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Question #: 263

Question: WHAT ARE THE HEALTH RISKS OF LIVING NEAR A CELL PHONE TOWER?

Current Solution

There is very little radiofrequency (RF) energy exposure to people inside a building from a cellular base station located on its roof. There are several reasons for this. First, the transmitters operate at low power levels. Second, the antennas are normally mounted near the edges of the roof and are aimed away from the building. Third, most cellular transmitters use "high gain" or panel antennas. Such antennas transmit most of their energy in a narrow beam (in the vertical direction) from their front surfaces, away from the building. They radiate very little energy downwards towards the roof or backwards from their rear surfaces. Finally, building materials absorb a significant fraction of the RF energy passing through them. As a result, the RF signal levels at any location inside the building are invariably low and far below safety limits. The situation might be different in some locations on the roof itself. RF signal levels close to (within a few feet) and directly in front of cellular base station antennas can easily exceed safety limits. Some precautions are needed to prevent people from walking directly in front of the antennas while they are transmitting. This applies also to paging and other systems that use rooftop antennas, some of which transmit at higher power levels than many cellular base stations. Kenneth R. Foster, Ph.D.

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Other Possible Solutions to this Question

  • ARE LIVING QUARTERS IMMEDIATELY BELOW ROOF-TOP CELLULAR TELEPHONE ANTENNA/TRANSMITTERS HAZARDOUS?

    There is very little radiofrequency (RF) energy exposure to people inside a building from a cellular base station located on its roof. There are several reasons for this. First, the transmitters operate at low power levels. Second, the antennas are normally mounted near the edges of the roof and are aimed away from the building. Third, most cellular transmitters use "high gain" or panel antennas. Such antennas transmit most of their energy in a narrow beam (in the vertical direction) from their front surfaces, away from the building. They radiate very little energy downwards towards the roof or backwards from their rear surfaces. Finally, building materials absorb a significant fraction of the RF energy passing through them. As a result, the RF signal levels at any location inside the building are invariably low and far below safety limits. The situation might be different in some locations on the roof itself. RF signal levels close to (within a few feet) and directly in front of cellular base station antennas can easily exceed safety limits. Some precautions are needed to prevent people from walking directly in front of the antennas while they are transmitting. This applies also to paging and other systems that use rooftop antennas, some of which transmit at higher power levels than many cellular base stations. Kenneth R. Foster, Ph.D.

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    ARE LIVING QUARTERS IMMEDIATELY BELOW ROOF-TOP CELLULAR TELEPHONE ANTENNA/TRANSMITTERS HAZARDOUS?

  • I'M SEARCHING FOR INFORMATION ABOUT THE HEALTH RISKS OF CELLULAR ANTENNAS' RADIATION. I NEED SCIENTIFIC (SCIENTIFIC PAPERS IN JOURNALS) THIS.

    Cellular telephone base stations are low-powered radiofrequency (RF) transmitters which operate at around 850-900 or 1800-1900 MHz (depending on the technology and region of the world). RF energy in a similar frequency range is used by many other technologies such as microwave ovens, UHF television, other communications systems, and radar. Health and safety issues related to RF energy have been studied for many years and there is an immense literature on the subject. Here are some sources that review health and safety issues related to RF energy from cellular base stations.

    A fact sheet published by the World Health Organization. There is also a Spanish version available on the WHO EMF website.
    Also see the IEEE EMBS Committee on Man and Radiation Report. Other reports are available through its website.
    The International Commission on Nonionizing Radiation Protection (ICNIRP) has published a lot on health and safety of RF energy. See its website. The ICNIRP published an article that describes the ICNIRP exposure limits for RF energy and their scientific rationale. See "Guidelines for Limiting Exposure to Time-Varying Electric, Magnetic, and Electromagnetic Fields (up to 300 GHz)," Health Physics Vol. 74, No 4, pp 494-522, 1998.
    A very detailed assessment of the scientific evidence related to health and safety of mobile telephones and base stations is in the recent (May 2000) report by the Independent Expert Group on Mobile Phones (IEGMP) titled "Mobile Phones and Health" This study concludes "the balance of evidence to date suggests that exposures to RF radiation at levels below [international exposure guidelines] do not cause adverse health effects to the general population" but that "there may be biological effects at exposures below those guidelines." Public exposure to RF energy from cellular base stations is invariably far below the ICNIRP exposure guidelines.

    Kenneth R. Foster
    Professor, Bioengineering
    University of Pennsylvania

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    I'M SEARCHING FOR INFORMATION ABOUT THE HEALTH RISKS OF CELLULAR ANTENNAS' RADIATION. I NEED SCIENTIFIC (SCIENTIFIC PAPERS IN JOURNALS) THIS.

  • what are the dimensions of the pillow blocks for the round linear guide rails?

    Are you referring to this part?: https://www.buildyourcnc.com/item/mechanical-rails-linear-ball-bearing-block

    Additional Information:
    yes that block

    Additional Information:
    I created a drawing of the linear bearing guide block that shows the dimensions that you need for mounting. Specifically, the mounting spacing is 1.38 inches both axially and transversely.

    You can see the drawing on the linear bearing guide block page here: https://www.buildyourcnc.com/item/mechanical-rails-linear-ball-bearing-block

    And directly here: https://www.buildyourcnc.com/images/20mm%20bearing%20guid%20block%20for%20round%20rail-800.JPG

    If you need further information, please let me know. Thanks.

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    what are the dimensions of the pillow blocks for the round linear guide rails?

  • WHAT EFFECTS OF CELL PHONES WILL THERE BE ON YOUNGER PEOPLE OPPOSED TO OLDER PEOPLE? THE AGE OR STATE DEVELOPMENT EFFECT DANGERS A PHONE?

    Physical size of the subject affects the fraction of the total radiofrequency energy that is absorbed in the body. To account for this known effect, the maximum permissible exposure standards for radiofrequency energy were set for the worst-case condition, that is assuming the body size for maximal absorption at a given frequency. Thus the maximum permissible exposure standards are fully protective for bodies of different sizes. For more detailed information, see the answers and the cited references to questions 79, 109, 694, and 893 under the Nonionizing Radiation section of the Health Physics Society Ask The Expert Web page. Gary H. Zeman, ScD, CHP

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    WHAT EFFECTS OF CELL PHONES WILL THERE BE ON YOUNGER PEOPLE OPPOSED TO OLDER PEOPLE? THE AGE OR STATE DEVELOPMENT EFFECT DANGERS A PHONE?

  • What are the technical details/dimensions for the 20mm Linear Guide Rail?

    For our Hiwin rail, you can find the specifications at this URL:
    https://www.buildyourcnc.com/item/mechanical-rails-HIWIN-Linear-20mm-Guide-Rail

    For our standard round linear rail, you can find the specifications at this URL:
    https://www.buildyourcnc.com/item/mechanical-rails-linear-guide-rails-20mm

    Additional Information:

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    What are the technical details/dimensions for the 20mm Linear Guide Rail?

  • What is the width and height of the round Linear Guide Rail 20mm? Specs are not listed on the product page.

    I just updated the Linear 20 mm Round Rail product page to reflect these measurements. https://www.buildyourcnc.com/item/mechanical-rails-linear-guide-rails-20mm

    For your convenience, here they are:

    Overall Height of Rail and Base: 37 mm (1.46 in)

    Width of Base: 45 mm (1.77 in)

    Mounting Holes on Center Widthwise: 30.226 mm (1.19 in)

    Mounting Holes on Center Lengthwise: 150 mm (5.9 in)

    If you need further information, please don't hesitate to ask be responding to this FAQ. Thanks.

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    What is the width and height of the round Linear Guide Rail 20mm? Specs are not listed on the product page.

  • THERE HAS BEEN A CELL PHONE BASE INSTALLED IN THE FIRE TOWER. PANELS ARE VERTICAL AND LOCATED ABOUT 75 FEET AT TOP OF UNLIKE SOME TOWERS I HAVE SEEN NO ROUND DISKS BEAMING LIGHTS. NIGHT, TOWER MATERIAL DARK. DOES THIS MAKE ANY DIFFERENCE RELATED HEALTH ISSUES WITH RF EXPOSURE IT POSSIBLE RECEIVE-ONLY TRANSMITTER ?

    There has been a cell phone base installed in the fire tower. The panels are vertical and located about 75 feet at the top of the tower. Unlike some towers I have seen there are no round disks and no beaming lights. At night, the tower and cell phone material are dark. Does this make any difference in any related health issues with RF exposure and is it possible the tower is a receive-only transmitter ?

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    THERE HAS BEEN A CELL PHONE BASE INSTALLED IN THE FIRE TOWER. PANELS ARE VERTICAL AND LOCATED ABOUT 75 FEET AT TOP OF UNLIKE SOME TOWERS I HAVE SEEN NO ROUND DISKS BEAMING LIGHTS. NIGHT, TOWER MATERIAL DARK. DOES THIS MAKE ANY DIFFERENCE RELATED HEALTH ISSUES WITH RF EXPOSURE IT POSSIBLE RECEIVE-ONLY TRANSMITTER ?

  • What is the phone number of sales?

    For sales, please call 281-815-7701 and follow the prompts of the automated message.

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    What is the phone number of sales?

  • What is the weight of the linear guide rails?

    This is a good question. I will weigh this part when I get into the office on Monday.

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    What is the weight of the linear guide rails?

  • What is the cost of the Planet-CNC software? Do you sell it?

    The base price for planet cnc is 69 Euros, which translates to $85.85 dollars. Can be found here (http://www.planet-cnc.com/index.php?page=shop)

    Additional Information:


    Additional Information:

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    What is the cost of the Planet-CNC software? Do you sell it?

  • What are the outside dimensions of the Laser Mirror Mounts?

    The outside dimensions for the laser mirror mounts found here:
    https://www.buildyourcnc.com/item/Laser-Component-Mirror-Mount-20mm
    and here:
    https://www.buildyourcnc.com/item/Laser-Component-Mirror-Mount-20mm

    Are 55.88mm (2.2") x 55.88mm x 44.5mm (1.76") thick. This includes the set screws that protrude on the back and the mirror holder that protrudes on the front. Not including the protrusions, the thickness is 22.23mm (0.875")

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    What are the outside dimensions of the Laser Mirror Mounts?

  • WHAT SOFTWARE CAN BE USED WITH THE BLACKTOOTH LASER CUTTER?

    If you take the standard parallel cable BoB (Break Out Board), then you will need control software (Mach 3 or EMC2) and CAM software to make your G-Code (such as CamBam). Personally I use CamBam and Mach 3, they work beautifully but don't expect to turn them on and know how they work out of the box. Give yourself a few weeks to get familiar with the basics. CamBam is VERY powerful software for it's price. I'm surprised how much I keep learning on what I can do with it...I highly recommend it if you want as much control as possible.

    Mach 3 + CamBam as a bundle costs $310. EMC2 will give you a free replacement for Mach 3 and is exclusively for Linux.

    If you use the USB BoB, it will cost an extra $75 + $75 for the software. This is an all-in-one package so no need for Mach 3 or CamBam.

    For etching rasters (jpeg, bmp, tiff, non-vectors, photos), I highly recommend PicEngrave. It has been a labor of love for the past 9 years and John has done a wonderful job with it. It easily compares in quality compared to software that is in the $200-$300 range. John's software runs $40 and can be found here: http://picengrave.com/ (don't let the modest website fool you, this stuff can do amazing things). DotG and the Mach3 engrave plugin are two other options and instructions can be found on Dustans page in the gallery on buildyourcnc.com website.

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    WHAT SOFTWARE CAN BE USED WITH THE BLACKTOOTH LASER CUTTER?

  • WHAT SOFTWARE CAN BE USED WITH THE BLACKTOOTH LASER CUTTER?

    I would say mechanically, between the official build instructions, Warren's awesome blog (http://blacktoothlaser.blogspot.com/) and the tips in the forum, the blackTooth is a really simple build. The challenges come with electronics and software. There's a number of different ways to drive the laser and motors. A decent understanding of electronics and computers is a must.

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    WHAT SOFTWARE CAN BE USED WITH THE BLACKTOOTH LASER CUTTER?

  • What brand and/or country of origin are the stepper motors?

    The stepping motors we sell are from China.

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    What brand and/or country of origin are the stepper motors?

  • What are the noise levels of the 1.5 Kw and 2.2Kw spindles?

    The noise level of the 1.5 kW and the 2.2 kW are very similar. The noise level is considerably quieter than typical routers. I am going to add sound db levels to this FAQ a bit later.

    Additional Information:
    The db (decibels) reading for the spindle is 70 and an 890 Porter Cable router (a lower powered tool than the spindle) measured 90 db. Both measurements were taken in the same environment and measured at the same distance from the tool.

    Additional Information:
    Practically silent. The inverter makes more noise!

    Additional Information:
    Practically silent. The inverter makes more noise!

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    What are the noise levels of the 1.5 Kw and 2.2Kw spindles?

  • What are the fault conditions of the DM556 and DM542 drivers?

    There are three main LED fault signals that the DM556 and DM442 drivers exhibit. There is a red and green LED. The red LED will show the fault signals.

    The fault signals are:

    - Over-Current: If there is continuous current that is above 16 amps, the Red LED will flash every three seconds. Over-current could be related to: a short in the motor coils, or two of the wires of the motor are shorted; of the motor wires/coil is shorted to ground.

    - Over-voltage: If the power supply output to the driver exceeds a voltage of 52 volts, the red LED will flash twice every three seconds.

    - Phase Error: Is the motor wires are not connect, or they are connected incorrectly, the red LED will flash four times every three seconds.

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    What are the fault conditions of the DM556 and DM542 drivers?

  • What are the overall dimensions of the GreenLean Machine?

    The overall dimensions of the GreenLean Machine are approximately 86 inches Tall by 116 inches wide.

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    What are the overall dimensions of the GreenLean Machine?

  • What are the specs of the stepper motors on the BlueChick

    The blueChick uses NEMA 23 425 oz/in motors.

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    What are the specs of the stepper motors on the BlueChick

  • What are the actual measurements of the 5/8 and 1/2 ID bearings?

    The dimensions for each bearing (5/8" and 1/2"):
    1/2": OD 1.1255" - 28.5877mm / height 0.3150" - 8.001mm

    5/8": OD 1.3750" - 34.925mm / height 0.3440" - 8.7376mm

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    What are the actual measurements of the 5/8 and 1/2 ID bearings?

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