Ofcom is changing the licence conditions to include an obligation to ensure that radio installations are safe in terms of RF radiation – the ICNIRP requirements. The following is about why and what it means to the individual Radio Amateur.
It has been know for many years that high RF fields can be felt by the human body and in 1973 The International Commission on Non-Ionising Radiation Protection (ICNIRP) was established to provide guidelines as to what constituted safe levels of exposure. Their latest Guidelines were published in 2020 and are concerned with frequencies between 100KHz and 300GHz and it is globally accepted as the treatise on this health physics issue.
In the UK, ICNIRP came into the public arena when claimed health effects were used to unsuccessfully block planning applications for mobile phone masts. Of the many reported health effects, only two have been scientifically demonstrated; body tissue heating and nerve and muscle excitation, and these are the basis for the ICNIRP Guidelines.
Body tissue heating comes in two flavours; whole body where blood circulation acts as a re-distribution and cooling system, and local heating where the blood supply is limited e.g. the eyes. Body heating is measured in Watts/Kgm for a specified duration and temperature rise, and there is also the SAR (Specific Absorption Ratio) measurement that finds common application in mobile phones. The conversion from health physics measurements to radio engineering measurements is complicated!
ICNIRP also categorises two types of “victim”; occupational where the “victim” is managing their own RF situation, and general public who remain unaware of their RF environment. The resulting limits are frequency dependent and known in the ICNIRP world as reference levels.
Spurred on by 5G, the UK Wireless Telegraphy Act has been updated to include the ICNIRP Guidelines, hence Ofcom has made it known to all holders of transmitting licenses that they must ensure compliance with the ICNIRP Guidelines. Ofcom has adopted whole body effects and the general public limits.
The Ofcom timetable for this change to the Radio Amateur community is:
License Variation by May 18th, 2021
Compliance by November 2021 above 10MHz
Compliance by November 2022 for frequencies below 10MHz
What are the implications for the Radio Amateur?
Ofcom offers an prototype assessment excel tool. Further development of this tool is required for frequencies below 10MHz, but this is not required until autumn 2022.
The RSGB offers the Ofcom excel tool
► EMF-1: What You Need to Know about EMF (8-page/1MB PDF)
► Calculator: RSGB/Ofcom calculator (3.0 MB MS-Excel Worksheet) to calculate your EIRP from practical station parameters—incorporating the Ofcom spreadsheet. We thank you for feedback received, we have incorporated a number of your ideas in the current version. This calculator will be updated to use exposure limits based on ICNIRP 2020 reference levels. For more information about using the calculator, see the video RSGB/Ofcom EMF Calculator Demonstration
Graham Coleman M5IIT