RF exposure to Humans, and much more.


Someone asked me if I would do a blog on the effects of RF on the human body, specifically the tower climber. This is not an easy thing to research because you have to narrow down the specifics. Now, this blog is all over the place, I am sorry, I was trying to explain too much. The bottom line is that RF will heat up the body, inside and out, if exposed to too much power or for too long to some power. Read on if you need to know more. (Like me on Facebook when you can!)

Let me explain, most reports talk about EMF and RF. EMF could cover anything from the 60Hz in your house to high frequency RF. EMF could be anything that has some type of AC. By the way, your voice is a form of EMF, if it goes through a speaker? Go to http://www.emfandhealth.com/EMFExplained.html  or http://www.safespaceprotection.com/overview-electromagnetic-fields.aspx for more information on EMF, this will explain the ranges. (If you don’t know the difference between AC and DC, learn by going here http://www.diffen.com/difference/Alternating_Current_vs_Direct_Current .) I was trying to get the field down to RF only. Then I had to separate the reports about cell phones next to your head because this is a main subject for research. Obviously most people just don’t care because how many people have phones next to their brains? I would say 99% of people. How many people use Bluetooth anything on their head, again, probably about 60% of people that have high-tech in their life.

I am going to break it down RF exposure the best I can for you. Remember that I don’t have any type of medical degree and if I did someone would have a different opinion. Here is my summation from what I have read. This isn’t news but RF exposure can heat up the human body. Now, let’s break that down to discuss several factors. You would need to look at the frequency and power. It’s how they affect water. Our body will react the same as water. For instance, let’s use a microwave oven as a comparison because 2.4GHz at high power will boil water but at lower power you would call it Wi-Fi and use it to connect our smart phone to our home router to save data charges. Compare power to heat on a stove, if the burner is set on low it will take a long time to cook but on high it will burn quickly.

Now, most of the documentation is old. When cell phones were new they used higher power, anyone remember the bag phone? It would run at 3 watts. Public safety handhelds used to be over 10 watts if they had a power source. Remember when you would see an officer stand next to his car and talk on his radio? Well, when it was keyed chances are good he was transmitting at 30 or more watts while standing next to the car, less than 5’ from the antenna. Just think about how things were about 15 or more years ago. Even this could have an effect on the body if you were exposed to it for too long. Things have changed now because the digital age allows us to do so much more with lower power. Less power means less effects on the human body. Just like lower heat on a stove will not burn us as fast. So things are better but it’s still a good idea to be safe and cautious. Here in the states we are fortunate to have these warning but to those of you doing a lot of work in Arica, lookout. Be smart by being aware of what is on the tower and where you will be climbing. Wear a sensor if at all possible.

Now, today, cell phones are very low power and smart, so they only jump in power when they know they have a weak signal from the tower. Also, we use Wi-Fi at home for data, so the phone is talking to a unit in our apartment or house. We don’t talk as much on the cell phones now because we text or use and app so the phone isn’t up to our head as much. Even if we make a call we may use a wired headset or a Bluetooth. Now, Bluetooth is usually 2.4GHz right against our heads, but it really doesn’t have enough power to penetrate the skin, or so they say. But now I am off topic, let me get back to the RF on the towers. The body can and will absorb RF, just like it would sunlight UV rays. You may not burn right away but if exposed to it long enough you may have problems, just like sunburn or worse. Long enough and to enough power could cause problems.

RF can be broken down into several areas. Let’s look at radio spectrum taken from Wikipedia, http://en.wikipedia.org/wiki/Radio_frequency in this chart below. I added the column to the right to help you understand where each range falls.

Frequency

Wavelength

Designation

Abbreviation[5]

 

3 – 30 Hz 105 – 104 km Extremely low frequency ELF

 

30 – 300 Hz 104 – 103 km Super low frequency SLF

 

300 – 3000 Hz 103 – 100 km Ultra low frequency ULF

 

3 – 30 kHz 100 – 10 km Very low frequency VLF

30 – 300 kHz 10 – 1 km Low frequency LF

 

300 kHz – 3 MHz 1 km – 100 m Medium frequency MF  
3 – 30 MHz 100 – 10 m High frequency HF  
30 – 300 MHz 10 – 1 m Very high frequency VHF

 

300 MHz – 3 GHz 1 m – 10 cm Ultra high frequency UHF

 

3 – 30 GHz 10 – 1 cm Super high frequency SHF

 

30 – 300 GHz 1 cm – 1 mm Extremely high frequency EHF

300 GHz – 3000 GHz 1 mm – 0.1 mm Tremendously high frequency THF  

Another chart from Wikipedia, http://en.wikipedia.org/wiki/Radio_spectrum

Band name

Abbreviation

ITU band

Frequency
and
wavelength in air

Example uses

Tremendously low frequency

TLF

 

< 3 Hz
> 100,000 km

Natural and artificial electromagnetic noise

Extremely low frequency

ELF

 

3–30 Hz
100,000 km – 10,000 km

Communication with submarines

Super low frequency

SLF

 

30–300 Hz
10,000 km – 1000 km

Communication with submarines

Ultra low frequency

ULF

 

300–3000 Hz
1000 km – 100 km

Submarine communication, Communication within mines

Very low frequency

VLF

4

3–30 kHz
100 km – 10 km

Navigationtime signals, submarine communication, wireless heart rate monitorsgeophysics

Low frequency

LF

5

30–300 kHz
10 km – 1 km

Navigation, time signals, AM longwave broadcasting (Europe and parts of Asia), RFIDamateur radio

Medium frequency

MF

6

300–3000 kHz
1 km – 100 m

AM (medium-wave) broadcasts, amateur radio, avalanche beacons

High frequency

HF

7

3–30 MHz
100 m – 10 m

Shortwave broadcasts, citizens’ band radio, amateur radio and over-the-horizon aviation communications, RFIDOver-the-horizon radar,Automatic link establishment (ALE) / Near Vertical Incidence Skywave(NVIS) radio communications, Marine and mobile radio telephony

Very high frequency

VHF

8

30–300 MHz
10 m – 1 m

FMtelevision broadcasts and line-of-sight ground-to-aircraft and aircraft-to-aircraft communications. Land Mobile and Maritime Mobile communications, amateur radio, weather radio

Ultra high frequency

UHF

9

300–3000 MHz
1 m – 100 mm

Television broadcasts, Microwave ovenMicrowavedevices/communications, radio astronomymobile phoneswireless LANBluetoothZigBeeGPS and two-way radios such as Land Mobile, FRS and GMRS radios, amateur radio

Super high frequency

SHF

10

3–30 GHz
100 mm – 10 mm

Radio astronomy, microwave devices/communications, wireless LAN, most modern radarscommunications satellites, satellite television broadcasting, DBS, amateur radio

Extremely high frequency

EHF

11

30–300 GHz
10 mm – 1 mm

Radio astronomy, high-frequency microwave radio relay, microwaveremote sensing, amateur radio, directed-energy weaponmillimeter wave scanner

Terahertz orTremendously high frequency

THz or THF

12

300–3,000 GHz
1 mm – 100 μm

Terahertz imaging – a potential replacement for X-rays in some medical applications, ultrafast molecular dynamics, condensed-matter physicsterahertz time-domain spectroscopy, terahertz computing/communications, sub-mm remote sensing, amateur radio

Broadcast is high power, or at least they used to be, not with digital it is a bit lower but they still need the power to reach all the free TVs out there. You know, all the people that don’t have cable or dish. If you are working in broadcast you know that RF from any of these will heat up your skin, maybe burning you from the inside before the outside. This is a major issue but it’s obvious to most climbers. They have RF sensors to alert them of any issues. They should also coordinate with the broadcast engineer to turn down power to a safe level before climbing around the antenna. This is why a lot of work was done early n the morning. That has changed because now the local news is a money-maker, so you need to be sure to have the news on at full power. Radio, same rules apply really. So in this case, high power RF is very, very bad on the body. Be smart, be cautious, and plan your climbs with the local engineer. You may need to wear an RF suit, RF Safety Solutions has a nice example here, http://www.rfsafetysolutions.com/RF%20Radiation%20Pages/RF_Protective_Garments.html if you would like to see a climber wearing one. They also show the Narda climber alert, the sensor to alert you about high concentrated RF that could be harmful to your body.

Let’s talk RF Personal monitors. They need to be worn on the outside. They usually have a light alarm, a beeping alarm, and come may vibrate. They are made for different frequencies. I don’t think one sensor will alert you to everything. You need to be aware of what you are working around. Broadcast is powerful, but you may be around a lot of the cell frequencies or microwave dishes, be alert of what you are getting into. This is good for installation but if you are doing service work you may not know the tower you are getting on. This will be a problem. So be cautious when you arrive, Try to make an evaluation and if possible talk to the local engineer or someone who knows that tower, if not use your eyes to see what is on the tower. Common sense will help and some research on your part.

RF exposure could come from any frequency, you need to be aware of how it could harm you. I found the lower frequencies don’t tend to bother you that much but the microwave frequencies can be a problem. The lower the power the better, make sure you know what you are climbing around. Back when paging was a big deal there was a lot of high power at the sites, but now paging has really thinned out and broadcast has dialed it back and land mobile radio is fading so power levels at most tower sites is dropping. This doesn’t mean you should take it lightly, if you can use a sensor at a busy site, it’s a good idea. If you’re climbing and you feel very, very warm in the winter, maybe it’s time to get down. Use your common sense, be aware of what is going on around you, and don’t be stupid!

If you’re working on the ground at a site then the FCC put out some guidelines at http://www.fcc.gov/guides/human-exposure-rf-fields-guidelines-cellular-and-pcs-sites if you would like to see what they think is safe. This is taken from their site, “In the case of cellular and PCS cell site transmitters, the FCC’s RF exposure guidelines recommend a maximum permissible exposure level to the general public of approximately 580 microwatts per square centimeter. This limit is many times greater than RF levels typically found near the base of cellular or PCS cell site towers or in the vicinity of other, lower-powered cell site transmitters. Calculations corresponding to a “worst-case” situation (all transmitters operating simultaneously and continuously at the maximum licensed power) show that, in order to be exposed to RF levels near the FCC’s guidelines, an individual would essentially have to remain in the main transmitting beam and within a few feet of the antenna for several minutes or longer. Thus, the possibility that a member of the general public could be exposed to RF levels in excess of the FCC guidelines is extremely remote.”

The FCC has an RF safety website, http://www.fcc.gov/encyclopedia/radio-frequency-safety that may help you understand the maximum exposure limit that RF may have on people.

RF Safety Solutions has a good presentation available at http://www.sbe.org/sections/documents/RFSafetyTrainingHandout.pdf that may be worth taking some time to review.

Credits:

FCC: http://www.fcc.gov/encyclopedia/radio-frequency-safety

FCC: http://transition.fcc.gov/oet/rfsafety/background.html

American Academy of Environmental Science: http://aaemonline.org/emf_rf_position.html

OSHA: https://www.osha.gov/SLTC/radiofrequencyradiation/

RF Safety Solutions: http://www.rfsafetysolutions.com/RF%20Radiation%20Pages/Biological_Effects.html

Health Physics Society: http://hps.org/hpspublications/articles/rfradiation.html

World Health Organization: http://www.who.int/peh-emf/en/

Fred Medrano, Health and Human Services Director, City of Berkley, 2006: http://www.ci.berkeley.ca.us/citycouncil/2006citycouncil/packet/071106/2006-07-11%20Item%2029%20Radio%20Frequency.pdf

American Tower: http://www.americantower.com/Assets/uploads/files/PDFs/RF%20Safety%20of%20Cellular%20Towers.pdf

Connecticut Dept of health http://www.ct.gov/dph/lib/dph/environmental_health/eoha/pdf/cell_phones.pdf

RF Exposure on Humans outlineWEBSITETAG (2)

14 comments

  1. Good work Wade. When regular consumer is using cellphone, 99.9989% of the exposure is coming form his phone, and the rest 0.001% is coming from the downlink (tower 2% and wifi 98%).

    And what is very worrying; the set limits 1.6w/kg (USA) are well passed, when the phone is 0-10mm distance from the body of the user. Check this with Quanta Monitor (free).

    Liked by 1 person

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    Like

  3. Wade, Thanks for a good article the more info we can provide those working in the industry hopefully the safer they will be in their daily “work” environment. RSI is always open to assist anyone in their knowledge level of RF. We have live or online classes and our website has a wealth of information available. http://www.rsicorp.com Which leads me to the fact we have just recently partnered with a company to provide a new line of Personal Protection Monitors to the US. Feel free to contact me at 888-830-5648.

    Liked by 1 person

  4. “By the way, your voice is a form of EMF, did you know that?”

    In what way is the human voice a form of EMF? I mean, yes, you can measure the frequency of sound, but it’s not electromagnetic, right?

    Like

    • First, thanks for reading the article! Actually it is a form in the fact of the vibrations and the frequency, it actually doesn’t have the electro or magnetic part unless heard through a speaker. So when you listen on your cell phone, guess what, EMF. It’s a stretch, I know. If you think I should pull that, maybe you’re right, I don’t want to mislead anyone.

      Like

      • Yeah I’d pull that stuff if I were you… Not everything that vibrates is EMF. EMF applies only to the electromagnetic spectrum (i.e. light) and a vibrating string or an oscillating speaker produce pressure waves in the air travelling at the speed of sound, not electromagnetic waves travelling at the speed of light – for that you need the movement of charged particles.

        I’d also remove the first 4 entries in the “Added by Wade” column in your table that all refer to sound as well – none of that is related to EMF. Having that kind of stuff mixed in just hurts the credibility of the rest of your article.

        Like

      • I’ll edit it. Those parts on the chart that were added by me was to give old time RF guys a reference, like the Ku band and the old TV frequencies. They were all used at one time. I will take them out to make it easier to understand. I will change the voice to state that it comes through a speaker.

        Like

  5. Wade,

    Thanks for covering this topic. I’d like to add a few bullet points:
    1. on rooftop or tower sites- make sure the site / sector is inactive before you begin working on it
    2. wear a personal RF monitor. if it beeps, you’re not safe
    3. protect you eyes. they are most sensitive to RF energy
    Ted Teofilak
    President
    RF Consulting Services Inc

    Like

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