Disclaimer: we are importing EMI/RF shielding fabric to offer protection. With plating material of nickel-copper, nickel with shielding effect of > 60 dB. In general, a shielding range of 10 to 30 dB provides the lowest effective level of shielding, while anything below that range can be considered little or no shielding. Shielding between 60 and 90 dB may be considered a high level of protection, while 90 to 120 dB is exceptional.
How does EMI affect the human body?
High frequencies tend to penetrate less while heating human tissue, similar to a microwave oven. It's been speculated that high-frequency electromagnetic energies may interfere and resonate with DNA and other cellular functions that may trigger cancerous changes.
The main effect of radiofrequency electromagnetic fields is heating of body tissues. There is no doubt that short-term exposure to very high levels of electromagnetic fields can be harmful to health.
What are electric and magnetic fields?
Electric and magnetic fields are invisible areas of energy (also called radiation) that are produced by electricity, which is the movement of electrons, or current, through a wire.
An electric field is produced by voltage, which is the pressure used to push the electrons through the wire, much like water being pushed through a pipe. As the voltage increases, the electric field increases in strength. Electric fields are measured in volts per meter (V/m).
A magnetic field results from the flow of current through wires or electrical devices and increases in strength as the current increases. The strength of a magnetic field decreases rapidly with increasing distance from its source. Magnetic fields are measured in microteslas (μT, or millionths of a tesla).
Electric fields are produced whether or not a device is turned on, whereas magnetic fields are produced only when current is flowing, which usually requires a device to be turned on. Power lines produce magnetic fields continuously because current is always flowing through them. Electric fields are easily shielded or weakened by walls and other objects, whereas magnetic fields can pass through buildings, living things, and most other materials.
Electric and magnetic fields together are referred to as electromagnetic fields, or EMFs. The electric and magnetic forces in EMFs are caused by electromagnetic radiation. There are two main categories of EMFs:
· Higher-frequency EMFs, which include x-rays and gamma rays. These EMFs are in the ionizing radiation part of the electromagnetic spectrum and can damage DNA or cells directly.
· Low- to mid-frequency EMFs, which include static fields (electric or magnetic fields that do not vary with time), magnetic fields from electric power lines and appliances, radio waves, microwaves, infrared radiation, and visible light. These EMFs are in the non-ionizing radiation part of the electromagnetic spectrum and are not known to damage DNA or cells directly. Low- to mid-frequency EMFs include extremely low frequency EMFs (ELF-EMFs) and radiofrequency EMFs. ELF-EMFs have frequencies of up to 300 cycles per second, or hertz (Hz), and radiofrequency EMFs range from 3 kilohertz (3 kHz, or 3,000 Hz) to 300 gigahertz (300 GHz, or 300 billion Hz). Radiofrequency radiation is measured in watts per meter squared (W/m2).
What are common sources of non-ionizing EMFs?
There are both natural and human-made sources of non-ionizing EMFs. The earth’s magnetic field, which causes the needle on a compass to point North, is one example of a naturally occurring EMF.
Human-made EMFs fall into both the ELF and radiofrequency categories of non-ionizing part of the electromagnetic spectrum. These EMFs can come from a number of sources.
Extremely low frequency EMFs (ELF-EMFs). Sources of ELF-EMFs include power lines, electrical wiring, and electrical appliances such as shavers, hair dryers, and electric blankets.
Radiofrequency radiation. The most common sources of radiofrequency radiation are wireless telecommunication devices and equipment, including cell phones, smart meters, and portable wireless devices, such as tablets and laptop computers.
Other common sources of radiofrequency radiation include:
· Radio and television signals. AM/FM radios and older VHF/UHF televisions operate at lower radiofrequencies than cell phones. Radio signals are AM (amplitude-modulated) or FM (frequency-modulated). AM signals are transmitted from large arrays of antennas that are placed at high elevation on sites that are off limits to the general public because exposures close to the source can be high. FM radio antennas and TV broadcasting antennas, which are much smaller than AM antennas, are generally mounted at the top of high towers. Radiofrequency exposures near the base of these towers are below guideline limits.
Radar, satellite stations, magnetic resonance imaging (MRI) devices, and industrial equipment. These operate at somewhat higher radiofrequencies than cell phones
· Microwave ovens used in homes, which also operate at somewhat higher radiofrequencies than cell phones. Microwave ovens are manufactured with effective shielding that has reduced the leakage of radiofrequency radiation from these appliances to barely detectable levels.
· Cordless telephones, which can operate on analogue or DECT (Digital Enhanced Cordless Telecommunications) technology and typically emit radiofrequencies similar to those of cell phones. However, because cordless phones have a limited range and require a nearby base, their signal strengths are generally much lower than those of cell phones.
· Cell phone base stations. Antenna towers or base stations, including those for mobile phone networks and for broadcasting for radio and for television, emit various types of radiofrequency energy. Because the majority of individuals in the general population are exposed only intermittently to base stations and broadcast antennas, it is difficult to estimate exposures for a population. The strength of these exposures varies based on the population density of the region, the average distance from the source, and the time of day or the day of the week (lower exposures on the weekends or at night. A study that used using personal portable exposure meters to assess exposures to different sources of radiofrequency EMFs among children in Europe found that the single largest contributor to the total radiofrequency EMF exposure was the proximity to base stations.In general, exposures decrease with increasing distance from the source. Exposures among maintenance workers have been found to vary depending on their tasks, the type of antenna, and the location of the worker in relation to the source. Cumulative exposures of such workers are very difficult to estimate.
· Televisions and computer screens produce electric and magnetic fields at various frequencies, as well as static electric fields. The liquid crystal displays found in some laptop and desktop computers do not produce substantial electric or magnetic fields. Modern computers have conductive screens that reduce static fields produced by the screen to normal background levels.
· Wireless local area networks, commonly known as Wi-Fi. These are specific types of wireless networking systems and an increasingly common source of radiofrequency radiation. Wireless networks use radio waves to connect Wi-Fi–enabled devices to an access point that is connected to the internet, either physically or through some form of data connection. Most Wi-Fi devices operate at radiofrequencies that are broadly similar to cell phones, typically 2.4 to 2.5 GHz, although in recent years Wi-Fi devices that operate at somewhat higher frequencies (5, 5.3, or 5.8 GHz) have appeared. Radiofrequency radiation exposure from Wi-Fi devices is considerably lower than that from cell phones. Both sources emit levels of radiofrequency radiation that are far below the guideline of 10 W/m2 as specified by the International Commission on Non-Ionizing Radiation Protection.
· Digital electric and gas meters, also known as “smart meters.” These devices, which operate at about the same radiofrequencies as cell phones, transmit information on consumption of electricity or gas to utility companies. Smart meters produce very low-level fields that sometimes cannot be distinguished from the total background radiofrequency radiation levels inside a home.
For household appliances and other devices used in the home that require electricity, magnetic field levels are highest near the source of the field and decrease rapidly the farther away the user is from the source. Magnetic fields drop precipitously at a distance of about 1 foot from most appliances. For computer screens, at a distance of 12–20 inches from the screen that most persons using computers sit, magnetic fields are similarly dramatically lower.
The problem I see:
1.The maximum limit of guidelines is 10w/m2 (given our current knowledge and often knowledge is revised after shit hits fan for long and huge suits are filed).
2. It does not take into account accumulated load or progressive load.
3. It has been found Glioma (brain tumour is most found on side one uses phone) and in spite it said “We found no evidence of increased risk of glioma, meningioma or acoustic neuroma. Suggests that amount of mobile phone use is not associated with brain tumour risk.”
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