SBI PO Exam Pattern: SBI has done some major changes in SBI PO Exam pattern and SBI PO syllabus 2015. The exam pattern of SBI PO consists of three phases...
“Mr. Watson — come here — I want to see you.” The first words on the telephone by Alexander Graham Bell who the inventor of telephone. The biggest technological invention ever made by man was in the field of telecommunication when the first telephone was invented on 10 March 1876.
After almost a century, in the last quarter of the 20th century, marked the first cellular hand-held mobile phone. RF waves with frequencies between 300 MHz (0.3 GHz) and 300 GHz. This broad definition includes both UHF and EHF (millimeter waves), and various sources use different boundaries.
The safety of cell phone towers is the subject of higher level of scientific debate. There is a growing body of scientific evidence that the electromagnetic radiation they emit, even at lower power level, is dangerous to human health.
The cell phone industry is expanding quickly, with over 4.3 billion subscribers around the world, which is expected to increase many-fold over the next decade. The industry has set what they say are “safe operating regions” of radiation exposure, but there are a growing number of doctors, physicists, and health officials who strongly disagree, and foresee a public health crisis.
These towers emit radio frequencies (RF), a form of electromagnetic radiation (EMR), for a distance of up to 2-1/2 miles. They are essentially the same frequency radiation as microwaves in a microwave oven.
Studies have shown that even at low levels of this radiation, there is evidence of damage to cell tissue and DNA, and it has been linked to brain tumors, cancer, suppressed immune function, depression, miscarriage, Alzheimer’s disease, and numerous other serious illnesses.
Children are at the greatest risk, due to their thinner skulls, and rapid rate of growth. Also at greater risk are the elderly, the frail, and pregnant women. Doctors from the United Kingdom have issued warnings urging children under 16 not to use cell phones, to reduce their exposure to radio frequency (RF) radiation.
Over 100 physicians and scientists at Harvard and Boston University Schools of Public Health have called cellular towers a radiation hazard. And, 33 delegate physicians from 7 countries have declared cell phone towers a “public health emergency”.
The U.S. Federal Communications Commission (FCC) is in charge of setting the standards of exposure for the public, and claims that, based on scientific studies, the current levels are safe.
Contrary to what the communications industry tells us, there is vast scientific, epidemiological and medical evidence that confirms that exposure to the RF and microwave radiation emitted from cell towers, even at low levels, can have profound adverse effects on biological systems.
One well-understood effect of microwave radiation is dielectric heating, in which any dielectric material (such as living tissue) is heated by rotations of polar molecules induced by the electromagnetic field. In the case of a person using a cell phone, most of the heating effect will occur at the surface of the head, causing its temperature to increase by a fraction of a degree. In this case, the level of temperature increase is an order of magnitude less than that obtained during the exposure of the head to direct sunlight. The brain’s blood circulation is capable of disposing of excess heat by increasing local blood flow.
A 2009 study examined the effects of exposure to radiofrequency radiation (RFR) emitted by standard GSM cell phones on the cognitive functions of humans. The study confirmed longer (slower) response times to a spatial working memory task when exposed to RFR from a standard GSM cellular phone placed next to the head of male subjects, and showed that longer duration of exposure to RFR may increase the effects on performance. Right-handed subjects exposed to RFR on the left side of their head on average had significantly longer response times when compared to exposure to the right side and sham-exposure.
Some users of mobile handsets have reported feeling several unspecific symptoms during and after its use; ranging from burning and tingling sensations in the skin of the head and extremities, fatigue, sleep disturbances, dizziness, loss of mental attention, reaction times and memory retentiveness, headaches, malaise, tachycardia (heart palpitations), to disturbances of the digestive system. Reports have noted that all of these symptoms can also be attributed to stress and that current research cannot separate the symptoms from nocebo effects.
Health hazards of base stations
Another area of concern is the radiation emitted by the fixed infrastructure used in mobile telephony, such as base stations and their antennas, which provide the link to and from mobile phones. This is because, in contrast to mobile handsets, it is emitted continuously and is more powerful at close quarters. On the other hand, field intensities drop rapidly with distance away from the base of the antenna because of the attenuation of power with the square of distance. Base station emissions must comply with safety guidelines (see Safety standards and licensing below). Some countries however (such as South Africa) do not have any health regulations at all governing the placement of base stations.
Occupational health hazards
Telecommunication workers who spend time at a short distance from the active equipment, for the purposes of testing, maintenance, installation, etcetera, may be at risk of much greater exposure than the general population. Many times base stations are not turned off during maintenance, but the power being sent through to the antennas is cut off, so that the workers do not have to work near live antennas.