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Here we discuss the accuracy of and calibration methods for EMF measuring instruments used for performing electromagnetic field (EMF) or electro-magnetic radiation EMR measurements to measure EMF exposure levels in gauss or milligauss. We discusses sources of error and variation in EMF measurements and we review and make suggestions for using several low-cost EMF measurement devices to determine the instantaneous electromagnetic field exposure.

See ENVIRO-SCARE, EMF & Property Values if you don't know what EMF, ELF, or electromagnetic fields are or if you want a summary of the possible health effects of EMF exposure and the more likely effect on the property value of homes located very close to power transmission lines. Readers who intend to make their own EMF measurements should be sure to also see WORKSHEET for EMF MEASUREMENTS and also WORKSHEET for EMF MEASUREMENTS - Example.

Also see Electric Power Lines, Electromagnetic Fields, Cancer Risk, & "Enviro-Scare" - The Normal Curve Cycle of Public Fear of Environmental Issues which discusses the impact of EMF and other environmental concerns on property values. And see ELECTROMAGNETIC FIELDS & HUMAN EXPOSURE which discusses EMF exposure in the workplace.

© Copyright 2009 Daniel Friedman, All Rights Reserved. Information Accuracy & Bias Pledge is at below-left. Use links at the left of each page to navigate this document or to view other topics at this website. Green links show where you are in our document or website.

The information provided here is for research and study purposes. The author makes no representation of unique expertise on this topic, other than having field experience in EMF measurement, having studied technical literature and having conversed with other experts and authors in the field for a number of years.

Small absolute health risk from EMF: Most researchers indicate that where a risk is present, the absolute risk level from EMF is likely to be small, and less than other less obscure hazards. (Automobile accidents, trip and fall, fire, and shock hazards, smoking and other health risks.) Consumers should not let focus on a specific emotionally-charged hazard distract them from these other more mundane but more dangerous concerns.

Evaluation of and Advice for Using Some Low-Cost Electromagnetic Field Measurement (EMF) Instruments for Consumer Use

For added confidence in our measurement results, we use two independent measurement instruments - a Safeco™ analog meter and a Walker Scientific™ digital meter.

Both instruments measure magnetic fields which may be generated from power lines, transformers, household wiring, computers, TV's, and other electric devices.

Measurements made by these devices should be considered as a general screening procedure designed to discover the possible presence of magnetic fields in and around the building or site. Such measurements are not exhaustive. Before making decisions involving any significant expense we recommend that additional instrumentation and expertise be considered.

The Walker™ digital meter provides a direct readout of field strengths in gauss or milligauss. The Safeco™ analog meter permits visual observation of field orientation and strength, but requires mathematical computations to develop a final field strength number.

Our staff are not experts in electromagnetic fields.

As the first and currently the only home inspection professional firm to offer this service in our area we have relied on the quality of instrumentation, information and consulting provided by the manufacturer, and field experience at a range of buildings and environments.

Accuracy and Calibration of Electromagnetic Field Measurement Instruments

Quite a few electromagnetic field strength metering devices are available to the public, and they're not costly. A typical price for a decent EMF measuring device is less than $200. with some instruments selling at twice that price.

Because some people offering to perform EMF measurement services are not careful about procedure, do not offer sound scientific advice, and may not themselves understand how to examine a property effectively, some consumers may be better off buying their own EMF meter or gaussmeter and using the procedures we describe here. See Definitions of Gauss vs Milligauss for details about gauss and milligauss and definitions of these terms

Please do not contact us with a request buy EMF measuring equipment. We do not sell anything. To do so would be a conflict of interest for this website. These devices are readily available from many electrical equipment and home inspection equipment suppliers.

Field Calibration of EMF Electromagnetic Field Strength Measurement Instruments

Our standard measurement procedure includes confirming normal instrument operation by measuring a known common field source - the electric meter at each property as well as at a baseline meter. We measure at 1' and 2' distances from the electric meter, typically finding a field strength between 2 and 7 milligauss in those areas.

Calibration of EMF Measurement Instruments With Electric Power Company Instruments for Measuring Electromagnetic Field Strength

we have compared our test measurements of specific sites with those obtained by local electric utility company representatives and have found our measurements and theirs to be in close agreement.

[Measurements made at the same electric meter at the same distances produced results within 7% of one another. Most power utility companies use equipment which is more sophisticated (and costly) than our own and their personnel may have additional training. See AHS Report #I9189105]

Instead of contacting us with a request to perform EMF Electromagnetic Field Strength measurements, in most cases it is more economical and convenient for a property owner to purchase their own instrument, making measurements under varying conditions. In this series of articles we describe how to make measurements using a consistent approach and using good documentation. See Recommended EMF Measurement Procedure for details of how to collect EMF measurement data.

Following good procedure and using instruments properly are two steps towards making accurate, repeatable EMF measurements. But because the load on a power transmission line is not under control of an individual property owner, and because the EMF strength varies as the power transmission line load varies, it is important to have an idea of that condition as well when attempting to characterize EMF exposure at a specific location. In contrast, EMF measurements are quite accurate and repeatable at other EMF sources such as close to electrical appliances and service entry cables.

Please do not contact us with a request buy EMF measuring equipment. We do not sell anything. To do so would be a conflict of interest for this website. These devices are readily available from many electrical equipment and home inspection equipment suppliers. See Evaluation of Low-Cost EMF Instruments where we describe several low-cost and reasonably accurate EMF measurement devices that are readily available.

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Use links just below or at the left of each page to navigate this document or to view other topics at this website. Green links show where you are in our document or website.

ENVIRO-SCARE, EMF & Property Values
ENVIRO-SCARE Defined, Effects
ENVIRO-SCARE Effects on Property Values
EMF MEASUREMENT PROCEDURES
EMF SURVEY PROCEDURE - Details
  Introduction to EMF Measurement
  EMF/EMR Measurement Procedure Overview
    EMF Variability
    Electrical Utility Workers & EMF Exposure
    EMF Instrument Sensitivity & Accuracy
    EMF Polarity & Shape Affect Measurements
    Distance from the EMF Source Affects Strength
    Time of day & Season Affect EMF Strength
  Local EMF Sources May Exceed Power Line Strength
  Recommended EMF Measurement Procedure
    Outside EMF Measurements
    Outside EMF Measurement Documentation
    Indoor EMF Measurements
    Other Indoor EMF Measurement Targets
    Workplace EMF Measurements
  EMF Measurement Documentation Details
  EMF Measurement Instrument Use
    Definitions of Gauss vs Milligauss
    Position-sensitive EMF Instrument Readings
  Interpreting Electromagnetic Field Strength EMF Survey
  Evaluation of Low-Cost EMF Instruments
    Accuracy & Calibration of EMF Instruments
    Calibration of EMF Instruments in the Field
    Calibration of EMF Instruments by Electric Company
    Descriptions of Low-Cost EMF Instruments
    F.W. Bell Model 4060 ELF Meter
    Safeco™ analog EMF ELF EMR meter
    Walker Scientific ELF-50D™ Digital EMF Meter
References for Electromagnetic Fields and Cancer
WORKSHEET for EMF MEASUREMENTS
WORKSHEET for EMF MEASUREMENTS - Example
WORKPLACE EXPOSURE to Electromagnetic Fields

References for Electromagnetic Fields and Cancer Risk/Carcinogenicity

• Electric Power Lines, Electromagnetic Fields, Cancer Risk, & "Enviro-Scare" - The Normal Curve Cycle of Public Fear About Environmental Issues - online document by DF
• A Procedure for Measuring EMF electromagnetic fields online document by DF
• Consumer Product Safety Commission, 800-638-CPSC.
• US Environmental Protection Agency, Office of Pesticides and Toxic Substances, TSCA Assistance Office (TS-799), 800-424-9065 or 202-554-1404.
• "Evaluation of Potential Carcinogenicity of Electromagnetic Fields," EPA Report #EPA/600/6-90/005B October 1990. EPA: 513/569-7562.
• "Biological Effects of Power Frequency Electric and Magnetic Fields" background paper, prepared as part of OTA's assessment of "Electric Power Wheeling and Dealing: Technological Considerations for Increasing Competition," prepared for OTA by Indira Nair, M. Granger Morgan, H. Keith Florig, Department of Engineering and Public Policy, Carnegie Mellon University, Pittsburgh, PA 15213
• "Biological Effects of Power Line Fields," New York State Powerline Project. Scientific Advisory Board Final Report, July 1, 1987.
• "Extremely Low Frequency (ELF) Fields," Environmental Health Criteria 35. World Health Organization, Geneva, 1984.
• "Electric and Magnetic Fields at Extremely Low Frequencies: Interactions with Biological Systems. In: Non ionizing Radiation Protection, World Health Organization, Regional Office for Europe, Copenhagen, 1987.
• "Electric and Magnetic Fields from 60 Hertz Electric Power: What do we know about possible health risks?," Department of Engineering and Public Policy, Carnegie Mellon University, Pittsburgh, PA 15213 1989.
• "Electromagnetic Fields Are Being Scrutinized for Linkage to Cancer," Sandra Blakeslee, New York Times, Medical Science section, April 2, 1991

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More Information on Building Diagnostic Inspections and Repairs

• Electric Power Lines, Electromagnetic Fields, Cancer Risk, & "Enviro-Scare" - The Normal Curve Cycle of Public Fear of Environmental Issues
• Electromagnetic Fields in the Workplace sample very good NIOSH document online, links to other NIOSH docs.

• Environmental Concerns in Buildings, hazards: allergens, asbestos, brownfields, - above ground or buried oil storage tanks, - A Procedure for Measuring EMF electromagnetic fields, - Electric Power Lines, Electromagnetic Fields, Cancer Risk, & "Enviro-Scare" - The Normal Curve Cycle of Public Fear of Environmental Issues - toxic gases & odors, IAQ, lead paint, - toxic mold inspections, - mold test kits - how to send a mold sample to our lab using an inexpensive and superior method - radon, sick buildings, UFFI (urea formaldehyde foam insulation), - sewage septic backup contamination testing & cleanup - water testing for bacteria, lead, etc.
• Electromagnetic Field Surveys & Hazards full list of our links to services and technical articles

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