There are many kinds of electromagnetic waves, such as light, infrared rays, ultraviolet rays, radio waves and even gamma rays. X-rays are all electromagnetic waves, so their harm depends on what kind of electromagnetic waves they are. Ordinary light waves are harmless, but ultraviolet rays will make people's skin cancerous and may also cause cataracts.

Microwave in radio waves is also very harmful to human body. The leakage of mobile phones and microwave ovens will emit microwave radiation. There is evidence that excessive microwave radiation may cause cancer. But this is not certain.

As for the harm of gamma rays and X rays, needless to say, because these electromagnetic waves are extremely high in frequency and energy, they can penetrate the human body, directly causing gene mutation in the human body and destroying human DNA, which is extremely harmful.