Shangri-la ranks first in ultraviolet rays. Because of the high altitude, close to Tibet, the air at high altitude is often thin and the sunshine is strong, so the ultraviolet rays are relatively strong.

Nujiang Prefecture ranks second in ultraviolet rays, located at high altitude, similar to Shangri-La. The air is thin, and the protective effect of the atmosphere on ultraviolet rays is weakened, resulting in higher ultraviolet intensity.

Lijiang ranks third in ultraviolet rays. Lijiang has a dry climate, thin clouds and strong solar radiation, so ultraviolet radiation is also relatively strong.