There’s no disputing that hybrid cars are good for the environment. But lately another issue has been raised: Are hybrids healthy for the drivers and passengers?

It’s a legitimate question. I’ve written extensively on the dangers of electromagnetic fields (EMF) myself, and have previously warned you about the potential dangers these hybrid vehicles might pose.

The flow of electrical current to the motor of a hybrid vehicle produces magnetic fields, which studies have associated with serious health risks, including a heightened risk of leukemia among children.

Additionally, since the batteries and power cables in hybrids are often placed close to the driver and passengers, it’s likely that some exposure to electromagnetic fields is unavoidable. And the exposure is a prolonged one as many drivers spend hours each day at the wheel.

So, should you buy a hybrid? Or are you gambling with your health while making an effort to go green?

Electro-Pollution Specialist Weighs in On the Potential Dangers

Stan Hartman is an environmental health consultant in Boulder, CO, specializing in electro-pollution. He believes the article featured in The New York Times contains many misleading statements that may frighten people unnecessarily.

“There's no more difficult a situation to try to get accurate EMF readings in than a moving car, and the errors will almost certainly be to exaggerate toward the high end, he states. 

With instruments that tend to do that already, and don't claim high accuracy to begin with (6 decibels compared to less than 1 for a good professional meter), they end up scaring people unjustifiably.” 

Hartman, who conducted his own EMF safety test of a 2007 Toyota Prius Hybrid, offered the following corrections and explanations to the Times article above:  

1. Trifield meters are useful, but it's important to be aware of their sensitivity to high frequencies when trying to determine ELF levels, and of the fact that standard Trifields, unlike most gaussmeters, are frequency-weighted. Higher frequencies read as higher magnetic fields.  So a 120 Hz field will read twice as high as a 60 Hz field, a 180 Hz field three times too high, etc., and they have significant sensitivity as high as 100 kHz, and some residual sensitivity to 100 MHz – on the magnetic, not radio/microwave setting. This can result in wildly high readings if they're interpreted as ELF when higher frequencies are present (like near the floorboards of cars with electronic ignitions, which include many more vehicles than just the Prius and other hybrids). 
   
   
2. AC magnetic field readings were consistently higher on the rear seats than on the front seats. Measurements in the rear passenger compartment were made in the center of the seats, away from the doors, to avoid confusion with the ELF magnetic fields from the magnetized, revolving steel wires in the tires.  Tire fields are too low-frequency to be detected by most gaussmeters, which have 30 or 40 Hz low-frequency filters to keep them stable while moving in the earth's field, but they're present in most if not all vehicles, even those with "polyester-belted" radials, which still have significant steel in them. They're usually confined to within a few inches of the back doors. 
   
   
3. ELF magnetic fields were highest when both the gasoline engine and the electric motor were running – when the vehicle was warming up, accelerating, climbing even slightly, or charging the battery. During hard acceleration, they could reach 6 or 8 mG at seat level on the rear seats, diminishing higher up from the seats. 
   
   
4. Operating on the electric motor alone, the readings in the back were usually less than 3 mG at seat level, diminishing upward to about 0.4 mG at head level. Average readings on the seats in the back under different driving conditions were around 2.8 mG. 
   
   
5. At the surface of the back seats, the highest AC magnetic fields were found to be oriented perpendicular to the ground, but this may have been simply because the pickup coils could be held closer to the seats in that position. 
   
   
6. At 60 Hz (actually between 54 and 66 Hz), levels were less than 1 mG at the places of highest exposure, on the rear seats.
   
   
7. For VLF magnetic fields (2-300 kHz), there was a regular fluctuation between approximately 0.6 and 12 mA/m (0.0075 – 0.15 mG) when the gasoline engine was engaged. Levels were 4-6 mA/m (0.05 – 0.075 mG) when operating on the electric motor alone.  
   
   
8. There was a less than 0.3 mG, constant, approximately 6 Hz pulse coming from the bottom of the door frames, on the left side only. 
   
   
9. There was an area of low-to-medium power density (depending on your point of view – it was less than 1 uW/cm²) high frequencies (> 10 MHz), apparently originating from the smart key slot, on the dash to the right and below the steering wheel. It extended 14 or 15 inches toward the driver's seat, where it diminished into the low nanowatt range. The driver's knees and right hand would be exposed to it. It might affect Trifield readings, and may be similar to readings for smart-key systems in other types of vehicles. 
   
   
10. There was an approximately 8 kV static electric field on the driver's door arm rest. 
    
    
11. The NY Times article's statements about Trifields and other AC gaussmeters not measuring DC fields is misleading – that “the meter is set up to test alternating current fields, whereas the power moving to and from a hybrid vehicle's battery is direct current.” Direct current motors, when they're spinning, put out alternating fields as well as DC fields, which are detectable on an AC gaussmeter when their rpms are within the meter's frequency range. I'm not sure what the rpm ranges are on hybrid electric motors, but when testing it's important to test with a meter that at least goes into the low VLF range (2 kHz), and with a VLF meter as well. 
    
    
12. Toyota's statement that the 50-60 Hz fields in the Prius are comparable to conventional gasoline-powered vehicles appears to be correct, but fields are higher at other extremely-low-frequencies on the back seats.  

Recommendations 

Hartman’s recommendation for Prius owners is to provide some kind of comfortable elevation above the back seats for long trips, and avoid seating children in the back for very long unless they're in a car seat that significantly elevates them above the seat – preferably the center seat, which is already slightly above the side seats and safer from side impacts.  

It's also best to avoid hard acceleration. There's a general reverse correlation between fuel economy and magnetic field exposure – the higher the mpg at any moment (which can be constantly displayed on the center touch screen), the lower the magnetic fields.  

Additionally, he notes you may also receive less high-frequency exposure if you keep the smart key inserted in the slot on the dash while driving, instead of in your pocket or purse, so the system doesn't have to keep "looking for it." However, he was unable to confirm this during his testing, and it's not certain that the high frequencies around the smart key slot were in fact from the smart key system. 

Some May Be More Sensitive Than Others 

All of that said, I still believe you need to use your own best judgment and not ignore the issue if you find that you are sensitive or “allergic” to electromagnetic fields – a health concern that is on the rise and gaining more attention.

And some of the concern over high EMF levels in hybrids comes straight from drivers who claim that their hybrids make them ill.

One such case is Neysa Linzer, who concluded that her new Honda Civic Hybrid caused her elevated blood pressure, and that EMFs were the reason for her falling asleep while driving on three occasions.

Naturally, if you’ve already been diagnosed with Electromagnetic Hypersensitivity Syndrome (EHS), or experience pain or other symptoms while exposed to electrical appliances, computers, wireless internet or cell phones, you will likely need to pay particular attention to potential exposures in your car as well, no matter how low. 

For others, however, Hartman’s findings may offer some reassurance that choosing a hybrid is still a viable option, although other alternatives that may be far better are showing up on the horizon, such as cars that run on compressed air. No word yet on whether or not they too produce questionable levels of EMF…