smart entry..health hazzard???

She definitely worries too much! Someone will correct me if I'm wrong, but I believe it on infrared frequencies just like all of your remote controls. Please don't tell us she also worries about remote controls... ;-)

No, it's definitely RF. If it were infrared, it would have to be line of sight. Ditto for fobs where you push buttons.

Yeah, silly me. I realized several hours later that I had to have been wrong when it hit me that IR couldn't work when it's in my belt pouch or pocket. Then I read in the manual that it's electro magnetic.

It's a radio frequency transmitter, but a very low-powered one. The thing lasts for over a year on a watch battery. There are thousands of low-level radio sources in today's world that are more powerful. The keyfob has a range of a couple of feet, far less than a garage door opener, cordless phone, walkie-talkie, baby monitor, etc. Shorter range than bluetooth even.

And it hasn't been proven that radio-frequency energy causes cancer anyway. Ask the 88-year-old ham operator that lived on top of Mt. Wilson for 35 years as the engineer who kept KTLA-TV and several 50-KW radio stations on the air, retiring at 74. He even climbed the towers live to change the bulbs. Healthy and sharp as a tack.

Well, silledad, I have to confess I got a good chuckle from your post. I thought that only my wife came up with questions like that!

Fact is, Toy wants nothing more than success for the Prius and it would be unlikely that they'd have anything very dangerous in the package!

Cordially,

Larry Morphew Proudly driving an '04 Prius

There is no epidemiological evidence for cell phone - brain cancer risk, and there would be far less exposure for the smart entry system than for a cell phone. The concern with cell phones mainly sprang from the position of the antenna, right beside the head. Some people have brains there, but not all of us ;-) Anyway... the very low on-time of the entry system means essentially no risk.

I took RF safety training last year at work, and the instructor explained the only recognized risks associated with RF are from internal heating.

Mike

Ha, consider the 1 Megawatt (That's right, one million watts) being transmitted from the top of Queen Ann Hill in Seattle. Or the RF from all of those sats above. Or any other TV transmitter.

Tell her not to worry, the RF output is very low.

Consider the inverse square law.

Now what's your point ?

Much less threat than a cell phone:

1. Almost certainly the fob is not next to her head.
2. The fob transmits only for a very short time, one burst when it gets within range of the car (which transmits a burst every 10 seconds or so calling to the fob).
3. the fob and car transmit much less power than a cell phone. Their ranges are only a few feet.

Anyone concerned about the dangers of cell phones and the like should stop smoking, exercise, lose weight, never drive, not fly long distances, and not live at an altitude above 2000 feet or so.

Ah, a smart guy..

I understand the relationship between radiated power and distance, as we are in the embedded wireless business.

Given a megawatt omnidirectional transmitter that is 1000' away vs. another that is one inch away, the equiv. energy would be about 7 mW. Since the duty cycle of a keyfob is perhaps .01, then the megawatt transmitter has the equiv. output of .7 watts.

My original point is clear to most, I would think: If those that are not living near megawatt transmitters for 20 years or more aren't showing signs of illnet, then a 10 milliwatt keyfob shouldn't be of concern.

In fact, the FCC has a chart for permissible field strengths for public exposure, with a separate curve for trained worker exposure. The trained worker exposure is 5 times higher across the spectrum as it is assumed the worker will take steps to manage the risk and minimize exposure, while the public may sit in the field and have a picnic. The chart is fairly simple, with only a few bends in the "curve" to take into account the wavelength in comparison to the size of body parts. Again, the only recognized risk is from heating, and the power levels are balanced against the body's ability to regulate its blood temperature. In addition, the exposure can be averaged over a 30 minute period for public settings, so the total energy from a keyfob averaged over half an hour is miniscule indeed.

More info is available at

- one of the best non-subscription online sources. My father was a radar tech in WW II (he had a Marine with a .45 assigned to him to protect our country's secrets in the event of imminent capture). He told me of warming himself in front of radar dishes, and that the Army told him he would be sterile as a result. My four brothers and I were born after that, so I guess he wasn't all that sterile.

Mike (Sr. Communication Field Engineer for an electric utility)

Reminds me of when I was in high school. I built a huge Tesla coil using radio station transmitter tubes and a 3KV / 1A transformer. It would light up a fluorescent lamp tube in my hand in the next room! Sometimes I'd have to leave my favorite gadget, like to go to the shoe store and wiggle my toes in the x-ray machine.