Designing to prevent infection

Photo © BigStockPhoto/Frank Boston
Photo © BigStockPhoto/Frank Boston

by Scott Blevins
U.S. healthcare organizations increasingly face the most daunting medical challenge since the pre-antibiotic age. While pharmaceutical manufacturers hope for a new era of treatment that is still years from the market, the challenge—and preventative solution—is found in the built environment itself.

Healthcare’s perfect storm is not an industry secret. The Centers for Disease Control (CDC), the media, and industry experts often focus on the ever-increasing number of multi-drug resistant and environmentally adaptive pathogens. These microorganisms commonly overwhelm limited Environmental Service Department resources and navigate air-handling systems with ease, leaving healthcare providers to battle increasing numbers of infections with ineffective environmental tools. Some of these pathogens are so environmentally adaptive they may rebound to a majority percentage of their pre-disinfection levels within a few hours of surface disinfection.1

However, as Healthcare Infection Control Practices Advisory Committee (HICPAC) states, the problem is multi-faceted. The challenge is not solely an increase in more dangerous pathogens—advances in medicine and an aging population have provided an increasing amount of immune-compromised patients highly susceptible to infection, which may become an environment’s host population.

Providers work on patients, not buildings. Across the nation, Environmental Service Departments are losing staff, unable to keep up with surface transfer potentials throughout an active hospital. Architects and designers now have their most important role to date in providing successful patient care. They may design an environment that inadvertently accumulates, propagates, and circulates pathogens—or one which is the best ally in continually mitigating surface and airborne microbial health safety concerns.

If advances in medicine and microbial-adaptive abilities are the ‘anvil,’ then the lesser-discussed factors of finance, regulation, and litigation are the ‘hammer’ confronting healthcare clients. In 2009, Medicare and private insurance ceased payment for hospital-acquired infection (HAI) incident expenses, putting the brunt of this burden on individual facilities. Subsequently, federal International Statistical Classification of Diseases and Related Health Problems 10th Revision (ICD10) regulations continue to tighten the paperwork, documenting an increasing number of HAI incidents—meaning an ever increasing number of non-paying patients under federal reporting.

Public awareness has grown thanks to mandatory public reporting, millions of additional patients battling multi-drug resistant organisms (MDROs) joining the community, high-profile patients raising awareness, and CDC issuing press releases on the “superbug of superbugs.” This is now the age of HAI litigation, resulting in numerous eight-figure lawsuits.

How can architects and designers help?
Healthcare workers (HCWs), infection preventionists, and environmental service staff work harder than ever to achieve positive patient outcomes, but they have little control over the actual physical environment provided to them which supports their success. It is critical to address transmission and environmental pollution from C. Difficile spores, methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococci (VRE) microbes, Norovirus, and ribonucleic acid (RNA) influenza via unprotected vectors such as toilet aerosolization, surface transfer, humidity levels, and HVAC travel.

Photo © BigStockPhoto/Tyler Olson
Healthcare staff work harder than ever to achieve positive patient outcomes, but they have little control over the actual physical environment provided to them. This is where the design professional comes in. Photo © BigStockPhoto/Tyler Olson

Healthcare-worker hand hygiene continues to be the best-known and recognized means of infection transmission. Numerous studies have been completed, documenting up to 40 percent of HCW hand contamination occurs from contact with the environment. Additionally, certain MDROs achieve 100 percent surface transfer success to multiple surfaces from origination, enabling exponential migration to what is quickly Sick Building Syndrome (SBS)—and once a facility is overwhelmed by microbial contamination, it can be hard to eradicate.

Patients may shed and exhale millions of pathogen particles daily, which may have weeks’ worth of environmental viability, putting a significant challenge on Environmental Services staff that may only have time to clean a surface once daily. Additionally, studies on microbial rebound have shown despite perfect cleaning and disinfection, surface porosity successfully harbors pathogen deposits such as MRSA and VRE that rebound up to 40 percent of their pre-cleaned level within a few hours, without recontamination.2

In most U.S. facilities, the existing minimum efficiency reporting value (MERV) filters do an excellent job of capturing 1-µm (0.04-mil) particles. Unfortunately, 0.3-µm (0.012-mil) particles—the same size HICPAC identifies as “potentially viable microorganisms, capable of indefinite suspension”—are often in the hundreds of thousands of particles per cubic foot. Particles are able to float from the lobby to the operating room, even picking up additional organic materials electrostatically from surfaces en route. Other environmental vectors—such as air dissemination to patient surfaces and the constant electrostatic particle interchange that occurs between surfaces and air—are well understood, but rarely addressed outside the highest level manufacturing facility clean rooms.

Specifying air-handling and surface products from a microbial perspective provides a direct and lasting impact on variables as diverse as:

  • patient care quality;
  • patient outcomes;
  • HCW hand hygiene;
  • surface hygiene;
  • indoor air quality (IAQ);
  • surface cleanability;
  • ongoing bioburden levels (or quantity of microbial material) of an occupied space;
  • transmission incidents; and
  • the facility’s financial viability.

Specifying for improved surface hygiene
Designers benefit from working with epidemiology, infection-prevention, and environmental hygiene client resources, along with expert consultant resources whenever available. The locations of highest touch deposits and most frequent interchanges—such as nurse stations or push plates—must be identified. Locations and equipment interacting with critical or multiple areas of a facility or its staff must also be noted, along with the potential traffic patterns of surface-borne microbes.

When selecting materials for high-contact surfaces, one must pay special attention to microscopic surface porosity and texture relative to cleanability, microbial rebound, pathogen reservoir development, and surface transfer potentials.

Self-disinfecting surfaces, or continually active antimicrobial materials and surface modifiers, should be specified to improve surface hygiene and cleanability. This also reduces the ‘anytime levels’ of colony-forming units (CFUs) of bacteria and resultant transmission potentials at high contact surfaces. Available materials include titanium dioxide (TiO2) and silicon (Si14) coatings, antimicrobial copper, and antimicrobial linen treatments.

Modifiers, such as Si14, virtually eliminate porosity, making surfaces inhospitable to deposits, and enabling them to be cleaned more efficiently. Being highly hydrophobic, this also prevents staining and improves the shine appearance of common materials. Active antimicrobials, such as TiO2, actually trap and destroy microbes and spores through a naturally occurring electrostatic property that incorporates continuous photo-catalytic oxidation. These coatings may be specified like any other coating, and then incorporated seamlessly by Environmental Services maintenance for periodic reapplication. The result is a space that cleans easier, has a lower microbial content, and diminishes health concerns rather than harboring and circulating them.

Engineered ultraviolet (UV) surface disinfection may be additionally employed at critical spaces, such as operating rooms, to guarantee surface sterility. Surface UV disinfection success is a function of output, distance, and exposure time, so these installations are typically best custom-designed for the specific space by a UV engineer.

Airborne prevention
In terms of preventing the spread of airborne infections, it becomes critical to work with mechanical engineers, infection prevention specialists, and epidemiologists to better understand the specific demands of a project. Employing independent IAQ resources adept in infection prevention can also assist in documenting bacterial loads and air dissemination potentials.

It is important to consider:

  • particulate air travel potentials (remembering ‘indefinite suspension’);
  • positive and negative pressurization relative to a true ‘air lock’ performance;
  • placement of patient bath exhausts;
  • air dissemination potentials; and
  • continual bioburden contribution of occupants.

Similarly, the design professional should consider the electrostatic particulate dissemination and detachment continually occurring between air and surfaces—and how this relates to IAQ, surface hygiene, HCW hands, and transmission potentials.

Depending on a hospital’s mechanical system, problematic particles can float from the lobby to the operating room, picking up additional organic materials electrostatically en route.
Depending on a hospital’s mechanical system, problematic particles can float from the lobby to the operating room, picking up additional organic materials electrostatically en route. Photo © BigStockPhoto/Vadim Kozlovsky

Existing MERV filtration systems should be replaced with low-pressure-drop high-efficiency-particulate-air (HEPA) performance wherever possible, and not just in surgical areas. Ultraviolet germicidal irradiation (UVGI) systems should be specified at 800 to 25,000 microwatts per centimeter squared to dramatically improve IAQ—this also eliminates coil cleaning and the resultant respiratory irritant exposure to compromised patients of coil-cleaning chemicals. Even the best chemical coil cleaning does not completely remove biological material, and allows cleaning agents to travel downstream into occupied areas.

Critical or high-risk areas may greatly benefit from ‘first pass kill’ air disinfection specifications (up to 25,000 microwatts per cm2), which, per federal or military specifications will prevent the airborne transmission of any known microbe, and may affect majority reductions of C. Difficile spores. Bi-polar cold plasma systems are specified more commonly to address pollution challenges, such as helicopter or ambulance exhaust, but also provide a potent microbial reducing performance for occupied areas, after an air-handler.

Attention to detail can have substantial impact in infection prevention. The cardboard housing on common AHU pre-filters, for example, may sag in the presence of moisture as well as feed mold and microbes; similarly, a plastic laundry cart may travel from the soiled utility room to the ER to the neonatal intensive care unit (NICU) twice daily, contacting numerous surfaces and staff en route, while an elevator button may be touched by 600 people—including MRSA or VRE-positive patients—in one 24-hour period between cleanings.

The good news
Most of these specifications provide significant returns on investment (ROIs) completely unrelated to their environmental health safety benefits. Si14 surface treatment, for example, has a remarkable electrostatic repellency, which improves appearance, stain-resistance, and cleaning at critical surfaces. It also extends exterior window cleaning cycles by up to 75 percent.

UVGI systems may be used to reduce fresh air intake in administrative or other areas not subject to American Society of Heating, Refrigerating, and Air-conditioning Engineers (ASHRAE) 170, Ventilation of Health Care Facilities, often resulting in up to 25 percent fresh air reduction and significant energy savings. Coil cleaning elimination alone can provide a quick return on investment and credits under the U.S. Green Building Council (USGBC) Leadership in Energy and Environmental Design (LEED) rating program. By recycling UV-sterilized cooling tower water, some facilities have saved tonnes in consumption annually.

Architects and designers now have many tools to create a safer environment, providing facilities ultimately with improved patient care and a much healthier bottom line. Surfaces and building equipment such as laundry carts and over-bed tables may be empowered to continually disinfect themselves. Further, air filtration can be improved to capture a larger number of microbial particles, and to sterilize the air at critical areas. Air movement and staff traffic may be anticipated to limit the potential of microbial migration from one patient to another.

Singular applications of these solutions have greatly lowered infection incidents. Many of these systems provide significant ROIs for owners, outside the targeted HAI reduction. Excellent resources exist from domestic manufacturers, as well from focused consultant and distribution organizations specializing in the wide range of healthcare environmental tools.

1 For more information, see the article, “Intrinsic Bacterial Burden Associated with Intensive Care Unit Hospital Beds: Effects of Disinfection on Population Recovery and Mitigation of Potential Infection Risk,” by Attaway et al. It appeared in the December 2012 edition of American Journal of Infection Control. (back to top)
2 See note 1. (back to top)

Scott Blevins is a managing partner at Portland, Maine-based I.C. Solutions. He has worked in healthcare construction management as a senior project manager and estimator since 2001, serving as a regular expert speaker to CSI, and engineering and environmental plant managers associations, on surface hygiene, antimicrobial systems, and air filtration. Blevins can be contacted via e-mail at

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