Figure 1. Electrical distribution systems. Transmission lines generate larger magnetic fields than distribution lines, but right-of-ways are usually wider, so distribution lines usually result in larger magnetic fields in buildings.
Are the electromagnetic fields in and around our buildings causing cancer? Is this the next big indoor health issue, or is it just a passing whimsy—interesting but insignificant? What should we as designers and builders be doing about these fields? There are still many more questions than answers about these fields and their possible health effects. Even so, we do know enough that we can make simple changes in the way we design and construct buildings, at little or no cost, to minimize risk.Electric current flowing through wire generates both electric and magnetic fields. Unlike high-frequency X-rays and gamma rays, which are strong enough to break chemical bonds (ionizing radiation), the electric and magnetic fields from 60-cycle electric current are extremely low-frequency (ELF) and thus low energy. No one ever worried about these fields because they are not strong enough to break chemical bonds—which was considered necessary to cause cancer or have other biological effects. Recent investigations, though, suggest that these low-energy fields may indeed be a cause of concern.