New Antibacterial Masks Prevent Secondary Infections—But Not Necessarily COVID

New research suggests that antibacterial face masks may potentially stop secondary transmission of bacterial infections. A secondary infection can occur when people touch contaminated surfaces like used or improperly-discarded masks.

In a study published on August 11 in ACS Nano, researchers used a carbon-based substance, called graphene, to produce antibacterial masks that could kill bacteria with 80% to almost 100% efficiency.

The big question is whether or not these antibacterial masks can potentially help prevent or reduce the spread of COVID-19, which is a viral, not bacterial, infection. The Centers for Disease Control and Prevention (CDC) states that transmission of COVID-19 occurs more often through respiratory droplets than through contaminated objects and surfaces, such as masks.

Greg Altman, PhD, co-founder of chemistry company Evolved by Nature, tells Verywell he's skeptical about how helpful an antibacterial mask can actually be.

"It’s not about whether or not the mask can kill the virus on the surface of the mask," he says. "It’s more about whether the mask can prevent the virus from being inhaled."

How Antibacterial Masks Work

Antibacterial refers to anything that kills bacteria or prevents them from growing and multiplying. Heat, as well as certain medications and chemicals, all have antibacterial properties.

While regular surgical masks and cloth masks may create a physical barrier to bacteria, they are not considered antibacterial. Researchers from the study tested how long bacteria can survive on regular masks and found that 90% remained alive after 8 hours.

To solve this problem, one of the study authors, Ye Ruquan, PhD, an assistant professor from the City University of Hong Kong department of chemistry, tells Verywell he and his colleagues created antibacterial face masks by writing on carbon-containing plastic films with a commercial infrared laser system. The laser changed the structure of the heat-resistant plastic, creating graphene—a single layer of carbon atoms arranged in a hexagonal pattern.

"You can think of graphene as a material between charcoal and a diamond," Altman says. "It is composed of carbon atoms that are produced by burning off all other molecules contained within the material—that’s what the laser is doing."

After creating the graphene, researchers tested its efficacy by exposing the antibacterial mask to E. coli and found that it was able to kill about 82% of the bacteria. For comparison, activated carbon fiber and melt-blown fabrics, which are commonly used to make regular masks, killed 2% and 9%, respectively.

The graphene worked in two different ways to kill bacteria, Ruquan says. The graphene could either dehydrate the bacteria, shrinking them until they could no longer survive, or the sharp edges of the graphene physically damaged the bacterial cell membranes, killing the bacteria as a result.

After eight hours, the research team tested the bacterial counts again and found that almost all of the E. coli on the surface of the graphene mask died, while over 90% of the bacteria on the regular masks was still alive.

"We conclude that activated carbon fiber and melt-blown fabrics are not antibacterial, while our graphene material is antibacterial and it is better than the commercial material," Ruquan says.

These conclusions led researchers to speculate that antibacterial masks could be an effective way to reduce secondary transmission of infections, a concern surrounding improper use and irresponsible discarding of used and contaminated face masks.

What Is Secondary Transmission?

"The concern of secondary transmission was raised by the World Health Organization," Ruquan says. "It means transmission not directly from an infected person: for example, the transmission of disease from secondary media, such as masks, bench, sewage, or other surfaces."

Ruquan says there's no clear data on how common secondary transmission is from masks, but a possible real-life scenario might look like this: You go into a public bathroom, touch a contaminated door handle, pull down your regular face mask, use the toilet, pull up your face mask, and then wash your hands. In these few minutes, you've potentially contaminated your mask with E. coli or salmonella, bacteria that can cause food poisoning.

If you use that same mask within the next eight hours, there's a good chance that around 90% of the bacteria are still on it, increasing your possibility of becoming infected through a secondary infection.

However, in that same scenario, if you were wearing an antibacterial face mask, the bacteria on your mask would be killed by the graphene. As a result, your risk of contracting a secondary infection would go down.

This also applies to improper disposal of contaminated face masks. If instead of reusing your mask, you accidentally dropped it on the floor on your way out of the bathroom and someone else to pick it up, the antibacterial qualities of the mask would help reduce their risk of becoming infected with bacteria.

Do Antibacterial Masks Prevent COVID-19?

There's no definitive answer for whether this kind of mask could prevent COVID-19 infection, but the research team tested the material against two other strains of human coronaviruses. They found that 90% of the viruses were inactivated within five minutes of exposure to graphene, while almost 100% were gone after 10 minutes under direct sunlight. There are plans to test COVID-19 specifically at a later time.

But Altman says the mechanism of protection in these masks works only against bacteria and is irrelevant to viruses, since viruses are pockets of genetic material, not living cells.

"My biggest concern is that whether the mask is made out of graphene, spun polypropylene (N95s), or sticky glue," Altman says. "The only property that matters in the protection against viruses is the porosity—or the mask’s ability to resist airflow that contains particles such as viruses."

Effectiveness is a big concern, but it's not the only one. Samantha Radford, PhD, an exposure scientist who studies how chemicals in the environment affect human populations, says it's possible that, over time, the mask could decompose and release graphene, causing other complications and health problems.

"Considering that the report says Ruquan believed [graphene's antibacterial properties] might be related to the damage of bacterial cell membranes by graphene's sharp edge, there is a strong chance that, if inhaled, these same particles could cause considerable lung damage," she says.

How to Reduce Risk of Secondary Transmission

While Ruquan is currently in contact with various companies about producing these masks, he says that getting the proper certifications and streamlining the process can take some time. For now, one of the best ways to prevent secondary transmission is to avoid touching your mask and face and to remove your mask properly. The CDC suggests washing your hands before touching your mask and only handling it by the ear loops or ties.

It's also important to safely discard used masks. The U.S. Food and Drug Administration (FDA) recommends placing used masks in a plastic bag, putting them in the trash, and then washing your hands. If you're wearing surgical masks, it's also recommended to change your mask frequently and avoid reusing them. Cloth masks should be washed in between uses.

The information in this article is current as of the date listed, which means newer information may be available when you read this. For the most recent updates on COVID-19, visit our coronavirus news page.