Contents
Everything you need to know about Health and Industrial Hygiene
y L. Harvey Kirk III, CSP*
INDUSTRIAL HYGIENE
Industrial hygiene (IH), also known as occupational hygiene, is the science of anticipating, recog-nizing, evaluating and controlling workplace environmental factors and stressors that can lead to illness or impaired health of workers or those in the surrounding community (American Industrial Hygiene Association, 1995). Industrial hygiene practice requires detailed knowledge of a broad array of physical and life sciences, and an organized and analytical approach to problem solving.
Figure 7.3.1. Industrial hygiene often involves sampling for contaminants in the workplace, and designing effective control procedures and equipment.
Terminology
In industrial hygiene terminology, toxicity refers to the ability of a substance to injure a bodily organ or system, interrupt a biochemical process or affect an enzyme system. Hazard refers to the injurious properties of a substance and the probability of injury. Risk refers to the degree of hazard and exposure factors such as route of entry into the body, how much of a substance is released and how easily it is absorbed into the body, length of exposure and effectiveness of control methods.
Recognizing Factors and Stressors
Due to the nature of the cement manufacturing process, the industry has its own set of unique IH hazards that should be recognized and controlled before they become harmful. These hazards can be divided into four main categories: 1) chemical hazards that can be irritating or toxic to the body’s organs or systems, 2) physical hazards, such as noise, vibration, radiation, and thermal or pressure extremes, 3) ergonomic stresses resulting from an improper interface of workers and workplace machines, tools and procedures that repetitively stress vulnerable areas of the body, and 4) biological hazards from living organisms that can adversely affect bodily functions. See Table 7.3.1.
Evaluations
Decisions about the risks industrial hygiene hazards pose to workers must be based on careful evaluation. Information needed includes: 1) the type and magnitude of each hazard, 2) whether they are acute (injurious in the short term) or chronic (injurious after long term exposure, usually many years), 3) degree of worker exposure, and 4) the adequacy of current control measures. Hazard exposure can be determined qualitatively by examining the work area, its processes and materials, and quantitatively by measuring worker exposures using area surveys and personal sampling techniques. Samples should be analyzed at accredited laboratories and results studied and compared to recommended or permissible exposure levels. Industrial hygiene standards often require special interpretation and may require the assistance of someone with specialized training.
Control Measures
There are three basic types of control measures, listed in order of preference of application:
1) engineering controls, which remove or reduce the hazard by improving, adding or replacing equipment that cleans, isolates, encloses or ventilates an area or process, 2) administrative meas-ures, which include reducing worker exposure time, and training to improve hazard recognition and exposure avoidance procedures, and 3) personal protective equipment, which workers wear to limit exposure to the various environmental factors and stressors they encounter in the workplace.
CHEMICAL HAZARDS AND CONTROLS
Chemical hazards occur in the cement industry when certain chemicals, compounds and substances are not properly used or controlled, and when there are excessive concentrations of air contaminants in the workplace. Toxic effects occur only when a chemical substance reaches a target receptor in a high enough concentration and for a sufficient time (Doull and others, 1980).
Chemicals and Compounds
Chemical substances may enter the body and possibly affect its systems through inhalation, inges-tion or absorption through the skin. Corrosives, irritants and solvents are examples of chemical hazards. Certain other substances are considered carcinogens or may affect specific organs or systems. All chemical substances should be used according to the manufacturers’ instructions, and all recommended precautionary exposure measures should be followed.
Carcinogens. Carcinogens are substances that can cause tumors to form or tissues to grow abnormally. There are few substances employed in the cement manufacturing process that are carcinogenic in nature. However, certain products used in maintenance operations may contain compounds that are listed as carcinogens or suspected carcinogens by the International Agency for Research on Cancer (IARC), the National Toxicology Program (NTP) or other agencies. Facilities should identify what carcinogenic substances or compounds may be present in the work environ-ment, advise employees and minimize or prevent exposure. Substitution with alternate substances, application of engineering or administrative controls and use of personal protective equipment are techniques that can be employed to reduce risk.
Some cement plants use alternative energy sources such as hazardous waste-derived fuels. These fuels are often blends of many different solvents and may contain varying concentrations of chem-icals or metals known to be carcinogens. Personnel handling such fuels and their by-products should be made aware of the potential hazards and appropriate controls should be employed.
Corrosives. Corrosive substances are strongly acidic or alkaline, and have pH factors of 0-2 or 12-14, respectively. Although they are usually found in laboratories, corrosives also include battery acid, rust removers and drain cleaners. They can cause severe blistering of the skin or burns of up to the third degree. Corrosives are an eye hazard and may produce irritating or toxic gas if burned or heated. Tissue damage may be permanent. Corrosives may ignite combustibles such as wood or paper, and can produce flammable gas on contact with metal. Best practices for handling corro-sives includes use of: 1) rubber gloves, 2) an apron, 3) eye and face protection, such as indirectly vented splash goggles and a face shield, and 4) a fume hood or respirator if vapors or mists are present. Personnel should not: 1) smell or inhale vapors, 2) siphon with one’s mouth, or 3) store or transport corrosives near flammable solids, oxidizers, ammunition, explosives or reactive chemi-cals. Corrosives containers should be labeled clearly. Acids and alkalies (sometimes called bases) should not be stored together. Spill cleaning and disposal is best accomplished by neutralizing, not by rinsing down drains. Diluting strong acids and alkalies can reduce: 1) their hazard when handling, and 2) their potentially harmful effects should a spill or splash occur. Eye washes and deluge showers should be provided near work and storage areas in case corrosives contact the eyes or skin.
Hematopoietic toxins. Hematopoietic toxins can damage the blood or the body’s ability to form blood. Route of entry into the body is usually by inhalation. Examples of hematopoietic toxins include carbon monoxide, benzene and epoxies that contain xylol, which in sufficient doses, can affect the blood’s ability to transport oxygen. Epoxies should only be used where good ventilation exists.
Hepatoxins. Hepatoxins are substances that can cause liver damage. Route of entry into the body is usually by inhalation. Examples of hepatoxins include propylene glycol, which is found in some epoxies. As with other toxic substances, provision of good ventilation is always the first priority when handling hepatoxins.
Figure 7.3.2. Continuously monitoring instruments can alarm if chemical hazards in the workplace reach action levels.
Irritants. Irritants are substances that can cause an inflammatory response or reaction of the eye, skin orrespiratory system, if it contacts the tissue in sufficient dose. Many substances are considered irritants, including numerous solids, liquids and gases. Good ventilation, safe handling and storage practices and use of personal protective equipment are measures that will prevent tissue irritation. Irritation is usually completely reversible; when the irritant is removed, the inflammation subsides. Clinker, cement and cement kiln dust (CKD) are alkaline materials that are also considered irritants. Mildly acidic neutralizing solutions and barrier creams are marketed to spread on the skin prior to exposure, but using gloves, disposable protec-tive clothing and practicing good personal hygiene best achieve injury prevention.
Mercury and mercury spill control. Mercury is used in cement plants for certain instrumen-tation and laboratory purposes. It is a heavy liquid that will vaporize, especially when it contacts hot surfaces. Inhalation of mercury vapors or contact with the liquid itself can cause eye or skin irritation, weakness, fatigue, chest pain, coughing, tremors, glandular disorders and more. Best practice is to store mercury in a closed, high-density polyethylene container. Glass is a second choice, but it is breakable. Mercury spill kits containing gloves, respirator, mercury sponges, suction tubes, absorbent powder and detailed use instructions should be placed in key areas, and employees should be trained to use it properly. Mercury spills should be cleaned up immediately and spill areas should be ventilated thoroughly. If mercury recycling is not possible, a reputable firm should be contracted to dispose of the collected waste mercury and used sponges (National Institute for Occupational Safety and Health, 1997).
Mutagens. Mutagens are substances that alter a cell’s genetic information and may lead to unde-sirable inherited conditions. The presence of mutagenic substances in cement plants would be considered unusual.
Nephrotoxins. Nephrotoxins are substances that can cause kidney damage. Lead, such as found in some older paint products, xylol and propylene glycol, such as used in some epoxies, are examples of nephrotoxins. Inhalation is the principal route of entry into the body, but ingestion is also possible.
Neurotoxins. Neurotoxins are substances that can affect the brain, central nervous system or nerve cells. They usually enter the body through inhalation, and may produce emotional or behav-ior abnormalities, or interfere with the body’s ability to control certain functions. Examples of neurotoxins include lead in paint products, or alcohols, petroleum napthas and ethylene glycols, such as found in some paint thinners. Substitution with less hazardous alternative substances should be explored. Good ventilation and the use of protective respiratory equipment are consid-ered to be best practices.
Reproductive toxins. Reproductive toxins are substances that affect either male or female reproductive systems and which may impair one’s ability to have children. The presence of repro-ductive toxins in cement plants would be considered unusual.
Sensitizers. Sensitizers are substances, which on first exposure, cause little or no reaction, but which, on subsequent or repeated exposure, may cause a marked response, not necessarily limited to the contact point. Sensitizers most commonly affect the skin, but also can affect the respiratory system. Sensitivity to a substance is usually dependent upon personal characteristics; what may sensitize one person will not necessarily affect another.
Solvents. Solvents are substances that will dissolve another material, such as acetone, metal cleaners, and paint thinners, even water. Although they are often thought to be hazardous, the degree of hazard varies from none to high. Solvents may be flammable or toxic through contact or inhalation of vapors. Substitution of potent products with less hazardous solvents is always a best practice. Other best practices include: 1) using gloves when handling solvents, 2) storing solvents in clearly labeled containers that are closed or covered when not in use, 3) providing good ventila-tion in work areas, 4) removing and washing clothing that comes in contact with solvents, and 5) removing solvent-exposed persons to fresh air if overexposure symptoms occur.
Systemic poisons. Systemic poisons are substances that spread throughout the body, damaging all organs and bodily systems. Systemic poisons are rarely found in a cement plant, although certain herbicides or animal poisons, if used or stored irresponsibly, could possibly cause systemic damage. Substances that are potentially systemic poisons should be used only when necessary, and then only in accordance with the manufacturer’s instructions. All recommended precautionary control measures should be followed.
Teratogens. Teratogens are substances that can cause birth defects in the fetus of a pregnant female. The presence of teratogens in cement plants would be considered unusual.
Air Contaminants
Air contaminants include dusts, fibers, fumes, gases, mists and vapors. If inhaled in sufficient doses, they could be hazardous to workers’ health. Facilities should identify which air contami-nants are present in the workplace and survey employees’ potential and actual exposure by performing bulk, area and personal sampling. When engineering and administrative controls are not feasible, or while they are being installed, exposure should be controlled with personal protec-tive equipment. (See also “Respiratory Protection”).
Dusts. Dusts are solid particles suspended in air. LimestonAe and portland cement dust are classi-fied as “nuisance particulates.” When inhaled or swallowed in small doses, they dissolve, pass through the kidneys and out of the body without adverse health effects (Holt, 1987). It should be noted, however, that some scientists believe no dust is completely inert and precautions should be taken to prevent overexposures even to dusts given the “nuisance” designation.
Calcined limestone and cement kiln dust (CKD), because of their percentage of calcium oxide (CaO), are considered chemical substances and have permissible respirable dust exposures that are fractions of those for nuisance particulates. Consult current regulations for exposure limits.
Dusts that include a certain fraction of respirable crystalline silica (SiO2) also have reduced permissible exposure limits. Silica accumulation in the lungs can cause silicosis, and crystalline silica has been classified as a known human carcinogen (Group I) by the International Agency for Research on Cancer (IARC). Permissible dust exposure limits vary according to the jurisdiction of regulatory agencies and authorities, and the current regulations should be consulted for each oper-ation. Some agencies incorporate the percentage of crystalline silica into an exposure limit for respirable dust, while others express the exposure limit in terms of the actual concentration of silica present.
Dust control best practices include source enclosure, spill and leak prevention, use of air pollution control devices, moisture addition and vacuuming instead of dry sweeping. Respirator selection and use should be based on contaminant type and concentration, and on respirator rated protec-tion factors.
Fibers. Fibers are particulates that have an aspect ratio (such as length to width ratio) equal to or greater than three to one (3:1). Fibers most likely found in cement facilities are naturally occurring mineral fibers, such as asbestos, or synthetic vitreous fibers (SVF), also known as man-made vitre-ous fibers (MMVF) or man-made mineral fibers (MMMF).
Asbestos formerly enjoyed widespread use for insulation purposes, but serious illnesses associated with inhaling or ingesting friable asbestos have curtailed or ended its use in many portions of the world. In many locations, regulations do not permit the use or storage of asbestos, and many facili-ties have removed asbestos from the workplace. Asbestos is listed by the International Agency for Research on Cancer (IARC) as a Class 1 carcinogen. Those facilities where asbestos is still in use should conduct a plantwide survey to determine the type, location and quantity of asbestos, and its condition. Surveys can aid in prioritizing abatement efforts, and in budgeting for systematic removal or encapsulation. Plants should ensure that friable asbestos does not become airborne, and train employees on asbestos hazards. The use of certified asbestos inspectors and abatement companies is recommended because strict environmental and engineering controls are required, including ventilation and use of high-efficiency particulate air (HEPA) filters and respirators.
Synthetic Vitreous Fibers (SVF) products are insulating materials that include 1) fiberglass, 2) mineral wools, 3) refractory ceramic fibers (also known as RCF or vitreous alumino-silicate fibers), and 4) amorphous calcium-magnesium-silicate fibers. Fiberglass and mineral wools have been classified by IARC as 2B carcinogens (possibly causing cancer in humans). Refractory ceramic fibers have also been classified by IARC as 2B carcinogens (possibly causing cancer in humans). As manufactured, calcium-magnesium-silicate fibers and RCF do not contain respirable crystalline silica, but when they are exposed to sustained, high temperature (>980°C) use, portions of the material may de-vitrify into crystalline silica, such as cristobalite or quartz, Group 1 carcinogens (Unifrax Corporation, 1998, 1999). If used in certain high-temperature cement applications, they could present a greater lung disease hazard when removed after use.
There are major differences between SVF products and asbestos: 1) SVF does not split longitudi-nally as do asbestos fibers, and 2) they are much more quickly dissolved by body fluids and there-fore less durable as a source of acute or chronic irritation (Rauscher, 1990). Durability is measured by a fiber’s in-vitro dissolution rate in simulated lung fluid, (kdis, laboratory testing), or in-vivo biopersistence factor (fiber half-life, T1/2, animal testing.) See Table 7.3.2, for a summary of the results from several studies.
For the purpose of comparing the relative hazard of certain fibers, several Year 2000 Permissible Exposure Levels (PELs) and Recommended Exposure Guidelines (REGs) are listed. Because these PELs and REGs may not be applicable in all jurisdictions, or because they may change over time, current regulations should be consulted for each operation. The United States Occupational Health and Safety Administration’s PEL for asbestos is 0.1 fibers/cubic centimeter (f/cc or f/cm3), and 1.0 f/cc for fiberglass and mineral wools. The REG for refractory ceramic fibers set by the Refractory Ceramic Fiber Coalition is 0.5 f/cc.
The European Union has established another set of guidelines to classify SVF products as to their hazard potential. These guidelines consider fiber respirability, chemistry, and biopersistence in animal testing. The Year 2000 regulatory criteria is: if 50% of fibers greater than 20µm long are cleared from the lungs in less than 10 days (the fiber half-life, T1/2), that fiber is not classified as a potential carcinogen (Zoitos, 1999). In recent years, several SVF products have seen the European carcinogenic labeling requirement lifted. In addition, vitreous fiber manufacturers have developed new products that have low bio-persistence (T1/2) ratings.
SVF manufacturers recommend the following best practices when handling their products:1) wearing loose clothing, 2) wearing safety glasses or goggles, 3) preventing dust production, 4) providing good ventilation, 5) using respiratory protection when fiber concentration exceeds the PEL value, 6) keeping work and home clothing separate, and 7) rinsing the washing machine after washing work clothes (Johns Manville, 1999).
Fumes. Fumes are airborne solid particles of metal that condense from heated vapors in the air. Examples of welding fumes are oxides of iron, lead, nickel, chromium, manganese, etc. Fumes, if inhaled in sufficient quantity, can cause nausea, dizziness, headache, metal fume fever, damage body organs or reduce the efficiency of bodily systems. Material safety data sheets (MSDSs) should be reviewed to determine hazards to which persons are exposed, and exposure limits. Local exhaust ventilation is a good engineering control because it draws fumes out of workers’ breathing zones. Filtering respirators offer secondary protection.
Gases. Gases are formless fluids that take the shape and size of their container. Their chemistry may pose health hazards, or they may serve as asphyxiates if they collect and displace oxygen in work areas. There are many gases to which cement plant employees could be exposed, including numerous products of the fuel burning process. Preventing and minimizing the release of gas into the air, ventilation and dilution are preferred control measures. Fixed and portable atmospheric monitoring equipment are available to detect gases and measure their concentrations. Respirators should be worn if concentrations exceed permissible limits and cannot be controlled through engi-neering controls.
Carbon dioxide (CO2) is odorless, colorless and slightly heavier than air. It is an asphyxiant and a cerebral vasodilator. If inhaled in large concentrations it can cause CO2 narcosis, a condition marked by rapid circulatory insufficiency, advanced lung failure, hypoventilation, coma and death. Inhalation in low concentrations may cause acute increased respiration and headache, but chronic harmful effects are not known. CO2 is often used as a fire control chemical and may accumulate as a hazard in process vessels or outside near ground level if it leaks from storage tanks or is discharged from fire control apparatus. See Chapter 7.2, “Fire and Explosion Protection” for a more detailed discussion of the hazard and controls. If one must enter such an environment, supplied-air respira-tors are required; filtering respirators offer no protection.
Carbon monoxide (CO) is another product of the combustion process. CO is odorless and color-less, and levels are generally far below conditions immediately dangerous to life and health (IDLH). Exposure to low concentrations of vented kiln gases or vehicle emissions above safe levels can interfere with oxygen exchange in the lungs and produce severe headaches. Exhausts from pyroprocessing and vehicles or tools powered by internal combustion engines should be vented safely out of enclosed work areas. Facility personnel should be aware that entry into confined spaces requires measuring CO levels, and that filtering respirators offer no protection to CO. Air should be supplied when concentrations exceed safe levels.
Flammable gases such as acetylene, LPG-MAPP®,natural gas and propane have numerous applica-tions in the cement industry and are considered serious fire and explosion hazards. In addition to these physical hazards, flammable gases are simple asphyxiants that, if leaked into the air, could exclude an adequate supply of oxygen to the lungs. Depending on the concentration and length of exposure, they could cause symptoms ranging from rapid breathing, fatigue or nausea to loss of consciousness, coma or death. Filtering respirators do not afford any protection. Use of monitors that measure flammable and oxygen deficient atmospheres is recommended before entering an area where leaked gas is suspected.
Hydrogen sulfide (H2S) is generated when organic matter decomposes in anaerobic conditions. Although it is sometimes called sewer gas, it has been found in wash pits for mobile equipment. Leaves, dirt and other organic material washed off vehicles and rotting below the water level can produce H2S. If a thin oil film covers the wash water, H2S can be trapped below the surface, and then released when the surface is disturbed, such as when solid materials are cleaned from the pit bottom. H2S gas accumulation can be prevented if the water’s surface is roiled, such as when air is bubbled through it.
Nitrogen may be found in plant laboratories or used in the head-spaces of fuel tanks. Although it makes up roughly 80% of the air we breathe, it is a simple asphyxi-ant if leaked in sufficient quantities into the work environment. It could displace oxygen and cause serious injury or death.
Oxides of nitrogen (such as nitro-gen dioxide, NO2) are found in kiln vent gases and diesel exhaust. Con-centrations in process gases are generally dilute, but poorly main-tained diesel engines or exhaust systems, or operation in enclosed or underground areas could over or expose operators and persons working nearby. Symptoms of overexposure include eye or respiratory tract irritation, coughing, chest pain, difficulty breathing or drowsiness. Filtering respirators do not offer protection from oxides of nitrogen; rather, supplied air respirators are required.
Figure 7.3.3. Ventilating workplaces will prevent the accumulation of potentially harmful air contaminants.
Oxides of sulfur (such as sulfur dioxide, SO2) are acidic gases produced when certain fuels are burned, particularly coal. Kiln exhaust gases are usually safely vented out of the kiln and diluted in the atmosphere. However, workers may be exposed if unusual meteorological conditions force exhaust gases down to lower levels, or if leaks develop in process ductwork or air pollution control devices. If workers are exposed, irritation of the respiratory system can occur. In that case, injury potential depends on dose. One cannot rely on the sense of smell to measure SO2 concentration, as its odor threshold is only about one-tenth the threshold limit value (TLV). Monitoring instru-ments are needed to measure concentrations, and should be deployed with automatic alarms at key locations if surveys or exposure experience indicates stack height or location is a problem.
Ozone (O3) is a powerful oxidizer and irritant to the eyes and mucous membranes of the respira-tory tract. It is generated by corona discharges in electrostatic precipitators and can be recognized by its bleach- or electrical burn-like odor. If kiln precipitators are energized and not positively vented, ozone can back-draft into the kiln or leak out of open equipment doors. Ozone causes headache, sore throat, coughing, chest tightness, burning eyes, profuse perspiration, nausea and fatigue. Best practices to control ozone exposure include hazard training employees, ensuring precipitators are de-energized, locked out and positively ventilated, and using an ozone monitor before and during kiln system entries (Sanderson and others, 1999).
Mists. Mists are liquid droplets suspended in air. Mixing, stirring, splashing, foaming or spraying liquids, such as paints or oils, may generate mists. The skin, lungs and eyes are potentially suscepti-ble to injury if exposed, so mist production should be contained and controlled (National Mine Health and Safety Academy, 1999). Protective clothing and filtering respirators should be supplied when required.
Vapors. Vapors are the gaseous form of substances that are liquids or solids at room temperature. Depending upon substance characteristics and physical conditions, they will evolve out of the substance if containers are not closed. Vapors posing potential human health hazards include gaso-line and other fuels, oils, paints and solvents. Vapors can cause adverse local effects to the skin, throat or lungs, produce narcotic effects in the central nervous system or cause toxic effects in the blood or other organs (National Mine Health and Safety Academy, 1999).
Preventing and minimizing vapor release into the air is best accomplished by safe storage and handling, in particular keeping containers closed. Ventilation or dilution should be considered a secondary measure, and evaluated for effectiveness. Liquid fuel and additive storage tank vents should be equipped with chemical cartridges to control “tank breathing” vapor release during fill-ing and withdrawal processes, or their headspaces provided with a blanket of nitrogen. Safe fuel and additive delivery and unloading procedures should be developed. Spilled liquids present the possibility that large quantities of vapors can be released in a relatively small area, therefore personal protective equipment should be provided and safe work procedures developed in the event of a spill. Facilities should consider when substitution of any chemical with a less hazardous substance is appropriate to reduce employee exposure. If engineering and administrative controls do not maintain vapor concentrations below safe levels, properly fitted respirators with appropri-ate chemical filters should be provided.
Chemical Hygiene Plan (Laboratory Safety)
Facilities should adopt a chemical hygiene plan to address and reduce exposure to hazardous chemicals in the laboratory. Written operating procedures must be formulated to address relevant safety and health issues. Procedures should specify criteria to be used to determine chemical expo-sures, exposure control methods, use of fume hoods and personal protective equipment, all labora-tory operations or activities needing special approvals, provisions for medical consultation and testing, additional protective measures to be used when working with highly hazardous chemicals and decontamination procedures to be used in the event of a spill. Laboratory employees should be trained about permissible exposure limits, physical and health hazards, symptoms of overexpo-sure, safe chemical use procedures and use of written reference materials such as MSDSs. Personal exposure monitoring and medical examinations are required at certain times.
Hazard Communication
Facilities use numerous chemicals and substances that pose potential chemical and physical hazards to employees using or exposed to them. Compressed gases, explosive and reactive chemi-cals, flammable and combustible liquids, solvents, corrosives, irritants, oxidizers, and substances with adverse toxicological properties are examples of such chemicals. Facilities should adopt a plan to ensure all hazardous materials are identified, employees informed of potential hazards to which they may be exposed and trained on safe handling procedures. Hazard Communication (HazCom) or Workplace Hazardous Materials Information Systems (WHMIS) should include a written program and provision of hazard reference materials (MSDSs). Labeling of containers and use of personal protective equipment and procedures should be proscribed and followed.
Package Delivery and Courier Shipments
Facilities should consider whether cement and other potentially hazardous materials sent via couriers or other package delivery services should be identified per the requirements of hazardous materials transportation regulations. If this policy is adopted, best practices include proper pack-aging and notifying the transporter of the contents and hazard class.
Respiratory Protection
Best practice for respiratory protection involves identifying air contaminants and controlling them through engineering and administrative controls. When engineering and administrative controls are not feasible or completely effective, while they are being installed or during emergencies, respi-rators may be used to protect workers.
Respiratory protection program. When respiratory protection is needed, a respiratory control program should be implemented. Key elements include: 1) exposure assessment through sampling and analysis, 2) central program control of assessments and respirator selection, record mainte-nance and program effectiveness evaluation, 3) adoption of written standard operating procedures regarding respirator issuance and use policies, 4) medical evaluations of respirator users to assure wearers do not have medical conditions that would put them at further risk, 5) selection of respi-rators commensurate with hazards and exposure, 6) training on respiratory hazards (respirator function, capabilities and limitations, how to properly fit, wear, and care for a respirator), 7) fit testing to assure a respirator is correctly sized and properly adjusted to one’s face, and 8) respirator maintenance, including inspection, cleaning and storage.
Respirators. Respirators may be classified as: 1) air purifying, 2) atmosphere-supplying, or 3) combination of air purifying/atmosphere-supplying. Air purifying respirators remove contami-nants from the air by filtering out dusts, mists and fumes, or by chemically adsorbing gases and vapors. These include disposable respirators, half mask or full facepiece cartridge or canister models, and battery powered air-purifying respirators (PAPR). Air-supplying respirators include demand, pressure demand and continuous flow airline models, and self-contained breathing appa-ratus (SCBA). Combination air purifying/atmosphere-supplying respirator provide protection if the air supply is lost. Combination-type units are restricted to atmospheres that are not IDLH.
Respirator selection should be based upon the type of contaminant; its concentration, work activ-ity, ambient conditions and respirator wear time. Respirators have been rated according to the level of protection they afford, such as specifying up to what multiple of permissible exposure are particular respirators effective. This is commonly referred to as the respirator protection factor. Respirators are increasingly protective in this order: half mask disposable, half mask air purifying, half mask air supplying, full facepiece air purifying, full facepiece atmosphere-supplying. Table 7.3.3 lists approximate relative protection factors for various respirators.
New disposable respirator rating systems evaluate the effectiveness of particulate-filtering respira-tors according to their filtering efficiency, and whether or not they should be used in the presence of oil mists. This system uses the numbers 95, 99 or 100 to designate filtering efficiency (95%, 99% or 99.97%, respectively), and the letters “N,” “R,” and “P” to designate selection criteria in the pres-ence or absence of oil particles. Oil mists can break down the filtering effectiveness of respirators, so proper respirator selection is important. “N” stands for “Not Resistant to Oil,” “R” stands for “Oil Resistant” and “P” stands for “Oil Proof.” The minimal rating for a cement plant disposable respirator should be N95. If oil mists are present, “R” or “P” series respirators should be used. When “N” series respirators are used in dirty environments, they should be used for one work shift only, and then discarded. When “R” series respirators are used in oily environments, they should be used for one work shift only. Any respirator should be changed when it becomes clogged, damaged or breathing becomes difficult.
PHYSICAL HAZARDS AND CONTROLS
Physical hazards include noise, radiation and thermal hazards.
Noise and Hearing Conservation
Cement manufacturing processes generate noise from crushers, screens, mills, blowers, fans, vibra-tors, power transmission devices, mobile equipment,tools, laboratory and office equipment (Kirk, 1998). If persons are exposed to excessive noise, particularly if they are not protected, they may suffer hearing loss. Best practices include establishing a hearing conservation program, identifying occupational noise sources and controlling employees’ exposure through engineering and adminis-trative controls. When such controls are not feasible or completely effective, while they are being installed or during emergencies, personal protective equipment, also called Hearing Protection Devices (HPDs), may be used to protect workers.
Physics of sound and noise. Sound is any pressure variation that can be detected by the human ear, whereas noise is sound that is unwanted by the listener. Sound is transmitted by waves, and is measured by amplitude (intensity), frequency in cycles per second (Hertz or Hz) and dura-tion (time). Other parameters are sound power and sound pressure. Since these values cover a wide range, it is convenient to express intensity, power, and pressure in terms of their respective levels, or decibels (dB). As the value of these properties increase, the potential damaging effect on human auditory system increases.
Decibels are logarithmic values and cannot be added algebraically. As a rule of thumb, the additive effect of noise sources can be estimated as shown in Table 7.3.4.
Noise exchange rate is an important term. This means: a reduction of 3 dB in sound intensity level requires a 50% reduction in sound intensity. When calculating permissible noise exposure, some regulatory agencies apply a 5 dB exchange rate instead of using the true value of 3 dB. That is, by regulation, a worker’s noise exposure can be increased by 5 decibels if exposure time is halved, or, exposure time can be doubled if noise exposure is reduced by 5 decibels. For industrial hearing protection programs, application of the 5 dB exchange rate is much less stringent than were the true 3 dB exchange rate used.
Effects of Noise Exposure. One type of hearing loss is sensorineural, i.e. noise induced hearing loss (NIHL), caused by damage to the hearing cells in the inner ear. This condition is always irre-versible. Besides excessive exposure to noise over a period of time, usually over many months or years, hearing loss can also be due to aging (presbycusis), or to conductive hearing loss.The latter may be caused by obstructions in the ear, such as wax buildup, or by certain illnesses or other medical conditions. Non-auditory effects of excessive noise exposure can include nausea, headache, vasoconstriction, high blood pressure, equilibrium and visual disturbances.
Loss of hearing acuity can make it difficult for one to understand, often because it becomes hard to distinguish between consonants. The power of speech is generally contained in the vowel sounds, but intelligibility comes primarily from the consonants. Occupational hearing loss in the important human speech frequencies of 2000-4000 Hz may be considered a disability and compensable under workers’ compensation laws.
Instrumentation for noise evaluation. Sound level meters (SLMs) measure sound pressure levels in decibels (dBs). Three weighting networks, A, B, & C, are common to sound level meters and cause meter sensitivity to vary with frequency. The A scale most closely approximates the range of the human ear and is most commonly used. Whenever expressing sound levels, the scale must be identified, such as “dBA.”
Octave band analyzers determine sound pressure levels at frequencies ranging from 31.5 Hz to 16,000 Hz. They are usually used in conjunction with SLMs and are necessary when designing engineering solutions for noise control. Sound level meters with octave band analyzers enable facility engineering and safety personnel to identify high noise level equipment and select appro-priate materials or equipment to reduce workplace noise levels.
Noise dosimeters worn by workers continuously measure personal exposure to changing sound levels over the course of a workday. They integrate and record the total sound energy to which workers are exposed, calculate the daily dose in dBA or percent allowable, and record peak levels. Sampling individ-ual workers using sound dosimeters can indicate workplace sound expo-sure for various tasks and help iden-tify hearing loss risk.
Hearing conservation programs. Facilities with high noise levels should implement a comprehensive hearing conservation program. Program components should include: 1) monitoring to determine task-specific noise exposure levels, 2) performing area surveys to identify loud equipment, 3) posting workplace noise levels, 4) using engineering controls and administrative procedures to reduce exposure, 5) training on the effects of noise exposure, including the benefit and use of HPDs, 6) audiometric testing of employees’ baseline hearing acuity, 7) audiometric monitoring over the course of employment, 8) keeping records, and 9) notifying employees of changes in hearing ability.
Control methods. Regular maintenance and proper lubrication will solve many noise level prob-lems. When they do not, engineering controls may be installed. These controls include fan and blower silencers, acoustical linings, curtains, doors and enclosures to block and absorb sound, substituting loud equipment like power transmission devices and vibrators with quieter models, relocating or enclosing loud equipment, and providing mobile equipment cabs and operators’ stations. Whenever feasible, engineering controls should be specified, purchased and installed with new equipment during the design and construction process. Replacing or retrofitting existing equipment is possible, but may be more costly and less effective. Facility operations and mainte-nance personnel should be aware that engineering controls must be properly installed and main-tained in order to achieve maximum and continued benefit.
Administrative controls include limiting work times in loud areas, and requiring certain safe work practices, such as keeping windows closed in air-conditioned mobile equipment cabs.
Personal protective equipment (specifically, HPDs) includes several styles of earplugs and earmuffs. In order to provide hearing protection,
earplugs must be installed properly in the ear canal, and earmuffs must have a good seal around the ear. Plugs and muffs vary in their effectiveness according to their design and the materials used in their construction. Noise Reduction Rating (NRR) measures HPD effectiveness, with higher NRR-rated HPDs affording more protection. Advertised NRRs reflect protection under optimum conditions; actual worker protection is much lower than rated, sometimes only half the NRR or less.Wearing time is very important; when HPDs are removed, even for a short time, the risk of hearing loss increases dramatically. Exposure to noise totaling just 15 percent of the time is equivalent to using little or no protection at all. Table 7.3.5 illustrates this point and makes a strong case for wearing hearing protection all the time, not just when it is convenient (Sterret, 2002).
At high sound pressure levels, sound can bypass the ear canal and be conducted through the skull. This is referred to as “bone conduction” and can also damage a person’s hearing. Ear muff-type HPDs can lessen this effect. Therefore, for sound levels of 105 dBA or more, dual hearing protec-tion, such as use of both earplugs and ear muffs, is recommended. Exposure to sound levels above 115 dBA, as measured by a slow response dosimeter or sound level meter, should not be allowed, although much higher instantaneous peak levels may be experienced.
Pressure Extremes
Extremes of pressure are found in spray cans, compressed gases and hydraulic fluid systems. Pressures of 700 kilopascals (100 psi) can be found in plant compressed air systems, while pres-sures in compressed gas cylinders can reach 15,000 kilopascals (2200 psi), or more. Hydraulic system pressures can equal or exceed these figures. Uncontrolled or rapid release of pressure poses an injury hazard to personnel.
Aerosol spray cans. Spray cans have been known to explode when stored in hot areas, even on the dashboards of vehicles parked in direct sunlight. They should be stored in cool locations. If flammable propellants are present, spray cans should be stored in flammable storage lockers or caged bins when not in use. These objects pose a fire hazard, and have been known to spread fire rapidly throughout a building when heat from an incipient fire causes them to explode and fly to various locations, simultaneously igniting more fuel.
Compressed gas cylinders. Compressed gas cylinder valves should be protected with the screw-on cap whenever they are stored or transported. A broken valve will allow the pressurized gas inside to escape and cause the cylinder to fly like a rocket, posing personal injury or property damage risk to anyone or anything nearby. Cylinders should be stored in clean, dry, well-ventilated areas, with full cylinders separated from empties. They should be secured in the upright position to prevent them from falling over and damaging the valve.
Compressed gas cylinders should never be stored near high heat sources, to avoid pressure buildup and possible explosion. Damaged, corroded, or leaking cylinders should be removed from service, tagged, moved to a secure location and the supplier notified. Pressure regulators should be employed and maintained in good condi-tion to control the use of compressed gases according to manufacturers’ instructions. Flammable gas cylinders warrant special handling.
Plant compressed air systems. Compressed air directed at a person can force foreign objects through the skin, create embolisms in blood vessels, rupture the bowels or remove an eye from its socket. Compressed air should never be directed at a person.
Radiation and Control
Ionizing radiation. Ionizing radiation sources in cement plants include laboratory X-ray machines, storage tank level indicators and mass flow meas-urement devices. These devices produce gamma and X-rays that can penetrate the body and damage internal organs. To protect employees against injury or illness resulting from overexposure to ionizing radiation, facilities should adopt a written radiation control plan. Best practices include:
1) licensing, if required, 2) appointing a qualified Radiation Control Officer, 3) securing radiation sources to prevent unauthorized removal, 4) shield-ing sources to prevent radiation from entering non-safe areas, 5) labeling areas where radiation equipment is used or stored with the standard magenta warning symbol, 6) locking source shut-ters closed before working on or entering equip-ment or structures that are radiation equipped, 7) surveying posted areas with radiation detection equipment, 8) training personnel on radiation hazards, safe work practices and emergency proce-dures, 9) monitoring exposure of personnel likely to receive in excess of 25% of the maximum permissible dose in any calendar quarter, or who enter high radiation areas, and 10) keeping records of radiation surveys, training, monitoring and personnel exposures. Notification of any spills, injuries, fires or other incidents involving radioactive materials should be made to the appropriate authorities.
Non-ionizing radiation. Non-ionizing radiation sources include lasers, infrared sensors, hot ob-jects and ultraviolet light sources such as generated by pyroprocessing and welding. Because these energies do not penetrate beyond the body’s surface, overexposure poses burn hazards mainly to the skin or eye. Injury prevention is accomplished by: 1) reducing energy levels, 2) erecting barriers, 3) reflecting radiation (such as heat), 4) increasing distance between workers and radia-tion sources, 5) limiting time of exposure, and 6) using personal protective equipment.
Thermal Hazards
The human body functions best within a narrow temperature range of 36°C to 38°C (97°F to 100°F), and it regulates itself by generating or losing heat as needed. Factors that influence body temperature include: 1) air temperature and air movement (convection), 2) contact with heated and cold surfaces (conduction), 3) transfer of heat through air (radiation), 4) humidity and perspiration (evaporation), and 5) body heat production (metabolism).
Heated materials and equipment. Because cement manufacturing requires extremes of heat throughout the process, heated materials are of particular concern, as they may range in tempera-ture from ambient to superheated. Raw meal, kiln and preheater feed, clinker and clinker dust, kiln burning zone coating, cement kiln dust, and refractories may look cool, but they can be extremely hot. Hot material or dust accumulations, piles, spills and coating buildups may be found in process vessels, dust collectors, conveyors, elevators, etc., or they may expelled into the atmosphere, or spilled or emptied or onto floors or walkways. Because these materials, especially piles or accumu-lations, are often self-insulating or are contained in heated or refractory-lined vessels, they may be cool on the surface, but very hot inside or at their base. They may remain very hot for many hours or days. To avoid serious burns, no one should ever pick up, handle or hold materials of unknown temperature. Hot material piles should be barricaded and/or signed and no one should ever walk on, reach into or step into any pile or accumulation of material. The unseen burn hazards of heated materials should be included in task and site-specific hazard training.
Heated equipment includes raw and finish mills, pyroprocessing apparatus such as preheater cyclones, calciners, kilns, burners, furnaces, and hot gas generators, conveyors, electrostatic precip-itators and other dust collectors, engines, motors and equipment that has been welded or cut with an oxy-fuel torch. Even handrails in certain sections of a plant may be a hot surface hazard. Hot surfaces should be signed where feasible and no one should ever handle or touch any potentially hot surface without properly selected personal protective equipment.
Heat stress. Heat stress occurs when the total heat load on one’s body from internal and exter-nal sources exceeds the body’s ability to cool itself. High temperatures and radiant heat sources identified with pyroprocessing and grinding processes combine with metabolic heat produced by exercise to drive body temperature up. If high humidity limits the body’s ability to evaporate perspiration and cool itself, heat overload is possible. Although evaporation is usually aided by increased air velocity, if the surrounding air temperature is greater than the body temperature, more heat will be transferred to the body than can be removed by evaporation. If the heat rise is too great, or is sustained for too long, injury can occur. Symptoms range from fatigue to fainting, and from cramps to exhaustion. In extreme cases, severe symptoms can occur. If failure of the central nervous system’s sweat regulating center causes perspiration to cease, the body’s tempera-ture can rise rapidly and convulsions or coma may result.
Heat stress hazard assessment can be accomplished by measuring the Wet Bulb Globe Temperature (WBGT). WBGT factors air temperature, radiant heat, humidity and air movement into one ther-mal index that can be used to guide work time and exertion. Heat stress prevention methods include: 1) training, 2) drinking plenty of water, 3) taking rest breaks, 4) wearing loose fitting clothes, 5) using protective clothing or cooling vests, 6) ventilating work areas, 7) spot cooling with mists, and 8) installing heat shields (Workers Compensation Board of British Columbia, 2000). Caffeine, which is a diuretic, alcohol, and metabolism-affecting drugs, such as diet pills, can inhibit the body’s ability to regulate itself, and should be avoided.
Acclimatization is the body’s process to adjust body functions to be more efficient in hot circum-stances. Over a two-week period of exposure to moderate heat, one’s sweat rate increases and sweat salt content drops. Oxygen consumption and heart rate decrease, resulting in a lower body temper-ature given the same environmental and work exertion conditions.
Hypothermia. Hypothermia can occur when core body temperature drops due to lengthy exposure to cold and/or wet conditions. Progressive symptoms are: 1) shivering and weakness, 2) disorientation and slurred speech, 3) heart and breathing rate reduction, 4) drowsiness, 5) unconsciousness and collapse, and 6) possible death. Prevention methods include: 1) avoiding cold, wet exposure, 2) insulating against heat loss by dressing in layers, especially using woolen blends, and 3) depending on co-workers to help recognize danger signs, escape the cold and get the body re-warmed before it is too late.
Frostbite. Frostbite occurs when liquids in the body’s extremities freeze. Relatively large, sharp crystals can damage flesh, or lack of blood flow through constricted blood vessels can cause tissues to die. Prevention is best accomplished by limiting exposure to cold conditions, especially when they are accompanied by wind. The hands, toes, ears and nose are most at-risk and should be protected when cold weather work is required.
BIOLOGICAL HAZARDS AND CONTROLS
Biological hazards include bioaerosols, bloodborne pathogens and zoonotic diseases.
Bioaerosols
Bioaerosols are airborne liquid or solid particulates released from a living organism, small enough to remain dispersed in air for a prolonged period of time. Bacteria and fungi are the most commonplace bioaerosols. Most environments contain a wide variety of bacteria and fungi; their types and concentrations are dictated by the prevailing conditions. Individual aerosolized particu-lates range in size from less than 0.1 µm to greater than 100 µm as reported in the American Conference of Governmental Industrial Hygienists’ guidelines (ACGIH, 1989). Typical bioaerosols encountered in the indoor cement environment are bacteria and fungi.
Bacteria. Bacteria are microscopic plants with single-celled or noncellular bodies that collect in colonies in soil, water, organic matter, or in the bodies of plants and animals. Bacteria have patho-genic potential, and can cause adverse chemical effects, especially in food.
Fungi. Fungi are microscopic plants that include molds, mildew, mushrooms and yeast, and live or feed on dead or decaying organic matter. For the average person, exposure to small and moder-ate amounts of molds is a fact of daily life, and those with normally functioning immune systems do not get ill. However, if workers are exposed to high concentrations of molds, especially if over a long period of time, or if they have existing lung disease or weak or challenged immune systems, the risk is higher. Potential health effects from toxigenic fungi like Stachybotrys and Aspergillus range from no effect to mild cold or flu symptoms, diarrhea, fatigue, allergic reactions or serious respiratory illnesses like bronchopulmonary aspergillosis.
Controls. Fungal molds and bacteria have been found when the right combination of moisture, temperature and food supply come together, such as in laboratory constant temperature and humidity rooms. Best practices to prevent fungal or bacterial growth and potential human illness include: 1) eliminating the fungi’s food supply by constructing the room of non-cellulose-based products (i.e. not using wood or paper), 2) decreasing the room’s humidity level by installing moisture cabinets of stainless steel construction, and 3) inspecting exposed surfaces, wall interiors, ceiling spaces or other hidden areas for evidence of fungal growth. Should minor cleaning be necessary, an application of 10% household bleach solution (one part household bleach to nine parts water) will control the hazard, but even the “dead” remains of fungi and their mycotoxins can be toxigenic and should be removed. Should major fungal colonies be discovered, remediation efforts should include: 1) removing cellulose-based wall and ceiling materials, 2) using removal, disposal and worker protection practices similar to those employed in asbestos abatement, and 3) cleaning and disinfecting all surfaces with a 10% or greater household bleach solution (Rice, 2000). (See other fungal hazards discussed below in “Zoonotic Diseases” section.)
Bloodborne pathogens (BBP). Of the large number of types of microorganisms that inhabit the planet, only a small proportion are harmful to man (Heinsohn, 1995). Exposure to those biological agents can result in acute and chronic disease. Bloodborne pathogens may pose risk to facility personnel, particularly first responders, if they are exposed to blood and other body fluids. Such pathogens include viruses, chlamydiae, rickettsiae, and mycoplasmas. Viruses are submicro-scopic, subcellular agents that range in size from 0.02 to 0.30 µm. There is some question as to whether viruses are actually living organisms. Chlamydiae are obligate parasites that are similar to bacteria but are much smaller in size. They have complex developmental cycles and preferentially infect mucous membrane tissue. Similar to chlamydiae, rickettsiae are obligate parasites that are similar to bacteria and can survive only within living cells. These agents are transmitted to man by arthropods, such as ticks, fleas, and lice. Mycoplasmas are the smallest cells that may exist inde-pendently and some are smaller than large viruses.
Viruses such as those that cause hepatitis B (HBV) and human immunodeficiency (HIV) are the bloodborne pathogens most likely to be passed from one person to another. Although workplace exposure is rare, facilities should adopt an exposure control plan that includes: 1) provision of BBP kits containing personal protection equipment and decontamination solutions, 2) training on kit use, 3) adopting universal precautions, i.e. considering all blood to be infected and treating it as if it were, to minimize the possibility of exposure, 4) reporting and recording blood and bodily fluid exposures, 5) offering exposed persons and all first aid providers the hepatitis B vaccination,
6) promptly decontaminating all surfaces, clothing and tools, and 7) properly disposing of waste.
ZOONOTIC DISEASES
Zoonoses are diseases that can be transmitted to humans by animals through contact with bacte-ria, rickettsiae, viruses, fungi or parasites. Diseases or illnesses that cement plant workers could contract include Histoplasmosis, tetanus, Lyme disease, Rocky Mountain spotted fever, rabies and certain dermatoses. The risk is usually small and in many cases largely dependent upon geographi-cal location and task assignments. Facilities should assess the likelihood of contracting such diseases and implement preventive measures commensurate with risk, such as controlling or elimi-nating populations of small animals and insects such as raccoons, skunks, cats and mosquitoes, and providing insect repellent and prompt, competent treatment of infections, wounds or bites.
Histoplasmosis. Histoplasmosis is an avian borne fungal illness that can possibly be contracted by cement workers. The fungus Histoplasma capsulatum is found worldwide, but is particularly endemic in the eastern half of North America. Fungal spores grow in manure-nourished moist soil and can be spread by pigeons, blackbirds, chickens and bats. When spores are disturbed, become airborne and are inhaled, infection of the respiratory system is possible. Although the disease can be life threatening, most infections are quite mild, no worse than the flu. Testing of human blood or bird manure samples to determine infection or the presence of spores is expensive, inconclusive and not recommended.
Best practice is to assume the fungus is present in endemic areas and focus on preventing human infection by: 1) excluding birds from roosting areas by screening eaves, netting rooftop ventilators,installing doors and hanging vinyl strips at passageways and around materials transport systems, 2) minimizing the chance of spores forming and becoming airborne by regularly removing and disposing of bird droppings using wet clean-up procedures, protective clothing and respirators, and 3) treating accumulations of manure and contaminated surfaces with a quaternary ammo-nium chloride blend that functions as a combination wetting agent, disinfectant, fungicide and deodorizer (Rhodes and others, 2000).
Lyme disease and rocky mountain spotted fever. Lyme disease and Rocky Mountain spot-ted fever are examples of tick-spread diseases that are potentially harmful to man. Cement plant exposure to ticks depends upon the plant’s geographical location and an individual’s work assign-ment. Persons whose job requires them to venture into grass and woods are much more likely to be exposed to ticks than those working in the mill. Those who may be at-risk should be trained to: 1) wear light colored clothing, with pants legs tucked into boots, 2) check frequently and remove ticks that may attach themselves to clothing or one’s person, 3) know the symptoms of each disease and seek medical attention if they suspect they have been bitten by an infected tick. Vaccinations are available for Lyme disease, but should be administered only if medical personnel consider the risk of contracting the disease to warrant such intervention.
ERGONOMIC HAZARDS AND CONTROLS
Ergonomics refers to efforts to adapt the workplace to the individuals working in it, and to elimi-nate or minimize job task risk factors that can cause physical disorders. Disorders develop over time due to continued exposure to certain environmental factors or physical stresses. Heavy weights, excessive force requirements, repetitive motions, contact stresses, adverse postural stresses, vibration, cold temperatures, and the use of heavy work gloves can lead to ergonomic problems.
At-risk tasks often involve manual material handling. Lifting heavy or bulky objects from the floor, above shoulder height or while seated or twisting may place employees at-risk. Exertion with the joints flexed, extended or rotated, pinch grips, pushing and pulling loads, poor posture or bending, especially under load, are also influencing factors. Any of these, especially when multiple factors are involved, or when coupled with work tasks of long duration or short recovery periods, play a role in determining whether or not an employee will develop disorders.
Body Systems At-Risk
Body systems subject to ergonomic disorders are the musculo-skeletal system, the nervous system and the cardiovascular system.
Musculo-skeletal system. Musculo-skeletal system disorders include: 1) joint sprains, caused by twisting or hyperextending, 2) muscle strains caused by over exertion or over stretching,3) tendon inflammation (tendonitis) caused by repetitive motions or excessive force, 4) arthritic conditions of the joints, perhaps caused by awkward positioning under load, 5) repetitive shock to the spine, such as from long operation of a haulage truck, and 6) degeneration of spinal discs, often caused by repetitive lifting with poor posture. These disorders develop over a period of time, ranging from a few hours to many years.
Figure 7.3.6. Flexed joints, pinch grips, repetitive motions and excessive force are some of the risk factors for ergonomic injury.
Nervous system. Nervous system conditions include: 1) compression of the median nerve in the wrist (carpal tunnel syndrome) due to repetitive motions, 2) compression of the ulnar nerve in the arm (cubital tunnel syndrome), from resting the elbows on hard surfaces, and 3) compression of the nerves at the shoulder (thoracic outlet syndrome) from working with one’s arms above the head.
Cardiovascular system. Cardiovascular system disorders include: 1) obstruction of blood flow to body tissue (compression ischemia) due to resting one’s limbs on hard or sharp objects, or 2) reduction of blood flow to the hands or fingers (segmental vibration, white finger) resulting from vibration while using hand held power tools.
Evaluation
Operations should analyze the work environment for indicators of ergonomic stressors, assess work tasks for the listed risk factors, review records to determine trends or history of cumulative trauma or repetitive stress disorders, interview workers and look for adaptations made to workstations or tools. Videos, slides and photographs are good tools to use when analyzing job situations.
Controls
To reduce the risk of ergonomic problems, facilities should make efforts to neutralize as many risk factors as possible. Adaptations of tools, equipment or workstations to avoid reaching, twisting, pinching or excessive force are often all that are required to improve a condition. New equipment may be helpful, but is not always indicated, nor is it always ergonomically friendly to workers unless ergonomic considerations are made in the design phase. Tools are available to reduce the effort or change the posture required to perform jobs.
Consideration should be made as to whether power tools or manual tools with a different sized or shaped handle are in order. Likewise, decisions should be made whether lifting problems can be solved with power-assist vacuum lifters, power operated tables to lift or position loads, loads with reduced weights or smaller dimensions, or teaching employees simple techniques like the one-hand assisted lift method.
Training
It is important to train workers so they know how to care for their bodies and prevent ergonomic disorders from occurring. Training should include physical limitations, how repetitive stress injuries develop, how to avoid injury by stretching prior to performing certain tasks, and the hazards associated with certain postural positions.
ACKNOWLEDGEMENTS
This chapter was prepared by the author for review and consideration to raise awareness of health and safety issues in the cement industry. Its contents reflect solely the views of the author and do not necessarily reflect the views of the Portland Cement Association or its members. The contents are not intended to provide authoritative language applicable to all safety aspects about cement manufacturing and in no way replace the obligation to follow applicable laws and regulations.
The author wishes to express his appreciation to the following, whose professional counsel and association over a period of years has contributed greatly to the author’s understanding of safety and industrial hygiene: Mr. Stephen Fletcher, CSP, Walkersville, Maryland; Mr. Jack Luckhardt, CSP, ARM, Oviedo, Florida; Mr. Steve Minshall, CIH, CSP, Blue Springs, Missouri; Mr. Mark Rice, P. Chem., CRSP, IHIT, Edmonton, Alberta, Canada; Dr. Steven Rhodes, PhD, CIH, Walkersville, Maryland; Mr. Michael Tilton, Houston, Texas; and Mr. Dale Valentine, Middleburg, Maryland. Thanks also to the numerous other safety professionals from all industries who freely shared their ideas and experience, and to the many cement industry employees whose hard work, ethics, inge-nuity, stewardship of resources and care for their fellow man prompted the author on behalf of the safety and health of others and aided in the accumulation of this information.
Above all, the author wishes to express his appreciation to his family, who demonstrated great patience and understanding during the hundreds of hours of nights, weekends, vacations and other family time consumed by the preparation of these safety and health chapters; to God, who gave the author the gift of writing; and to his father, who nurtured that gift and taught him to appreciate it.
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