If you want to prevent colds and flu, then humidify. The body's first line of defense against airborne disease is moist and healthy nasal passages. But prolonged exposure to dry air can dry out the nasal passages, causing them to lose their ability to block airborne nasties from breaching this defensive barrier.

Using typical local winter conditions, outside 20-degree air at 80 percent relative humidity, when brought inside and heated up to 72 degrees, now has a relative humidity of only 11 percent, which is extremely dry. Similarly, 30-degree air at 80 percent relative humidity heated to 72 degrees has a relative humidity of only 17 percent. These conditions can dry out the nasal passages over extended exposure, such as night after night while sleeping.

The solution is to add humidity to the air inside your home, especially where you sleep. This allows the nasal passages to remain moist and healthy, even with daily exposure to dry indoor conditions elsewhere. As an added preventative measure, saline (salt solution) nasal sprays are inexpensive and designed to provide the nasal passages with a healthy dose of moisture just as the body likes.

Do these two things and you take a major step toward remaining cold and flu free all winter.

CHUCK LONG, Kennewick