What is an EMF assessment?
It depends mostly on who is asking the question, and who it is being asked of.
Any "EMF assessment" that does not properly quantify the four aspects (1) magnetic, 2) electric, 3) harmonic, 4) RF), is Not an EMF assessment.
Simply, EMFs are Electromagnetic Fields, and encompass frequencies from single digits (or parts thereof) to about 500 terahertz or so (500,000,000,000,000 Hz), being around the frequencies of visible light. Faster than that, although still part of the EM Spectrum, you\\'re dealing more with classical particle physics.
A peculiar aspect of EMFs is that within about one wavelength of the source, at any frequency, the individual components of EMF (Electric and Magnetic) behave as separate entities. The wavelength is, of course, based on frequency, that being the slowest are the longest. The wavelength for 60 Hz, for instance, is about 3000 miles. So proper assessment of 60 Hz entities requires separate 1) Magnetic and 2) Electric field measurement. But there are companies that will charge you a couple of dozen thousands of dollars exclusively for a Magnetic field assessment, and call it an "EMF assessment", when in fact it is far from it. For human-occupied spaces, 60 Hz, or 50 Hz is common, while faster frequencies are also present, based on the manner in which we use the available power .
Depending on the nature of wiring type, and manner of install, those human-occupied / living spaces will be rich with Electric fields and / or Magnetic fields. A lot of engineering effort has been expended to ensure the supply voltage remains the same, or very closely so, regardless of load, so the Electric field (which is produced by Voltage) if present, will remain fairly constant, but of course alternating at 60 or 50 Hz. The Magnetic field, in contrast, should be non-existent, as long as wiring is installed properly. The Magnetic field, if present, will vary unpredictably with load, and be chaotic in frequency content, based on the type of load. The biological interactions of the two components are different, and while people may not initially or tangibly react to them, let them persist long enough, or be strong enough, and just about anyone will respond, negatively. Genuinely sensitive people, may react immediately.
Enter ethics, morals, and liability
Become aware of the problem, and depending on who owns it, these concerns come into play, possibly against any possible benefit to those exposed (if reducing a field for me increases it for someone else, is that ethical?).
Enter the Dirty Electricity sales team
Your electricity, is dirty, because of fast frequencies, so you must buy a filter from us . . . Better yet, install several, or many, and use power strips to increase the number of outlets . . . Really? Well, if you believe what these charlatans are marketing, you really need those filters. Dirty electricity has been around since the existence of fluorescent lighting, which is close to how long electricity has been around. But in the last 25 years or so, an apparently bright university professor, and an enterprising electrician, came up with "filters" to cure this blight. Since then several other producers have jumped on the dirty electricity bandwagon, not to mention those that sell lucky charms to "harmonize, balance, or purify" your electricity with a no-effect plug-in, or magnetic stick-on. Alice in Wonderland, anyone?
Dirty electricity is the presence of 3) Harmonic content, or echoes (faster frequencies) of the power frequency. Depending on the presence of Electric or Magnetic fields, Harmonics can drive people up a wall much faster than the presence of single-frequency electric or magnetic fields. Depending on manufacturer-installed filtering, harmonics may not be an issue, but field-installed filtering is not an option, since proper filtering involves design based on theory, testing, modification, redesign, testing, modification, redesign, testing, etc. This process is time consuming, and best left to manufacturers\\' engineers (who are supposed to know how their end products are supposed to function).
But the dirty electricity sales team has another ace up their sleeve,
Microsurge Electrical Pollution, MEP for short.
Ever notice how the lights dip in intensity when the fridge starts cooling? Normal. Other high current appliances being present will increase the occurrence of these power "dips." But some people would have you believe that is a dangerous component of MEP, and their same filters named above will do the trick. Getting the picture?
Harmonics-rich devices are tightly controlled at the manufacturing stage, to prevent EMI / electromagnetic interference with other electronics, but not with people. The engineers, however, forgot to note that we (and they too) are electromagnetically-based. So the inherent EMC / electromagnetic compatibility quality of any device is dubious, depending on where and how it is applied, when there are exposed individuals present. Knowing a device is a problem, the proper solution is to discard the product, since adequate filtering is only available at the engineering / manufacturing stage.
Going past the Harmonics we get into genuine Radio Frequency / RF
4) RF is wireless energy, that once created will depart into free space, regardless of the condition of the source, until it is absorbed, diffused, or otherwise. RF is classically anything above about 30 MHz (30,000,000 Hz), and consists of inseparable Electric and Magnetic fields. Depending on the frequency, it will have good structure penetration ability (slower RF), or good data cartage ability (faster RF), but not both. The predominant component of clasical RF is its Electric field.
Any "EMF assessment" that does not properly quantify the four aspects (1) magnetic, 2) electric, 3) harmonic, 4) RF), is Not an EMF assessment. I know, I\\'m repeating myself, but some people\\'s attention span is short.
On Metering
To detect or quantify any of these entities requires some standardized instruments. For Electric fields a Voltmeter may suffice. For Magnetic fields you require a coil which is then connected to an appropriate meter. For RF a high frequency Voltmeter within the instrument measures its Electric field component, which then does internal calculations to arrive at the desired units.
All meters are either broadband or narrow-band, the latter more appropriately named Spectrum Analyzers. Broadband meters provide a single number for a range of frequencies, whereas narrow band ones provide a wealth of information, such as visualizing individual frequencies and their intensities relative to each other.
A simple voltmeter to measure 120V, for instance, responds best to 60 Hz, similarly for one measuring 240V at 50 Hz. What if there are Harmonics present? Well, the meter may display an unusual reading, or be calibrated to respond to proper weighing of the higher frequencies. The latter are RMS (root mean squared) engineered. Within their stated range RMS meters provide legitimate, and repeatable, numbers, properly quantifying harmonic content if present.
Using a voltmeter, one can use a human as a probe as a surrogate to measure Electric field exposure (from a single source), when compared to some stable zero voltage reference. This is known as Body Voltage / BV measurement. This method can be used to effectively trace most residential wiring right through most walls and floors (unless they are composed of conductive materials). This provides a single number for the expected frequency range, typically 60 Hz or 50 Hz.
Using a coil, one can measure the amount of magnetism in free space, or near sources, when coupled to a meter. While a Voltmeter measures Electric field "stress / potential," a meter coupled with a coil (known as an amp-meter / ammeter) measures the "flow" of energy. The latter can be conveniently packaged in a dedicated instrument known as a Gaussmeter / Tesla meter. Of interest here is that Current can vary dramatically in higher frequency (Harmonic) content, much more so than Electric fields, so that gaussmeters can display a value as much as 50 times greater than an RMS instrument, when Harmonics are present. Most gaussmeters, as well as digital multimeters (DMMs), are Not RMS-engineered.
While a meter can be used to quickly assess if there is a problem, field probes that provide simpler response can also be used. A gaussmeter can quickly advise if there is a magnetic field in free space, which in many cases implies a problem. A non-contact voltage probe can quickly advise if there is a relevant electric field present.
When dealing with Harmonics, one must consider intended bias. Harmonics are echoes of the originating frequency, and the strongest are closest to the source frequency. "Dirty electricity" meters are specifically blinded by internal circuitry from sensing frequencies below about 4 kHz (4,000 Hz). This is because 1) the offered "filters" produce harmonics themselves in this range, and 2) certain "authorities" have deemed that those lower frequencies are not biologically relevant. Convenient, but Reality counters this narrative.
A USB-powered analyzer or a computer\\'s sound card can easily be used with appropriate software to function as a waveform and spectrum analyzer to provide Electric and / or Magnetic and / or Harmonic information content with the appropriate probe. This eliminates the bias just mentioned, and "sifts the wheat from the chaff," as many have bought into the "dirty electricity" bandwagon, including engineers (who get lost when confronted with a spectrum analyzer).
When dealing with RF, a plethora of instruments become available, each with a limited frequency range, as say 50 MHz to 3 GHz, or 200 MHz to 8 GHz. Most such meters are broadband, giving you a single number over an entire frequency range. Broadband meters with differing frequency range sensitivities are Not comparable, since one may detect a frequency while the other does not, unless the area being measured is known to have limited or possibly exclusively known frequencies within the range of both instruments.
RF can also be detected with an analyzer, to determine the presence and intensities of various frequencies. RF analyzers may be quite expensive, and subject to many settings that can stifle their quick and effective use.
Most meters provide instantaneous / Real-time detection / measurement of existing field values. Time-based detection, as in data-logging, is beyond the scope of this document as it requires different instruments with data extraction ports, and requires a dedicated installation free from tampering (which may even be client-caused). Datalogging is also extremely limited by sampling rate and storage capability.
Metering symmetry, or lack thereof
Metering in general can be single axis or three axis.
The single-axis type, as in a coil and meter / gaussmeter, must be rotated slowly across the X, Y, and Z directions, until it is properly aligned with the source, to identify the greatest intensity. These are most inexpensive.
The three axis types have three sensors within them, aligned in the X, Y, and Z directions to provide an immediate field intensity measurement, without rotating the meter. This should not be confused with a "Trifield," which is brand name.
This single or three axis distinction mostly applies to Magnetic or RF metering. Most Electric metering is single axis.
On field characteristics
Most fields of concern are Alternating. That is, they vary cyclically, repeatedly and predictably, over time. They may additionally vary sporadically or unpredictably as to average intensity. For instance, the common 120V varies rhythmically between +170V and -170V 60 times per second, each polarity offering power capability, yet its true average is zero. The 240V 50Hz system alternates between +340V and -340V 50 times per second. The lower numbers, 120 and 240, were introduced long ago to equate their power output capability when compared to DC voltage systems.
Most electric fields are of constant intensity, albeit alternating constantly.
Most magnetic fields are similar to above when related to a single source.
Most RF fields, in contrast, are pulsed. That is, they provide linear information that is broken up into packets, and the packets are then broadcast, with the receiver reintegrating the packetized data into linear information that may consist of voice, images, text, or other data.
While intensity overall is relevant, so is also the pulse repetition rate (PRR), not to be confused with the frequency over which these pulses occur.
While the nuances of the differing fields are relevant, their proper assessment eludes many, forcing the client to seek a second, third, or more opinions to get to the root of the problem, if there is one.
On Clients
A certain number of clients, few thought they be, believe they are being persecuted by EMFs. While this is possible, it is most unlikely, and is also beyond the scope of this document.
Many clients want to get to the root of the problem, and resolve it. In contrast, some clients want an RF-free environment, while also entertaining use of their mobiles. They need a different planet to play on, as realistically there is no such thing as an EMF-free environment, and one so made is not habitable for any reasonable length of time, because humans were not intended to live in electrically conductive and isolating cocoons (which is the Only way an "EMF-free environment" can be accomplished).
Additionally, trying to force some entity producing EMF / RF into compliance with a client\\'s desires, based on some diminuitive meter that detects lowest possible levels, is barking at the moon, when legally actionable levels are quantum levels higher. If you wish (and can) reduce your environmennt\\'s exposure levels, whatever they may be, then fine. But trying to force the issue of reducing externally-sourced emissions, when doing so will increase others\\' exposures is unethical, hypocritical, and will not get you an audience with me.
For proper EMF assessment contact the author:
Sal La Duca, at eainc at emfrelief.com.
Other pertinent details available elsewhere within this website.