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Here we discuss how to interpret the results of an electromagnetic field (EMF) or electro-magnetic radiation EMR measurement survey. 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.

© Copyright 2010 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.

Readers are urged to consult expert sources and to give any suggestions regarding these notes to the author. Some studies by some experts have suggested a possible link between exposure to electromagnetic fields and various cancers or other health problems. Other studies suggest that no definite correlation could be demonstrated. It is likely that the jury will be out on this matter for some time, for both economic and political reasons.

Guide to Interpreting Electromagnetic Field Strength EMF Survey Results

It is very dangerous for untrained personnel to express opinions for which they have no scientific basis. There are very few standards for allowable exposure to EMF. See Definitions of Gauss vs Milligauss for details about gauss and milligauss and definitions of these terms

The health studies are, according to some experts, inconclusive. Some health studies showed an increase in childhood leukemia and other diseases at long exposure to field strengths as low as 1 or 2 mG. However, keep in mind that "doubling" the risk of a disease may in some cases be doubling a number that was extremely small to start with. Doubling a very small number yields still a very small number. If your clients are worried about EMF but smoke, or don't fasten seat belts, or have dangerous stair or railings, their attention has been misdirected.

Pending acceptance of conclusive research by the scientific and engineering community at large, the most accurate position which can be taken by a consultant is that this is a controversial subject.

There may be a health risk from EMF exposure, but regardless of the real level of health risk, there are definitely economic risks because of fear felt by some property buyers.

Building owners and occupants should not let this topic distract them from attending to other high risks that may be at a given property such as tripping hazards, fire hazards, shock hazards, and carbon monoxide hazards.

While the health risks remain under argument, with some recent studies suggesting that there may really be a risk, it is possible to infer whether or not a given property is likely to be exposed to EMF:

1. Any property which uses electrical devices will have at least some measurable electromagnetic fields. If the fields are continuous and close to people the people may be exposed. (EG. sleeping with head 8" from the electric meter-- you can move away, or sleeping in a building 50 ft from a 500KV power transmission line--you cannot move away within the building to escape the field).
2. If you do not find any EMF levels at a property that is served by electricity and has electrical power turned on and some devices in operation (even an electrical clock) then you should doubt your instruments.
3. If we measure any detectable electromagnetic field outside and all around a building attributable to a nearby power line, it is very likely that at times the building and its interior are exposed to more powerful fields (when load on the line is greater)
4. If we can measure no EMF at a given property (attributable to a power line which is nearby) but if the line is within 1000 meters of the building (at 500KV) then it's still quite possible that under some conditions (of heavy load) the building will be in a field.
5. As EMF field strength falls off with the square of the distance, and as field strengths are less for smaller transmission and distribution lines, this 1000 meters is not a sacred distance.
6. The effect on property value and resale-time for properties located close to power transmission lines should be confirmed by frank conversation with real estate sales people (unless the conversant has a conflict of interest), is real, and is in our opinion rather independent of any demonstrable health hazard.

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.

The EMF Field strength at any given moment depends on the load on the power line: A serious problem has limited research and conclusions regarding possible hazards of electromagnetic fields in the U.S.: the lack of publicly available load data. EMF field strength varies depending on the load on the system/conductors. Measurements made at different times and under different conditions will vary widely. Additional explanation of the causes of variation and error in measurements of electromagnetic fields can be found at my article on Enviro-Scare and EMF this website.

In our opinion if you can establish any field measurement at a property it is likely that under some conditions the field strength will be greater than the time of your measurement. Further, even if you measure no field effects, if the property is close to large power transmission or some power distribution lines, it is possible that at some times and conditions it's in a measurable field.

This material represents research thinking. Anyone having any comment, content correction or suggestion is welcome to contact the author.

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. See Recommended EMF Measurement Procedure for details of how to collect EMF measurement data.

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. 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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