Inhaling a salt-water aerosol, a treatment often used for asthma, may also reduce the spread of germs that can spread disease, according to a new report.

People suffering from a variety of illnesses exhale bacteria and viruses which can spread disease to others.

A small study involving 11 people found that about half of them exhaled much larger amounts of germs than the others. For those people the salt-water treatment reduced the viruses or bacteria being exhaled for six hours.

The study is reported in this week's issue of Proceedings of the National Academy of Sciences.

"Roughly half our subjects exhaled tens of (germ) particles per liter, while the other half exhaled thousands of these particles. The number of exhaled particles varied dramatically over time and among subjects, ranging from a low of one particle per liter to a high of more than 10,000," lead researcher David A. Edwards of Harvard University said in a statement.

Those producing 500 or more particles per liter of air were considered high-producers.

The patients were given a six-minute inhalation of aerosol salt-water solution, a treatment often used for asthma patients.

Tests during the following six hours showed a sharp reduction in the number of particles exhaled by the high-producing individuals.

The researchers concluded that the treatment increased surface tension among fluids lining human airways, producing larger droplets that are less likely to remain airborne and exit through the mouth.

"Administration of nebulized saline to individuals with viral or bacterial illnesses could dramatically reduce spread of these pathogens without interfering with any other treatments," Edwards said.

But it was a small study with just six individuals in the high-producer category, and the researchers noted that much more study is needed on the topic.

While the saline treatment resulted in a 72 percent drop in the number of viruses or bacteria exhaled by the high-producing group, there was an increase in the germs exhaled by the low producers, though none jumped into the high-producing category.

Diseases that can spread through exhaled particles include measles, influenza, foot and mouth disease, chicken pox, bronchitis, smallpox and tuberculosis.

Funding for the research was provided by the biotechnology firm Pulmatrix and the Technical Support Working Group, a federal office that coordinates research for combating terrorism.