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Cold Stress Cold temperatures can cause a general decrease in body temperatures and/or
affect specific body areas. Generalized cold injury is called
Cold temperatures also can cause freezing injuries (frosting and frost bite) and non-freezing injuries child blains, French foot, and immersion foot). Cold stress causes shivering. It also affects peripheral and superficial (skin) blood vessels by causing them to constricts, especially in the extremities, nose and ears. Others responses to cold stress include skin cooling and reduced blood flow to the hands and feet that can lead to blunted sensations of touch and pain and loss of dexterity and agility during cold exposures longer than an hour. Dehydration can impair performance and increase the risk of injury. It is a response to cold-induced divers is and/or inadequate fluid intake or nutrition. Shelters, vehicles and clothing are examples of military material systems that may cause cold stress. Shelters may cause cold stress if heating is inadequate. Clothing systems can cause cold stress and injury if they are not properly insulated, layered and ventilated. Non freezing injuries may occur if clothing restricts blood circulation and the hands feet get wet.
Physical: The impact to the eyes or a body surface by a sharp or blunt object. Musculoskeletal: The effects on the system while lifting heavy objects. Trauma is a health hazard category that has been evaluated infrequently in the HHA program. Consequently, its concepts, hazard evaluation, risk concerns, and implications toward soldiers have not been fully developed. The primary focus is limited to health consequences addressed by the U.S, Army's ergonomics program. Ergonomics is a "term applied to the field the
studies and designs the human-machine interface to prevent injury and
illness and to improve work performance."
There are specific workplace conditions that can contribute to the development of WMSD's. These are considered to be occupational risk factors and include the following: repetitive motions (especially during prolonged activities), sustained or outward postures, excessive bending or twisting of the wrist, continued elbow or shoulder elevation (e.g. overhead work), forceful exertions (especially in an awkward posture), excessive use of small muscle groups (e.g. Pinch grip), acceleration and velocity of dynamic motions, vibration, mechanical compression, restrictive work stations (e.g. inadequate clearances) improper seating or support, inappropriate hand tools, machine-pacing and production-based incentives extreme temperatures, and extended exposure to hazardous or annoying noise. The combined effect of several risk factors in some job or workstation may lead to a higher probability of causing a WMSD. There are many jobs that can cause WMSD's. In addition to work place conditions identified in the army ergonomics pamphlet. Di Nardi (1981) also lists some of the typical job activities associated with common LTD's - cumulative trauma disorders of the upper extremities. These activities are diverse and include functions such as turning crews, grinding, buffing, polishing, hammering, surgery, typing, keying, wiring etc. Vibration Vibration is an oscillatory motion characterized by alternate increase and decrease in displacement. Oscillatory motions or vibrations in humans usually occur through physical contact with a vibrating source. Whole-body vibrations occurs when oscillatory motions are transmitted to the entire body through contact with a vibrating source at the feet of a standing individual all the buttocks of a seating individual, and along the entire side of the body of supine individual.
Resonance is a factor that affects the hazard potential of vibration exposure. Resonance describes the interaction b/w the human body and a vibration source such that the body causes the vibration to amplify. The resonant vibration can cause large displacements in the body which can result in damage. The effects associated with exposure to vibration include physiological changes, discomfort performance decrements, pain and degenerative processes. Examples if physiological effects include increase in heart rate, respiration rate, cardiac output, mean arterial blood pressure, pulmonary ventilation and oxygen uptake, and hyper ventilation. Discomfort and pain have been observed to affect the lower back, gastro intestinal and stomach areas, and thoracic area. Low-back discomfort can ultimately lead to clinical diagnosis of degenerative discusses including herniated discs, osteochondrosis, spondylosis, and other disorders of the spinal column. The primary source of WBV is from transportation vehicles, including ground, air, and water vehicles. Vehicle vibrations can be generated by exposure to specific environmental conditions (eg ground terrain, wave conditions) and/or vibrations occurring by design (e.g. engines, motor blades etc). Other sources of WVB include heavy machinery and buildings and vibrations that are transmitted directly through air or water. For e.g., military ground crews can be exposed to WVB resulting from exposure to aircraft propeller washes. The primary source of segmental vibration occurs with the operation of hand tools, Tools that produce the most severe vibrations include chain saws, jack hammers and tools used in a factory environment. Regardless of the hazard category that is evaluated, health hazard assessors rely upon various tools and techniques to help estimate and characterize potential risk. Generally, these tools and techniques can be characterized as those that are used to defect and quantity potential hazards, methods to assess potential health impacts, and control measures to eliminate or reduce hazards to acceptable levels. Acoustic Energy Control strategies for eliminating or minimizing the potential hazards from noise are the same as those for other occupational hazards. The ideal control is to design and build systems so that they do not produce hazardous noise levels. Typical measures for noise control include use of personal, protection equipment and limiting the exposure duration. Earmuffs and carp lings and the types of personal protection often used. Biological Hazards Chemical Hazards Examples of direct-reading instruments are prominent in the assessment of air brominates. Technologies include colorimetric indicators (e.g. detector tubes) air borne particulate analyzers (e.g. optical, electrical radio actives thermal, electromagnetic, chemi-electromagnetic and chromatographic analyzers). Techniques used include spectrometry (e.g. infrared spectrometry, atomic absorption spectrometry, inductively coupled plasma spectrometry, ultraviolet visible spectrophotometer, and mass spectrometry and chromatography (e.g. liquid, gas, high-performance liquid chromatography and ion Chromatography). Other techniques include: - microscopy, X-ray spectroscopy, electro-analysis, immunes as say, and surface analysis. Oxygen Deficiency Ventilation Ventilation is one of the principal methods to prevent or eliminate oxygen-deficient atmosphere in confirmed and enclosed spaces. It can be accomplished by supplying forced air to either dilute or displace air contaminants. Exhaust ventilation, coupled with fresh make up air, also can be used to remove oxygen-reducing point-source contaminants. Ventilation rates and air exchanges are determined by fan capacity, duct size, and type of containments to be removed. Instruments that can be used to determine air-exchange rates, airflow and air capacity includes variety of products that measure pressure, volumetric flow rate, and air velocity. Examples of such instruments include the U-tube manometer, pilot tube; vane anemometer, thermal anemometer, incline and anemometer, aneroid garages, smoke tube, tracer gas. Sometimes it is necessary to remove oxygen from a confined space to prevent a fire or explosion. This can be done by inserting, which requires introducing a non reactive (invert) gas (e.g. nitrogen, organ or carbon dioxide) to displace the oxygen. Individuals who enter this type of space must wear a supplied air respirator. A supplied air respirator also can be worn if ventilation cannot be used or if it will not correct an oxygen deficient atmosphere. Ambient Pressure Changes Non ionizing Radiation Prevent or eliminate oxygen-deficient atmosphere in confined and enclosed spaces. This can be accomplished by supplying forced air to either dilute or displace air contaminants. Exhaust ventilation, coupled with fresh make up air, also can be used to remove oxygen - reducing point-source contaminants. Ventilation rates and air exchanges are determined by fan capacity, duct size, and type of contaminants to be removed. Instruments that can be used to determine air-exchange rates, airflow and air capacity include a variety of products that measure pressure, volume etc. Response criteria include clinically visible response coetaneous erythematic, minimally visible retinal lesion, microscopic cellular change, or permanent or temporary changes in visual function. Control of laser operation by engineering controls, such as enclosures and safety interlocks, can eliminate or control the hazard. Hitchcock et al (1998) describes several types of instruments that can be used to measure RF (radio frequency) fields, body currents, and contact currents. These include instruments that make densitometry measures, current monitors, personal monitors and frequency counters. There are engineering administrative control strategies to minimized exposures and health hazards associated with RFR (Radio-frequency radiation). Examples of engineering controls include using system sector blanking to prohibit radiation in certain areas, incorporating dummy loads, shielding high voltage power supplies, and incorporating warning devices when the sources are activated. Administrative controls are publishing warning messages in technical manuals; providing safety training an briefings, periodically inspecting wave guides, interlocks etc and installing barricades, fences, signs, and warning devices to prohibit access to unauthorized areas. Ionizing Radiation Techniques discussed by Popendorf (1998) to control, prevent, or minimize occupational health hazards in hypobaric environments reflect the range of options available in other typical workplaces. These include engineering controls (e.g. increasing air, pressure in aircraft cachepots and cabins), using personal protective equipment (e.g. equipment similar to supplied air respirators that increase the availability of oxygen by increasing its molar fraction in the breathing air), and acclimatization. Ion-particle-counting instruments and dose measuring instruments are types of instruments used for detecting and measuring ionizing radiation. The principles of ion-particle-counting instruments are used both in portable radiation-detection instruments and in laboratory instrumentation for measuring radioactivity in environmental samples and bio as say specimens. Examples of ion-particle-counting instruments are the gas-filled particle counter (e.g. the ionization chamber, proportional counter and Geiger counter) and the scintillation detector. Examples of dose-measuring instruments are the free air ionization chamber (laboratory instrument), the air-wall ionization chamber (condenser type pocket dosimeter), the ion current chamber (cultic pie), and the thermo luminescent dosimeter. Since neutrons are not directly ionizing, they must interact with another medium to produce a primary ionizing particle, and require refinements in detectors or measurement and dosimetry. Shock In order to assess risk, an injury assessment value (IAV) is measured and compared to the lower bound of an ITL (injury threshold levels). The numerical relationship between the known ITL and the measured IAV defines an injury assessment criterion. Injury criteria has been established for the prediction of head (closed brain) injuries. Chest-trauma cervical, spinal and lumbar spinal column fractures; and pelvis and lower extremely injuries. These criteria translate engineering measurements such as forces, accelerations and deflections, into probabilities of injury occurrence. Heat Stress There are variety of instruments that measure temperature, radiant heat, humidity and air velocity, and some electronic devices integrate the individual measures to produce a single heat index. Examples of heat measuring devices include liquid-in-glass thermometers, bimetallic thermometers, resistance thermometers and thermo couples. Radiant heat can be measure with a radiometer or globe thermometer. Humidity can be measured with a psychomotor or hygrometer. Engineering and administrative controls and personal protective equipment can be employed to prevent or minimize the occurrence of heat stress. Engineering controls may include air conditioning, ventilation and isolation of heat sources. A micro climatic cooling rest is an example of personal protective equipment. Application of a work-rest schedule based upon a heat indicator level and planned consumption of adequate quantities of drinking water are examples of administrative controls. Cold Stress Clothing systems designed for cold temperatures must be layered, provide adequate insulation, and fit properly. Loose clothing layers with air spaces below them under a wind and water resistant outer garment, and insulated boots play key roles in preventing cold injury. Engineering and administrative controls and personal protective equipment can be employed to prevent or minimize the occurrence of cold stress. Engineering controls may include provision of adequate heating sources in vehicles and shelters. Trauma
The methods for reducing WBV exposure can be through design or by administrative controls. Design methods may involve the vehicle suspension system and/or the seating system. The vehicle suspension characteristics should allow for a wide range of vehicle loads but avoid a natural frequency in the region of human resonances. Seal-cushioning and suspension mechanisms can attenuate the transmission of vibration to vehicle occupants. Administrative controls can include rest periods or intermittent participation in specific mission profiles. Health Hazard Assessment ExpertiseThere are numerous scientists, engineers, and technician who specialize in the health and engineering sciences that support the HHA program (Table pg 577) Acoustical Energy: (Noise and Overpressure): A variety of professionals may be involved with acquiring and interpreting noise data and making recommendations control hazard sources. These may include industrial hygiene and environmental health professional's audiologists, and acoustic engineers. In the recent passenger army physicians were involved in the assessment of blast overpressure to apply and validate a mode predict the potential for developing adverse health effects.
Chemical Substances: Multiple specialists may be involved with assessing chemical hazards. There are several factors that may influence who may be involved with the assessment. These include identifying, sampling, and analyzing the chemical (s); quantifying the potential exposure; determining hazard and risk and recommending appropriate control measures. The skills and expertise of analytical chemists, industrial hygienists, toxicologists, other enwall health professionals, toxicologists and risk assessors may be employed to assess chemical hazards. Oxygen Deficiency (Ventilation): Professionals who may measures and assess oxygen-deficient environments typically include industrial hygienists, gas-free engineers, and environmental health professionals. These are individuals who are trained to operate direct-reading instruments that measure atmospheric oxygen concentrations and are knowledgeable about the risks associated with oxygen-deficient atmospheres. Oxygen Deficiency: (High altitude): Physicians especially aviation medicine and diving medicine specialists, and certain physiologists are knowledgeable about the dynamics and effects of oxygen deficiency due to reduced atmospheric pressure. Some industrial hygienists also specialize in this area. Radiation Energy: Health physicists are the primary professionals who measure and assess radiation hazards. Also, some industrial hygienists and other environmental health professionals may be specially trained in radiation assessment. Shock: People who would be proficient to assess shock include professionals who are skilled in physics and engineering. This would include physicists and engineers, especially automotive safely engineers and biomechanical engineers. Physicians also may be involved with helping to define and establish when detrimental health effects occur to body organ systems. Temperature Extremes and Humidity: (Heat Stress): There are several professionals who may evaluate and assess the potential for people to develop heat stress. Physiologists and physicians may be involved predicting the types of health effects that may occur at various levels of neat exposure and subsequent to the development of heat related medical conditions enwall health professionals and industrial hygienists typically monitor ambient and work environment and recommend control measures to prevent heat-related illness. Temperature Extremes and Humidity: (Cold Stress): There are several professionals who may evaluate and assess the potential for people to develop cold stress and injury. Physiologists and physicians may be involved in predicting the types of health effects that may occur at various levels of cold exposure and subsequent to the development of cold-related medical conditions. Environmental health professionals and industrial hygienists typically monitor ambient and work environments and recommend control measures to prevent cold-related illness. Trauma: People who would be proficient to assess ergonomic concerns would include ergonomics, biomechanical engineers, human factors engineers, industrial hygienists, some physicians and some environmental health professionals. Vibration: People who would be proficient to assess vibration hazard potential would include biomechanical engineers, human factors engineers, some industrial hygienists, some physicians and some environmental health professionals. Tools That Support the Overall Health Hazard Assessment Process The material developers (acquisition community, e.g. program and project managers) are the Risk Managers. Risk assessment generally is a four-stage process that evaluates the potential for people to develop disease or die from exposure to biological, chemical or physical agents. The risk management process is separate from but includes risk assessment. Managing risk includes consideration and integration of variety of other factors (e.g. technology, economics and funding, politic is, social concerns, military needs and requirements, and others). That influences the outcome of design and production decisions. The four basic steps in the risk assessment process are:
Hazard Identification is the process of determining
the type of adverse health effects that a biological, chemical or physical
agent may cause. The key element of the HHA Program is to identify and recommend strategies that will eliminate or decrease exposures to hazardous agents. Generally, there are several ways that any one potential hazard can be controlled. The strategies may range from completely eliminating the hazard from the system or process to removing the person from the system or process. Generally removing the hazard and engineering controls is the best strategy because they do not rely upon an individual to comply with an activity or practice. Thus, there is a hierarchy of control strategies that can be recommended to control health hazards. The hierarchy of control strategies, in order of preference from health perspective, includes engineering controls, work administrative controls. (See Table)
Table: Hierarchy of Control Strategies and Examples to Eliminate or control Chemical, Physical and Biological Hazards
In this module analysis of quality of life in the context of environment has been presented.
1. How quality of life is affected by the environment?
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