UVC and Hospital Infection Control

Every year, greater than two million people contract a hospital-acquired infection (HAI), which can sometimes be antibiotic-resistant. In 2013, such infections led to at least 23,000 deaths (CDC). HAIs kill more people than auto accidents, AIDS, and breast cancer combined.

Emerging diseases, such as COVID-19 (SARS-CoV-2), Sudden Acute Respiratory Syndrome (SARS) and Middle East Respiratory Syndrome (MERS), require vigilance in health care facilities to protect facility workers, staff, patients, and visitors against the spread of such pathogens.

Infection control is like a war being fought on three fronts: HAIs, antibiotic resistant microorganisms (ARMs), and emerging diseases.

Engineering of infection-control systems in health care facilities plays an essential role in fighting this war. There are guidelines, such as the ANSI/ASHRAE/ASHE Standard 170-2013, Ventilation of Health Care Facilities (ASHRAE 2013); however, there is no single guide which encompasses all of the information and/or verified suggestions that engineers will need.

Ultraviolet germicidal irradiation (UV-C) kills all known microorganisms.  This article outlines some basic information about infectious diseases and provides engineering-level guidance for continuously reducing, or even preventing infectious pathogens from growing on surfaces or circulating in hospital spaces and HVAC systems.

Basics

It helps to understand the types of pathogens and how they manifest as diseases (etiology), which includes their virulence (how they affect people); their transmission (how they are spread), and which interventions work best for which diseases.

Types

Here, we will focus on two types of pathogens which are of concern — bacteria and viruses.

 • Bacteria – Bacteria inhabit water, soil, animals, and humans, etc., and are responsible for illnesses such as strep throat, urinary tract infections, and tuberculosis to name just a few. A serious issue with bacteria is their increasing resistance to available drugs – these are known as antibiotic-resistant microorganisms (ARMs), such as MRSA (Methicillin-resistant Staphylococcus aureus).

• Virus – Viruses are small infectious agents that replicate in the living cells of other organisms, including such as in humans, animals, and plants. They are typically smaller than bacteria and are extremely difficult to treat with drugs. Viruses include coronaviruses, (Enterovirus D68), SARS, MERS, Ebola, and colds and flu.

Transmission

This basic information provides a knowledge foundation for design of interventions that intercept or interrupt transmission, and therefore reduce the spread and risk of infectious agents. There are many modes of transmission; those we have covered are outlined below:

 • Direct contact: Transfer of microorganisms that occurs during physical contact, such as touching, kissing, and contact with blood and other bodily fluids (Mt. Sinai 2014).

• Indirect contact: Contact with a contaminated surface, such as door handles, bed rails, medical instruments, etc. (Mt. Sinai 2014).

• Droplet contact: Contaminated droplets expelled by an infected person through breathing, talking, coughing, or sneezing, and directly reaching another person’s mouth, nose, or eyes. Droplets can also be produced during medical procedures, such as bronchoscopy, surgery, autopsy, etc. (Mt. Sinai 2014).

• Airborne transmission: Some droplet nuclei and/or residue from evaporated droplets or dust particles containing microorganisms, can survive and remain suspended in air for extended periods of time, and some are resistant to drying out, prolonging the potential risk for transmission.

• Fecal-oral transmission: Digestive tract microorganisms may be spread to surfaces, food, water, or medicine and ingested by another person, or may be spread through indirect contact with flushing toilets and medical instruments.

• Close contact: A term used commonly as a means of transmission of the Ebola virus. According to the CDC, “close contact” includes exposure through caring for, or living with, an infected person, having direct contact with a patient’s bodily fluids or respiratory secretions, sharing eating utensils or drinking vessels, or touching a person directly. Close contact does not mean walking past a person or briefly sitting across from a person in a waiting room, for examples.

Virulence, Infectiveness, and Treatability

Virulence refers to the potential to impact an infected person’s health, including the mortality rate of the infection (how many people die after becoming infected). Aside from pathogen specifics, virulence is influenced by many factors, including age, health, vaccinations, and the infected patient’s access to health care.

Infectiveness is the ability of a disease to spread. The term “reproduction number” (Ro) is used to numerically rate the transmission potential of a disease. The higher the Ro, the more contagious a disease will be.

Treatability is an informal term that represents the difficulty of treating an infection with vaccinations or medication. Viruses are tough to treat, and bacterial infections that were once treatable with antibiotics are now mutating to become multidrug-resistant forms (WHO 2014).

The War

As mentioned above, the war against infectious diseases is being waged on three fronts — hospital-acquired infections (HAIs), microbial resistance to known drugs, and emerging diseases.

Hospital-Acquired Infections (HAI’s)

HAIs are extremely prevalent in U.S. hospitals. Research by the CDC on U.S. acute-care hospitals found that in 2011, approximately 1 in 25 patients had at least one health care-associated infection. This amounts to about 722,000 HAIs in 2011; about 75,000 of those infected patients died during hospitalization. Greater than half of these infections occurred outside of an intensive care unit (Magill 2014).

Furthermore, diseases that are normally spread via air or via contact can also spread through alternative transmission paths. For example, the Clostridium difficile (C. diff) bacterium, a frequent HAI pathogen, is commonly spread through fecal-oral transmission. However, several studies have found that it can also become airborne during cleaning of a room, and spread both within the room and outside the room (King 2012, Best 2010).

Antibiotic Resistance

The resistance of pathogens to medicines is now occurring at an alarming rate, and no major new antibiotics have been developed in the last 30 years (WHO 2014). The dire situation prompted a warning from the World Health Organization: “Without urgent action we are heading for a post-antibiotic era, in which common infections and minor injuries can once again kill” (WHO 2014).

In 2014, the US President’s Council of Advisors on Science and Technology released a report regarding antibiotic resistance (PCAST 2014) which stated that the “evolution of antibiotic resistance is occurring at an alarming rate and is outpacing the development of new countermeasures.” The report’s recommended strategies included improved stewardship of antibiotics (reducing the unnecessary or misplaced use of antibiotics); increased surveillance of antibiotic-resistant strains of bacteria to enable earlier identification of outbreaks; limiting the spread of antibiotic-resistant organisms; and accelerating the development of new antibiotics (PCAST 2014).

It is unclear when increased focus on antibiotic-resistant bacteria will occur, or whether it will yield positive results. While these efforts are being ramped up, hospitals will need to continue to improve their protocols and infrastructure, to protect against and minimize antibiotic-resistant bacterial infections and outbreaks.

To help fight this crucial battle, and the battles on the fronts of HAIs and emerging diseases, engineers have one major and extremely well-tested tool they can turn to: Ultraviolet energy in the “C” band, a widely-used technology that kills bacteria and viruses on surfaces, in room air, and in HVAC supply air streams.

Emerging diseases

Emerging diseases are a major threat because they evade treatment by masquerading as known diseases, eliciting similar symptoms. Instead of being a known variant of, for example, the cold or flu, it may be an entirely new pathogen or disease, that is more virulent and/or infectious than a genetic variant of a known disease.

The impact of emerging diseases is not always the same in different countries. For example, U.S. health care workers exposed to SARS did not contract the disease, however, in other countries, there were worker infections sufficient to lead to hospital closure.

Ebola has been extremely harmful to health care workers. As of September 23, 2014, the World Health Organization reported that more than 240 health care workers had died from the disease, some of whom were the most prominent doctors in their countries (WHO 2014-2).

Infection Control

The UV-C waveform is an extremely effective supplemental approach to fighting infectious diseases (Memarzadeh 2010). No known microorganisms are entirely resistant to the physical effects of the UV-C frequency.

UV-C can be inexpensively installed throughout health care facilities, with upper-room units for interior spaces, UVC lamps in HVAC ducts, and exhaust systems for airstream disinfection and in air handlers, to disinfect airstreams, air filters, coils, drain pans, and other potential areas for microbial growth and proliferation.

The following section is intended for applications which focus on airborne transmission and transmissions that include airborne components.

Fortification

UV-C supplements other infection-control protocols for sterilization, disinfection, and manual cleaning. In addition to their 24/7 action of killing pathogens, they also provide some level of protection when workers do not, or cannot, follow established protocols, or if existing protocols are sidestepped by emerging diseases, or when HVAC or room-pressurization systems have been compromised.

A “fortification” approach provides another level of protection. Again, UV-C is effective against all pathogens from either known or emerging diseases, and it does not contribute to drug resistance or secondary contamination.

UV-C installations can be positioned in key spaces and/or in HVAC equipment, where pathogen sources and pathways exist. Interior and perimeter spaces can be protected using upper-room units. Air handling systems which serve high-risk areas can be protected using airstream-disinfection systems. And areas of HVAC systems which are known reservoirs for pathogens can be bathed with surface-cleaning UV-C systems.

Upper-Air Units

Infections from airborne pathogens (which fall out or plate out onto equipment surfaces and floors) are generated by people (Nardell 1999). Upper-air UV-C systems effectively intercept these microorganisms in the room air (First 1999).

Another use of UV-C is to intercept microorganisms that come from other sources, or where pathways for cross-contamination exist. They kill pathogens that are circulated by pressure differentials, drafts, or the movement of people, such as from entering or leaving a room or even from cleaning. They are also effective against droplet nuclei produced by coughing, sneezing, or the changing of bed linens.

Upper-room units may be installed in emergency rooms, waiting rooms, patient rooms, isolation rooms/wards, surgery suites, and childcare rooms — really, anywhere infectious agents exist. Guidelines are available from manufacturers, or from the National Institute for Occupational Safety and Health (NIOSH 2009).

Airstream Disinfection

Airstream disinfection systems use UV-C lamps to kill pathogens from outdoor and/or return air (which contain airborne pathogens). Kill ratios of over 99.9% on a first-pass basis have been modeled and, as air is re-circulated, with each subsequent pass, concentrations are further reduced (mass balance).

Airstream disinfection is ideal in high-risk areas, such as neonatal care centers, surgical suites, and isolation rooms/wards. Guidance may be found in ASHRAE handbooks, as well as the Ultraviolet germicidal irradiation handbook (Kowalski 2009).

Notable applications include at the Pentagon, for protection against bioterror agents, at the CDC, for protection against catastrophic spillages of infectious agents, and in the isolation units at Emory University hospital, where Ebola patients, Dr. Kent Brantly and Nancy Writebol, were taken to recover.

HVAC Surface Cleaning

Surface-cleaning UV-C systems provide 24/7 irradiation of HVAC components, to destroy viruses, bacteria, and mold, which settle and thrive on coils, ducts, air filters, and drain pans. UV-C prevents these elements from becoming microbial reservoirs for pathogen growth and subsequent conveyance into airstreams. They also provide first-pass kill ratios of up to 30% for airborne pathogens, with additional benefits of restored cleanliness, heat exchange efficiency, and energy use (ASHRAE 2011- Fencl 2013/2014).

HVAC surface-cleaning was documented in a case study at a neonatal intensive care unit (NICU) at the University of Buffalo Women and Children’s Hospital (Ryan 2014). The study found significant reductions in microbial loading on NICU surfaces to nearly 0 cfu after four months of operation. The study concluded that “decreased HVAC microbial colonization was associated with reduced NICU environment and tracheal microbial colonization. Significant reductions in VAP [ventilator-associated pneumonia] and antibiotic use were also associated with UV-C”.

Summary

Health care leaders are increasingly united in the war against infectious diseases and the repercussions in terms of human lives, lost productivity, health care costs, and overtaxed health care resources. Although intensive efforts are underway in the areas of new medicines, diagnostic procedures, and surveillance systems, the outcome of these efforts is yet unknown, and there will always be additional hurdles including error, negligence, and the ongoing genetic mutations and evolutions of bacteria and viruses.

From a cost perspective, upper-air UV units can cost as little as $2.50 to $3.10 per sq ft of treated space. Air-stream disinfection systems range from $0.60 to $0.80 per cfm, and HVAC surface disinfection systems cost approximately $0.10 to $0.15 per cfm — inexpensive when compared to the damage from pathogens that the industry is working to minimize.

UV-C systems are a cost-effective, proven, and readily available method of addressing all three fronts of the war against infectious diseases. The variety of ways in which UV-C can be applied enables engineers and operators to tailor UV-C installations to meet desired outcomes while working within the reality of budget constraints.

 References

1. (Atkinson 2009). J. Atkinson, et. al. “Annex C - Respiratory droplets,” Natural Ventilation for Infection Control in Health-Care Settings. World Health Organization; 2009. ISBN-13: 978-92-4-154785-7.

2. (Best 2010). E.L. Best, et. al. “The potential for airborne dispersal of Clostridium difficile from symptomatic patients.” Clinical Infectious Diseases, June 1, 2010.

3. (CDC 2013). U.S. Dept. of Health and Human Services, Centers for Disease Control, Antibiotic Resistance Threats in the United States. 2013.

4. (CMS 2014). Centers for Medicare & Medicaid Services (CMS) Webpage for the Value-Based Purchasing Program (http://www.cms.gov/Medicare/Quality-Initiatives-Patient-Assessment-Instruments/hospital-value-based-purchasing/index.html). Accessed October 6, 2014.

5. (Fencl 2013). Fencl, F., “Rightsizing UV-C Lamps for HVAC Applications:  Using ASHRAE Recommendations to Simplify Sizing,” HPAC Engineering, October, 2013. Available at http://bit.ly/1lKJ2jk.

6. (Fencl 2013). F. Fencl. “Illuminating Info: UV-C For HVAC,” Engineered Systems, September, 2013. Available at http://bit.ly/1iygqXH.

7. (Fencl 2014).  F. Fencl. “Maintaining Energy Efficiency with UV.” Filtration & Separation. July/August 2014.

8.  (Fencl 2014). “Dirty Sock Syndrome: What It Is, How to Prevent It.” The Air Conditioning, Heating, Refrigeration News. Online article: http://www.achrnews.com/articles/127583-dirty-sock-syndrome-what-it-is-how-to-prevent-it. September 8, 2014.

9. (First 1999) M.W. First, E.A. Nardell, et. al. “Guidelines for the application of upper-room ultraviolet germicidal irradiation for preventing transmission of airborne contagion – Part 2: Design and operational guidance.” ASHRAE Transactions. 105:869–876.

10. (King 2012). M.F. King, C.J. Noakes, P.A. Sleigh, M.A. Camargo-Valero, “Bioaerosol Deposition in Single and Two-Bed Hospital Rooms: A Numerical and Experimental Study” Building and Environment (2012) is available to download (DOI10.1016/j.buildenv.2012.09.011)

11. (Kowalski 2009). W. Kowalski. Ultraviolet germicidal irradiation handbook. Springer-Verlag, Berlin. 2009.

12. (Magill 2014). S. S. Magill, M.D. PhD. et. al. “Multistate Point-Prevalence Survey of Health Care–Associated Infections.” The New England Journal of Medicine,  March 27, 2014.

13. (Medline 2014). MedLine Plus, a Website of the National Institutes of Health and the National Library of Medicine, http://www.nlm.nih.gov/medlineplus/viralinfections.html. Downloaded October 6, 2014

14. (Memarzadeh 2010).  F. Memarzadeh, et. al. “Applications of ultraviolet germicidal irradiation disinfection in health care facilities: effective adjunct, but not stand-alone technology.” American Journal of Infection Control. June 2010.

15. (Nardell 1999). E.A. Nardell and J.M. Macher. “Chapter 9: Respiratory infections — Transmission and environmental control,” Bioaerosols: Assessment and control. American Conference on Governmental Industrial Hygienists. 1999.

16. (Nardell 2013). E. Nardell et. al. “Upper-room ultraviolet germicidal irradiation (UVGI) for air disinfection: a symposium in print.” Photochemical Photobiology. July-August 2013.

17. (NCSL 2008).  National Conference of State Legislators (NCSL). Medicare Nonpayment for Medical Errors. August 2008. Downloaded from http://www.ncsl.org/Portals/1/documents/health/MCHAC.pdf on October 7, 2014.

18. (NIOSH 2009). The National Institute for Occupational Safety and Health (NIOSH). Environmental Control for Tuberculosis: Basic Upper-Room Ultraviolet Germicidal Irradiation Guidelines for Health care Settings. DHHS (NIOSH) Publication Number 2009-105. 2009.

19.  (PCAST 2014). President’s Council of Advisors on Science and Technology. Report to the President on Combating Antibiotic Resistance, September 2014.

20. (Rau 2014). J. Rau for National Public Radio. “Medicare Penalizes Nearly 1,500 Hospitals for Poor Quality Scores. Morning Edition. November 15, 2014.

21. (Ryan 2011). R.M. Ryan et. al. “Effect of enhanced ultraviolet germicidal irradiation in the heating ventilation and air conditioning system on ventilator-associated pneumonia in a neonatal intensive care unit.” Journal of Perinatology, September 2011.

22. (WHO 2014-2). World Health Organization. Unprecedented number of medical staff infected with Ebola. http://www.who.int/mediacentre/news/ebola/25-august-2014/en/. Downloaded October 6, 2014. (WHO 2014). World Health Organization. Antimicrobial resistance: global report on surveillance 2014. April 2014. ISBN: 978 92 4 156474 8.

SIDEBAR

HAI’s and Medicare

The prevalence and costliness of hospital-acquired infections has been noted by Medicare administrators. As a result, two Medicare payment adjustments have been established to increase pressure on hospitals to reduce HAIs through preventive measures.

The first was established in 2006 with the Deficit Reduction Act (DRA), which contained language such that after “October 1, 2008, hospitals will not receive additional payment for cases in which one of the selected conditions were not present on admission.” (NCSL 2008). This began to establish tracking and nonpayment of selected HAIs, in collaboration with the CDC. The program was developed with a plan to increase in stringency over time.

The second was established in 2013, when the Centers for Medicare & Medicaid Services (CMS) established the Hospital Value-Based Purchasing Program, which pays more to hospitals with performance indicators above a defined threshold which is considered “good” and less to hospitals below the threshold (CMS 2014). Under the program, payment adjustments are established using a methodology that includes “hospital acquired conditions,” some of which are selected hospital-acquired infections. 1,451 hospitals began a period of receiving reduced payments for each Medicaid patient they treat for one year beginning October 1, 2014. Bonuses in payments to 1,231 hospitals will also occur during the same time period (Rau 2014). Increasing stringency over time also is expected in the program.

JANUARY 1, 2015

Forrest Fencl

Ultraviolet Germicidal Irradiation: Current Best Practices

"Ultraviolet germicidal irradiation (UVGI) is the use of ultraviolet (UV) energy (electromagnetic radiation with a wavelength shorter than that of visible light) to kill or inactivate viral, bacterial, and fungal species. The UV spectrum is commonly divided into UVA (wavelengths of 400 nm to 315 nm), UVB (315 nm to 280 nm), and UVC (280 nm to 200 nm). The entire UV spectrum can kill or inactivate many microorganisms, but UVC energy provides the most germicidal effect, with 265 nm being the optimum wavelength."

"Scenario: Workers using ultraviolet (UV) lamps may have skin or eye exposure to stray ultraviolet light emissions. Such workers need to know acceptable levels of irradiance (measured in milliwatts per square centimeter (mW/cm2)) and how to monitor for stray radiation. The exposed UV dose would be in units of millijoules per square centimeter (mJ/cm2). [In most cases, the UV lamp would be a low pressure mercury lamp, so almost all the UV light is at 253.7 nanometers (nm).]"

"The ionizing radiation standard covers alpha, beta, gamma, and X-rays; neutrons; high-speed electrons and protons; and other atomic particles; but does not include sound or radio waves, or visible, infrared, or ultraviolet light. Therefore, there are no OSHA-mandated employee exposure limits to ultraviolet radiation."