Engineering and Public Health at CDC
G. Scott Earnest, PhD,1 Laurence D. Reed,
MS,2 D. Conover, PhD,1 C. Estill,
MS,2 C. Gjessing, MS,1 M. Gressel,
PhD,1 R. Hall, MS,1 S.
Hudock, PhD,1 H. Hudson,
MPH,1 C. Kardous, MS,1 J. Sheehy,
PhD,1 J. Topmiller, MS,1 D. Trout,
MD,2 M. Woebkenberg, PhD,1 A. Amendola,
PhD,3 H. Hsiao, PhD,3 P. Keane,
MBA,3 D. Weissman, MD,4 G. Finfinger,
PhD,5S. Tadolini, PhD,5 E. Thimons,
MS,5 E. C.ullen, PhD,6 M. Jenkins,
MS,6 R. McKibbin,6 G. Conway,
MD,7 B. Husberg, MPH,7 J. Lincoln,
PhD,7 S. Rodenbeck, PhD,6 D. Lantagne,
MS,7 J. Cardarelli, II, PhD8
1Division of Applied Research and Technology, National Institute for Occupational Safety and Health, CDC; 2Division of Surveillance, Hazard Evaluations, and Field Studies, National Institute for Occupational Safety and Health, CDC; 3Division of Safety Research, National Institute for Occupational Safety and Health, CDC; 4Division of Respiratory Disease Studies, National Institute for Occupational Safety and Health, CDC; 5Pittsburgh Research Laboratory, National Institute for Occupational Safety and Health, CDC; 6Spokane Research Laboratory, National Institute for Occupational Safety and Health, CDC; 7Spokane Research Laboratory, Alaska Field Station, National Institute for Occupational Safety and Health, CDC; 8Division of Health Assessment and Consultation, Agency for Toxic Substances and Disease Registry
Corresponding author: G. Scott Earnest, PhD, Division of Applied Research and Technology, National Institute for Occupational Safety and Health, CDC, 4676 Columbia Parkway, Cincinnati, OH 45226. Telephone: 513-841-4539; Fax: 513-841-4506; E-mail: firstname.lastname@example.org.
Engineering is the application of scientific and technical knowledge to solve human problems. Using imagination, judgment, and reasoning to apply science, technology, mathematics, and practical experience, engineers develop the design, production, and operation of useful objects or processes. During the 1940s, engineers dominated the ranks of CDC scientists. In fact, the first CDC director, Assistant Surgeon General Mark Hollis, was an engineer. CDC engineers were involved in malaria control through the elimination of standing water. Eventually the CDC mission expanded to include prevention and control of dengue, typhus, and other communicable diseases. The development of chlorination, water filtration, and sewage treatment were crucial to preventing waterborne illness. Beginning in the 1950s, CDC engineers began their work to improve public health while developing the fields of environmental health, industrial hygiene, and control of air pollution (1). Engineering disciplines represented at CDC today include biomedical, civil, chemical, electrical, industrial, mechanical, mining, and safety engineering. Most CDC engineers are located in the National Institute for Occupational Safety and Health (NIOSH) and the Agency for Toxic Substances and Disease Registry (ATSDR).
Engineering research at CDC has a broad stakeholder base. With the cooperation of industry, labor, trade associations, and other stakeholders and partners, current work includes studies of air contaminants, mining, safety, physical agents, ergonomics, and environmental hazards. Engineering solutions remain a cornerstone of the traditional "hierarchy of controls" approach to reducing public health hazards (2).
Key Engineering Contributions to Public Health
CDC engineers at NIOSH Hamilton Laboratories have worked in industrial ventilation, isolation and containment, contaminant control, indoor environmental quality, and computational fluid dynamic modeling. Successful engineering-control studies have led to advancements for 1) controlling air contaminants, such as asphalt fumes, silica, and lead; 2) developing strategies under national emergency preparedness to protect buildings from attacks by chemical, biologic, or radiologic agents (3); 3) preventing transmission of infectious diseases in occupational settings (4,5); and 4) controlling carbon monoxide on recreational boats (6).
CDC engineering work has focused on innovative solutions for controlling air contaminants. During the mid-1990s, NIOSH engineers, working with paving equipment manufacturers, designed a control that reduced worker exposure to asphalt fumes by 80% (Figure 1) (7). NIOSH engineers have studied control of respirable silica dust in nearly a dozen industries---in one example, employee exposure to respirable silica dust was reduced approximately 87% after a china manufacturing plant implemented its dust-control recommendations. CDC engineers at NIOSH also have designed studied, and had installed ventilated booths for radiator repair shops, reducing blood lead levels of workers in those shops by 70%.
CDC engineers have contributed substantially to the practice of lung-function testing. Accomplishments include development of the standard approaches to testing lung-function equipment; international leadership in developing and disseminating lung-function testing standards; and collaborations with epidemiologists in studies of occupational and general populations. A notable collaboration between NIOSH and the CDC National Center for Health Statistics led to development of a commonly used set of reference values for evaluating spirometry in the United States (8).
Mining presents a challenging work environment; concerns include excessive noise levels, dust exposures, explosive and toxic gases, and massive equipment in near-constant motion. The NIOSH mining research program developed engineering controls for surface and underground mining to improve miners' health and safety. Successful controls adopted within the mining industry include water-jet sprays for dust control, noise reductions on conveyors and drill units, roof and structural support systems, designs for improved ventilation, mine-escape operations, and improved materials-handling systems.
The mining community has successfully implemented products resulting from engineering research. These products include several programs that helped improve roof, floor, and sidewall stability and prevent the likelihood of roof collapse and major causes of death and injuries (9). Coal pillar recovery guidelines and mobile roof supports have made pillar recovery safer (10). Guidelines for designing deep-cover mines to prevent coal bumps (violent failures of highly stressed coal) contributed to 7 consecutive years without fatalities. A research and education campaign on rock-fall injuries and use of surface controls in coal mines has reduced rock-fall injury rates by approximately 25%.
CDC engineers at NIOSH conduct safety engineering research to prevent occupational injuries by developing practical products and interventions in areas such as fall prevention, machine safety, and equipment safety research. Examples of engineering-control research include improved lock-out devices for paper balers and rollover protective structures for tractors, equipment responsible for numerous deaths and injuries. More rigorous standards have been examined for machine safeguarding, to better match international standards (11). Other projects include improving the safety of roof-bracket assemblies to protect roofers and construction workers from disabling or deadly falls (12) and developing improved work practices and computer modeling on scissor-lift tip-over controls to prevent fatalities. NIOSH safety engineers also study personal protective equipment for workers exposed to fall-from-elevation hazards (13). Research on the interface between the human body, machinery, and protective equipment represents an advancing area of safety engineering. These practices have provided the basis in developing injury-control innovations and moved many safety engineering technologies to product-design practices, standardization, and commercialization.
NIOSH engineers and epidemiologists worked together in Alaska after deck machinery on commercial fishing vessels was identified as the cause of 40% of injuries requiring hospitalization in one of the country's most dangerous industries. Engineering researchers developed a solution to prevent entanglements from a capstan-style deck winch. Fishermen praised the device as a safety and productivity improvement that reduces injuries and work stoppages (14).
Physical Agents: Noise, Heat, and Radiation
Hearing loss prevention engineers at CDC study the effects of noise-induced hearing loss that affects an estimated 30 million U.S. workers. Engineers design and develop instruments and methods to assess and characterize hazardous noise exposures. NIOSH engineers have an international reputation for their work on hearing protection devices, controlling exposure to impulsive noise, and novel engineering noise-control research. They developed and patented EarTalkTM, a hearing-protection and communication system that enables workers to communicate in noisy environments (Figure 2). They also developed a novel system for characterizing exposure to impulsive noise and applied for U.S. and international patents (15,16).
Engineering assessments have shown that workers are exposed to ionizing radiation from technologies recently developed to improve homeland security. These technologies (many of which were introduced to market after the terrorist attacks of September 11, 2001) use X-rays to screen checked baggage at every major airport throughout the world for explosive materials or use gamma radiation to screen cargo containers for illegal contraband. NIOSH engineers characterized unnecessary exposures from these technologies and recommended measures to prevent or reduce these exposures (17).
Engineers support the NIOSH program to reduce work-related musculoskeletal disorders and contribute to the design of new or improved exposure-assessment techniques, tools, and equipment. According to the Bureau of Labor Statistics, approximately 32% of lost workdays result from overexertion or repetitive motion. CDC engineers developed an exposure-assessment technique to quantify risk factors associated with workplace postures and job tasks. Workers using nonpowered hand tools have been studied using force sensor technology to identify the portion of the work cycle resulting in the greatest forces to the hand. Effective interventions and solutions that reduced repetitive motion injuries have been applied to the agriculture, shipyard, mining, and construction industries (Figure 3). NIOSH also conducted an intervention trial that demonstrated a strategically designed patient-lifting program can markedly reduce musculoskeletal injuries to nursing staff in health-care facilities. CDC engineers at NIOSH worked to produce patentable devices to address specific concerns when commercially available interventions were not available (18--20).
Engineers at ATSDR are involved in determining, through engineering interpretation of environmental investigations and sampling results, how the public could be exposed to hazardous materials in the environment. In addition, situation-specific sampling methodologies have been developed to determine how exposures have occurred to hazardous materials. Cutting-edge environmental modeling techniques are used to reconstruct past exposures from contaminated drinking water supplies. These remodeling techniques permit more accurate determination of adverse health impacts and reduce the exposure misclassification bias in ATSDR epidemiologic studies. During emergency response situations, ATSDR engineers analyzed community infrastructures to help determine when the public could safely return home (21,22).
Water quality is a public health concern worldwide. CDC engineers at the National Center for Infectious Diseases, working with epidemiologists, have conducted water quality testing, developed standardized chlorine-dosing regimens, and collaborated to develop regional safe-water systems that are inexpensive and easy to transport and have the appropriate chlorine dosing. Engineering design has increased the impact of this program by making the chlorine solution available at lower cost to more persons in developing countries. Last year, 8 billion liters of water were treated in 15 countries throughout Africa and Asia.
For decades, CDC engineers have played a key role in enhancing U.S. and international public health by focusing on CDC goals concerning healthy communities, workplaces, homes, and schools. CDC engineers are meeting public health challenges by conducting laboratory and field studies, overseeing research and development that result in solutions-based products, conducting disaster relief and emergency response, and engaging in public health program management. Engineers are an integral part of the public health team that helps define what is possible, identify existing limitations, and shape workable solutions. Their efforts have contributed immensely to reducing disease and preventing injury in the United States and around the world.
- Engineer Professional Advisory Committee, US Public Health Service. Engineer's career planning handbook (January 2003). Available at http://www.usphsengineers.org/handbook.
- Plog BA, Niland J, Quinlan PJ, Plogg H, eds. Fundamentals of industrial hygiene. 5th ed. Itasca, IL: National Safety Council; 2002.
- NIOSH. Guidance for filtration and air-cleaning systems to protect building environments from airborne chemical, biological, or radiological attacks. Cincinnati, OH: US Department of Health and Human Services, CDC, National Institute for Occupational Safety and Health; 2003. NIOSH publication no. 2003-139.
- Lin C, Horstman RH, Ahlers MF, et al. Numerical simulation of airflow and airborne pathogen transport in aircraft cabins---part 1: numerical simulation of the flow field. ASHRAE Trans 2005;111 (Part I):755--63.
- CDC. Guidelines for preventing the transmission of Mycobacterium tuberculosis in health-care settings. MMWR 2005;54(No. RR-17).
- Earnest GS, Dunn KH, Hall RM, McCleery RE, McCammon JB. An evaluation of an engineering control to prevent carbon monoxide poisonings of individuals on and around houseboats. AIHA J 2002;63:361--9.
- Mead KR, Mickelsen RL, Brumagin TE. Factory performance evaluations of engineering controls for asphalt paving equipment. Appl Occup Environ Hyg 1999;14:565--73.
- Hankinson JL, Odencrantz JR, Fedan KB. Spirometric reference values from a sample of the general US population. Am J Respir Crit Care Med 1999;159:179--87.
- Barczak TM. Updating the NIOSH Support Technology Optimization Program (STOP) with new support technologies and additional design features. In: Peng SS, Mark C, Khair AW, eds. Proceedings of the 20th International Conference on Ground Control in Mining. Morgantown, WV: West Virginia University; 2001:337--46.
- Mark C, Chase FE, Pappas DM. Reducing the risk of ground falls during pillar recovery, In: Yernberg WR, ed. Transactions of Society for Mining, Metallurgy, and Explorations, Inc., Vol. 314. Littleton, CO: Society for Mining, Metallurgy, and Exploration, Inc.; 2003:153--60.
- Etherton J, Taubitz M, Raafat H, Russell J, Roudebush C. Machinery risk assessment for risk reduction, Human and Ecological Risk Assessment 2001;7:1787--99.
- Bobick TG, McKenzie EA Jr. Using guardrail systems to prevent falls through roof and floor holes. In: Proceedings of the 2005 ASSE Professional Development Conference; June 12--15, 2005; New Orleans, Louisiana. Des Plaines, IL: American Society of Safety Engineers; 2005: Session 601.
- Hsiao H, Bradtmiller B, Whitestone J. Sizing and fit of fall-protection harnesses. Ergonomics 2003;46:1233--58.
- Thomas TK, Lincoln JM, Husberg BJ, Conway GA. Is it safe on deck? Fatal and non-fatal workplace injuries among Alaskan commercial fishermen. Am J Ind Med 2001;40:693--702.
- NIOSH. Criteria for a recommended standard occupational noise exposure: revised criteria, 1998. Cincinnati, OH: US Department of Health and Human Services, Public Health Service, CDC, National Institute for Occupational Safety and Health; 1998. DHHS (NIOSH) publication no. 98-126.
- Kardous CA, Willson RD, Murphy WJ. Noise dosimeter for monitoring exposure to impulse noise. Applied Acoustics Journal 2005;66:974--85.
- CDC. X-ray exposures from airport screening machines. Available at http://www.cdc.gov/niosh/topics/airportscreener.
- Albers JT, Estill CF, MacDonald LA. Identification of ergonomics interventions used to reduce musculoskeletal loading for building installation tasks. Appl Ergon 2005;36:427--39.
- Estill CF, McGlothlin JD, Hagedorn RT, Flesch JP. Hazard controls: controlling the ergonomic hazards of wiring tasks for household appliances. Appl Occup Environ Hyg 1999;14:289--91.
- Lowe BD, Wurzelbacher SJ, Shulman SA, Hudock SD. Electromyographic and discomfort analysis of confined-space shipyard welding processes. Appl Ergon 2001;32:255--69.
- New York City Department of Health and Mental Hygiene, ATSDR. Ambient and indoor sampling for public health evaluations of residential areas near World Trade Center, New York, New York: sampling protocol. Atlanta, GA: US Department of Health and Human Services, ATSDR; 2001.
- Maslia ML, Aral MM. Analytical contaminant transport analysis system (ACTS)---multimedia environmental fate and transport. Practice Periodical of Hazardous, Toxic, and Radioactive Waste Management 2004;8:181--98.
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