The radiofrequency (RF) portion of the electromagnetic spectrum includes signals emitted by mobile phone signals, cell phone towers, Bluetooth devices and Wi-Fi, among other forms of wireless communications.
Different types of electromagnetic radiation are classified by their frequencies. At one end of the electromagnetic spectrum are extremely low frequency (ELF) waves with a frequency of 3–30Hz. At the other end of the electromagnetic spectrum, electromagnetic radiation known as gamma rays oscillate at 300EHz.
History of Electromagnetic Wave Transmission and Detection
The great scientist Heinrich Hertz was the first man to transmit and detect electromagnetic waves. In his famous experiment, a high voltage was applied to two zinc spheres connected by copper wire with a small 7.5mm gap in the middle. The resulting sparks in the gap created standing electromagnetic waves. Hertz detected these waves with a simple half-wave dipole antenna. This was a clear case of electromagnetic wave propagation and detection. Before Hertz’s experiment, the famous mathematician James Clerk Maxwell had already laid out the foundation for electromagnetic radiation by formulating four mathematical equations.
When Is RF Radiation Dangerous?
Electromagnetic radiation falls into two categories, ionizing and non-ionizing radiation.
How is non-ionizing radiation different from ionizing radiation? It’s a matter of energy—specifically, whether or not radiation has enough energy to ionize atoms or molecules, which damages DNA. RF radiation is non-ionizing and therefore is not immediately harmful to humans, though at high enough power levels it is still dangerous. Ionizing radiation begins at the ultraviolet section of the electromagnetic spectrum (sunburn is a common effect of the ionizing radiation of UV rays) and continues through to X-rays and gamma rays.
How Is RF Radiation Regulated?
RF electromagnetic radiation is classified asthe range between 3kHz and 300GHz. So much of modern life includes billions of devices that operate within this range, so who tests and regulates products that occupy this section of frequencies in the electromagnetic spectrum?
In the United States, the Federal Communications Commission (FCC) governs consumer safety. The FCC is responsible for regulating products that employ electromagnetic radiation. It governs the safety of devices like mobile phones by specifying the maximum limits for radiation. In accordance with the National Environmental Policy Act of 1969 and recommendations from the National Council on Radiation Protection and Measurements, the FCC adopted safety regulations for transmitters that emit RF radiation between 300kHz and 100GHz.
Cellular facilities, radio and television broadcast stations, satellite-to-earth stations, and experimental radio stations fall under the jurisdiction of the FCC. They are subject to routine evaluation for compliance to FCC standards and guidelines, especially when they file an application for building or modifying a transmitting facility or when they renew a license. If they do not comply with FCC standards and guidelines, the agency can shut them down. Applicants who fail to meet the FCC’s RF exposure guidelines will result in the FCC preparing what’s known as a formal Environmental Assessment. This is potentially followed up by the FCC creating an Environmental Impact Statement and possibly rejecting an application. The technical guidelines for evaluating RF safety are found in the FCC's OET Bulletin 65.
Specific Absorption Rate (SAR) is used to determine the compliance of mobile phones and devices. SAR reflects the rate at which human body tissue absorbs RF radiation, and is measured in watts per kilogram. If the SAR of a consumer device is above 1.6W/kg, it is considered noncompliant. If you want to look up the SAR testing information for your mobile phone, call *#07# on your phone. On the iPhone 11, after dialing this number, the phone automatically opens the Legal and Regulatory section under Settings. From there, the FCC ID appears.
If dialing the number doesn’t work for you, you can try to locate the FCC ID number for your phone model on the case. Sometimes, you must remove the battery to find it. After you find the FCC ID number, go to the FCC’s Equipment Authorization page. Click on the “FCC ID” search and enter your number.
How Exactly Do Manufacturers Comply with FCC Regulations?
Interestingly, cell phone RF testing is overseen by the manufacturers themselves. For instance, Apple or Google will send their latest iPhone or Pixel to an independent lab for testing. In the case of the iPhone 11, testing was done by an agent at UL (Underwriters Laboratories). If the independent lab finds that the phone passes muster, as in the case of the iPhone 11, the FCC approves it and the phone is cleared for the companies to bring it to market.
Recently, the independent California-based RF Exposure Labtested the iPhone 11 Pro and found that it has an SAR of 3.8W/kg, twice the FCC maximum rate. In its report, RF Exposure Lab specified that the tests it ran on the device were in accordance with FCC guidelines. The iPhone 11 Pro that it tested, which was placed 5millimeters away from a mannequin engineered to simulate human tissue, ran more than two times the legal limit. This is far different than what Apple reported initially. Apple’s reports showed the iPhone 11 Pro coming in under the FCC’s specified SAR. But there’s a catch. RF Exposure Lab was commissioned by Penumbra Brands to test the iPhone 11 Pro. Penumbra brands sells products like Gadget Guard, a phone case that protects against radiation.
According to Apple’s information page on RF radiation levels regarding the iPhone 11 Pro, “The SAR limit is 1.6 watts per kilogram in countries that set the limit averaged over 1 gram of tissue and 2.0 watts per kilogram in countries that set the limit averaged over 10 grams of tissue.” The statement goes on to mention that hands-free options are available to reduce exposure to RF radiation, but that “cases with metal parts may change the RF performance of the device, including its compliance with RF exposure guidelines, in a manner that has not been tested or certified.”
Perhaps more concerning is that the FCC’s RF Exposure testing uses SAR limits that were set 25 years ago, before smartphones had even hit the market. The FCC’s tests for SAR examine the effects of phones at 5 millimeters away from the body, using a dummy for simulation. When we carry our phones in our pockets, the distance is more like 2 millimeters. Notably, the World Health Organization (WHO) classified RF radiation as “possibly carcinogenic to humans” in 2011. The FCC also doesn’t test for the effect of mobile phone RF radiation on lower sperm counts. This could mean that the FCC’s SAR tests are both out of date and incomplete.
How Does the FCC Create, Establish, and Update Its Guidelines?
The FCC is directed by five commissioners who are appointed by the president of the United States and confirmed by the United States Senate for five-year terms. The commissioners set proposed guidelines and then vote on them. For example, in 2019, FCC commission members voted unanimously to approve the T-Mobile and Sprint merger.
Guidelines are perhaps indirectly influenced by the FCC’s subcontractors. The FCC spent $647.5 million on 6,813 contractor transactions over the past 10 years, with Computech ranking first. Computech helped the FCC develop and implement Automated Auction Systems (AAS). The AAS was designed to help the FCC choose licensees for electromagnetic spectrum awards. Prior to the AAS, the FCC used a combination of lotteries and hearings to select single licensees. With the AAS, the FCC now uses simultaneous competitive bidding, which helps the agency generate revenue for the U.S. Treasury.
As far as updating the old RF exposure testing guidelines, the commission would have to prioritize it, add the item to its agenda, and vote on the matter. It is unclear at this time if it plans to do so.
Build a DIY Faraday Cage
If all this talk of RF radiation has left you feeling anxious, you may be interested in knowing how to shield yourself by building your own Faraday cage. Faraday cages are simple enclosures used to block or attenuate electromagnetic fields. If you want a quick way to shield yourself from your phone’s RF radiation, simply wrap it in aluminum foil.