During the 1940s, engineers dominated the ranks of scientists at the Centers for Disease Control and Prevention (CDC). 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 work to improve public health while developing the fields of environmental health, industrial hygiene and control of air pollution.
Engineering disciplines now represented at CDC include biomedical, civil, chemical, electrical, industrial, mechanical, mining and safety engineering, and 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 control” approach to the control of public health hazards.
CDC engineers at National Institute for Occupational Safety and Health (NIOSH) Hamilton Laboratories have long 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 controlling air contaminants such as asphalt fumes, silica and lead, developing strategies under national emergency preparedness to protect buildings and the public (Figure 1) from attacks by chemical, biologic, or radiological agents, preventing infectious disease transmission in occupational settings, and controlling carbon monoxide on recreational boats.
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 percent (Figure 2). 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 by 79 percent to 94 percent after a china manufacturing plant implemented its dust- control recommendations. CDC engineers at NIOSH also have designed and installed ventilated booths for radiator repair shops, reducing blood lead levels of workers in those shops by 70 percent.
CDC engineers have made major contributions 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 was with CDC’s National Center for Health Statistics, which led to development of a commonly used set of reference values for evaluating spirometry in the United States.
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 widely 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 NIOSH engineering research. These products include two programs that helped eliminate tailgate blockages, a major source of injury. The underground stone ground control safety initiative greatly reduced fatalities in stone mines. Coal pillar recovery guidelines and mobile roof supports have made pillar recovery safer. Guidelines for designing deep-cover mines to prevent violent failures of highly stressed coal contributed to seven 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 percent.
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 for machine safeguarding, to better match international standards, have been examined. Other projects include improving the safety of roof-bracket assemblies to protect roofers and construction workers from disabling or deadly falls 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.
Research on the interface between the human body, machinery and protective equipment represents an advancing area of safety engineering. These efforts have provided the basis for the development of injury-control innovations and have 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 percent of hospitalized injuries 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 significant safety and productivity improvement that reduces injuries and work stoppages.
Physical Agents: Noise, Heat and Radiation
Hearing loss prevention engineers at CDC study the effects of noise-induced hearing loss, which 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 (Figure 3). This novel device is particularly suited for use by emergency responders (Figure 4). They also developed a novel system for characterizing exposure to impulsive noise and applied for U.S. and international patents.
Engineering assessments have shown that workers and the public are exposed to ionizing radiation from technologies recently developed to improve homeland security. These technologies (many of which came 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 exposures from these technologies and recommended numerous measures to prevent these exposures or to reduce them by up to 50 percent.
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 percent 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 5). NIOSH also conducted an intervention trial that demonstrated a strategically designed patient-lifting program that can significantly reduce musculoskeletal injuries to nursing staff in healthcare facilities. CDC engineers at NIOSH worked to produce patentable devices to address specific concerns when commercially available interventions were not available.
CDC engineers 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 people have been exposed to hazardous materials. Cutting-edge environmental modeling techniques are used to reconstruct past exposures from contaminated drinking water supplies. These reconstruction techniques permit more accurate determination of adverse health impacts and significantly reduce the exposure misclassification bias in epidemiologic studies. During emergency response situations, CDC engineers analyzed community infrastructures and healthcare facilities to help determine when or if they could be safely used. (Figure 6)
Water quality is a worldwide public health issue. CDC engineers at the National Center for Infectious Disease, working with epidemiologists, have conducted water quality testing, developed standardized chlorine dosing regimes, 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 people in developing countries. Last year, 8 billion liters of water were treated in 15 countries throughout Africa and Asia.
For more than sixty years, CDC engineers have played an important role in enhancing U.S. public health by focusing their efforts 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. CDC engineers are an integral part of the public health team that help to define what is possible, identify existing limitations and shape workable solutions. Their efforts have contributed greatly to reducing disease and preventing injury in the United States and around the world.