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#35317 03/07/04 11:59 PM
Joined: Jan 2004
Posts: 615
J
Jps1006 Offline OP
Member
I have a customer who owns a three story commercial building with a couple of cell attena (sp?) on the roof. I have to go up there every now and then to change light bulbs. When they were first put in there was a sign that said "warning: FCC restricted area", but that sign has since fallen off and blow away I think. It had some article # on it.

Are any of you familiar with the saftey issues of exposure to RF? Are there any saftey precautious I can take when up there?

Something else I thought as I drove past a bucket truck next to a tower with a guy up there; When people are up there servicing those, do they have to shut the tower down or do they work right there with all that RF?

Joined: Dec 2003
Posts: 886
H
Member
It's not all that much RF. I don't remember exactly what these are limited to but it's something like 10 watts ERP. Your temporal lobe gets more exposure from your cell phone antenna while you are talking than you would on the ground next to the tower.

-Hal

Joined: Jan 2004
Posts: 615
J
Jps1006 Offline OP
Member
The location I am refering to has the antenna mounted at roof height. you can stand right next to it. There is a sign that says do not stand any closer than 7 feet, and avoid standing directly in front, but I am a little leary about being up there at all. If I'm up there for more than twenty minutes, I get a weird headache. To be honest I don't know if its a real headache or (as an MD would call it) psycosymatic, meaning I fool myself into having one because I expect it.

I'm curious if anyone else has any experience with cell towers or antenna.

Joined: Apr 2002
Posts: 2,527
B
Moderator
Apparently the guy who pioneered microwave cooking accidentally discovered the heating effect from RF when repeatedly finding very soft candy bars in his pockets. I wonder if that's still a good indicator of too much of a 'dose'?

[I guess that is not as bad as one of Edison‘s engineers working with early X-rays. They say that he had huge blisters on his skin and most of his hair had fallen out from 'personal' research.]




[This message has been edited by Bjarney (edited 03-08-2004).]

Joined: Dec 2003
Posts: 886
H
Member
The sign is probably an OSHA requirement. Still, I wouldn't make a "career" out of being in front of those antennas but I doubt it will cause you any harm.

Just by your questions I can tell you are spooked by this. I seriously doubt that your headaches have anything to do with the RF but more from the stress of worrying about it.

This isn't microwave and it isn't x-ray. Keep in mind also that it is not permitted to object to the location of cell sites on the basis of health concerns since no danger has been proven.

Like I said above, I would be more concerned with long term use of a cell phone itself if I were going to worry about health risks since such use results in a higher exposure than what you are talking about.

-Hal

[This message has been edited by hbiss (edited 03-09-2004).]

Joined: Jan 2004
Posts: 66
C
Member
Im guessing the "FCC restricted area" sign had to do with FCC laws and NOT health concerns. if someone who was unfamiliar with the equipment were to gain access to the antenna, it is possible that they could adjust or damage it in such a way that other communications would be disrupeted, which would violate FCC laws and put the owner of the equipment in a position to recive substatial fines.

Joined: Sep 2001
Posts: 806
N
Member
The FCC does set recommended exposure levels for RF radiation. At cellular frequencies (800 MHz band), the recommended maximum exposure for the general public is 580 microwatts per square centimeter (µW/cm2).

If you work around this equipment, you should be familiar with the exposure guidelines. A good overview is available right on the FCC's own website:
http://www.fcc.gov/oet/rfsafety/cellpcs.html

Joined: Dec 2003
Posts: 886
H
Member
Thanks NJwirenut. I was hoping you would jump in here with that information. My recall is a little fuzzy.

-Hal

Joined: Jan 2004
Posts: 615
J
Jps1006 Offline OP
Member
Thanks guys.

You're right Hal, being next to those antenna does freak me out a little. Over the years you hear things and don't know which ones are true and which ones aren't.

The one that stuck with me was when I got my first flip phone back around 1992. Talking to some guy whose cousin's brother-in-law knows somebody who works for an independant lab that was commissoned by the big "M" to put to rest some of the uncertainy about the health issues of the small portable phone with the antenna 3/4" from your brain. Well the way the story goes is that after dumping tons of money into the study, the results were never released. Due to confidentiality agreements that was all he could say, except that he would NEVER use one nor will he ever let his children. True or not? I don't know, but it sticks with me.

Thanks NJwirenut. looks like great info. I'll come back tonight and read that thing through.

Joined: Aug 2001
Posts: 7,520
P
Member
This is an area where the effect of the inverse-square law is not widely understood. Basically, it means that every time you double your distance from an energy source, the strength decreases four-fold.

In simple terms, let's say that 1W ERP into an antenna gives a certain field strength measured at a distance of 2 inches from the antenna.

Now if you increased the power to even as much as 100W ERP, the field strength measured at a distance of as little as 5 feet would already be down to about 10% of that measured at 2" with the 1W source.

It really is that much difference, and something which the cell-tower protesters don't seem to realize (and somewhat ironic that they're getting much greater exposure from their own cell-phones!).

UHF TV towers broadcast at frequencies approaching those used by cell-phones, and it's quite normal for the transmitter to be operated on reduced power when maintenance is being carried out in the vicinity of mthe antennas. But we're talking about ERP here which can be many hundreds of kilowatts, not just a few watts of the typical cell-tower (the main transmitter serving London is 1MW ERP, for example!).


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