File Name: rf and microwave radiation safety handbook .zip
Technology exploiting RFR for radar, communications, and anti-electronic weapons supports U.
Radiofrequency RF is a term which may be applied to electromagnetic radiation of frequency between kHz and GHz but generally its use is restricted to frequencies between kHz and MHz and the term microwave is applied to radiation of frequency from MHz to GHz. Frequency and wavelength are inversely related and, in free space, a frequency of kHz corresponds to a wavelength of 13 km; MHz is equivalent to a wavelength of 1 m and GHz to 1 mm. The position which microwave and RF radiation occupies in the electromagnetic spectrum is shown in Figure
RF energy is nonionizing electromagnetic radiation and should not be confused with X-rays and other ionizing radiation. RF energy, when absorbed in sufficient amounts by workers, may produce adverse thermal effects resulting from heating of deep body tissue which may include potentially damaging alterations in cells.
Section V of the Appendix to this Bulletin lists engineering controls, such as shielding, and other immediate actions that should be taken. Workers near RF sealers may be unaware of their exposure to RF emissions, because the RF energy from sealers and heaters can penetrate deeply into the body without activating the heat sensors located in the skin.
A false sense of employee safety may exist; in many instances, worker exposures to RF energy may not have been properly assessed. This has been due, largely, to the complex problems of measurement and thus the misapplication of the instruments available for monitoring RF energy levels.
Recently, monitoring instruments that facilitate accurate measurement of worker exposure have been developed. Federal survey teams, equipped with these new instruments, have detected excessive exposures of workers to RF energy.
The Institute would appreciate receiving information concerning adverse health effects among workers which might be associated with their exposure to RF energy in the workplace and information on methods for retrofitting existing RF sealers and heaters in order to control the emission of RF energy.
NIOSH and OSHA request that manufacturers, distributors, and users of RF sealers and heaters transmit the information in this Bulletin to their customers and employees, and that professional societies, trade associations, and unions inform their members.
RF sealers have been used for more than 30 years, but there are no reliable, documented estimates of the number of units in present use or of the number of workers operating RF sealers. However, it is generally believed that the number of RF sealers and heaters in use is approximately 20, and that there are about 30, to 40, workers operating these units.
RF sealers are used to heat, melt, or cure materials such as plastic, rubber, or glue. An extensive list of occupations involving the use of RF sealers and heaters is presented in Section II of the attached Appendix. Effects on reproduction and on the development of offspring of females exposed during pregnancy have also been reported.
As previously mentioned a false sense of employee safety may exist in many industrial settings because worker exposures to RF energy may not have been properly assessed. The recent development of monitoring instruments that facilitate accurate measurement of worker exposure to RF energy allowed for a series of studies at workplaces where RF sealers and heaters are used.
This Bulletin will provide an overview of the potential adverse health effects associated with the use of RF dielectric heaters. The Appendix contains technical information to assist research, engineering, and manufacturing personnel in evaluating this potential hazard and for initiating appropriate modification and controls to prevent unwarranted worker exposure.
Excess amounts of RF energy absorbed by workers may produce adverse thermal effects resulting from heating of deep body tissue. These thermal effects may include potentially damaging alterations in cells caused by localized increases in tissue temperature. C of the attached Appendix can cause net increases in tissue or body temperatures, and that exposures at or above these values should be avoided. For radiation frequencies similar to those commonly used with RF sealers and heaters, reported observations at relatively low energy levels in laboratory rats or rabbits included changes in: electroencephalographic EEG recordings of electrical activity of the brain, 6 conditioned reflex behavior 6 , 7 chemical composition of the blood, 6 the endocrine hormonal system, 6 , 8 and the immunologic infection defense system.
E of the attached Appendix. For the frequencies at which these observations have been made the rates of energy absorption in man are much greater than in the laboratory animals.
Other adverse health effects on the eye, heart rate, and the central nervous system have been observed in laboratory animals exposed to electromagnetic energy at higher frequencies in the microwave region of the electromagnetic spectrum see Section IV. A of the attached Appendix. The extent to which these latter effects may also be caused by absorption of energy at the lower frequencies employed by RF sealers is not known.
There is no convincing evidence to indicate that RF energy can cause cancer in humans. There have been reports which suggest an association between RF exposure and reproductive damage in animals and humans.
These reports, primarily from Eastern Europe and the Soviet Union, list a variety of reproductive and developmental effects resulting from occupational exposures of workers and experimental exposures of laboratory animals to electromagnetic energy at frequencies in the RF and microwave ranges.
Reported effects from exposure of women to fields of relatively high intensity RF and microwave energy have included changes in menstrual pattern, increased incidence of miscarriage, and decreased lactation in nursing mothers. There is a report of changes in spermatogenesis production of male germ cells in the testicles among workmen exposed to nonionizing electromagnetic energy. NIOSH surveys indicate that a large majority of the workers using RF sealing and heating equipment are women of child-bearing age.
OSHA is presently enforcing both of these mean squared field strengths averaged over any 0. The present Federal was derived using data principally from experiments with animals at microwave frequencies, not at the lower radiofrequencies. The standard was intended to prevent thermal effects. The extent to which biological effects attributed to the absorption of RF energy by animals reflect an occupational hazard to workers is not fully known.
There are uncertainties in extrapolating experimental results from animals to humans and to frequencies other than those used in the experiments. These problems have been compounded by the difficulty in properly measuring near-field RF energy exposures, which has been only recently resolved. NIOSH recommends that future research projects dealing with RF energy meet requirements for: 1 better exposure dosimetry and quantification of biological results, 2 use of adequate experimental controls, and 3 uniform reporting of experimental parameters and results.
While scientists are not in complete agreement on the interpretation of available data on biological effects, NIOSH believes there is sufficient evidence of such effects to cause concern about human exposures.
Mention of company name or product does not constitute endorsement by National Institute for Occupational Safety and Health or the Occupational Safety and Health Administration. Automotive workers: Drying of trim base panels, embossing of heel pads to carpets, heat sealing body interior trim panels, heat sealing convertible tops and vinyl roofs, heat sealing upholstery covers for seats and backs.
Furniture and wood workers: decking assembly, door lamination, fabrication of posts and rafters, fiberboard fabrication, laminated beams, lumber edge glueing, plywood panel patching, plywood or particleboard scarf glueing, ski lamination, veneer panel glueing. Glass fiber workers: Drying and curing sizing on machine packages, drying coatings on continuous moving strands, drying glass fibers on forming tubes, drying roving packages. Paper product workers: Correcting moisture profile on continuously moving webs, drying resin coatings, drying twisted twine packages, gluing paper, heating coating on continuous webs.
Ceramics — Drying of ceramic objects. Chemical — Activation of chemical reactions. Electronics — Tube aging and testing. Laser — RF-excited gas lasers.
Medical — Diathermy and experimental cancer therapy. Scientific Equipment — Low temperature ashing of samples. Welding — RF-stabilized welding. Rubber products workers: Drying latex foams, gelling latex foams, preheating prior to curing latex foams, preheating prior to molding. Textile workers: Drying continuous webs, impregnated or coated yarns, rayon cake packages, slasher coatings, and wound packages. Mention of company name or product does not constitute endorsement by the National Institute for Occupational Safety and Health or the Occupational Safety and Health Administration.
Radiofrequency energy or RF radiation is part of the electromagnetic energy spectrum. With regard to the energy emitted from a RF sealer or heater, electromagnetic radiation may be considered as a series of waves of energy propagated through space and composed of oscillating electric and magnetic fields. These waves are produced by moving electric charges, and may be of natural origin e. The wave of electromagnetic energy is characterized in part, by:.
Wavelength and frequency are inversely related; as the wavelength increases, the frequency decreases. A graphic representation of the electromagnetic radiation spectrum is presented in Figure 1. When electromagnetic radiation contains sufficient energy at frequencies much higher than radiofrequencies , it can ionize atoms of the material absorbing the energy i. Radiation of sufficient energy to cause ionization of molecules in biological tissue is often referred to as ionizing radiation, whereas radiation of insufficient energy to cause this effect is referred to as nonionizing radiation.
The ionizing and nonionizing regions of the electromagnetic spectrum are shown in Figure 1. While nonionizing radiation absorbed by biological tissue is not capable of ionizing atoms or molecules, it nevertheless may produce changes in the vibrational and rotational energies of the biological molecules, leading to changes in the molecules or dissipation of the energy in the form of heat. RF sealers and heaters generate, by means of electronic circuitry, oscillating fields of electric and magnetic energy.
RF sealers generally operate within the band of frequencies from 10 to 70 MHz a megahertz MHz is one million cycles per second , although most of the sealers operate at nominal frequencies from 13 to 40 MHz. A few wood glueing machines operate at frequencies as low as 3 — 6 MHz, and a few RF heaters used for plastics operate at frequencies as high as — MHz. RF electromagnetic energy emitted from an RF sealer or heater is considered nonionizing radiation by virtue of its frequency and quantum energy.
Unshielded or improperly shielded RF sealers or heaters can leak stray RF energy. In the measurement of RF energies, the distances from the RF source at which the measurements are being made must be considered.
For purposes of this Bulletin, distances from the RF source can be categorized as being either far field or near field.
The far field includes all distances from the RF source greater than approximately ten times the wavelength. Wavelengths corresponding to frequencies used by RF sealers and heaters may range from about one meter to a few hundred meters.
The frequency of 27 MHz, which is typical for many RF heaters, is associated with a nominal wavelength of about 11 meters. The value of the power density in the far field can be measured with a power density monitor, or can be calculated from measurement of the intensity of either the electric field or the magnetic field alone. The near field comprises distances from the RF source less than about five wavelengths which includes the immediate vicinity of the RF device where most worker exposures to RF energy occur.
In the near fields electromagnetic waves have different characteristics than in the far field. Furthermore, in the occupational setting near a RF sealer or heater, the electromagnetic field generally is not uniform, and the energy field incident upon a worker is complex and depends on many factors.
A power density monitors designed for use in the far field, is likely to give exceedingly inaccurate measurements in the near field. Further, in the near field, as opposed to the far field, there is no simple mathematic equivalency between values of power density and measurements of either electric or magnetic field strength.
In the past, values of far-field power density have been used in various public health guides and recommendations for exposure limits, including those intended for occupational settings. However, a power density value, which can be measured or calculated for far-field conditions is not appropriate for quantifying near-field exposure of a worker operating an RF sealer or similar device.
In the near field, measurements of both the electric and the magnetic fields are necessary to properly characterize worker exposure conditions. Instruments are now commercially available to make near-field measurements of the electric and magnetic fields. When RF energy propagating through space encounters an object, it may be reflected by the object forced to change direction of travel , transmitted through the object, or absorbed by the object.
Humans can absorb RF energy at the frequencies used by most RF sealers and heaters. In workers who are not in contact with an electrical ground, the highest absorption rates for whole-body irradiation can occur at frequencies between 60 and MHz with a peak at approximately 80 MHz. Hence, workers near RF sealers and heaters can absorb considerable amounts of the stray energy emitted from the RF machines.
Effects of directly touching an electrical ground plane can lower, by as much as one half, the frequency at which an irradiated body will maximally absorb energy. RF shielding material incorporated into the floor, walls, and ceiling of some RF workrooms could constitute such a ground plane. Details of some experiments performed in laboratory animals with low intensity RF energy at frequencies commonly used with sealers and heaters are summarized in the following table.
Table 1. Control of the emission of RF energy from RF sealers and heaters should rely on the application of properly designed and installed shielding material.
The shielding should be placed on or around the equipment so as to minimize occupational exposure due to emissions of stray RF energy. All shielding material should be properly grounded. Shielded conductors should be used for conveying RF current, and path impedance should be minimized by using good conductor materials.
Jump to navigation. Many consumer and industrial products make use of some form of electromagnetic energy. Because of its regulatory responsibilities in this area the Federal Communications Commission FCC often receives inquiries concerning the potential safety hazards of human exposure to radio-frequency RF energy. The information on this page provides answers and information to inquiries regarding RF Safety. The FCC is required by the National Environmental Policy Act of , among other things, to evaluate the effect of emissions from FCC-regulated transmitters on the quality of the human environment. Specifically, the FCC: 1 streamlines its criteria for determining when a licensee is exempt from our RF exposure evaluation criteria; 2 provides more flexibility for licensees to establish compliance with our RF exposure limits; 3 specifies methods that RF equipment operators can use to mitigate the risk of excess exposure, both to members of the public and trained workers such as training, supervision, and signage ; and 4 upholds its prior decision to consider the exposure limit for the outer ears to be the same as for other body extremities.
The leading professional guide to RF and microwave safety issues. A practical handbook for all involved in electronic design and safety assessment, RF and Microwave Radiation Safety covers the problems of RF safety management, including the use of measuring instruments and methods, radiation hazards and risks resulting from electromagnetic interference, as well as reviewing current safety standards and the implications for RF design. The second edition takes into account a wide range of technical and legislative changes, and has been revised in line with the latest EU and international standards. Issues raised by increasing levels of microwave pollution from mobile phones and other sources are also confronted. Introduction to RF and microwave radiation Sources of radio frequency radiation Effects of RF radiation The development of standards for human safety The calculation of RF field quantities Mobile communication systems RF radiation measuring instruments and methods X-rays and X-ray measuring instruments Planning surveys and measurements Conducting radiation measurements and surveys Designing to reduce radiation hazards RF radiation safety management and training Appendices: Useful data and relationships Technical and organisation abbreviations Information sources including the internet. Reviews of the first edition: "For industries where there is an RF radiation hazard, this is a very well written and practical guide to a subject which is quite technically difficult. There are many useful references and illustrations.
RF energy is nonionizing electromagnetic radiation and should not be confused with X-rays and other ionizing radiation. RF energy, when absorbed in sufficient amounts by workers, may produce adverse thermal effects resulting from heating of deep body tissue which may include potentially damaging alterations in cells. Section V of the Appendix to this Bulletin lists engineering controls, such as shielding, and other immediate actions that should be taken. Workers near RF sealers may be unaware of their exposure to RF emissions, because the RF energy from sealers and heaters can penetrate deeply into the body without activating the heat sensors located in the skin. A false sense of employee safety may exist; in many instances, worker exposures to RF energy may not have been properly assessed.
In the end, it addresses topics such as use of the decibel, decibels and power, and decibels and voltage. Select 2 - Sources of radio frequency radiation. Book.
The most common health hazard of radiation is sunburn , which causes between approximately , and 1 million new skin cancers annually in the United States. Claims of harm from low levels of non-ionizing radiation sometimes described as "electrosmog" are unsupported by science. Dielectric heating from electromagnetic fields can create a biological hazard. For example, touching or standing around an antenna while a high-power transmitter is in operation can cause burns the mechanism is the same as that used in a microwave oven. The heating effect varies with the power and the frequency of the electromagnetic energy, as well as the inverse square of distance to the source.
- Но немец даже не шевельнулся. Росио изо всех сил уперлась руками в его массивные плечи. - Милый, я… я сейчас задохнусь! - Ей стало дурно. Все ее внутренности сдавило этой немыслимой тяжестью. - Despiertate! - Ее пальцы инстинктивно вцепились ему в волосы.
- Мы ищем совсем не. Соши показала на экран. Все сгрудились вокруг нее и прочитали текст: …распространено заблуждение, будто на Нагасаки была сброшена плутониевая бомба. На самом деле в ней использовался уран, как и в ее сестрице, сброшенной на Хиросиму. - Но… - Сьюзан еле обрела дар речи. - Если оба элемента - уран, то как мы найдем различие между. - А вдруг Танкадо ошибся? - вмешался Фонтейн.
Если бы я сумел слегка модифицировать этот код, - продолжал Стратмор, - до его выхода в свет… - Он посмотрел на нее с хитрой улыбкой. Сьюзан потребовалось всего мгновение. Стратмор сразу заметил изумление, мелькнувшее в ее глазах, и взволнованно изложил свой план: - Если бы я получил ключ, то смог бы взломать наш экземпляр Цифровой крепости и внести нужные изменения… - Черный ход, - сказала Сьюзан, мгновенно забыв о том, что Стратмор ей лгал. Она все поняла. - Вроде Попрыгунчика.
Он решил было обратиться в полицию - может быть, у них есть данные о рыжеволосых проститутках, - но Стратмор на этот счет выразился недвусмысленно: Вы должны оставаться невидимым. Никто не должен знать о существовании кольца. Может быть, стоит побродить по Триане, кварталу развлечений, и поискать там эту рыжую девицу. Или же обойти все рестораны - вдруг этот тучный немец окажется. Но и то и другое вряд ли к чему-то приведет.
Согласен, - сказал Джабба. - Этот парень был диссидентом, но диссидентом, сохранившим совесть. Одно дело - заставить нас рассказать про ТРАНСТЕКСТ, и совершенно другое - раскрыть все государственные секреты. Фонтейн не мог в это поверить. - Вы полагаете, что Танкадо хотел остановить червя.
- Он перевел взгляд на схему. - Там темно как в преисподней! - закричала. Джабба вздохнул и положил фонарик рядом с. - Мидж, во-первых, там есть резервное электроснабжение.
Как кот, пойманный с канарейкой в зубах, святой отец вытер губы и безуспешно попытался прикрыть разбившуюся бутылку вина для святого причастия. - Salida! - крикнул Беккер. - Salida. Выпустите. Кардинал Хуэрра послушно кивнул.
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Such effects may or may not be characterized by a measurable temperature rise, which is a function of thermoregulatory processes and active adaptation of the animal.Zite C. 16.05.2021 at 23:34
12 Radio frequency radiation safety management and training. Appendix 1 2 RF and Microwave Radiation Safety Handbook. Although we provision of digital instruments which can store and download data can.