Environmental intolerance attributed to electromagnetic fields, like those generated by smartphones, is a descriptive term for symptoms purportedly caused by exposure to electromagnetic radiation. Although the thermal effects of electromagnetic fields on the body are established, determining a direct cause-effect relationship has been elusive so far. Unknown until about 20 years ago, the prevalence of electromagnetic hypersensitivity (EHS) is increasing as the effects of electromagnetic fields, even at intensities well below radiation safety standards limits, come to light. Whatever their cause, EHS symptoms are a real and sometimes disabling problem for the affected person.