For a thoughtfully designed indoor environment
This field is known as static electricity. It is caused by charge separation and is facilitated—or even made possible—by plastics. For instance, walking across a carpet generates a charge separation, creating a voltage difference relative to the surroundings. This accumulated charge discharges instantly upon contact with earthed objects or other people.
These are magnetic fields that can originate from radiators, steel reinforcement in ceilings, innerspring mattresses, or even metal bed frames. This distorts the Earth’s uniform magnetic field, thereby having a negative effect on the body.
This field is generated by all wiring, cables, switches, and outlets whenever they are live—meaning the field is emitted 24 hours a day once the circuit breaker is switched on. This is the standard operating state of the electricity grid. Naturally, the alternating electric field is also emitted by any connected power leads and extension leads. The human body absorbs this alternating field, thereby becoming electrically charged relative to the earth. This so-called coupling voltage can be detected using specialised measuring instruments and can range from a few millivolts to several volts. Only values below 20 millivolts (mV) are considered tolerable. This continuous exposure level is recommended as a biological limit because the human cell voltage lies in the range of 30 to 70 mV.
It is generated only when current flows through the cable. The strength of this field depends on the magnitude of the current flowing through it. Twisted cables and conductors significantly attenuate these fields because their effects partially cancel each other out. In contrast, overhead lines and flat webbed cables significantly increase these fields due to the large spacing between conductors. According to VDE standard 0848, a magnetic flux density of 5,000 nanoteslas (nT) is permissible for continuous human exposure. Here, too, the electro-biological guideline value is 20 nT. Hundreds of electro-biological studies have shown that the first reversible adverse effects in humans occur at levels as low as 30 nanoteslas.
Note: Certification confirms that a product met the requirements of the applicable testing programme at the time of testing. It does not provide a comprehensive assessment of a product’s suitability for health or of the health effects of an entire indoor environment.
Testing building products against published criteria since 1982.
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