Photograph of a flatscreen computer monitor, probably with only a trivial electromagnetic field or EMF.Electromagnetic Fields: EMFs In The Workplace - NIOSH
Current EMF research & exposure limit recommendations

  • WHAT ARE EMFs - ELECTROMAGNETIC FIELDS ? - CONTENTS:What are Electromagnetic Fields - EMFs? NIOSH guide to electromagnetic field exposure in the workplace; Safety limits for EMF exposure - workplace standards; Common sources of EMF exposure - sources of electromagnetic fields in the workplace; Average EMF exposure for workers in the workplace, edited, expanded with references to EMF equipment & EMF measurement procedures.
  • POST a QUESTION or READ FAQs about workplace exposure to electromagnetic fields - EMF radiation

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What are Electromagnetic Fields - EMFs?

This document discusses common sources of exposure to electromagnetic fields and methods to reduce exposure, as well as mentioning some exposure standards.

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EMF EXPOSURE - What do we know about workplace exposures to Electromagnetic Fields - EMFs?

EMFs are invisible lines of force created whenever electricity is generated or used. EMFs are produced by power lines, electric wiring, and electric equipment and appliances. The frequency of EMFs is measured in hertz (Hz, or cycles per second).

People are exposed to both electric and magnetic fields, but scientists are most concerned about magnetic fields. This fact sheet deals only with magnetic fields that have frequencies near 60 Hz the frequency of electric power in North America.

Static magnetic field around a bar magnet.


While this NIOSH document is focused on the workplace it is of interest to home owners as well. Everyone in our modern society is exposed to the electric and magnetic fields (EMFs) that surround all electric devices.

Recently, scientific studies have raised questions about the possible health effects of EMFs. This fact sheet answers frequently asked questions about EMFs in the workplace.

You can use this information to help identify EMF sources at work and to take simple steps for reducing exposures. However, you cannot use this information to judge the safety of your exposures, since the scientific evidence does not yet show whether EMF exposures are hazardous. [This is a NIOSH document.

Also see EMF RF FIELD & FREQUENCY DEFINITIONS for a simple explanation of different types of radio frequency (RF) and electromagnetic frequency (EMF) types and where they are found.

Workers may be exposed to high magnetic fields if they work near electrical systems that use large amounts of electric power (for example, large electric motors, generators, or the power supply or electric cables of a building).

High magnetic fields are also found near power saws, drills, copy machines, electric pencil sharpeners, and other small electric appliances.

The strength of the magnetic field depends on equipment design and current flow not on equipment size, complexity, or voltage. Though some electric equipment produces EMFs of other frequencies, most health research has considered only frequencies near 60 Hz.

[Click to enlarge any image]

These electric heaters for metal parts expose workers to magnetic fields that are 10,000 times greater than the average magnetic fields found outside the workplace.

TYPICAL EMF EXPOSURES - What are some typical Electromagnetic Fields - EMF exposures on the job?

The EMF exposures for many jobs have not been measured, but the following table shows average exposures to magnetic fields for typical workers who use electric equipment. Exposures during a work shift vary with the strength of the magnetic field, the worker s distance from the EMF source, and the time the worker spends in the field. For comparison, the table also lists worker exposures off the job.

Average magnetic field exposures for various types of workers (in milligauss*

                                    Average daily exposures
        Type of worker                 Median**     Range
Workers on the job:
    Clerical workers without
       computers                       0.5       0.2 - 2.0
    Clerical workers with
       computers                       1.2       0.5 - 4.5
    Machinists                         1.9       0.6 - 27.6
    Electric line workers              2.5       0.5 - 34.8
    Electricians                       5.4       0.8 - 34.0
    Welders                            8.2       1.7 - 96.0
 Workers off the job
    (home, travel, etc.)               0.9       0.3 - 3.7
*Magnetic fields are often measured in gauss or milligauss (one thousandth of a gauss = 1 milligauss).
**The median is the middle measurement: half the workers have average daily exposures above this point and half below.

EMF and CANCER? - Do Electromagnetic Fields - EMFs cause cancer or other health effects?

Studies have shown that some workers exposed to high magnetic fields have increased cancer rates. But such associations do not necessarily show that EMF exposures cause cancer (any more than the springtime association of robins and daffodils shows that one causes the other). Scientists have looked carefully at all the EMF evidence, but they disagree about the health effects of EMFs except to say that better information is needed.

EMF EFFECTS - What DO studies show about the health effects of Electromagnetic Fields - EMFs in workers?

Many studies report small increases in the rate of leukemia or brain cancer in groups of people living or working in high magnetic fields. Other studies have found no such increases.

The most important data come from six recent studies of workers wearing EMF monitors to measure magnetic fields. All but one study found significantly higher cancer rates for men with average workday exposures above 4 milligauss.

However, the results of these studies disagree in important ways such as the type of cancer associated with EMF exposures. So scientists cannot be sure whether the increased risks are caused by EMFs or by other factors.

A few preliminary studies have also associated workplace EMFs with breast cancer, and one study has reported a possible link between occupational EMF exposure and Alzheimer s disease.

The data from all of these studies are too limited for scientists to draw conclusions. However, a national research effort is under way, and more study results are expected in a few years.

No increased leukemia has been reported overall in studies of welders, yet they are among the occupations with the highest EMF exposures.

EMF EXPOSURE LIMITS - Have limits been set for worker exposures to Electromagnetic Fields - EMFs ?

Because of the scientific uncertainty, no Federal limits for worker exposures to EMFs have been recommended or established in the United States.

Two private organizations have developed guidelines to protect workers from the known effects of extremely high exposures (that is, those more than 1,000 times the exposures typically found in occupational environments). However, these guidelines do not address the possible health effects of the low EMF exposures usually found on the job.

Current EMF Electromagnetic Field Exposure Limit Recommendations

  • U.S. CDC, EMF "Electric and Magnetic Fields" [PDF] cites NIOSH research and includes links to documents including a Manual for Measuring Occupational Electric and Magnetic Field Eposures and other helpful guides. Retrieved 29 Jan 2015, original source: Included in this document's citations are
    • "ELF Electromagnetic Fields and the Risk of Cancer" by the Advisory Group on Non-ionising Radiation of the National Radiological Protection BoardExternal Web Site Icon
      (now called the Radiation Protection Division of the Health Protection Agency)
      NRPB Documents Volume 12, No. 1 (2001)
      This British risk evaluation reviews the evidence on cancer risks from residential and occupational ELF-EMF exposures and makes recommendations on policy and further research. The Board of the NRPB issued a ResponseExternal Web Site Icon on its implications for future research and EMF exposure limits.
    • Non-ionizing Radiation, Part I: Static and Extremely Low Frequency Electric and Magnetic Fields [PDF large document 445 pages - Ed.] Monograph by the International Agency for Research on Cancer IARC Monographs, Volume 80 (2002) IARC International Agency for Research on Cancer, World Health Organization WHO,
      This risk assessment is part of a highly-respected international program to evaluate all carcinogens. The complete monograph is available as a PDF file. [the CDC link is broken but we provide the PDF in the link just aboe - Ed.]
    • Non-Ionizing Radiation, Part 2: Radiofrequency electromagnetic fields (vol 102), (Lyon France, 2013) [PDF480 pp], IARC International Agency for Research on Cancer, World Health Organization WHO, retrieved 29 Jan 2015,original source
    • Evaluation of the Possible Risks from Electric and Magnetic Fields (EMFs) from Power Lines, Internal Wiring, Electrical Occupations and AppliancesExternal Web Site Icon (Report from the California EMF Program (2002)
      This report by the California Department of Health Services evaluates the evidence for the risks of all diseases from exposures to residential and occupation ELF-EMF, concentrating on more recent studies. It uses a new method of risk assessment, based on the Bayesian philosophy of science. Public comments and criticisms of this report are posted on the same website. The California EMF Program also published Policy Options in the Face of Possible Risk from Power Frequency Electric and Magnetic Fields (EMF) Adobe PDF file [PDF - 76 KB]External Web Site Icon which analyzes possible government actions under different regulatory philosophies, including a cost-benefit analysis for power line modifications.
    • Extremely Low Frequency Fields - Environmental Health Criteria 238 Monograph from the World Health Organization (2007)External Web Site Icon
      This comprehensive monograph reviews all aspects of ELF-EMF health risks, research and hazard management. It also makes recommendations for occupational health policy, including precautionary measures to deal with the possible cancer risks.
    • NIOSH Fact Sheet: EMFs in the Workplace
      NIOSH Publication No. 96-129 (1996)
    • EMF Questions and Answers: Electric and Magnetic Fields Associated with the Use of Electric Power Adobe PDF fileExternal Web Site Icon
      National Institute of Environmental Health Sciences publication (2002)
      This NIEHS booklet written with input from NIOSH provides in-depth information about ELF-EMF exposures in homes, workplaces, and transportation. It also describes what researchers have learned about the health effects of EMFs and identifies some methods for managing exposures.
  • "Magnetic Field Safety Guide" [PDF], Cornell University Environmental Health Safety Standard Operating Guideline, MFS-1 V4, retrieved 29 Jan 2015 original source:
    This is a detailed and helpful guide with some suggsted EMF exposure limits is provided by Cornell University.

Should workers and employers try to reduce exposures to Electromagnetic Fields - EMFs?

The National Institute for Occupational Safety and Health (NIOSH) and other government agencies do not consider EMFs a proven health hazard.

Because some studies have associated high magnetic field exposures with increased cancer risks, the government will continue studying EMFs.

While research continues, concerned workers and employers might consider the following simple, inexpensive measures for reducing EMF exposures:

  • Inform workers and employers about possible hazards of magnetic fields.
  • Increase the worker's distance from the EMF source. Since magnetic fields often drop off dramatically within about 3 feet of the source, workers can stand back from electrical equipment, and work stations can be moved out of the 3-ft range of stronger EMF sources.
  • Use low-EMF designs wherever possible (for the layout of office power supplies, for example).
  • Reduce EMF exposure times. No action should be taken to reduce EMF exposure if it increases the risk of a known safety or health hazard such as electrocution.

EMF exposures depend on the worker's distance from the source.

What is NIOSH doing about Electromagnetic Fields - EMF exposures?

NIOSH has been evaluating the possible health effects of EMFs since 1991. NIOSH scientists have measured the fields in workplaces where employees are concerned about their EMF exposures; they are also studying the biological effects of EMFs. In addition, NIOSH scientists work cooperatively with researchers in universities and other Federal agencies to share their study results. These cooperative efforts have increased recently under the National EMF Research and Public Information Dissemination (RAPID) program.

How to obtain printed copies of the NIOSH Electromagnetic Fields Fact Sheet.

"NIOSH Fact Sheet: EMFs in the Workplace," DHHS (NIOSH) Publication No. 96-129, is available from:

NIOSH Publications Dissemination,
4676 Columbia Parkway
Cincinnati, Ohio 45226-1998

Tel: 1-800-35-NIOSH (1-800-356-4674)

Fax: (513) 533-8573


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