I have worked with Electromagnetic Sensitivity Syndrome people for 28 years. Some are sensitive to Radio fields like Cellular Phone 4G emissions, like Smart Meters from the utilities, like Radar, like FM radio towers. Some to ELF (Extremely Low Frequency) magnetic fields (measured with Gauss meters in milliGauss or Teslas), like 60 cycle power lines. Some to the Electric field of 60 cycles (measured in Volts per meter.)
There are several books on the subject.
There are dozens of Gauss meters in the market. The most authoritative website for health effects is microwavenews.com