Electric, magnetic fields growing growing concern - Indoor Environment

The effects of electrical and magnetic fields (EMF) on the general public - and specifically their impact in the workplace - are becoming a matter of public concern. This article is designed to acquaint the reader with this area of growing concern.

What is EMF?

Wherever electrical power is generated, carried or used, electrical and magnetic fields are also generated. Both homes and offices have electrical and magnetic fields which are produced by power lines, equipment wiring and electrical appliances (such as copy machines, typewriters, computers, etc.). While concern has been focused mainly on exposure to 60 Hertz magnetic fields generated by power lines, there is a growing concern among property owners and managers regarding the effect of these electrical and magnetic fields on humans - and the liability which may be the end result.

Electrical and magnetic fields of various frequencies are produced by any equipment which operates on electricity. Typical sources in the office environment include the building power distribution system as well as devices ranging from light bulbs to computer terminals. Because the strength of these fields diminishes with distance from the source, similar fields can be present at (1) a given point which is close to a weak source or (2) far from a strong source. This produces two separate areas of concern regarding exposure of workers: proximity to a weak source (such as a computer terminal) or distance from a strong source (such as a major element of the power distribution system).

The effects of EMF on the office environment vary based upon the fundamental differences among (1) 60 Hertz electric and magnetic fields, (2) the fields produced by power distribution equipment and (3) the fields produced by office equipment. Electric fields are produced by the presence of voltage and are likely to be of substantial magnitude in the workplace only where unshielded high voltage equipment is nearby. The only such sources commonly found in the power distribution systems of commercial buildings are transformers with primary voltages such as 4,160 or 13,200 volts. Not all buildings have such equipment and, in those that do, office workers are rarely close enough to be exposed to high electric fields. (High voltage cables, which may run throughout the building, are shielded and produce no external electric field). Magnetic fields, however, are produced by the flow of current and therefore are highest where conductors carry high currents. Higher currents are found in conductors at lower voltages - such as 208 or 480 volts - which are present throughout any commercial building, and in close proximity to workers. Typical sources of high magnetic fields are large cables, bus or switchboards. Thus, a building's power distribution system may produce substantial magnetic fields at many locations where significant electric fields may not be present at all - and high magnetic fields (due to high currents) are likely to be found where electric fields are low (due to low voltages).

A long-standing source of concern is the long-term exposure of workers in close proximity to weak field sources, principally operators of video display terminals. Newer concerns address the exposure of individuals whose worksites are located at some distance from elements of the building power distribution system - which are strong field sources.

What Are The Health Effects of EMF?

The effects of magnetic fields on CRT monitors - and the resulting distortion - have been recognized for many years and have become increasingly familiar over the last eight years as computer terminals have proliferated. Until very recently, the issue of health effects was rarely brought up, and the only concern was eliminating the CRT distortion or other equipment problem. As workers continue to see the effects of magnetic fields on their equipment, and as they hear more about studies into the possible health effects of these fields, magnetic fields in the workplace will become an increasingly important issue.

Exposure to electric fields produced by the building power distribution system is less likely to be an issue because fewer workers are near strong sources of electric fields. And electric fields can be shielded by relatively simple means (the field cannot penetrate any grounded conducting surface). Shielding of magnetic fields is a more difficult and complex problem because magnetic fields readily penetrate most materials.

Significantly, many of the larger corporations in the greater New York area are beginning to receive EMF complaints from employees who sometimes refuse to work in areas of known elevated EMF levels. Further, some clients of realtors and developers in the greater New York area now consider EMF as a factor in deciding whether to rent or to buy office space.

Several studies have attempted to determine if there are any adverse health effects from 60 Hertz magnetic fields - but the results have generally been inconclusive. Other major studies are underway at this time. Meanwhile, various organizations and agencies are considering proposing exposure limits for both 60 Hertz electric and magnetic fields. Government involvement is inevitable and limits will almost certainly be established in the future even if the results of studies continue to be inconclusive.

There are basically three courses of action to reduce or eliminate exposure where equipment is affected by 60 Hertz magnetic fields produced by a building's power distribution system or where workers are exposed to such fields: 1. Move the equipment or worker away from the affected area. 2. Shield the equipment or worker from the ambient field. 3. Move the source of the field away from the equipment or worker.

From a building operations standpoint, any of these options have significant economic implications. 1. Moving equipment or workers from an affected area may result in waste or inefficient use of valuable space. 2. Shielding the equipment or worker from an ambient field may be very expensive due to the cost of shielding materials and related reconstruction of an area. The shielding of some areas may be impossible due to the nature of the construction. 3. Individual equipment items may often be effectively shielded at reasonable cost - but this does nothing for the exposure of the worker. 4. Moving the source of the field away from the equipment or worker may mean moving switchboards, cable and conduit, busway, etc. This is virtually impossible to do in an existing building and there may be no better place to which the equipment could be moved. In the design of new buildings, however, the location of such equipment to help reduce exposure of workers to fields can be considered.

In addition to the economic implications, there are the significant personnel considerations. Any action taken to protect equipment, but not people, from ambient fields will raise concerns among people who work in the area. If workers know about the presence of 60 Hertz magnetic fields (which they often do because they have seen the effects on computer terminals or other equipment), they may be fearful because they associate such fields with other electromagnetic radiation. This confusion is intensified by increasing media attention to the situation - which means that complaints from workers can be expected. Failure to take action may result in loss of productivity or other labor problems as well as possible legal problems if exposure limits are eventually established.

If owners know about the presence of magnetic fields and workers do not, failure to take action may pose an even greater risk of future legal problems. Any action that is taken, however, will establish the owner's recognition of a possible problem. This will lead to the need for further action in what could be a great number of locations, even in a small building.

COPYRIGHT 1992 Hagedorn Publication
COPYRIGHT 2004 Gale Group