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This paper discusses a recommended procedure for performing electromagnetic field (EMF) or electro-magnetic radiation EMR measurements either by engaging a professional or by consumers using low-cost instruments which 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.

Because RF and EMF measurement tools need to be properly chosen to measure the particular type and frequency of RF or EMF signal that is of interest, be sure to 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. Also see Definitions of Gauss vs Milligauss for details about gauss and milligauss and definitions of these terms.

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 EMF ELECTROMAGNETIC FIELDS & HUMAN EXPOSURE which discusses EMF exposure in the workplace.

© Copyright 2012 InspectAPedia.com, All Rights Reserved. Information Accuracy & Bias Pledge is at below-left. Use page top links to major topics or use links at the left of each page to navigate within topics and documents at this website. Green links show where you are in a document series or at this 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.

Steps in A Recommended Electromagnetic Field Measurement Procedure - How to make Outdoor & Indoor EMF Measurements

we have documented a proposed procedure for making site surveys of electromagnetic field strength in order to improve the accuracy and repeatability of such measurements. We welcome critique and suggestions for this procedure. Contact Us with criticism.

As we explained earlier:

Instead of contacting us with a request to perform EMF Electromagnetic or RF Radio Frequency 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 signal transmission for RF sources such as radio, TV, or cell towers, 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 or RF 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 This article describes several low-cost and reasonably accurate EMF measurement devices that are readily available. See Radio Frequency RF Detection Meters This article describes several low-cost and accurate radio frequency or RF detection and measurement devices suitable for radio, TV, cellphone, microwave, and similar signals.

Outside Measurements of Electromagnetic Field Strength at a Property

Document these Outdoor EMF measurement Parameters and Readings

1. Estimated or measured distance from nearest point on building to point directly below nearby power line
2. Same, for distance from corners of building to the point named above.
3. The date and time of the EMF measurement, for comparison with power transmission line load level data for that same time.
4. The EMF levels found at each location

Indoor Measurements of Electromagnetic Fields

If the outside of the building is in a strong EMF, all measurements inside the building might be expected to produce the identical number.

However if the inspector agrees to a detailed site survey we recommend spot checks in every room as well as at obvious common interior targets of interest (such as an electrical device which is normally kept "on" and which is close to the head of a bed (clocks).

You will observe that while there may be a strong field close to a clock, the field will fall off to undetectable in 2 feet or so.

Other indoor targets of opportunity in residential properties

Commercial properties have special targets of opportunity for EMF Measurements:

Local power distribution systems, electric meter buses which may produce a field which is further distributed by building plumbing or wiring

Special high-amp equipment such as X-ray machines, computer equipment, compressors

EMF Measurement Documentation Requirements

Document date, time, location, weather conditions (hot means air conditioners are running and load may be higher; time means it is at least theoretically possible to correlate the measurement results with actual load data if the power company would provide it)

Document distance from measurement location to suspected source of EMF and identify that source

Document any reports of medical anomalies (if anyone volunteers such information or if your procedure or study permits its collection)

See WORKPLACE EXPOSURE to Electromagnetic Fields for information about exposure to electromagnetic fields in the workplace.

Please see WORKSHEET for EMF MEASUREMENTS - Example for a sample worksheet that collects EMF measurements and summarizes the results.

Readers are urged to consult expert sources and to give any suggestions regarding these notes to the author. Readers may want to see our EXCEL Spreadsheet EMS_Survey_Sample1.xls for an example of common locations and measurement points. This spread sheet includes computations necessary to produce mathematically valid measurement results for those who are using position-sensitive instruments.

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.

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.

Instead of contacting us with a request to perform EMF Electromagnetic or RF Radio Frequency 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. See Evaluation of Low-Cost EMF Instruments This article describes several low-cost and reasonably accurate EMF measurement devices that are readily available. See Radio Frequency RF Detection Meters This article describes several low-cost and accurate radio frequency or RF detection and measurement devices suitable for radio, TV, cellphone, microwave, and similar signals.

Questions & Answers regarding this article

Questions & answers about how to measure electromagnetic fields, EMF radiation at and around buildings

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EMF MEASUREMENT INSTRUMENTS
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