With a vaccine still months away for most people in the United States and years away in many other countries, a specific kind of mask is the most effective way to immediately protect essential workers in a wide range of industries who may be at greater risk of exposure to Covid-19. Federal, state, and local governments, employers, and academic institutions should help make them widely available and ensure their adoption.
In May, we wrote about the need for better masks and, in June, outlined the criteria for them, which includes protection from aerosols, small respiratory particles that can stay in the air for hours, especially in crowded, enclosed spaces with poor ventilation. (Recently, the U.S. Centers for Disease Control and Prevention (CDC) acknowledged that Covid-19 can spread by aerosols.) By conducting an extensive review of preexisting and emerging mask designs, we discovered elastomeric N95 masks (eN95s) are the best alternative to N95s, which continue to be in short supply even in health care settings. They are reusable, offer N95-level protection from both small particles (aerosols) and larger droplets, and are widely available for at least the immediate future.
The large-scale distribution of these masks would help address one of the major flaws in the U.S. health care system that the pandemic has exposed: Low-income Americans, especially people of color, have been disproportionately hit by the novel coronavirus. Not surprisingly, many of them work in high-risk essential jobs. Two of us have taken care of numerous people who were likely infected with Covid-19 in these scenarios. If these patients had been wearing N95-caliber masks at the time they were exposed, they may not have gotten infected.
Aside from their short supply, disposable N95 masks require people to be trained to use them properly and to be tested in order to achieve an adequate fit — an airtight seal around the mouth and nose. If they are not properly fitted, the level of protection they provide can decline dramatically.
While somewhat bulky, eN95s — which were recently highlighted by National Nurses United and the California State Firefighters Association — can overcome these problems.
Cost-effective. We found that eN95 masks, with filters, typically cost $20 to $80. For example, a 3M elastomeric mask with a P95 filter costs $23 on Amazon. (P100 filters offer more protection with less breathability.) One hospital system in Pittsburgh found that using eN95 instead of disposable N95s cost dramatically less per month, and a month after making this switch, no one on the staff wanted to revert to using disposable N95s. A hospital in San Antonio had a similar experience after switching to eN95s.
Reusable. Thanks to their washable plastic body, eN95 masks are reusable. However, their filters — which are made from electrostatically charged material that can filter out even aerosols — need to be replaced periodically. The length of time each filter can be used depends on the conditions in which it is worn and the design of the particular model, but in general, filters can be used for up to 40 hours in a row. Rotating them and thereby allowing used ones to naturally decontaminate can extend their lives. The cost of the replaceable filters ranges from $2 to $10 apiece — similar to the cost of disposable N95s.
Elastic fit. Compared to disposable N95s masks, eN95s are more likely to provide an airtight face seal without the fit being tested. That’s because the stretchy materials from which they are made (e.g., gel, rubber, or silicone) adapt to the shape of the user’s face and don’t require a nose bridge that has to be manually adjusted. This attribute is especially important for less-experienced users.
N95 approval. New mask designs need to undergo rigorous testing and approval from the National Institute of Occupational Safety and Health (NIOSH) to be reliably used for N95-level protection. This process typically takes months and millions of dollars in investment. But eN95 are already NIOSH-approved.
Few short-term supply limits. Several manufacturers — including Envomask, Honeywell, and 3M — make eN95s. Several models, for example, are in stock on Amazon; compatible filters are typically sold separately.
The one drawback of existing eN95 models is they provide limited protection for others. Many eN95 models have an exhale valve that does not filter the air breathed out by the wearer. An infected wearer, therefore, could infect those around him or her. This is less of an issue if everyone in a closed workplace is wearing an eN95 at all times. However, for these masks to be used in scenarios where not everyone is wearing one, innovations will be needed. Workarounds have been proposed, such as putting a surgical mask or cloth mask over the filter or trying to seal it using tape. It is unclear, though, if these techniques provide adequate filtration of outgoing air; further studies are needed.
Getting N95-level protection to frontline essential workers requires urgent action by several groups:
Federal government. Federal agencies, including NIOSH, should promote the use of eN95s in high-risk workplaces. If the masks are widely adopted, existing production capacity will ultimately be inadequate to satisfy the much larger demand that materializes over time. So instead of waiting until a shortage occurs, the federal government should take steps now to increase production. (Given that the demand for such masks typically craters after an epidemic is over, it is unclear whether the private sector will be willing to make new investments in the expensive machinery needed to make many more of them unless the government provides incentives.)
In the immediate term, the Defense Production Act could be used to expand production. To entice companies to expand manufacturing capacity to meet longer-term needs, the federal government could provide essential industries and perhaps consumers grants or credits to buy the masks. It already provides such assistance to fire fighters for buying personal protective equipment, and legislators have made proposals to extend this aid to small businesses and the general population.
State and local governments. They can mandate organizations provide eN95s to their employees who work in high-risk settings and can enter into long-term supply agreements to purchase them for their own essential workers and perhaps the public.
Employers. They shouldn’t wait for government regulations and should provide eN95s now to all workers deemed essential, including firefighters, workers in meat-packing plants and fast food restaurants, and farm workers.
Academic institutions can help consumers choose between eN95 options by evaluating and posting findings on which masks and filters are most effective.
Nine months into this pandemic, many frontline workers are still not being adequately protected from Covid-19 infection. The widespread distribution of eN95s can help address this alarming deficiency and prepare the United States and the rest of the world for future disease outbreaks, wildfires, bioterrorist attacks, and other threats.