Tag Archives: Clean Rooms

Resolving issues must begin with an understanding of the fundamentals of both contamination and ESD control

By Roger Welker, R.W. Welker Associates

Both contamination levels and electrostatic discharge (ESD) are widely recognized as critical factors affecting yield and reliability in an ever-increasing number of industries. Although contamination has long been recognized as affecting semiconductors, disk drives, aerospace, pharmaceutical and medical device industries, today other industries-such as automobile and food production-are discovering the benefits of contamination control. ESD control has also experienced a similar growth in applications. In fact, today, control of electrostatic charge on surfaces is a widely recognized method of helping to reduce the impact of contamination, providing a synergistic benefit.

Despite the large number of degreed professionals working in contamination and ESD control, these fields remain misunderstood and underappreciated. The misunderstanding often arises because of the interdisciplinary nature of the two fields. Because so many different academic disciplines are required in order to provide a comprehensive understanding, the problems and solutions often appear confusingly complex when, in fact, the vast majority of contamination or ESD problems can be solved using very simple analysis. In addition, there is a long-standing perception that what is good for contamination control is bad for ESD control and vice versa. The following statements clearly point out why this is not the case:

1. Control of charges on surfaces in cleanrooms derives a benefit for contamination control. In this regard, selecting materials with a low tendency to tribocharge and that can be grounded because they are static-dissipative or conductive is desired. However, alone, these two solutions are insufficient in the vast majority of cases and the use of air ionization provides further benefit. Thus, the use of air ionization can provide a benefit for contamination control, regardless of the ESD sensitivity of products or processes within the cleanroom.

2. Control of electrostatic discharge in cleanrooms can provide a benefit by minimizing ESD and EM-induced microprocessor upset, regardless of the ESD sensitivity of products or processes within the cleanroom.

3. Airflow in mixed-flow cleanrooms is not optimized for performance of air ionizers not equipped with fans or compressed air sources. Fan-powered or compressed-gas ionizers are preferred in mixed-flow cleanrooms for this reason. However, fan-powered or compressed-gas ionizers can increase redistribution of contamination and can have a detrimental effect. The requirements of ESD (e.g., discharge time and float potential) must be balanced with contamination (airborne particle count, surface contamination rates, etc.).

4. Ionizers placed near ceilings or bench-mounted HEPA filters can perform well in unidirectional flow applications, particularly for controlling surface contamination. Conversely, airflow in unidirectional flow cleanrooms and clean benches can cause isolation effects or flow stratification, which prevents ionizers from achieving discharge time performance. Proper ionizer deployment must take into consideration cleanroom airflow effects.

5. Ceiling-mounted, room-type ionizers may not provide rapid discharge times. As the ESD sensitivity of devices tends toward lower voltages, only local fan- or gas-powered ionizers can achieve acceptable ESD performance. In these cases, balancing the requirements of ESD failures and contamination failures becomes precarious.

6. All ESD control materials and equipment must be qualified for contamination performance when they are used in contamination-sensitive applications. Similarly, all contamination control materials and equipment must be qualified for ESD performance when they are used in ESD applications.

7. Continuous monitoring systems are available for both contamination and ESD control applications. Their use in workstations that simultaneously require both forms of control can serve to minimize upsets in processes.


Figure 1. This illustration shows the possible effect on airflow of centering the layout of tooling within the process aisle of a cleanroom on a grade-level floor.
Click here to enlarge image

Any attempt at rectifying these two problems should begin with an understanding of the fundamentals of both contamination and ESD control and with defining the specific requirements that must be met. Following this should be an examination of the available analysis methods useful for solving contamination and ESD problems, especially with regard to the selection of materials.

One unconventional approach to building a contamination- and ESD-controlled workplace avoids the conventional approach of discussing the architectural and utility aspects of room construction, and instead focuses on the airflow character within the room and how that airflow is affected by tool and workstation placement (see Figs. 1 and 2).


Figure 2. This illustration shows the possible effect on airflow of bulkhead mounting tools within the process aisle of a cleanroom on a grade-level floor.
Click here to enlarge image

Cleaning processes and the equipment needed to support them must also be considered from the perspective of both the supplier and the user. Design and certification of tooling involves materials selection and evaluation of problems common to all industries affected by contamination and ESD. Continuous monitoring systems for contamination and ESD must also be taken into account.

Consumable materials and supplies should be chosen with a view toward requirements of both contamination and ESD control. In the late 1960s throughout the 1970s, many materials that were good for contamination control were bad for ESD control and vice versa. Today this is no longer true.

Of course, contamination originating from people and how to contain it must be major considerations, along with personnel behavior and discipline. Related to this is one area that has been sadly neglected-that of change-room design and layout.

Finally, overall management of the cleanroom and ESD-protected workplace environments must come into play. Companies dealing with contamination and ESD range in size from those having a single sensitive facility to multinational corporations having cleanrooms and ESD-protected workplaces on virtually every continent.

Roger W. Welker is founder and principle scientist at R.W. Welker Associates, an independent consulting firm specializing in complex contamination, electrostatic discharge, and quality control issues. He can be contacted at [email protected].

Editor’s note: This article contains excerpts from the new book Contamination and ESD Control in High-Technology Manufacturing by Roger Welker, R. Nagarajan, and Carl Newberg (John Wiley & Sons, 2006). In it, “the authors set forth a new and innovative methodology that can manage both contamination and ESD, often considered to be mutually exclusive challenges requiring distinct strategies.”

By Hank Hogan

In the good old days-say, five years ago-shrinking semiconductor features meant contamination challenges due to eliminating smaller particles. However, as new materials are introduced at a rapid rate, that’s no longer the case. A look at lithography and back-end processing shows why this isn’t your father’s-or even your older brother’s-fabrication process and what that means for contamination control.

Larry Thompson, president of the consulting firm IPSSLP (Austin, TX), notes that the lithography critical dimension (CD) budget, like killer particles, tracks feature size. “Because that CD budget is shrinking, you have to have better and better control over the airborne contamination,” he says.

New materials, though, are now having an impact. Immersion lithography substitutes water for air between the last lens and the wafer, allowing finer imaging. However, contaminants in or under the resist can be struck by an intense laser, which could result in a bubble that scatters light and deposits volatiles nearby. Because of this, notes Thompson, companies are contemplating making the last lens a flat, replaceable element.

Now just being deployed, immersion lithography will someday play out. Extreme ultraviolet (EUV) lithography is a contender for the next imaging technology. EUV photons are about 13 nanometers wavelength, almost 15 times shorter than today’s state-of-the-art 193 nm. Producing those short wavelengths leads to a lot of particles, mainly in the tool itself.

An alternative involves imprinting, a technique in which a template with the desired features stamps out resist patterns. It allows very high resolution-if the mold is built correctly. Achieving that requires controlling contaminants, which is a significant challenge since the template is an exact reproduction and not a shrink as is the case currently. Contamination, “both airborne and in the material itself, [is] far more critical in imprint than in a 4X reduction,” says Thompson.

In back-end processing, new materials already can cause contamination. In an effort to boost circuit performance, manufacturers are turning to high-stress nitrides and oxides, along with low capacitance, or low-k, materials that are brittle and don’t adhere well.

Film stress is a problem, notes Chris Long, a senior engineer with IBM (Essex Junction, VT). “You take them through subsequent processing and at high-stress points…the film [starts] cracking and then popping off,” he says.

The problem occurs on wafers and tools. Exposed to varying humidity when the tool is opened for preventive maintenance, the film can form small airborne flakes. These can land on other tools, load ports, or elsewhere. Reducing airflow in a fab to save energy and money exacerbates the issue.

Ensuring that multiple tools spaced closely together aren’t opened at the same time can minimize the problem. Another solution might be to change tool cleaning procedures. Adding humidity control would also help, as would temporarily turning up area airflow.

Other new materials present their own contamination problems. Atomic layer deposition of a film, for example, offers great step coverage down microscopic trenches. However, it can also result in a nonuniform film on the back of a wafer, increasing potential backside contamination.

One solution is increased backside cleaning and inspection. A trend is for wafers to be divided into various cleanliness zones, including front and back.

Finally, Long notes the contamination impact will grow as feature sizes shrink below the current 65 nanometer state-of-the-art, requiring diligence in attacking such problems. “We may see issues if we don’t keep those [problems] on the radar screen and try to fix them ahead of time,” he says.

particles


November 1, 2006

compiled by Angela Godwin

DSM sells pharmaceutical production site

DSM Pharmaceutical Products, a Business Group of Royal DSM NV, has signed an agreement with Albemarle Corporation of Baton Rouge regarding the sale of the assets and business associated with DSM’s pharmaceutical production site in South Haven, MI., which is focused on the production of generic active pharmaceutical ingredients (APIs). “We are very pleased that through the transaction with Albemarle we have been able to secure the future of the site and to safeguard the employment of more than 100 of our people in South Haven”, says Leendert Staal, President of DSM Pharmaceutical Products. Terms of the deal were not disclosed.

Guidelines for modern ization of drug manufacturing

Last month, the Food and Drug Administration (FDA) issued a final guidance on quality systems, a set of formalized practices and procedures to ensure quality of human and veterinary drugs and human biological drug products during manufacturing. The guidance enhances FDA’s cGMP regulations. The document, “Quality Systems Approaches to Pharmaceutical Current Good Manufacturing Practice (cGMP) Regulations,” is expected to help manufacturers maintain consistent high quality and improve efficiency. It aims to demonstrate the benefits of incorporating modern quality principles-which should foster technical advancements-into manufacturing processes to better ensure the safety and efficacy of drugs for people and animals. Another goal of the guidance is to increase drug-production efficiency, which should help lower costs and prevent shortages of critical medicines due to manufacturing failures that can result in production stoppages and recalls. The full text of the guidance can be found at www.fda.gov/cder/guidance/7260fnl.htm.

EaglePicher Technologies, LLC (Inkster, MI; www.eaglepicher.com), a leading producer of batteries and energetic devices for the defense, space and commercial industries, and the City of Joplin, MO, announced the construction of a new 24,000-square-foot facility for the development and production of lithium-ion (Li-Ion) cells and batteries for U.S. military critical applications. The facility will be located in the Crossroads Industrial Park in Joplin, Missouri.

The new facility is being constructed by Crossland Construction Company, Inc. (Columbus, KS; www.crosslandconstruction.com) and will include dryrooms and cleanrooms fabricated by Scientific Climate Systems, Inc. (Houston, TX; www.dryrooms.com). The rooms will be used for critical process steps with dedicated air handling systems for each process. The facility will also have a full diagnostic laboratory on-site, paperless tracking of all cell and battery build and performance data, PLC capability and bar coding for all process steps. EaglePicher Technologies is investing over $10 million in the new facility.

The new building will be designed to maximize lean manufacturing and to minimize contamination risk. Internationally known independent laboratories will perform cell performance certification and environmental qualification. The facility will also include state-of-the-art security features.

Construction will be completed on or before December 29, 2006 and product production is expected to begin by the fourth quarter of 2007. EaglePicher expects up to 100 new high-tech employees in the facility within 3 to 5 years.

The Institute of Environmental Sciences and Technology (IEST) recently announced three scholarships for full-time students in the educational programs of science or engineering. A new scholarship in memory of Robert N. Hancock, a Fellow and Past President of IEST, long-time member of the Editorial Board of the Journal of the IEST, and a leader in the field of environmental engineering, is available. The Robert N. Hancock Memorial Scholarship, in the amount of $500, will be offered annually by IEST for the best original technical paper written by a student and published in the Journal of the IEST. The Eugene Borson Scholarship, in the amount of $500, is offered to a full-time high school senior, or undergraduate college or university student enrolled full-time in an accredited institution. Eugene (Gene) Borson was a Fellow of IEST, and was a leader in the field of aerospace environmental and contamination control engineering. Each applicant must submit a one-page essay describing his or her career goals and how IEST can help achieve these goals. A science, mathematics, or engineering faculty member must give a recommendation for each applicant. Finally, the Park Espenschade Memorial Scholarship, in the amount of $500, is offered by IEST for the best one-page essay on how IEST can help achieve your career goals. The Park Espenschade Education Fund was established to honor Park Espenschade’s enthusiasm, energy, devotion, and commitment to the education and training of young people in the environmental sciences. Each applicant must be recommended by a science, mathematics, or engineering faculty member, and be a full-time high-school senior, or undergraduate college or university student. For more information, visit the IEST Web site: www.iest.org.

With extensive industry feedback, the International SEMATECH Manufacturing Initiative (ISMI; http://ismi.sematech.org) has detailed the initial scope of its 300 mm Prime (300 Prime) effort, a strategy for improving 300 mm manufacturing productivity that draws on lessons learned from previous technology conversions, and recognizes the importance of collaboration, consensus-building, and compromise among chipmakers and equipment suppliers.

The ISMI program was launched in January and has subsequently involved discussions not only between ISMI member companies but with the industry in general. It now offers specific examples of how 300 Prime might be introduced in ways that encompass different levels of risk and investment. For example, a small-risk implementation might involve updating process tools with recipe and parameter management (RaP), a single wafer tool may replace a batch system for moderate risk, or implementation of a new high-speed factory-wide automated delivery system would represent higher risk.

Program Manager Tom Abell acknowledges that 300 Prime remains a work in progress, and actively encourages tool suppliers to become early contributors of ideas, skills and viewpoints through a set of advisory panels and discussions with ISMI. He characterizes 300 Prime as an evolutionary process scalable to 450 mm manufacturing, with timing dependent upon the possibilities that 300 Prime may hold. “Our view is that 300 Prime/450 mm transition should comprise a staged set of solutions that can be fine-tuned to a chipmaker’s particular business model,” he said.

A clear understanding of the scope of 300 Prime will enable the industry to make technology decisions to improve current productivity while ensuring a sound pathway for a future transition to larger wafers, Abell noted. These decisions range from issues on wafer thickness and carrier size to batch size, factory dimensions, wafer transport mechanisms, and standards for process control data.

To address these issues, ISMI has joined with SEMI (www.semi.org) to establish two engineering groups to collaboratively engage suppliers and chipmakers: the Manufacturing Technology Forum (MTF) and the Joint Productivity Working Group (JPWG). Inputs from both groups will help ISMI develop a 300 Prime capability assessment through 2006 and beyond.

According to Abell, ISMI will seek additional supplier views throughout the remainder of the year at key industry meetings around the globe, including a review of 2006 results and 2007 plans for 300 Prime and 450 mm during SEMICON Japan in Chiba, December 6-8.

The U.S. Food and Drug Administration (FDA) recently alerted the public to a voluntary recall being conducted by Perrigo Company (Perrigo) of Allegan, Michigan, for 383 lots of acetaminophen 500 mg caplets manufactured and distributed under various store brands. Metal fragments ranging in size from “microdots” to portions of wire 8 mm in length were found in about 200 caplets after 70 million caplets were passed through a metal detector. FDA is currently investigating the cause of the metal particles, but Perrigo originally informed FDA of the problem after discovering through its own regulatory quality control procedures that its tableting equipment was wearing down prematurely.

Click here to enlarge image

Approximately 11 million bottles containing varying quantities of acetaminophen 500 mg caplets are affected by the recall. To date, no related illness or injuries have been reported and no consumer complaints have been received by the FDA or Perrigo. Based on information currently available, the FDA believes the probability of serious adverse health consequences is remote; however, swallowing an affected caplet could result in minor stomach discomfort and/or possible cuts to the mouth or throat. Consumers should consult their physician if they suspect they’ve been harmed by use of this product.

Consumers can determine whether they have a recalled product by locating the batch number printed on the container label. For a list of batches affected, visit www.fda.gov/oc/po/firmrecalls/perrigo/perrigobatchlist.html. A list of stores that carry store brands potentially affected by this recall is located on FDA’s Web site at www.fda.gov/oc/po/firmrecalls/perrigo/perrigocustlist.html.

According to a recent statement, FDA does not anticipate that this action will cause a shortage of acetaminophen.

Particles


October 1, 2006

compiled by Angela Godwin

New space for growing engineering firm

Evergreen Engineering (Eugene, OR; www.evergreenengineering.com), an engineering consulting firm serving industries such as bioscience, clean manufacturing, and semiconductor, has leased 8,133 square feet of office space in Hillsboro, OR, in order to accommodate its growing staff. The new space will also provide an in-house venue for client-oriented training sessions and seminars.


FDA issues guidance for cGTP

Following serious allegations of safety violations against two cell manufacturers, the FDA last month issued a guidance to industry aimed at reminding manufacturers of human cells, tissues, and cellular- and tissue-based products (HCT/Ps) of their regulatory responsibilities. The guidance, “Compliance with 21 CFR Part 1271.150(c)(1) – Manufacturing Arrangements,” reminds HCT/P manufacturers that they are responsible for ensuring that current good tissue practices (cGTP) are observed-within their own establishments as well as by contract manufacturers. According to the FDA, cGTP “require manufacturers to recover, process, store, label, package and distribute human cells or tissues in a way that prevents the introduction, transmission, or spread of communicable diseases and prevents contamination during manufacturing.” “Patient safety is our primary concern,” said Jesse Goodman, MD, MPH, director of FDA’s Center for Biologics Evaluation and Research (CBER). “This guidance serves to emphasize the important role that manufacturers play in enhancing tissue safety by helping to ensure that those that perform work for them also comply with the regulations.” To access the guidance, visit http://www.fda.gov/cber/gdlns/cgtpmanuf.htm.


Microcontamination control company announces organizational changes

Particle Measuring Systems (PMS; www.pmeasuring.com), an industry leader in particle monitoring and microcontamination control, recently announced organizational changes to the company. Kristi Urquidi, a PMS employee for eight years, has transitioned from vice president of manufacturing to vice president of engineering. Paul Kelly, president of PMS, said, “Ms. Urquidi has done an outstanding job of developing our operations capabilities and will bring that perspective, along with her exceptional project management skills, to the engineering department.” In addition, Brad Schindler, who has extensive experience in the semiconductor industry, was named the company’s new director of manufacturing. Of the recent changes, Kelly said, “Particle Measuring Systems has experienced tremendous growth over the last several years. These changes position us to continue to lead the way in microcontamination monitoring as we develop new products and expand into new markets.”


New hybrid membrane technology

DuPont has introduced its Hybrid Membrane Technology (HMT), a new offering for air and liquid filtration that is designed to fill the performance gap between traditional nonwovens and microporous films. The material comprises continuous submicron fibers and is available on a commercial scale in the form of “membrane-like” sheet structures. HMT will be the leading technology provided in a portfolio of DuPont Nonwoven technologies that will be offered through DuPont Separations Solutions (DSS), a new growth initiative dedicated to developing and implementing technologies for filtration. According to Matt Trerotola, vice president and general manager of DuPont Nonwovens, “Trends ranging from stricter regulatory requirements to rising energy costs are requiring organizations in industries such as automotive, food and beverage, HVAC and life sciences to seek new separation and filtration technologies that deliver increased levels of safety and efficiency. The launch of the DuPont Separations Solutions initiative and the introduction of HMT demonstrate our commitment to providing these and other industries with the technologies required to fill their diverse needs-both today and into the future.”

At a cost to the industry of more than $5 billion annually, hospital-acquired infections are responsible for at least 90,000 deaths each year

By Bruce Flickinger

Improving patient health and well-being is obviously the prime directive for any healthcare organization, but the dramatic rise in the rate of hospital-acquired infections means that hospitals often do the patient more harm than good. Handwashing and hygienically designed facilities are the keys to combating this problem.

In July 2005, Pennsylvania became the first state-indirectly, and perhaps unwittingly-to officially contribute to the emerging trend toward more consumer-empowered healthcare. Through an organization called the Pennsylvania Health Care Cost Containment Council (PHC4), the state began mandating the reporting of hospital-acquired infection numbers from all hospitals and healthcare facilities in the state, and made this information available to the public. While PHC4’s mission primarily concerns escalating health costs, quality of healthcare, and improving access to care, the public posting of infection rate numbers has already begun to change the way patients make decisions about their healthcare providers.

Five additional states have since enacted mandatory laws for reporting hospital infection rates and another 32 are ready to enact similar legislation. “The writing is on the wall,” says Maryanne McGuckin, Dr. ScEd., senior research investigator and adjunct associate professor at the University of Pennsylvania, Philadelphia. “People used to come to a doctor or hospital and just want to ‘get better.’ But there’s more empowerment now, and patients are not shying away from asking questions.”

To this point she adds, “If you ask your surgeon about what his facility’s infection rate is, and he doesn’t know or says ‘don’t worry about it,’ it’s time to find another surgeon.”

McGuckin’s group at the University of Pennsylvania, through a program called Partners in Your CareSM, has many years’ experience and thousands of data points regarding hand hygiene, hospital-acquired infections (HAIs), and the impact that patients themselves can have on the healthcare dynamic. Most recently, it released results of a survey, co-sponsored by Steris Corp., that found that consumers cite infection rates and cleanliness as two of the three most important criteria when choosing a hospital, outranking other factors such as reputation and proximity.

“We asked people what is important to them when picking a doctor or a hospital, and we thought the top responses would be insurance or geographic location,” McGuckin says. “But the top-ranking factors were cleanliness and infection rates. And these were the main reasons for leaving or discontinuing treatment, as well.”

In addition to public reporting of infection rates, increased media coverage of antibiotic-resistant organisms has brought the issue of HAIs to the fore, and the numbers are disconcerting: HAIs, or “nosocomial” infections, are generally reported to occur in 5 to 10 percent of patients, and are responsible for at least 90,000 deaths each year at a cost of more than $5 billion annually. That’s more people dead each year from HAIs than from AIDS, breast cancer, or car accidents. It’s therefore fair to say that many patients leave the hospital in worse shape than when they arrived.

The University of Pennsylvania survey also confirmed another unfortunate statistic: that handwashing by healthcare workers typically occurs only about 50 percent of the time between patient contacts. This is a major contributor to the rise in HAIs; a second cause is the growing antibiotic resistance among virulent organisms, notably Staphylococcus aureus and enterococci species. Controlling the situation is enough of a challenge, but the healthcare community now clearly has to contend with the fact that consumers are more aware that data about infection rates are available to them, so they are more cognizant of the risk of infection in the healthcare setting.

Best practices are unevenly applied

What does this new paradigm mean for hospitals and healthcare facilities? Firstly, the focus has concentrated on two critical areas: proper hand hygiene, and facility design and engineering that promote good patient health and mitigate the spread of disease. Secondly, there are a number of guidelines and industry standards that mandate procedures for better infection control. Most notable among these are the 2005 standards proffered by the Joint Commission on Accreditation of Health Care Organizations (JCAHO), the nation’s most prominent healthcare accrediting body. The new set of standards specifically calls for procedures and processes to have a measurable impact on infection rates and outcomes.

A number of industry groups have developed guidelines and best practices documents. One, for example, is the Society for Healthcare Epidemiology of America (SHEA; Alexandria, VA), which recently published guidelines for the prevention of transmission of methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE) within healthcare settings. Chief among the recommendations is an emphasis on adherence to hand-hygiene guidelines. Other measures SHEA points to as preventing the nosocomial transmission of MRSA include improved antibiotic stewardship, staff cohorting, maintenance of appropriate staffing ratios, reductions in length of hospital stays, contact isolation, active microbiologic surveillance and better staff education.


Hospital-acquired infections are most commonly associated with procedures and activities performed on the patient. The patient’s own normal flora can play a role, along with hands-on contact from healthcare staff. Infection control practitioners are emphasizing the concept of interventional patient hygiene, where measures are implemented to control overall patient bioburden. Photo courtesy of Shands Hospital, Gainesville, FL.
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Researchers analyzing the effectiveness of these guidelines published a report in the American Journal of Medicine (June 2006), writing that “currently, the efficacy of many of these individual infection control interventions remain in doubt,” adding that “many studies reporting improvement in infection control outcomes involve simultaneous institution of several of these measures, making it impossible to tease out the effects of any of the individual components.”

There is other evidence that, despite the existence of industry best practices, infection control (IC) efforts are a mixed bag throughout the healthcare community. A study published in Infection Control and Hospital Epidemiology (March 2006) assessed IC staffing resources, organizational structures and clinical processes, and how they were related to reducing the incidence of HAIs in 31 community healthcare facilities. Although the researchers found positive ratios between the number of patients and the number of IC staffers in the facilities studied, they reported inconsistent IC practices and wide variation in IC department structure and processes. Their conclusion: there is a need for more-effective implementation of current evidence-based recommendations for preventing HAIs and reducing the risk of harm to patients.

Officer in charge?

Most hospitals employ one or more IC practitioners (ICP) to coordinate infection monitoring and control efforts. McGuckin paints a picture of the typical hospital IC unit as overworked, understaffed, and with “a lot of responsibility but not much authority or funding.” Ideally, there should be one IC practitioner for every 200 beds, she says, but in reality this one person, although they might have some administrative help, is the only IC staffer at a typical 300-bed community hospital.

The ICP and hospital epidemiologist officer head up the IC committee, which typically meets monthly to discuss infection rates and hygiene procedures, policies, and product evaluations, and which usually includes representatives from varied departments, such as housekeeping, the lab, surgery, administration, and dietary services. “The problem is, if a facility’s infection rates are under control, then people ask, what exactly is our ICP officer doing?” McGuckin says.

Loretta Litz Fauerbach is director of infection control at Shands Hospital at the University of Florida, in Gainesville, a private, not-for-profit hospital that specializes in tertiary care for critically ill patients. Fauerbach makes the important distinction between sterile procedures and a clean facility. “Instruments and body sites like the heart can be sterile or microorganism-free, but a hospital can only be clean,” she says. “It’s impossible to establish a sterile environment in a facility where people come and go and patients are seen. It would be cost-prohibitive [and] not very conducive to patient-staff interactions.”

Fauerbach and others emphasize that HAIs are most commonly associated with procedures and activities performed on the patient. The patient’s own normal flora can play a role, along with the hands-on contact from healthcare staff. “Thus the most important function of a facility is to minimize the potential for cross-contamination between patients and/or staff by providing easy access to handwashing or alcohol-based waterless hand rubs,” says Fauerbach, who is a member of the Association for Professionals in Infection Control and Epidemiology (APIC).

“The concept of interventional patient hygiene is becoming very important,” McGuckin adds. “It involves looking at overall patient bioburden [because] so many other things come into play besides handwashing. You need to look at catheter care, oral care, pressure ulcers, surgical site infection, the use of prepackaged bathing towels instead of washbowls. When you’ve reduced the bioburden of both the patient and the worker, then you’ve got a good handle on infection control.”

Hygiene by design

Observers point to two key facility design strategies for reducing bioburden and preventing cross-contamination among patients and workers: single-occupancy rooms and the strategic and prolific placement of handwashing and alcohol wipe stations.

Fauerbach says single-occupancy rooms are key to assuring that “cross-contamination between patients is minimized and that staff have the appropriate opportunities to perform hand hygiene and/or remove any protective garb before going to the next room and the next patient. The physical separation of the patient makes compliance easier.” She adds that new room designs should have designated areas for easy access to gowns, gloves, and other personal protective equipment to make it easier to use those items during patient care.

“There is overwhelming evidence that the risk of infection is less in single rooms versus double rooms,” says Anjali Joseph, PhD, director of research with the Center for Health Design (CHD; Concord, CA), an organization that works to promote research, education, advocacy, and technical assistance to improve the quality of healthcare through evidence-based building design. “Single rooms are easier to disinfect after a patient is discharged, and the viral load is less as there are fewer visitors and staff in the room. Also, the risk of infection through contact transmission of pathogens is reduced.”

Joseph adds, “The highest concentration of visitors and people are in the public areas of the facility, such as the lobby or cafeteria, and most immunocompromised patients are not exposed to these sources of pathogens. But they are at increased risk if the patient shares his or her room with another person because this increases the traffic within the room.”

Unfortunately, many hospitals currently in operation were built prior to the patient safety initiative of private rooms, so healthcare providers must be alert to the potential for cross-contamination in a multi-bed room. Fauerbach says facility design can encourage good hand hygiene and removal of any protective garb when going from one patient to the next by having alcohol hand rubs readily available at the bedside and in the room. Also, the availability of sinks and personal protective equipment helps to facilitate compliance. She again emphasizes that “it’s important to provide space for gloves, gowns, and other equipment within the room so the healthcare provider doesn’t have to search for these items when they’re providing care.”

“It’s important to provide well located, accessible and visible sinks, and multiple handwashing-liquid dispensers and alcohol rubs inside and outside of patient rooms,” concurs Joseph. “This helps improve poor handwashing compliance, which is the key problem in addressing nosocomial infections from the staffing perspective.”

An additional vehicle for reminding and encouraging good hygiene practices among workers is the patients themselves. “Patients do observe what the workers are doing,” McGuckin says. “We asked them [in the survey], if encouraged to do so, would they remind a healthcare worker to wash their hands, and most indicated they would. This is the essence of our program: involving and empowering the patient as part of the healthcare team.”

McGuckin’s database of information involving hundreds of healthcare centers shows that “if you involve the patient, you can increase the level of hand hygiene by 60 percent within five months. So having patients remind healthcare workers to wash their hands is critical. The patient is always there, so there’s an ongoing vigilance.”

Look before you build

Another key feature for a hospital is its ability to be readily cleaned and maintained. Although surfaces generally are not linked to the direct transmission of infection, they should be nonporous, easy to clean, and able to withstand rigorous cleaning regimens.

This, along with a number of other facility design criteria, is explored in a 16-page paper recently released by CHD, authored by Joseph and titled “The Impact of the Environment on Infections in Healthcare Facilities.” In it, she distinguishes between frequent hand-contact surfaces, such as medical equipment, door knobs, bed rails, light switches, patient toilet areas and privacy curtains, and minimal hand-contact surfaces, such as walls and floors. The former obviously need to be cleaned and disinfected more frequently than the latter.

Joseph also addresses the issue of carpet versus vinyl flooring, noting that while there is scant evidence linking carpet contamination with nosocomial infections, carpet can support the growth of fungi and bacteria, and studies have shown that the air over carpeted areas tends to have higher pathogen levels compared with hard flooring. “While carpeting contributes to noise reduction, a possible reduction in falls and resultant injuries, and to a less institutional ambience, it should be avoided in areas where spills are likely to occur and in high-risk patient care,” she says.

Though noting that such considerations are important, McGuckin echoes the opinion of many observers in noting that “it’s hard to find direct correlation between infection rates and environmental conditions. Most disease transmission is via the hands, not dirty walls and floors.”

While facility-design issues are not as much of a headache for newly constructed facilities, they can be a major budgetary and logistical concern for older facilities, which often need to be rebuilt or refit-construction projects that create their own infection-containment concerns. Hospitals are generally in a near-continual state of expansion and rebuilding, so containment of these projects is a major issue with regard to the spread of infection.

“There are many instances of the spread of infection during periods of construction and renovation,” Joseph says. She lists a number of measures in her paper that can be implemented to prevent the spread of airborne pathogens from construction sites to the rest of the hospital. These include using portable HEPA filters; installing barriers between the patient-care and construction areas; using negative air pressure in construction/renovation areas relative to patient-care spaces; and sealing patient windows.

APIC has had a guideline for preventing infections associated with construction for many years, and CDC’s Healthcare Infection Control Practices Advisory Committee (HICPAC) also offers guidance on environmental infection control and the management of construction risks. “Today, the industry standard is to perform an infection control risk assessment (ICRA) on each and every construction project to assure the safety of patients, staff, and visitors,” Fauerbach says. “The project is also to be monitored along the way to ensure compliance with recommendations made in the ICRA and to identify any new issues that need to be addressed.”

The ICRA, Fauerbach says, should be done in cooperation with the facility construction staff, infection control, and the nursing and medical staff of the affected area. With appropriate planning and intervention, risks of construction-related infections (both airborne and waterborne) can be minimized. “JCAHO is also interested in seeing documentation of this process when they survey a hospital,” she says.

JCAHO stipulates that the ICRA delineate infection control issues that impact air and water quality, in particular, during any healthcare construction project. It should include ongoing monitoring requirements to ensure the health and safety of patients and staff while buildings are being constructed-and that new buildings or renovations will be constructed to facilitate ongoing cleanliness and mitigate related infection-control problems after construction.

People as a source of problems

Air quality is a primary concern in the healthcare setting, whether or not construction is under way. Evidence from many studies leaves no doubt that air ventilation and filtration play decisive roles in affecting air concentrations of pathogens such as Aspergillus and, as such, have major effects on infection rates. Considerations include type of air filter, direction of airflow and air pressure, air changes per hour in the room, humidity, and ventilation system cleaning and maintenance.

The overarching goal is to reduce the amount of particulate matter in the air through proper, well-maintained ventilation systems. Peak efficiency for removing particles from the air typically occurs between 12 and 15 air changes per hour, Joseph notes. Particles bearing potentially pathogenic organisms are introduced into the environment in three main ways: by activities involving the respiratory tract, such as coughing or sneezing; by movements that shed bacteria from the skin; and by the disturbance of dust. So, again, people have the biggest impact on an environment’s cleanliness, and while this can be controlled in a finite cleanroom environment, a hospital is a larger and much more variable situation.

“The standards for filtration vary depending on the unit and its function,” Fauerbach says. “The operating room, for example, has a different set of standards than does a general patient-care area. One level of HEPA filtration can be used in the overall hospital ventilation system, with a higher efficiency being reserved for the protective environment for the immumosuppressed patient.”


A nurse prepares to enter the contact isolation unit at Shands Hospital at the University of Florida in Gainesville. There is ample evidence that immunocompromised and other high-acuity patient groups have lower incidence of infection when housed in HEPA-filtered isolation rooms. Photo courtesy of Shands Hospital, Gainesville, FL.
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CHD and others advocate laminar airflow rooms with HEPA filters for operating-room suites and areas with ultraclean room requirements, such as those housing immunocompromised patient populations. However, “laminar flows are relatively expensive and difficult to achieve because furnishings, vents and other features can create turbulence,” Joseph notes.

Joseph and others point to convincing evidence that immuno-compromised and other high-acuity patient groups have lower incidence of infection when housed in HEPA-filtered isolation rooms. She cites one study in which bone-marrow transplant recipients assigned beds outside of a HEPA-filtered environment were found to have a tenfold greater incidence of nosocomial Aspergillus infection compared to other immunocompromised patient populations.

“HEPA filters are strongly recommended by the CDC for spaces housing immunocompromised patients,” Joseph says. “Most hospitals have a filtration system that is 90 percent effective in filtering out harmful pathogens. Once the frames for the filters are in place, it is possible to increase the efficiency of the filters by adding HEPA filters for special-care areas of the hospital, such as surgical areas, burn ICU units and protective environments for immunocompromised patients.”

Whether via people, the air or physical surfaces, infectious agents can and do prosper in even the best-maintained healthcare settings. Their prevalence can be attributed to a number of factors, but their transmission among patients and workers can clearly be reduced by proper facility design and engineering, and staff compliance to good hygiene principles.

Perhaps more importantly: “It is critical to have infection-control information available to the public in a way that they can interpret and use it,” McGuckin says. “Hospitals are businesses, and patients are their customers. Hospitals have to be accountable to them. That’s the way it is in every other industry, and it should be in healthcare, too.”

Resources

1. Association for Professionals in Infection Control and Epidemiology (APIC), http://www.apic.org.

2. Center for Health Design (CHD), http://www.healthdesign.org. Visit this Web site to access the report “The Impact of the Environment on Infections in Healthcare Facilities.”

3. Partners in Your Care Program, http://www.med.upenn.edu/mcguckin/handwashing. For more information about the program, contact Dr. McGuckin at [email protected]. Visit http://www.steris.com/aic/partners.cfm to access a copy of the University of Pennsylvania Caravan® Survey report.

4. Society for Healthcare Epidemiology of America (SHEA), http://www.shea-online.org.

5. CDC Guideline for Environmental Infection Control in Healthcare Facilities (2003), http://www.cdc.gov/ncidod/dhqp/gl_environinfection.html.

6. CDC Guideline for Hand Hygiene in Healthcare Settings (2003), http://www.cdc.gov/ncidod/dhqp/gl_handhygiene.html.

They still don’t get it


October 1, 2006

Last June, I wrote an editorial entitled “Why doesn’t the food industry get it?,” in which I made the case that expecting the entirely voluntary application of modern contamination control standards and practices to ensure a safe food supply was totally unrealistic and, in fact, dangerous and irresponsible. Not surprisingly, this position elicited a strong condemnation from some food industry advocacy groups and individuals (although at least one particularly vocal critic has now apparently completely reversed his opinion, for which I guess I will have to take some small credit).

I would prefer to be able to take credit, however, for actually generating some level of improvement to the situation and to a lowered public health risk. Unfortunately, I clearly cannot.

As of September 24, the FDA reported that, to date, 173 cases across 25 states had been reported to the CDC of illness due to E. coli infection from contaminated fresh spinach and spinach products. Of these, there were 27 cases of hemolytic uremic syndrome (HUS), 92 hospitalizations, and one death.

The good news, I guess, is that the FDA further reported that the source of the contaminated spinach had been isolated to three California counties and that “voluntary” recalls were underway. Most exasperating, however, was the statement that, “The public can be confident that spinach grown in the non-implicated areas can be consumed.” I’m sorry, but I have to ask the question, on what possible basis should this public confidence rest (unless it wasn’t by accident that the statement left out the word “safely” before “consumed”)?

How long is the public going to put up with this farce? This case is certainly not an isolated incident. In fact, one company involved in this latest large outbreak, Dole Food Company, was also involved in a similar E. coli outbreak in prepackaged salads almost exactly a year ago. Dole’s very responsible response this time around has been to disavow any relationship with the actual packager, Natural Selection Foods (other than apparently licensing their brand name to them). It is encouraging to note, however, that Dole said in a company statement that it “supports the voluntary recall of the Natural Selection Foods’ spinach that Natural Selection Foods produced and packaged…as a precautionary measure in keeping with Dole’s commitment to consumer safety.” (italic added)

Feel free to visit FDA’s recall page and make your own evaluation of how the current voluntary system is working (http://www.fda.gov/opacom/7alerts.html). During a random 4-month sampling period, September-December 2005, I tracked 13 recalls by the FDA alone “directly related to adultery by dangerous forms of contamination.” Among these contaminants-Listeria, Salmonella, Clostridium botulinum, and E. coli.

I wonder why I didn’t take more comfort when, in March 2006, the FDA issued a draft “Guide to Minimize Microbial Food Safety Hazards of Fresh-cut Fruits and Vegetables.” I mean the guidance “recommends that processors encourage the adoption of safe practices by their partners throughout the supply chain, including produce growers, packers,” etc., and it also “recommends that fresh-cut processors consider a Hazard Analysis and Critical Control Points (HACCP) system to build safety into their processing operations.” (italic added) I guess Dole, for one, and Natural Selection Foods, for another, didn’t see any merit in adopting these recommendations.

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John Haystead,
Editor-in-Chief