The Vicks V790N humidifier is made to combat germs and make your air better than ever, which means a healthier life for you and your family. It's featured with ultraviolet light which can kill up to 99.999% of germs, mold, and bacteria in the water. V790N has 2 separate water tanks for continuous operation. It can go for 24 hours to be a good selling point for this unit. Also the fact that you can put medication in it was a real bonus as well. One thing you need to keep in mind is that it may take six or seven minutes for the unit to warm up before it works to its fullest potential, so be patient.