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This paper discusses the basics of how we can reliably measure the level of electromagnetic radiation or electromagnetic fields (EMF). Detailed EMF survey procedures are provided later in this article series at Recommended EMF Measurement Procedure.

Before buying test equipment to measure the strength of electromagnetic fields, readers should see EMF RF FIELD & FREQUENCY DEFINITIONS to be sure that they understand the types of electrical fields that exist, the typical sources of different types of electromagnetic fields (power lines, AM and FM radio towers, cell towers, other equipment), and thus the type of test equipment that would be used to assess field strength.

Readers who need to measure EMF themselves or who intend to hire someone to do so should also be sure to review our more detailed EMF measurement procedures at Electromagnetic Radiation Field EMF SURVEY Procedure and also see EMF Survey Worksheet - Excel Spreadsheet and EMF Survey Worksheet - Sample & Explanation. Our page top photo shows a Safeco™ electromagnetic field measuring instrument. This the EMF readings that this instrument obtains are position sensitive - where you point it makes a difference even in the same spot.

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.

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The Basics of Measuring Electromagnetic Field EMF Exposure Levels

As we explain at EMF RF FIELD & FREQUENCY DEFINITIONS, there is a wide range of electrical field types when arranged by frequency, from lower frequencies emitted by electrical power lines (EMF), AM and FM radio frequencies (radio towers - MF and HF or VHF), cell phones, FM and TV radio frequencies (UHF) and others in the electromagnetic spectrum.

Question: Can I Hire You to Make Site Measurements of Electrical Fields?

I wonder if you test the RF and magnetic fields given off from cell phone towers. We have recently moved into a building that I just found out that the building owners have placed cell phone towers on the roof. I am worried since I have a baby. Please let me know if you service. A.F. - New York City.

Reply:

We no longer offer on-site investigation services for measuring electromagnetic fields, though certainly you can hire local experts who can provide that service, have the necessary equipment, and are trained in its use. But before hiring someone to measure magnetic fields, here are a few things to consider:

First, if your object is personal safety for building occupants, there are other immediate potential hazards that should be attended first, as the absolute risk from other hazards can be very significant. Explicit, competent, documented electrical field strength measurements are more reliable than unsubstantiated opinions based on visual observation and fear. No one should be cavalier about people's health, but keeping risks in perspective serves everyone and helps assure that building owners, occupants, parents focus on the big risks first. Review basic building safety items such as

• Working smoke alarms and CO alarms, properly installed and located
• Safe steps and railings in the building and at its entrances
• Exposure to cigarette smoke
• Exposure to high levels of allergenic or toxic mold
• See BUILDING SAFETY HAZARDS GUIDE and ELDERLY & VETERANS HOME SAFETY

Guide to Hiring Someone to Measure Electromagnetic Field Strengths: EMF

If a building owner or occupant is concerned about EMF or other electromagnetic field strength levels at a property (power lines, cell phone towers, radio transmitter towers, other sources), the local power company or other service providers may be willing to perform site measurements at no charge.

Independent experts provide thorough site profiles for fees ranging from $500. to $2,500. and some include extensive consulting which helps protect realtors from future liabilities and can calm inappropriately frightened buyers or sellers. But below you will read why for many circumstances we do not recommend this approach.

For electromagnetic field testing, whether it is UHF (cell phones), VHF and HF (radio towers), or EMF (power lines), and particularly for EMF testing, unless there is a legal issue that requires that the inspection and test be performed by an independent expert, you may prefer to purchase some equipment and following the procedures we’ve outlined for making an on-site survey of electrical field strengths yourself.

Particularly because the strength of electrical fields can vary enormously depending on the level of use of the emitting system, there is a risk that you hire someone at a high cost whose measurement results by no means tell you the average nor long term level of electrical field exposure at that location.

For a thoughtful, informed person who will read, it’s not technically difficult to use most electrical field measurement devices, and there are these advantages:

• the cost will be a small fraction of bringing in an independent person
• you can repeat the test under different power line load conditions (for EMF) or transmitter use cycles (RF etc). something that makes a big difference in the electrical field strength
• you can take your time and make many readings at different locations and different times of day, month, and year , being careful to be accurate
• if your object is prudent avoidance of EMF exposure (as the science is conflicted for reasons we’ve discussed), then you might find small local sources that need a change, like an electric clock by a bed headboard, or a bed headboard placed on a wall where an electrical service entry cable passes

Hiring an EMF RF consultant compared with doing it yourself

Our own personal ethical views, combined with even the most basic technical understanding of issues around RF and EMF hazards make us very reluctant to recommend hiring an "expert" perform EMF and RF field investigations for homeowners or apartment dwellers in most circumstances. Why?

1. Signal strength can be enormously variable at a given location, depending in the case of EMF on the actual current load on the
   power transmission lines, and in the case of high frequency RF, on the transmission activity, antenna direction, and other factors.
   As a result, momentary or single-point-in-time measurements can be quite misleading. See EMF Procedures & Causes of EMF Measurement Error & Variation .
2. Inappropriate expense? On every environmentally fearful topic a quick industry is bred of people who are poorly trained, sometimes unethical, but who prey on consumer fear to become wealthy - the behind the scenes comments from some of these folks can be very disturbing. Professionals are obligated to proceed responsibly in accepting field investigation assignments, respecting both the client's physical health and their financial impacts as well.

   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.

Three Approaches to Measuring RF and EMF Hazards at Properties

For at least these reasons, we recommend one several different different approaches, among which you should choose, or if you can
describe to us a further viewpoint, Contact Us.

1. EMF RF Exposure Litigation: If you are involved in or anticipate litigation, then indeed it is appropriate to have a neutral third party professional make a
   site investigation and to document conditions there.
2. Accurate, longer term EMF or RF measurements at low cost: If #1 does not apply, then a more informed site risk profile is one that would collect measurements over time, under different conditions of load, season of the year, transmission activity, supplemented by basic research to identify the particular source nearby and its character.
   
   For example, if it is a power transmission line, the maximum KVA rating of the line and its distance from the building of concern are of paramount interest, even if an instantaneous measurement gives low results. Rather than pay an independent $1800. U.S. or more to perform a single site survey, purchase the appropriate test instruments and make your own measurements, over time. To assist in this procedure we have provided a series of articles organized at EMF SURVEY PROCEDURE - Details.
   
   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.
   
   At Evaluation of Low-Cost EMF Instruments we list a number of tools that are easy to use, but whose accuracy also depends on the actual measurement procedure - where and how measurements are obtained, which is what we discuss in the EMF Survey Procedure article above, and for which we also provide example field data collection sheets.
   
   Please do not contact us with a request buy RF or 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 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.
   
   Approach #2 is likely to cost just a few hundred dollars U.S. at most, and allows longer and more extensive measurements.
3. If there is a special concern at a property, such as health complaints that appear to be building or site-related but that need
   further investigation, then bringing an expert to the site is indeed more likely to be ethically and cost-justified.

Guide to Making Your Own Electromagnetic Field Strength EMF / RF Measurements

If you're simply curious about finding and measuring local EMF strengths around a home, an alternative might be to simply purchase an inexpensive electromagnetic field strength measuring device.

But before dashing about recording numbers, it is important to understand both the peculiarities of EMF field strength meters and the peculiarities of the size, shape, pattern, and time variation of electromagnetic fields themselves.

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.

Suggestions for using some sample EMF measuring instruments and a discussion of the sources of error and variation in EMF measurements are discussed in more detail at our Electromagnetic Radiation Field EMF SURVEY Procedure located at this website.

At Evaluation of Low-Cost EMF Instruments such as the TriField EMF and RF meter shown here we show several different types of EMF measuring instruments and discuss their properties.

Please do not contact us to buy 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.

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 RF (radio frequency) or EMF (electromagnetic field) measurements. But because the transmission from a cell tower, television tower, or the load on a power transmission line is not under control of an individual property owner, and because the RF or 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, RF or 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 RF or 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 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 measuring EMF or RF electromagnetic field and radio frequency field exposure levels.

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EMF MEASUREMENT PROCEDURES
EMF SURVEY PROCEDURE - Details
  Introduction to EMF Measurement
  EMF/EMR Measurement Procedure Overview
  Local EMF Sources May Exceed Power Line Strength
  Recommended EMF Measurement Procedure
  EMF Measurement Documentation Details
  EMF Measurement Instrument Use
  Interpreting Electromagnetic Field Strength EMF Survey
  Evaluation of Low-Cost EMF Instruments
  EMF ELF Instruments
  Radio Frequency RF Detection Meters

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
• "Questions and Answers about Biological Effects and Potential Hazards of Radiofrequency Electromagnetic Fields", Federal Communications Commission, Office of Engineering and Technology, US FCC, OET Bulleting 56, 4th Edition, August 1999
  " Many consumer and industrial products and applications make use of some form of electromagnetic energy. One type of electromagnetic energy that is of increasing importance worldwide is radiofrequency (or "RF") energy, including radio waves and microwaves, which is used for providing telecommunications, broadcast and other services. In the United States the Federal Communications Commission (FCC) authorizes or licenses most RF telecommunications services, facilities, and devices used by the public, industry and state and local governmental organizations. Because of its regulatory responsibilities in this area the FCC often receives inquiries concerning whether there are potential safety hazards due to human exposure to RF energy emitted by FCC-regulated transmitters. Heightened awareness of the expanding use of RF technology has led some people to speculate that "electromagnetic pollution" is causing significant risks to human health from environmental RF electromagnetic fields. This document is designed to provide factual information and to answer some of the most commonly asked questions related to this topic." - original source: U.S. Federal Communications Commission Office of Engineering and Technology, http://www.fcc.gov/Bureaus/Engineering_Technology/Documents/bulletins/oet56/oet56e4.pdf
• "Magnetic Field Exposure and Cancer: Questions and Answers [ copy on file as /emf/EMF_Fact_Sheet_NCI_NIH.pdf ] - ," National Cancer Institute, U.S. National Institutes of Health, web search September 2010, original source: http://www.cancer.gov/cancertopics/factsheet/Risk/magnetic-fields
  makes these five key points about EMF
  • Electric and magnetic fields (EMF) are areas of energy that surround any electrical device. EMFs are produced by power lines, electrical wiring, and appliances (see Question 1).
  • Electric fields are easily shielded or weakened by walls and other objects, whereas magnetic fields are not. Since magnetic fields are more likely to penetrate the body, they are the component of EMFs that are usually studied in relation to cancer (see Question 1).
  • Overall, there is limited evidence that magnetic fields cause childhood leukemia, and there is inadequate evidence that these magnetic fields cause other cancers in children (see Question 2).
  • Studies of magnetic field exposure from power lines and electric blankets in adults show little evidence of an association with leukemia, brain tumors, or breast cancer (see Question 3).
  • Past studies of occupational magnetic field exposure in adults showed very small increases in leukemia and brain tumors. However, more recent, well-conducted studies have shown inconsistent associations with leukemia, brain tumors, and breast cancer (see Question 4).
• EMF RF FIELD & FREQUENCY DEFINITIONS 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. 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.
• Definitions of Gauss vs Milligauss for details about gauss and milligauss and definitions of these terms.
• 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
• ICNIRP: International Commission on Non-Ionizing Radiation Protection. Health Issues related to the use of hand-held radiotelephones and base transmitters. Health Physics. 1996;70:587-593.
• IRPA, 1988, International Radiation Protection Association. Guidelines on limits of exposure to radio frequency electromagnetic fields. IEEE United States Activities, COMAR, Washington, DC.
• NCRP, 1986, National Council on Radiation Protection. Biological effects and exposure criteria for radiofrequency electromagnetic fields. Report 86, (Bethesda, MD: National Council on Radiation Protection and Measurements) pp. 1-382.
• Rothman KJ, Chung-Kwang C, Morgan R, et al. Assessment of cellular telephone and other radio frequency exposure for epidemiologic research. Epidemiology. 1996;7:291-298.
• Valberg PA. Radio frequency radiation (RFR): the nature of exposure and carcinogenic potential. Cancer Causes Control. 1997;8:323-332.
• Wolf R, Wolf D. Increased incidence of cancer near a cell-phone transmitter station. Int J Cancer Prevention 2004;1:123-128.
• World Health Organization (WHO). Electromagnetic fields and public health: base stations and wireless technologies. 2006. Accessed at www.who.int/mediacentre/factsheets/fs304/en/index.html on February 23, 2010.

Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair

• Our recommended books about building & mechanical systems design, inspection, problem diagnosis, and repair, and about indoor environment and IAQ testing, diagnosis, and cleanup are at the InspectAPedia Bookstore. Also see our Book Reviews - InspectAPedia.
• 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.
• Electromagnetic Field Surveys & Hazards full list of our links to services and technical article
• 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
• Environmental Concerns in buildings, hazards: allergens, asbestos, brownfields
• ...