The filter capacity of an air purifier is limited. In the case of serious air pollution, the filter will be saturated after a few months, and it needs to be cleaned or replaced regularly. If it is not cleaned regularly, if the humidity is right, the bacteria will multiply on the accumulated dust. At this time, the air purifier will not only be effective, but will become another source of pollution. The negative ions released by the purifier can not only purify the air, but also wear a portable air purifier for a long time. It can also enhance human immunity, improve myocardial function, lower blood pressure, enhance myocardial function, improve sleep and promote human metabolism.