Type of Radiation in Cars
As modern mobility systems transition from mechanical to electric and evidence-based frameworks, new variables emerge in vehicle safety and engineering standards. One such variable, often overlooked in early development stages, is electromagnetic radiation.
While the term “radiation” evokes a broad spectrum from ionizing (e.g., X-rays) to non-ionizing types (e.g., ELF, RF), the automotive context primarily involves non-ionizing emissions, which arise as byproducts of electrical operation.
Electric, hybrid, and connected vehicles inherently contain high-current systems and multiple wireless transceivers. These introduce varied electromagnetic fields (EMFs), characterized by frequency and amplitude, across cabin zones. The concern does not stem from isolated, acute exposure, but from continuous, low-level presence during vehicle use, sometimes under high load conditions (e.g., acceleration or charging).
Classification of Radiation in Vehicles
In automotive systems, radiation classification matches with the source’s operational frequency. Below is a systematic outline of relevant EM field types found in-vehicle:
Static Magnetic Fields
These fields are non-alternating and typically originate from DC sources. In vehicles, this includes traction batteries (when idle or charging), as well as permanent magnet assemblies within braking mechanisms.
Their magnitude may vary with proximity and is particularly relevant in fast-charging scenarios where high currents pass through fixed conductors. SMFs do not oscillate but may interfere with magnetic sensors or other passive components.
Extremely Low and Ultra Low Frequency (ELF and ULF) Fields
Defined within the 0–3 KHz range, ELF and ULF fields represent the most biologically scrutinized segment due to their association with residential power lines and related epidemiological data. In vehicles, ELF emissions arise from alternators, motor drives, and inverter switching.
Cabin locations nearest to underfloor cabling, motor enclosures, or inverters may exhibit localized peaks above 30 µT under specific load conditions (source: JRC Science for Policy Report). These values exceed those typically encountered in homes or offices, prompting the need for source localization and shielding consideration.
Intermediate Frequency (IF) Fields
IF fields (3Khz Hz – 10 MHz) are produced by inductive elements operating at higher switching speeds. Wireless charging platforms and proximity detection systems fall into this category.
While currently limited in application, the progression toward autonomous operation suggests a probable rise in IF-based modules. This calls for early-stage evaluation of interference risk and human exposure assessments, particularly in multi-modal signal environments.
Radiofrequency (RF) Fields
Spanning 10 MHz to 300 GHz, RF fields are emitted by Bluetooth, Wi-Fi, GPS, V2X, and cellular systems. Individually compliant with ICNIRP guidelines, the aggregate field strength from multiple concurrent RF systems may present increased cabin exposures. This is especially critical in enclosed, shielded environments (e.g., vehicles with metallized glass or deep seating wells) where reflection and field summation are possible.
EM Field Sources by Vehicle Category
The total EMF profile in a vehicle depends heavily on drivetrain configuration and onboard electrical density.
Internal Combustion Engine (ICE) Vehicles
Legacy systems generate limited EMFs. The primary sources (alternators and spark systems) emit ELF fields. Field strength is relatively low due to the absence of high-voltage propulsion components.
Hybrid Electric Vehicles (HEVs)
Hybrids combine combustion engines with electric motors and high-capacity battery packs. EMF contributions arise from overlapping AC/DC power conversion stages and dynamic energy flow during regenerative braking.
High ELF concentrations are typically recorded at footwells and under-seat zones.
Battery Electric Vehicles (BEVs)
Fully electric platforms concentrate EM activity around the traction system, including inverters, DC/DC converters, and fast-charging equipment. Under acceleration or rapid DC charging, ELF fields exceeding 100 µT have been documented adjacent to the charge port.
Battery placement along the vehicle floor also positions field hotspots directly beneath occupants. This warrants evaluation of seating ergonomics and shielding layers.
Assessment and Measurement Methodologies
Measurement of in-vehicle EM fields employs three primary methodologies:
| Method | Description |
| Point-Based Field Mapping | Static sensor placement at key cabin coordinates (e.g., headrest, legroom). |
| Wearable Dosimetry | Personal dosimeters worn by test subjects during active driving simulations. |
| Controlled Lab Evaluation | Use of calibrated equipment such as triaxial magnetometers and Helmholtz coils in electromagnetic isolation chambers. |
Primary metrics:
- Magnetic fields measured in µT (microteslas)
- Electric fields measured in V/m (volts per meter)
Significant variation in readings is observed due to factors such as seating position, drive cycle phase (e.g., acceleration), and nearby infrastructure (e.g., high-voltage overhead lines during outdoor testing).
Policy Implications and Future Research Needs
Standardization
Current EMF measurement lacks uniformity. The IEC 62764 and IEC 62226 standards, while emerging, are not yet globally adopted. Harmonization is important to allow valid cross-comparison of test data and OEM benchmarking.
Design Guidelines
Manufacturers are encouraged to:
- Implement shielding around high-current components
- Improve cable routing to reduce cabin exposure
- Integrate active cancellation where feasible
Regulatory Direction
Institutions such as the European Commission and Germany’s BfS promote:
- Revisiting public exposure limits in electrified mobility environments
- Increasing transparency of in-vehicle EMF reporting
- Funding longitudinal studies on chronic exposure in sensitive populations
As electric and connected mobility expands, so does the electromagnetic environment inside vehicles. The exposure profiles are changing in complexity and magnitude. For the public, especially daily commuters, rideshare drivers, and children, this introduces a prolonged exposure profile not previously considered in conventional vehicle safety design.
Moving forward, OEMs and regulatory bodies must jointly address this invisible variable. Through applied research, standardization, and design adaptation, it is possible to maintain innovation momentum while safeguarding public health in the transport environment.
