Saline Solution Halts Spread of Pathogens

Inhaling a simple saline solution may reduce by 72 percent the number of airborne pathogens an individual transmits through ordinary breathing, Harvard scientists and researchers at the biotech firms Pulatrix and Inamed have recently discovered.

David A. Edwards, Gordon McKay Professor of the Practice of Biomedical Engineering in Harvard’s Division of Engineering and Applied Sciences, was the head author for this research which occurred last spring. Edwards’ article will be published Monday in the National Academy of Science and includes co-author Howard Stone of Harvard’s Division of Engineering and Applied Sciences, Edward Nardell at Harvard Medical School, and five researchers from Pulmatrix and Inamed.

Edwards said he began the study in response to the anthrax attack in the fall of 2001.

“[I was interested in] the biological concerns relating to our vulnerability and the vulnerability of livestock in terms of pathogen attack,” he said. “Not knowing what the path is, or not having a vaccine, how do we protect ourselves?”

With this question in mind, Edwards looked to create a solution that used physical rather than chemical means to prevent the spread of infections such as tuberculosis, the common cold, influenza and SARS.

“By altering the surface tension properties in pathogen-laden droplets in the lungs, we could affect the number of pathogenic bioaerosols exhaled when you breath, cough or talk,” he said. Edwards explained that the saline solution would make the small pathogen droplets larger and less likely to remain in the air, causing them to “fall out” and greatly reducing the number of pathogens exhaled.

The study included 11 healthy males and measured the number of bioaerosol products per liter which were exhaled during the course of normal breathing.

Edwards said that one of the results that stood out was how the subjects fell into two different groups, “a high producer group” and “a low producer group.”

Six of the 11 individuals produced approximately 98 percent of the pathogen-laden droplets.

Of the high-producing subjects, inhaling the saline solution reduced the number of pathogen-laden droplets that were exhaled by 72 percent.

There are several possible applications for the study, but scientists note that more study, specifically investigating the spread of particular pathogens in a larger sample population, needs to occur before they can draw any conclusions about the success of this procedure in stopping the spread of disease.

“There is a lot of interest [for this procedure] in any place where there is a relatively closed environment such as homes with children during flu season, hospitals, or the military,” Edwards said.

Dr. Edward A. Nardell, an associate professor at Harvard Medical School, who co-authored the study, cited other potential applications such as curbing “infectious diseases in poor countries.”

“This is just a more technical version of covering your cough or sneeze,” Nardell said. “And its really, really cheap.”

Edwards said that he plans to be involved in other studies that will investigate whether this procedure can reduce the spread of airborne pathogens among both humans and livestock.