Waves measuring under 0.4 micrometers are referred to as ultraviolet. These short waves are extremely dangerous to living organisms. Long term exposure to ultraviolet radiation would seriously hurt and even kill most lifeforms on Earth, including humans.
The Sun produces a significant amount of ultraviolet waves. Fortunately, most of these waves never reach the surface of the Earth. They are either absorbed, or reflected and bounced away by molecules in the upper atmosphere.