The UV light in the base of a humidifier is a UV sterilization lamp. It is not harmful to humans.
For your reference, here are the information about the UV light on the humidifier:
1. The UV sterilization lamp inside the humidifier first kills 99.99% of bacteria in the water, making the moisture purer. The purified moisture is then turned into steam and released into the room, increasing the humidity in the air;
2. The sterilization lamp is enclosed inside the humidifier, so the UV light source is not visible and does not pose any harm to humans.
Note:
It is recommended to turn off the power before cleaning or adding water to the base of the humidifier.