Surgical masks can do a good job of catching viral aerosols before they hit our airways. But just because they are stopped in their tracks doesn't mean they become any less infectious, leaving open the possibility of contracting things like SARS or influenza so long as the mask remains in close contact. Scientists have come up with a way to catch and kill these harmful pathogens in one fell swoop, through a special salt treatment that "deactivates" the viruses once they are trapped by the mask.

Researchers at the University of Alberta's Department of Chemical and Materials Engineering were moved to pursue this kind of technology after realizing that a lot of people don surgical-style masks during outbreaks of influenza and other viruses under the assumption they offer more protection than they actually do. While they may trap the aerosols that carry viruses they do nothing to destroy them, meaning handling the mask can still lead to transmission.

"Surgical masks were originally designed to protect the wearer from infectious droplets in clinical settings, but it doesn't help much to prevent the spread of respiratory diseases such as SARS or MERS or influenza," says Hyo-Jick Choi, leader of the research.

Another area of Choi's research focuses on the development of oral vaccines such as pills or lozenges, where a certain roadblock actually provided the inspiration for the new bug-busting masks. The trouble with oral vaccines of this type, Choi had found, was that as they are dried out, crystals with sharp edges form that destroy the virus used in the vaccine, therefore making it ineffective.

But what if this chemical process could be used for good? Choi and his team came up with a sodium chloride salt solution and used it to treat the mask filters with a view to exploring this possibility. The thinking was that as the aerosol droplet carrying the virus comes into contact with the filter, the salt would dissolve and then recrystallize during drying, taking out the virus in the process.

The researchers put this theory to the test and found that when the sides of the mask were tightly sealed, the salt-coated filters showed a much higher filtration efficiency than a regular mask, and that viruses showed rapid decline. They also tested it on mice, and found that those infected with a virus through the salt-coated filters experienced a 100 percent survival rate.

Through their experiments, the team says it has optimized the salt treatment to up the effectiveness of the filters. And conveniently, because table salt is already known to be perfectly safe, it says that the road to implementation could be relatively smooth.