he high frequency itself doesn't pose any threat, except maybe from electrocution. This is a hazard for any welding machine. What you REALLY need to be worried about is sparks, ultraviolet light from the arc, hot objects, and fumes from welding, these pose very real and tangible health risks. In other words, the fumes are FAR more likely to kill you than the high-frequency circuit. Bit of a side note: The danger posed by the small amounts of radio waves and microwaves produced by electrical devices is hugely overblown and probably does not exist. Let me give you an example. Microwave ovens work because water is a good absorber of microwaves....(College Physics 101.) Something that's not well known, is the physical fact that if an atom or molecule can *absorb* a specific frequency it will also *emit* that same frequency if it becomes excited. The consequence of this fact is that a cup of coffee emits more energy in the form of microwaves, than dozens of cell phones! In fact the human body itself emits more microwaves than a typical cell phone, simply by virtue of being warmer than absolute zero...... Just some food for thought.