Science & Technology group member, Phil Chadwick, gave an enlightening talk on how electromagnetic fields affect the human body. Electromagnetic fields are present everywhere in our environment. Electric fields are produced by natural sources such as the local build-up of electric charges in the atmosphere associated with thunderstorms, while the earth’s magnetic field is used by birds and fish for navigation. This talk covered radio, light and microwave frequencies.
Only frequencies above the ionisation barrier (which is in the upper ultraviolet light range) have enough energy to damage DNA. Frequencies below this can sometimes have small effects, but not permanently damage the body. Electromagnetic fields drive electric and magnetic currents in the body, which can sometimes affect the nervous system. The human nervous system works on the range of 10 – 100 Hz, with the peak sensitivity at about 20 Hz. These frequencies are thousands of times below the electromagnetic frequencies that cause problems. The exceptions are for people with pacemakers and insulin pumps, where upon it is the electronics that is affected (not the human directly).
There are a few occupations where the cumulative effects add up to being potentially dangerous, but mitigating measures are taken to deal with them. The first signs are the body twitching. One example is electric welding. The exposure of someone who happens to be close to where welding is taking place, won’t be adversely affected, but anyone who regularly uses an electric welder needs to take precautions.
Two other examples are MRIs and X-rays that are used in hospitals. Medical procedure levels are low, so for the ordinary person who only has a few of them, the diagnostic benefits far outweigh the possible harmful effects. However, staff who conduct the MRIs and X-rays are exposed thousands of times, so have to be protected by standing far enough away and behind screens.
People have been concerned about the effects of using mobile phones, where you are basically putting a small radio frequency transmitter next to your head! The frequencies mobile phones work at may cause a small temperature rise in the body, rather than damage, although most of the cause of your warm ear is that you are holding a lump of plastic against it, not the transmitter in the phone.
Mobile phones have had wide spread use for over 20 years and there has been no increase in brain cancer or deaths. Twenty years ago mobile phone transmitted at 125mW, but now they are down to 20mW, so modern phones working at less than sixth of the power than they did 20 years ago, are not a problem now.
And as for fears about 5G causing covid – well, we won’t go there – it is such nonsense!
Wendy Lefevre
Some group activities and meetings are held at Ty Price, St Thomas Community Hall, St Thomas’s Square. There is no off street parking here. The approach on foot is a gentle slope to double entrance doors. The ground floor of the building is fully accessible and there is a disabled toilet. The stairs to the first floor are wide and well-lit with a handrail on both sides, but there is no lift. There is a hearing induction system on the ground floor.
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