As David explains, our upper airways keep our lungs clean and humidified. Some simple steps are to be aware of nose breathing, avoiding cold dry and dirty air... all is well! Unfortunately, we mouth breathe about 50% of the time today. Why? One reason is that 81 million Americans have rhinitis. The consequence to dehydration began to dawn on scientists about 40 years ago. It took another 37 years to discover how to rehydrate, what's the answer? ... FEND on!