The negative ions are released by the electronic brush, this personal air purifier emits more than 7 millions negative ions per second, so eliminates smoke smell, odors, dust, polle and fresh your personal spacethe mini air purifier is an elegant necklace included in the package, so it can wear on your neck,hand,bag, trousers hook or just put it on your desk. Enjoy fresh air that's completely natural and healthy to breathe at home or outdoors.It can work for 28 hours, you can feel clean, refreshed air anywhere anytime.The negative ions will connect to any airborne pollutant,and any other illness-carrying particles due to their electrostatic charge. This makes the contaminated air particles too heavy to stay airborne, forming a microscopic health shield to protect you for any situation.