Ultraviolet is ionising radiation. That means that it will ionise (turn into ions) some substances due to being a high energy form of electromagnetic radiation. If these 'substances' happen to be in your skin then you can start to see how UV radiation can be bad.
Because of radiation.
Nuclear weapons emit nuclear radiation, with gamma radiation being the most common and dangerous.
Ionizing radiation by definition is radiation with a high enough energy to remove electrons from their orbits. This is dangerous because it emits x-rays, damages tissue, can cause long term damage like cancer, and heats things up.
If you are referring to 3k background radiation, the Big Bang.
UV originate from sun. these are high frequency rays.
The gas which absorb ultraviolet radiation is ozone. It absorbs the harmful Uv radiations from the sun.
Ozone in stratosphere helps to absorb the UV rays. These are the harmful rays of the sun.
CFC's are the products. They react with ozone to deplete it.
It depends what type of caner: Lung: avoid smoking or toxic fumes Skin: Ultraviolent radiation etc.
When sick people are treated with radiation, that does not make them radioactive. Radiation is dangerous, but radiation patients are not.
Any electromagnetic radiation can be dangerous. Alpha waves are higher on the radiation scale than x-rays so yes, they are dangerous.
The gas in stratosphere which helps to protect earth from ultraviolet radiations is ozone. It is present as ozone layer in the atmosphere.
Ulraviolet radiation is the portion of the electromagnetic spectrum extending from the violet end of visible light to the X-ray region.Ultraviolet (UV) radiation lies between wavelengths of about 400 nanometres and 10 nanometres, corresponding to frequencies of 7.5 × 1014 Hz to 3 × 1016 Hz.