Flu spreads faster in cold weather

We can tell our grandmas they were right. New research from the Journal of the American Medical Association shows that the flu virus spreads easier in cold and dry weather. We used to explain that the increase in indoor activity in the colder months makes the flu season a cold-weather event. But, that's not the whole story.

The flu virus is exhaled from the body attached to aerosol water droplets. In as series of medical studies, the flu was spread through a population of guinea pigs. Since guinea pigs were in separate cages and do not sneeze or cough, the virus was spread only through breathing. Results showed that the flu spread much faster in colder air and in drier air.

When the air is dry, water aerosols and viruses move efficiently. But in damp air, the virus can't stay airborne; the aerosols containing the virus tend to combine with other water aersols and settle out of the air. Warm air can hold more moisture than cold air, so cold air tends to be drier and is better at spreading the flu.

After further study of the ginea pigs, researchers concluded that the spread of flu is also affected by the health of the mucus layers that line the nose and throat. In warm conditions, the mucus layer traps viruses and carries them from the body. Cold air damages the mucus layer, making the it more viscus and hindering the ability of the mucus to rid the infection.

So grandmas, bring on the chicken soup. link