RF Safety

Ama­teur Radio is basi­cal­ly a safe activ­i­ty. In recent years, how­ev­er, there has been­con­sid­er­able dis­cus­sion and con­cern about the pos­si­ble haz­ards of elec­tro­mag­net­ic fields (EMF), includ­ing both RF ener­gy and pow­er fre­quen­cy (50−60 Hz) EMF. FCC reg­u­la­tions set lim­its on the max­i­mum per­mis­si­ble exposure(MPE) allowed from the oper­a­tion of radio trans­mit­ters. Fol­low­ing these regulations,along with the use of good RF prac­tices, will make your sta­tion as safe as pos­si­ble.

How EMF Affects Mammalian Tissue

All life on Earth has adapt­ed to live in an envi­ron­ment of weak, nat­ur­al, low fre­quen­cy elec­tro­mag­net­ic fields, in addi­tion to the Earth’s sta­t­ic geo­mag­net­ic field. Nat­ur­al lowfre­quen­cy EM fields come from two main sources: the sun and thun­der­storm activ­i­ty. Dur­ing the past 100 years, man-made fields at much high­er inten­si­ties and with dif­fer­ent spec­tral dis­tri­b­u­tions have altered our EM back­ground. Researchers con­tin­ue to look at the effects of RF expo­sure over a wide range of fre­quen­cies and lev­els.

Both RF and pow­er fre­quen­cy fields are clas­si­fied as non­ion­iz­ing radi­a­tion because the fre­quen­cy is too low for there to be enough pho­ton ener­gy to ion­ize atoms. Ion­iz­ing radi­a­tion, such as X‑rays, gam­ma rays and some ultra­vi­o­let radi­a­tion, has enough ener­gy to knock elec­trons loose from atoms. When this hap­pens, pos­i­tive and neg­a­tive ions are formed. Still, at suf­fi­cient­ly high pow­er den­si­ties, non­ion­iz­ing EMF pos­es cer­tain health haz­ards.

It has been known since the ear­ly days of radio that RF ener­gy can cause injuries by heat­ing body tis­sue. Any­one who has ever touched an improp­er­ly ground­ed radio chas­sis or ener­gized anten­na and received an RF burn will agree that this type of injury can be quite painful. Exces­sive RF heat­ing of the male repro­duc­tive organs can cause steril­i­ty by dam­ag­ing sperm. Oth­er health prob­lems also can result from RF heat­ing. These heat relat­ed health haz­ards are called ther­mal effects. A microwave oven is an appli­ca­tion that puts ther­mal effects to prac­ti­cal use.

There also have been obser­va­tions of changes in phys­i­o­log­i­cal func­tion in the pres­ence of RF ener­gy lev­els that are too low to cause heat­ing. These func­tions gen­er­al­ly return to nor­mal when the field is removed. Although research is ongo­ing, no harm­ful health con­se­quences have been linked to these changes.

In addi­tion to the ongo­ing research, much else has been done to address this issue. For exam­ple, FCC reg­u­la­tions set lim­its on expo­sure from radio trans­mit­ters. The Insti­tute of Elec­tri­cal and Elec­tron­ics Engi­neers, the Amer­i­can Nation­al Stan­dards Insti­tute and the Nation­al Coun­cil for Radi­a­tion Pro­tec­tion and Mea­sure­ment, among oth­ers, have rec­om­mend­ed vol­un­tary guide­lines to lim­it human expo­sure to RF ener­gy. The ARRL main­tains an RF Safe­ty Com­mit­tee, con­sist­ing of con­cerned sci­en­tists and med­ical doc­tors, who vol­un­teer to serve the radio ama­teur com­mu­ni­ty to mon­i­tor sci­en­tif­ic research and to rec­om­mend safe prac­tices.


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