Near field and far field: Where is the boundary between them? And what must I keep in mind?
These are common questions asked by many who are concerned or interested in the topic of safety in electromagnetic fields (EMF). Electric, magnetic and electromagnetic fields exist wherever voltages and currents are present. Electromagnetic fields are emitted from broadcasting facilities for radio, television and telecommunications as well as in industrial facilities and medical equipment. High-voltage power lines emit this radiation as an undesired product; however, in telecommunications they purposely emit this radiation to transmit information. Electromagnetic fields do pose a biological risk to human health if individuals are exposed to this radiation consistently or for extended periods of time. EMF recommendations, standards and regulations intend to guide the limit of such harmful radiation. The Biological effects of EMF depend on:
The field strength
The field type (E or H field)
The duration of exposure
The extend of exposure (part of body or entire body)
The signal shape
High frequency (HF) fields of between 1MHz and 10 GHz penetrate body tissue and the absorbed energy heats up. Higher frequencies result in greater depth of penetration. Very high field strengths are needed to produce problems such as cataracts (cloudy areas that form in the lens of the eye) or skin burns. This will not incur in normal everyday exposure to radiation, but can occur in the immediate vicinity of powerful radar systems. Low frequency levels of electromagnetic fields can result in altered calcium flows or inhibition of melatonin, changes in protein levels and enzyme activity, possible nervous effects, healing processes in broken bones can be accelerated or halted, minor to sever impairment of heart function and other acute damages to health.
Protection against harmful EMF radiation in the workplace is important to prevent severe health effects amongst employees and other stakeholders. Personnel that will be operating, managing and monitoring equipment that produces electromagnetic radiation need to receive training in the relevant safety measures, which should include the following:
Basic principles of electromagnetic radiation
Measurement methods, test equipment and preventing
Practical training in making measurements and logging results
Individual protective measures
What to do if limits are violated
The detection of EMF radiation is important in preventing its harmful effects on the human biological system. The detection of EMF radiation can be achieved through the use of measuring equipment. Narda EMF radiation equipment is available from Air-Met Scientific including:
To view the full range of Narda products download the Product Guide here.
EMF radiation detection and protection is a broad subject that is important for organisations that deal with EMF radiation. We recommend that you download the ‘Everything you always wanted to know…’ brochure by Narda below to read more about EMF radiation in detail and how you can prevent the effects of it in your workplace.