What is the range of harmful frequencies?

The rumor machine does say there are a few low frequencies which are harmful, but some of these frequencies are used in important frequency sets that seem to work without harmful effect. Very high frequencies are harmful because the photon energy is greater, and they have enough energy to knock  electrons away from the atoms. This is much higher than the frequencies we use in Spooky. As a general rule of thumb, frequencies above visible light are usually harmful.