Radman alarms
A common question we get is what to do if a personal monitor like the Radman gives an alarm. One answer is whatever it says in your company EMF safety policy.
Every organisation issuing personal monitors to its workforce should have an EMF safety policy, this might sound more complicated than it actually is, an EMF safety policy can be a page or two and that’s it. EMF safety policy information is provided in our EMF safety management training.
Also you need to consider if it’s a genuine alarm. If you hold a monitor on or very close to steelwork or feeder cable (particularly on VHF and other lower frequency broadcast sites) the monitor can overestimate field strength (current is induced in the sensor through coupling effects rather than true field strength estimation).
But typically the straight answer to a straight question is if your personal monitor goes into constant alarm do not remain in that area. If you need to work in the area you’ll need to seek further advice. But if you’re moving past an antenna, say walking to a place where you need to work on a rooftop and you get an alarm and it stops once you’re away from the antenna, then stay away from the antenna and just report the alarm once you’ve finished your work.
An important point to note is that the alarm is not indicating a go/no go situation regarding health effects, it’s just an indication that field strength is becoming higher with regard to the CEMFAW action level (AL) (or ICNIRP reference level, in terms of the numbers pretty much the same thing). The AL is there to make sure you don’t get anywhere close to field strengths that might cause health effects.
On most monitors the first alarm represents 50% of the AL, a second alarm may sound at say 100%. Technically as long as field strength is <100% a worker can remain in the area indefinitely. However most organisations take the view that if possible (and it usually is), it’s better to reduce risk by temporarily reducing power. Also note alarms don’t take time or spatial averaging into account (methods used to make a truer picture of the exposure level) so in most if not all situations alarms from personal monitors represent a worst case.
The ALs are in themselves, in terms of what could cause a health effect, relatively low. The clue is in the name, they represent a call to take some ‘action’ to assess or avoid the risk.