This application measures the magnitude of the magnetic field. The Tesla Meter will respond to a static magnetic field as well as the magnetic field radiated through the application of alternating current.
The research on the adverse biological affects in the presence of magnetic fields, weather static or alternating, is inconclusive, so it's best to practice prudent avoidance. Low level magnetic fields are naturally generated by the Earth. Higher level magnetic fields are generated from microwave ovens as well as the clock radio next to your bedside.
Use this Tesla Meter to make a qualitative assessment of the strength of magnetic field exposure.