HAB-2 payload carried several Ultraviolet sensors in UVA / UVB range (wavelength 280-400nm) and UVC range (100-280nm).
UVC rays are extremely harmful and cause skin, eye, and even direct DNA damage. Most UVC rays from the Sun are absorbed by the ozone layer in the atmosphere, with most of the ozone concentrated at the altitude of 50,000-100,000 ft.
HAB2 Altitude Profile
Here is chart of UVC radiation measured by HAB2 sensor:
High Altitude Baloon – Altitude profile for UVC radiation
You can see how UVC radiation increased as the balloon flew above the ozone layer.