How can electromagnetic energy be harmful?

Answer 1

Many parts of the EM spectrum are harmful. Ultraviolet can cause skin cancer, microwaves can cause heating of body mass, X-rays and gamma rays cause ionisation of body mass and too much exposure will cause cancer or acute damage to the blood cells which will cause rapid death. X-rays are a vital medical tool, but must be carefully used to avoid damage. If you have had hospital X-ray treatment you will have seen that the radiographers go behind a screen during exposure, because they are doing it all day and woulg get too much exposure otherwise

Answer 2

Electromagnetic energy can be harmful when exposure is at very high levels, such as from ionizing radiation like X-rays and gamma rays, which can damage cells and DNA leading to various health issues including cancer. It can also cause thermal effects when absorbed by tissues, resulting in burns or other damage.