Saturday, July 1, 2017

Hybrid & Electric Cars: Electromagnetic Radiation Risks

Hybrid and electric cars may be cancer-causing as they emit extremely low frequency (ELF) electromagnetic radiation (EMR) or magnetic fields. Recent studies of the levels of EMR emitted by these automobiles have claimed either that they pose a cancer risk for the vehicles' occupants or they are safe.

Unfortunately, the little research conducted on this issue has been industry-funded by companies with vested interests on one side of the issue or the other which makes it difficult to know which studies are trustworthy. 

Meanwhile, numerous peer-reviewed laboratory studies conducted over several decades have found biologic effects from very limited exposures to ELF EMR. These studies suggest that the EMR guidelines established by the self-appointed, International Commission on Non-Ionizing Radiation Protection (ICNIRP) are inadequate to protect our health. Thus, even if EMR measurements do not exceed the ICNIRP guidelines, occupants of hybrid and electric automobiles may be at increased risk for cancer and other health problems.

Given that magnetic fields have been considered "possibly carcinogenic" in humans by the International Agency for Research on Cancer of the World Health Organization since 2001, the precautionary principle dictates that we should design consumer products to minimize consumers’ exposure to ELF EMR. This especially applies to hybrid and electric automobiles as drivers and passengers spend considerable amounts of time in these vehicles and health risks increase with the duration of exposure.

In January, 2014, SINTEF, the largest independent research organization in Scandinavia, proposed manufacturing design guidelines that could reduce the magnetic fields in electric vehicles (see below).  All automobile manufacturers should follow these guidelines to ensure their customers' safety. 

The public should demand that governments adequately fund high-quality research on the health effects of electromagnetic radiation that is independent of industry to eliminate any potential conflicts of interest. In the U.S., a major national research and education initiative could be funded with as little as a 5 cents a month fee on mobile phone subscribers.

Following are summaries and links to several studies and news articles on this topic. 


Note that many experts believe the ICNIRP guidelines for maximum general public exposure to electromagnetic fields do not adequately protect the public from health risks.

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Electric and magnetic fields <100 KHz in electric and gasoline-powered vehicles

Tell RA, Kavet R. Electric and magnetic fields <100 KHz in electric and gasoline-powered vehicles. Radiat Prot Dosimetry. 2016 Dec;172(4):541-546.
Abstract
Measurements were conducted to investigate electric and magnetic fields (EMFs) from 120 Hz to 10 kHz and 1.2 to 100 kHz in 9 electric or hybrid vehicles and 4 gasoline vehicles, all while being driven. The range of fields in the electric vehicles enclosed the range observed in the gasoline vehicles. Mean magnetic fields ranged from nominally 0.6 to 3.5 µT for electric/hybrids depending on the measurement band compared with nominally 0.4 to 0.6 µT for gasoline vehicles. Mean values of electric fields ranged from nominally 2 to 3 V m-1 for electric/hybrid vehicles depending on the band, compared with 0.9 to 3 V m-1 for gasoline vehicles. In all cases, the fields were well within published exposure limits for the general population. The measurements were performed with Narda model EHP-50C/EHP-50D EMF analysers that revealed the presence of spurious signals in the EHP-50C unit, which were resolved with the EHP-50D model.
https://www.ncbi.nlm.nih.gov/pubmed/26769905
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Passenger Exposure to Magnetic Fields due to the Batteries of an Electric Vehicle

Pablo Moreno-Torres Concha; Pablo Velez; Marcos Lafoz; Jaime R. Arribas. Passenger Exposure to Magnetic Fields due to the Batteries of an Electric Vehicle. IEEE Transactions on Vehicular Technology. 65(6):4564-4571. Jun 2016.
Abstract
In electric vehicles, passengers sit very close to an electric system of significant power. The high currents achieved in these vehicles mean that the passengers could be exposed to significant magnetic fields (MFs). One of the electric devices present in the power train are the batteries. In this paper, a methodology to evaluate the MF created by these batteries is presented. First, the MF generated by a single battery is analyzed using finite-elements simulations. Results are compared with laboratory measurements, which are taken from a real battery, to validate the model. After this, the MF created by a complete battery pack is estimated, and results are discussed.
Conclusion
Passengers inside an EV could be exposed to MFs of considerable strength when compared with conventional vehicles or to other daily exposures (at home, in the office, in the street, etc.). In this paper, the MF created by the batteries of a particular electric car is evaluated from the human health point of view by means of finite-elements simulations, measurements, and a simple analytical approximation, obtaining an upper bound for the estimated MF generated by a given battery pack. These results have been compared with ICNIRP's recommendations concerning exposure limitation to low-frequency MFs, finding that the field generated by this particular battery pack should be below ICNIRP's field reference levels, and conclusions concerning the influence of the switching frequency have been drawn. Finally, some discussion regarding other field sources within the vehicle and different vehicles designs has been presented. Due to the wide variety of both available EVs and battery stacks configurations, it is recommended that each vehicle model should be individually assessed regarding MF exposure.
http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=7297855

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Magnetic Field Exposure Assessment in Electric Vehicles

Vassilev A et al. Magnetic Field Exposure Assessment in Electric Vehicles. IEEE Transactions on Electromagnetic Compatibility. 57(1):35-43. Feb 2015.
Abstract
This article describes a study of magnetic field exposure in electric vehicles (EVs). The magnetic field inside eight different EVs (including battery, hybrid, plug-in hybrid, and fuel cell types) with different motor technologies (brushed direct current, permanent magnet synchronous, and induction) were measured at frequencies up to 10 MHz. Three vehicles with conventional powertrains were also investigated for comparison. The measurement protocol and the results of the measurement campaign are described, and various magnetic field sources are identified. As the measurements show a complex broadband frequency spectrum, an exposure calculation was performed using the ICNIRP “weighted peak” approach. Results for the measured EVs showed that the exposure reached 20% of the ICNIRP 2010 reference levels for general public exposure near to the battery and in the vicinity of the feet during vehicle start-up, but was less than 2% at head height for the front passenger position. Maximum exposures of the order of 10% of the ICNIRP 2010 reference levels were obtained for the cars with conventional powertrains.

http://ieeexplore.ieee.org/abstract/document/6915707/
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Characterization of Extremely Low Frequency Magnetic Fields from Diesel, Gasoline and Hybrid Cars under Controlled Conditions

Hareuveny R, Sudan M, Halgamuge MN, Yaffe Y, Tzabari Y, Namir D, Kheifets L. Characterization of Extremely Low Frequency Magnetic Fields from Diesel, Gasoline and Hybrid Cars under Controlled Conditions. Int J Environ Res Public Health. 2015 Jan 30;12(2):1651-1666.

Abstract
This study characterizes extremely low frequency (ELF) magnetic field (MF) levels in 10 car models.
Extensive measurements were conducted in three diesel, four gasoline, and three hybrid cars, under similar controlled conditions and negligible background fields.

Averaged over all four seats under various driving scenarios the fields were lowest in diesel cars (0.02 μT), higher for gasoline (0.04-0.05 μT) and highest in hybrids (0.06-0.09 μT), but all were in-line with daily exposures from other sources. Hybrid cars had the highest mean and 95th percentile MF levels, and an especially large percentage of measurements above 0.2 μT. These parameters were also higher for moving conditions compared to standing while idling or revving at 2500 RPM and higher still at 80 km/h compared to 40 km/h. Fields in non-hybrid cars were higher at the front seats, while in hybrid cars they were higher at the back seats, particularly the back right seat where 16%-69% of measurements were greater than 0.2 μT.

As our results do not include low frequency fields (below 30 Hz) that might be generated by tire rotation, we suggest that net currents flowing through the cars' metallic chassis may be a possible source of MF. Larger surveys in standardized and well-described settings should be conducted with different types of vehicles and with spectral analysis of fields including lower frequencies due to magnetization of tires.
Excerpts
Previous work suggests that major sources of MF in cars include the tires and electric currents [4,5]. The level of MF exposure depends on the position within the vehicle (e.g., proximity to the MF sources) and can vary with different operating conditions, as changes to engine load can induce MFs through changes in electric currents. Scientific investigations of the levels of MF in cars are sparse: only one study evaluated fields only in non-hybrid cars [6], two studies of hybrid cars have been carried out [4,7], and few studies have systematically compared exposures in both hybrid and non-hybrid cars [8,9,10,11,12], some based on a very small number of cars 
In hybrid cars, the battery is generally located in the rear of the car and the engine is located in the front. Electric current flows between these two points through cables that run underneath the passenger cabin of the car. This cable is located on the left for right-hand driving cars and on the right for left-hand driving cars. Although in principle the system uses direct current (DC), current from the alternator that is not fully rectified as well as changes to the engine load, and therefore the current level, can produce MFs which are most likely in the ELF range. While most non-hybrid cars have batteries that are located in the front, batteries in some of them are located in the rear of the car, with cables running to the front of the car for the electrical appliances on the dashboard. In this study, all gasoline and diesel cars had batteries located in the front of the car.
...the percent of time above 0.2 µT was the most sensitive parameter of the exposure. Overall, the diesel cars measured in this study had the lowest MF readings (geometric mean less than 0.02 μT), while the hybrid cars had the highest MF readings (geometric mean 0.05 μT). Hybrid cars had also the most unstable results, even after excluding outliers beyond the 5th and 95th percentiles. With regard to seat position, after adjusting for the specific car model, gasoline and diesel cars produced higher average MF readings in the front seats, while hybrid cars produced the highest MF readings in the back right seat (presumably due to the location of the battery). Comparing the different operating conditions, the highest average fields were found at 80 km/h, and the differences between operating conditions were most pronounced in the back right seat in hybrid cars. Whether during typical city or highway driving, we found lowest average fields for diesel cars and highest fields for hybrid cars.
Previous works suggest that the magnetization of rotating tires is the primary source of ELF MFs in non-hybrid cars [5,15]. However, the relatively strong fields (on the order of a few μT within the car) originating from the rotating tires are typically at 5–15 Hz frequencies, which are filtered by the EMDEX II meters. ....
Overall, the average MF levels measured in the cars’ seats were in the range of 0.04–0.09 μT (AM) and 0.02–0.05 μT (GM). These fields are well below the ICNIRP [17] guidelines for maximum general public exposure (which range from 200 μT for 40 Hz to 100 μT for 800 Hz), but given the complex environments in the cars, simultaneous exposure to non-sinusoidal fields at multiple frequencies must be carefully taken into account. Nevertheless, exposures in the cars are in the range of every day exposure from other sources. Moreover, given the short amount of time that most adults and children spend in cars (about 30 minutes per day based on a survey of children in Israel (unpublished data), the relative contribution of this source to the ELF exposure of the general public is small. However, these fields are in addition to other exposure sources. Our results might explain trends seen in other daily exposures: slightly higher average fields observed while travelling (GM = 0.096 μT) relative to in bed (GM = 0.052 μT) and home not in bed (GM = 0.080 μT) [1]. Similarly, the survey of children in Israel found higher exposure from transportation (GM = 0.092 µT) compared to mean daily exposures (GM = 0.059 µT). Occupationally, the GM of time-weighted average for motor vehicle drivers is 0.12 μT [18].
Open access paper: http://bit.ly/1u9lUTN
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Design guidelines to reduce the magnetic field in electric vehicles

SINTEF, Jan 6, 2014

Based on the measurements and on extensive simulation work the project arrived on the following design guidelines to, if necessary, minimize the magnetic field in electric vehicles.

Cables
  • For any DC cable carrying significant amount of current, it should be made in the form of a twisted pair so that the currents in the pair always flow in the opposite directions. This will minimise its EMF emission.
  • For three-phase AC cables, three wires should be twisted and made as close as possible so as to minimise its EMF emission.
  • All power cables should be positioned as far away as possible from the passenger seat area, and their layout should not form a loop. If cable distance is less than 200mm away from the passenger seats, some forms of shielding should be adopted.
  • A thin layer of ferromagnetic shield is recommended as this is cost-effective solution for the reduction of EMF emission as well EMI emission.
  • Where possible, power cables should be laid such a way that they are separated from the passenger seat area by a steel sheet, e.g., under a steel metallic chassis, or inside a steel trunk.
Motors
  • Where possible, the motor should be installed farther away from the passenger seat area, and its rotation axis should not point to the seat region.
  • If weight permits, the motor housing should be made of steel, rather than aluminium, as the former has a much better shielding effect.
  • If the distance of the motor and passenger seat area is less than 500mm, some forms of shielding should be employed. For example, a steel plate could be placed between the motor and the passenger seat region
  • Motor housing should be electrically well connected to the vehicle metallic chassis to minimise any electrical potential.
  • Inverter and motor should be mounted as close as possible to each other to minimise the cable length between the two.
Batteries
  • Since batteries are distributed, the currents in the batteries and in the interconnectors may become a significant source for EMF emission, they should be place as far away as possible from the passenger seat areas. If the distance between the battery and passenger seat area is less than 200mm, steel shields should be used to separate the batteries and the seating area.
  • The cables connecting battery cells should not form a loop, and where possible, the interconnectors for the positive polarity should be as close as possible to those of the negative polarity.
http://bit.ly/1qw29Tb

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Magnetic Fields in Electric Cars Won't Kill You

Jeremy Hsu, IEEE Spectrum, May 5, 2014
Summary
“The study, led by SINTEF, an independent research organization headquartered in Trondheim, Norway, measured the electromagnetic radiation—in the lab and during road tests—of seven different electric cars, one hydrogen-powered car, two gasoline-fueled cars and one diesel-fueled car. Results from all conditions showed that the exposure was less than 20 percent of the limit recommended by the International Commission on Non-Ionizing Radiation Protection (ICNIRP).”
“Measurements taken inside the vehicles—using a test dummy with sensors located in the head, chest and feet—showed exposure at less than 2 percent of the non-ionizing radiation limit at head-height. The highest electromagnetic field readings—still less than 20 percent of the limit—were found near the floor of the electric cars, close to the battery. Sensors picked up a burst of radiation that same level, when the cars were started.”
http://bit.ly/1pUuOxB
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ELF magnetic fields in electric and gasoline-powered vehicles

Tell RA, Sias G, Smith J, Sahl J, Kavet R. ELF magnetic fields in electric and gasoline-powered vehicles. Bioelectromagnetics. 2013 Feb;34(2):156-61. doi: 10.1002/bem.21730.

Abstract
We conducted a pilot study to assess magnetic field levels in electric compared to gasoline-powered vehicles, and established a methodology that would provide valid data for further assessments. The sample consisted of 14 vehicles, all manufactured between January 2000 and April 2009; 6 were gasoline-powered vehicles and 8 were electric vehicles of various types. Of the eight models available, three were represented by a gasoline-powered vehicle and at least one electric vehicle, enabling intra-model comparisons. Vehicles were driven over a 16.3 km test route. Each vehicle was equipped with six EMDEX Lite broadband meters with a 40-1,000 Hz bandwidth programmed to sample every 4 s. Standard statistical testing was based on the fact that the autocorrelation statistic damped quickly with time. For seven electric cars, the geometric mean (GM) of all measurements (N = 18,318) was 0.095 µT with a geometric standard deviation (GSD) of 2.66, compared to 0.051 µT (N = 9,301; GSD = 2.11) for four gasoline-powered cars (P < 0.0001). Using the data from a previous exposure assessment of residential exposure in eight geographic regions in the United States as a basis for comparison (N = 218), the broadband magnetic fields in electric vehicles covered the same range as personal exposure levels recorded in that study. All fields measured in all vehicles were much less than the exposure limits published by the International Commission on Non-Ionizing Radiation Protection (ICNIRP) and the Institute of Electrical and Electronics Engineers (IEEE). Future studies should include larger sample sizes representative of a greater cross-section of electric-type vehicles.
https://www.ncbi.nlm.nih.gov/pubmed/22532300

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Mythbuster: EMF levels in hybrids
Consumer Reports News: August 4, 2010

Summary

“Some concern has been raised about the possible health effects of electromagnetic field radiation, known as EMF, for people who drive in hybrid cars. While all electrical devices, from table lamps to copy machines, emit EMF radiation, the fear is that hybrid cars, with their big batteries and powerful electric motors, can subject occupants to unhealthy doses. The problem is that there is no established threshold standard that says what an unhealthy dose might be, and no concrete, scientific proof that the sort of EMF produced by electric motors harms people

“We found the highest EMF levels in the Chevrolet Cobalt, a conventional non-hybrid small sedan.”

[The peak EMF readings at the driver’s feet ranged from 0.5 mG (milligauss) in the 2008 Toyota Highlander to 30 mG in the Chevrolet Cobalt. The hybrids tested at 2-4 mG. Here are some highlights from the tests. EMF readings were highest in the driver’s foot well and second-highest at the waist, much lower higher up, where human organs might be more susceptible to EMF.

“To get a sense of scale, though, note that users of personal computers are subject to EMF exposure in the range of 2 to 20 mG, electric blankets 5 to 30 mG, and a hair dryer 10 to 70 mG, according to an Australian government compilation. In this country, several states limit EMF emissions from power lines to 200 mG. However, there are no U.S. standards specifically governing EMF in cars.”

“In this series of tests, we found no evidence that hybrids expose drivers to significantly more EMF than do conventional cars. Consider this myth, busted.”

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Israel Preps World’s First Hybrid Car Radiation Scale

Tal Bronfer, the truth about cars, March 1, 2010

Summary

“The Australian Radiation Protection and Nuclear Safety Agency (ARPANSA) recommends a limit of 1,000 mG (milligauss) for a 24 hour exposure period. While other guidelines pose similar limits, the International Agency for Research on Cancer (IARC) deemed extended exposure to electromagnetic fields stronger than 2 mG to be a “possible cause” for cancer. Israel’s Ministry of Health recommends a maximum of 4 mG.”

“Last year, Israeli automotive website Walla! Cars conducted a series of tests on the previous generation Toyota Prius, Honda Insight and Honda Civic Hybrid, and recorded radiation figures of up to 100 mG during acceleration. Measurements also peaked when the batteries were either full (and in use) or empty (and being charged from the engine), while normal driving at constant speeds yielded 14 to 30 mG on the Prius, depending on the area of the cabin.

The Ministry of Environmental Protection is expected to publish the results of the study this week. The study will group hybrids sold in Israel into three different radiation groups, reports Israel’s Calcalist. It’s expected that the current-gen Prius will be deemed ‘safe’, while the Honda Insight and Civic Hybrid (as well as the prev-gen Prius) will be listed as emitting ‘excessive’ radiation.”

http://bit.ly/1pUu7Ep

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Fear, but Few Facts, on Hybrid Risk

Jim Motavalli, New York Times, Apr 27, 2008

Summary

“... concern is not without merit; agencies including the National Institutes of Health and the National Cancer Institute acknowledge the potential hazards of long-term exposure to a strong electromagnetic field, or E.M.F., and have done studies on the association of cancer risks with living near high-voltage utility lines.

While Americans live with E.M.F.’s all around — produced by everything from cellphones to electric blankets — there is no broad agreement over what level of exposure constitutes a health hazard, and there is no federal standard that sets allowable exposure levels. Government safety tests do not measure the strength of the fields in vehicles — though Honda and Toyota, the dominant hybrid makers, say their internal checks assure that their cars pose no added risk to occupants.”

“A spokesman for Honda, Chris Martin, points to the lack of a federally mandated standard for E.M.F.’s in cars. Despite this, he said, Honda takes the matter seriously. “All our tests had results that were well below the commission’s standard,” Mr. Martin said, referring to the European guidelines. And he cautions about the use of hand-held test equipment. “People have a valid concern, but they’re measuring radiation using the wrong devices,” he said.”

“Donald B. Karner, president of Electric Transportation Applications in Phoenix, who tested E.M.F. levels in battery-electric cars for the Energy Department in the 1990s, said it was hard to evaluate readings without knowing how the testing was done. He also said it was a problem to determine a danger level for low-frequency radiation, in part because dosage is determined not only by proximity to the source, but by duration of exposure. “We’re exposed to radio waves from the time we’re born, but there’s a general belief that there’s so little energy in them that they’re not dangerous,” he said.”