Since the field strength of emissions from any given device or conductor is related to the energy level of the current and voltage which created it, it is reasonable to assume that devices which by their very nature require higher levels of power will, all other things being equal, generate higher levels of EMFs. For example, color monitors, high resolution displays and larger display formats are, generally speaking, all indicators of higher levels of electromagnetic fields. The same generalizations can be made of television sets. The exception to this, of course, is children, who tend to sit close to the TV screen. Although exposure reduction can be realized by distance, the common recommendation to sit 28 inches from a VDT display is arbitrary and overly simplistic.
Electromagnetic fields drop off rapidly with distance, but the issue is more complex than that.
The rate at which field strengths drop off is determined by the form of the radiation source. For instance, if the radiation is emitted by a single wire source, the fields drop off inversely with distance. If the radiation is from a 2-wire source, where currents flow in opposite directions and produce a partial field cancellation, field strength falls off inversely as the square of the distance. Fields created by toroidal coils fall off inversely as the cube of the distance. It is widely reported that radiation levels are stronger in the back and sides of a VDT than the front and, therefore, users should be more concerned about their co-workers' displays rather than their own.