” in N95 stands for NIOSH—the U.S. National Institute for Occupational Safety and Health—and 95 reflects the filtering efficiency of the mask, effectively filtering out 95% of particles of a certain size.2681 Surgical masks are typically made out of paper with a gelatinous layer and must be changed every four hours or when they become wet with saliva or other fluid, whichever comes first.2682
Although they do not have N95’s filtration capacity or resilience, the advantage of surgical masks is better breathability—causing less thermal and physical discomfort and fatigue2683 —and better affordability. Surgical masks are sold at pharmacies for pennies; N95 masks are available at hardware stores for a dollar or more each. Whether either mask would provide sufficient protection in a pandemic, though, is a matter of controversy.2684
There is no doubt that surgical masks can filter out some larger respiratory droplets. During the SARS outbreak, high-risk personnel wearing surgical masks seemed 15 times less likely to contract the disease.2685 Because droplets are the primary means by which influenza spreads, authorities such as the U.S. Department of Health and Human Services have settled upon surgical masks as amply protective,2686 especially given their cost-effectiveness.2687
Although droplet spread is the principal method, true airborne transmission of influenza virus in particles too small to be filtered out by surgical masks has been documented.2688 Yes, respiratory droplets settle to the ground, but sweeping the floor as much as a day later can agitate tiny desiccated particles of virus back into the air, which may pass through surgical masks and have been shown to be infectious in a laboratory setting.2689 N95 masks are made out of a special, nonwoven polypropylene fabric that generates static electricity to trap tiny particles.2690 No mask provides a perfect barrier, but N95 masks would be expected to provide greater protection to airborne virus than surgical masks.2691 “N100” masks (even more expensive) filter out an estimated 99.7% of fine particles.2692 Whichever, they need to be worn and disposed of properly.
A gap between face and mask of even a few millimeters can render a mask ineffective. The presence of beard stubble, for example, can undermine a mask’s efficacy.2693 In occupational settings, facial hair is shaved and N95 masks are meticulously fitted to match each individual’s face for size and shape and often tested using bitter-tasting test aerosols to double check for an airtight seal. In a household setting, the best option would probably be to duct-tape the entire periphery of the mask to one’s clean-shaven face.2694
Handling or reusing worn masks risks hand contamination.2695 If need be, masks may be reused by the same person unless they become damaged, wet, dirty, or hard to breathe through.2696 Ideally, though, all masks should be used only once2697 and properly disposed of using gloves.2698
None of these masks protect the eyes. Those in contact with infected persons should consider practicing the “m3g” approach popularized during SARS2699 —mask, gown, gloves, and goggles.2700 Gowns should ideally cover the body and arms, and be tucked under the gloves at the wrist. Surgical or examination gloves are designed for single use and disposal. Washing or disinfecting gloves can cause deterioration of the thin material. Proper utility gloves, on the other hand—the rubber gloves used for housekeeping chores—can be decontaminated and reworn.2701 And silicone-seal swimming goggles are the recommended eyewear. Wear glasses? Tightly fitting safety goggles with tape over air vents will help protect your eyes.
Even with these precautions, influenza is so contagious that exposure to crowded public settings or contact with potentially infected persons should be kept to an absolute minimum. During a massive bird flu outbreak in the Netherlands in 2003, investigators could not demonstrate a protective effect on poultry workers of masks and safety goggles. The official government account suspected that workers became infected by taking their contaminated overalls off after they had removed their masks and goggles.2702 Considering the Netherlands outbreak and the lack of data from 1918 showing that compulsory masking was an effective public health strategy, the World Health Organization is permissive but not encouraging of national laws enforcing mask wearing by decree in national pandemic response plans.2703
In terms of individual strategies, the best recommendation may be what finally shook out of the SARS crisis:2704 in public, surgical masks for the sick and N95 masks for the healthy.2705 The CDC is encouraging all hospitals, physicians’ offices, and other health care providers to issue surgical masks to all incoming patients showing any evidence of a respiratory illness as part of “universal respiratory etiquette.” In Japan, this is already routinely practiced. When people in Japan with a cold or cough need to go out into a public setting, they will often wear a surgical mask. This civic mindedness is a practice worth emulating.2706
Like the alcohol, it seems prudent to stockpile masks before the next pandemic hits. Two companies supply up to 90% of the world’s surgical and N95 masks from plants overseas2707 and neither could meet a significant jump in demand, in part because the necessary supply of component parts from second- and third-tier countries would presumably collapse along with the rest of international trade.2708 Right now, both companies are reportedly working at 95% capacity and predict that it would take years to build another factory to make more masks.2709 “The bottom line,” Osterholm said, “is we will run out of masks very quickly.” He asks everyone to imagine the fear and panic, people thinking, “I can’t get a vaccine, I can’t get an antiviral drug that will work and I can’t get a mask. What do I do?”2710
When Turkey confirmed the presence of H5N1 just in birds, masks sold out in Serbia in one day.2711 Sales of masks in the United States have already jumped with one New York retailer describing a leap from 25 sold per week to 5,000.2712 Masks are not easily replicated at home. When mask prices shot through the roof in Asia during the SARS epidemic,2713 some strapped bras to their faces.2714 Improvised masks made out of woven material, such as cotton cloth or gauze, however, offer little protection from airborne pathogens (but do remind the wearers not to touch their faces in public before decontaminating their hands).
Some countries are stocking up on masks in addition to antivirals.2715 No such stockpile has been planned in the United States, leaving it up to individuals to arrange for their own safety. The North American investment firm BMO Nesbitt Burns underscored the need to take personal responsibility in its report on pandemic planning. “Face masks would fly off the shelves and restocking would be impossible,” its global economic strategist wrote. “Black markets in face masks (as an example) would develop and crime would become a serious problem. The military and National Guard, as well as police and firefighters, would be needed to maintain the peace, and yet their ranks will be depleted by illness.”2716 Having the tools on hand (and face) to practice simple hygiene measures may improve one’s chances of falling into the half lucky enough only to watch others become ill.