Back to Practical Guides
Guide 9

Buying a Vehicle with Low EMR in Mind: Two Field Families, and the Limits of Measuring and Switching Things Off

What ELF and RF fields actually look like inside electrified vehicles, why the standard measurement method misses short-lived peaks, and the real risks and limits of trying to switch transmitters off yourself.

Conceptual illustration of an SUV in cutaway, showing RF waves radiating from a cell tower built into the cabin and ELF magnetic field lines from a horseshoe magnet under the vehicle, representing the two families of in-cabin EMR exposure

Buyers who want a low-EMR cabin tend to ask two questions. What is this vehicle emitting, and can I turn it off? Both are fair questions. Both are harder to answer than a spec sheet or a forum thread suggests. This guide sets out the two families of exposure, what the best vehicle survey to date found, why the standard measurement method misses part of the picture, and what to weigh before interfering with any vehicle system.

Two Different Exposures, Neither a Substitute for the Other

Extremely low frequency (ELF) magnetic fields come from the high-current parts of electrified drivetrains: battery, inverter, motor and the cabling between them, along with many auxiliary loads such as heated seats, fans and window motors. Published surveys report strong variation by model, by seat and by driving state. A 2015 characterisation study (Hareuveny and colleagues) recorded cabin peaks of around 30 µT near front footwells. An older survey of seven conventional cars found 0.05 to 3.9 µT in the left front seat and up to 14 µT at rear footwell level. Peaks near a DC fast-charging connection have been reported at about 200 µT static and 100 µT ELF (Gryz and colleagues, 2022). For reference, ICNIRP general-public reference levels sit between 100 and 200 µT depending on the edition, while precautionary levels proposed in some jurisdictions and in building-biology practice are far lower, at 0.2 to 0.4 µT (200 to 400 nT). IARC classifies ELF magnetic fields as possibly carcinogenic to humans (Group 2B).

Radiofrequency (RF) fields come from the vehicle's own transmitters: cellular and other telematics modems, Wi-Fi, Bluetooth, keyless-entry systems and millimetre-wave radar sensors, alongside any devices occupants bring in. RF is also classified by IARC as possibly carcinogenic (Group 2B). It is a different physical and biological problem from ELF, and the two should not be ranked against each other. How an RF field interacts with a body depends on frequency, modulation, pulsing, duration and the tissue or biological substrate receiving it. A low reading on one family says nothing about the other.

Two further points apply to both. Exposure varies widely between models and even between seats in the same car, so assumptions about a whole category of vehicle (electric, hybrid, petrol) are unreliable. And fields can change after repairs, component replacement or accident damage, which matters when buying used.

Transients: What the Standard Measurement Leaves Out

The most comprehensive vehicle magnetic field survey to date was commissioned by Germany's Federal Office for Radiation Protection (BfS) and the federal environment ministry, and carried out by Seibersdorf Laboratories with the femu research centre at RWTH Aachen University and ADAC's technology centre. It measured fields at the seats of 14 vehicles from model years 2019 to 2021 (11 battery electric cars, 2 hybrids and 1 with a combustion engine), on roller dynamometers, a closed track and public roads, and included some electric two-wheelers. The findings most useful to a buyer:

  • The strongest fields were in the foot and lower-leg area in front of the seats. Head and torso levels were generally low
  • Values differed greatly between vehicles, between positions within a vehicle and between operating states. Motor power did not predict field strength
  • Driving style mattered. Hard acceleration and braking produced much stronger fields, briefly
  • Short peaks of under a second also occurred when the vehicle was switched on, when components activated automatically and when the brake pedal was pressed. The highest single local value was recorded when a hybrid was switched on
  • In this sample, all-electric cars were not generally exposed to stronger fields than conventional or hybrid vehicles

The significant finding concerns how fields are measured. The international standard for vehicle magnetic field measurement (IEC 62764-1) excludes transients shorter than 200 milliseconds, on the grounds that they are difficult to measure reliably and repeatably. The survey team measured them anyway, and BfS has said the standards should be extended to cover them. According to reporting in Microwave News, the project leader found that leaving out events shorter than 200 ms would substantially lower the highest recorded exposure index in 70 to 80 per cent of the cars examined, and that peak fields often exceeded the European reference levels, in one case (a hybrid at start-up) by a large multiple. Those figures come from that reporting and the project leader's comments, and should be checked against the full German-language report before being relied on.

The study's own conclusion needs stating fairly. Computer simulations of induced fields in the body found the ICNIRP "basic restrictions" were not exceeded, because exposure inside cars is highly localised, whereas the reference levels assume uniform whole-body exposure. On that basis BfS concluded that health-relevant effects are not expected on current knowledge. Both readings can be held at once. The restrictions are written around acute effects; they do not address chronic, repeated, low-level exposure. Epidemiological studies of childhood leukaemia, by contrast, report associations at long-term average fields of roughly 0.3 to 0.4 µT (300 to 400 nT). Health research on repeated transient exposure specifically is sparse: a few occupational studies decades ago raised concerns and were not followed up.

The practical points for buyers are that a vehicle described as compliant with the standard may still produce brief, strong, localised peaks that the standard never counted, and that a measurement taken only at steady speed will miss them. A second part of the BfS programme, on fields during charging, was still to be published at the time of writing. In this first part, in-cabin exposure during charging was reported as generally lower than while driving; proximity to the charging cable and connector is a separate matter.

Illustration of an electric vehicle charging at a street charging station at night, with a city skyline in the background
Charging itself is a separate exposure question from driving — stay clear of the cable and connector while it's in use.

What Is, and Is Not, Well Understood About Vehicle RF

Exposure guidelines for RF, including those of ICNIRP and ARPANSA and including at millimetre-wave frequencies, are set on thermal mechanisms, an assumption that is endemic to guideline-setting and is rarely examined by the people who rely on it (see the Regulatory Capture chapter for how that assumption became entrenched). "Low power" in a sensor specification is an engineering and regulatory descriptor. It is not a statement about biological effect. Automotive radar at 77 GHz uses modulated waveforms, and research into the biological effects of that kind of modulated millimetre-wave exposure is sparse. The fields of science that should be examining it have not done so adequately, and perhaps they should have, given that the people with an interest in the answer are not only the occupants of the vehicle but also pedestrians, cyclists and the occupants of every other vehicle that passes within range of its sensors. Absence of studies is not a finding of safety, and a buyer should not read a manufacturer's compliance statement as one.

Measuring a Vehicle Properly

Measurement beats assumption, but only if the instrument is fit for the job.

  • Many low-cost consumer meters are inaccurate to the point that readings are not worth the time spent taking them. Their frequency response, calibration and isotropy are often poor or undocumented, and RF meters can misread modulated and pulsed signals badly

  • For ELF, use a calibrated triaxial instrument with a documented frequency response covering the range of interest, and with fast enough time resolution to log peaks and waveforms rather than only averages. A meter that averages or responds slowly will miss exactly the events described above. For RF, use a calibrated analyser suited to the bands and modulation involved
  • If you do not have access to accurate equipment, engage a specialist (a building biologist or EMR consultant with calibrated gear) rather than relying on a cheap meter
  • Measure at each seat at foot, seat and head height, and across operating states: switch-on, idle, steady cruise, gentle and hard acceleration, regenerative braking, heated seats and other auxiliary loads, charging, and with connectivity systems in their various settings
  • If you are shown a measurement report, ask whether it followed the standard and, if so, which short events it excluded

Can the Vehicle's Systems Be Shut Down?

Sometimes. Settings menus often allow wireless features to be switched off, and some manufacturers offer further privacy or connectivity controls. Beyond that, the picture is difficult, and it differs by manufacturer, model, year and country.

  • The vehicle may not behave as you expect. Some connectivity modules have backup power or wake on events, so cutting a fuse or a SIM does not prove the module is silent. Only measurement will tell you
  • Safety systems can be affected. Emergency calling, stolen-vehicle tracking, crash notification and some driver-assistance functions can depend on connected hardware. Interference may produce fault codes, degraded functions or unpredictable behaviour
  • Legal and locality factors vary. Some jurisdictions require emergency-call capability in new vehicles; others do not. Roadworthiness rules, warranty terms, insurance conditions and software-update access can all change if systems are disabled or modified
  • Support is thin. Auto trades are generally not trained in RF, and RF specialists are generally not trained in vehicle electronics. A single tradesperson who can modify the vehicle safely and verify the RF result is unlikely to be found, so most buyers end up on their own
  • Shielding is not a universal fix. Enclosing a transmitter changes its behaviour in ways that depend on the device. Some adaptive links may raise their output to hold a connection; fixed-output sources will not; others may fail. Do not assume either way without measurement. Conductive shielding also does little against ELF magnetic fields, which are only perturbed by high-permeability materials and are impractical to shield in a cabin (see the Shielding: Materials, Methods & Limitations chapter)

We do not publish wiring or modification instructions for vehicle systems.

Three Pathways for a Buyer

Conservative: choose well, then verify. Before shortlisting, look for published measurement data: the BfS electromobility results, China's C-GCAP and C-AHI programmes, the Israeli Ministry of Environmental Protection measurement spreadsheet, and the European Commission Joint Research Centre report on electrified vehicles. Ask the manufacturer or dealer, in writing, which wireless and connected functions can be disabled, how, and what stops working as a result. Have the specific vehicle measured with calibrated, fast-logging equipment before purchase, including during hard acceleration and braking. Stay away from the charging cable and connector while charging. Risk: low. Rollback: decline the purchase, or assign seating to the lowest-reading positions.

Integrative: use what the vehicle offers. Switch off Bluetooth, Wi-Fi, remote access and data sharing where the menus allow, use wired phone connections, and keep personal devices away from the highest-reading positions. Smoother acceleration and braking reduced peak fields in the survey, and the lower legs and feet are where fields were highest, so seating position and footwell use are worth attention. Use heated seats and other high-current auxiliaries sparingly if measurement shows they add peaks. Re-measure afterwards, because a menu setting is a request, not proof. Risk: minimal. Rollback: re-enable the settings.

Experimental: hardware-level interruption. Removing SIMs, interrupting power to modules or altering antennas. Exposure reduction is plausible but must be demonstrated by measurement, since backup power paths or other transmitters may remain. Risks are technical, legal and safety related, as listed above, and some of them cannot be undone cleanly. If a buyer proceeds, they should first record the vehicle's original state with photographs and notes, make only reversible changes, take their own before-and-after readings with calibrated equipment or a specialist, and accept that no trade or manufacturer is likely to stand behind the result. Rollback: restore the original configuration and clear any logged faults.

The Summary for Buyers

Both families of field deserve attention. Choose a vehicle partly on its measured fields, including the brief peaks that standard compliance testing does not count, and on how much control it gives you over its transmitters. Treat any claim that a system "cannot" or "can easily" be shut down with suspicion until you have verified it for your exact vehicle, your jurisdiction and your insurer. Use accurate instruments or a specialist. Do your own research, and keep your changes reversible.

Sources

Need Professional EMR Assessment?

EMRSTOP provides comprehensive EMR/EMF assessments for homes, workplaces, and clinics.

Book a Consultation