Dave, do you know that our mucus actually helps spread the flu virus? That's a surprise! I knew that our mucus protects us from certain microbial invaders, but help the flu virus? No.

So, researchers had set out to uncover why the flu virus remains infectious for extended periods in the air. This is interesting because previous studies have shown that flu virus sprayed into the air in the lab degraded faster when the humidity was higher. That's right, the virus survives better in dry versus wetter conditions. So, this told us how the virus behaves inside a heated building in the winter, except the virus doesn't normally get into the air on its own. It's expelled by people who are coughing or sneezing.

That's why in this study, scientists working with the swine flu from the two thousand nine pandemic, combined the virus with human airway secretions, and then sprayed it into a test chamber. No matter the condition of the test chamber, dry indoor to tropical, wet air, the virus remained suspended for one hour, about the amount of time for old air to move out and to cycle in new air in a typical building.

This means that virus in the mucus secretions is protected and less vulnerable to environmental changes. So, then how do you protect yourself from the flu? The annual flu shot remains the most effective.

Treating or filtering re-circulated air inside buildings could help along with increases in air exchange inside buildings. The bottom line is the flu is not going away and we need multiple approaches to control this virus which kills nearly fifty thousand Americans during epidemic years.