methods and effects of mechanical ventilation, ultraviolet

Methods and Effects of Mechanical Ventilation, Ultraviolet Light and Bipolar Ionization on Airborne and Surface Borne Pathogens

Evolution Energy Partners - 2020

Prepared by:Robert E. Holdsworth, MBB, CEM, CLEP, CEA, CLMC, LEED AP O&MVice President, Engineering

Copyright 2020 by Evolution Energy Partners LLC. All rights reserved.

Suggested citation: Evolution Energy Partners, 2020. Methods and Effects of Mechanical Ventilation, Ultraviolet Light and Bipolar Ionization on Airborne and Surface Borne Pathogens (Coronavirus). Exton, PA.

Evolution Energy Partners LLC1 E Uwchlan Ave,North Point Office BuildingExton, PA 193411.877.280.4655www.evolutionep.com

Introduction

“Changes to building operations, including the operation of heating, ventilating, and air conditioning systems can reduce airborne exposure to SARS-CoV-2”ASHRAE – Position on Airborne transmission of SARS-CoV-2

The advent of SARS-CoV-2, the strain of the coronavirus that causes COVID-19, has changed the way building owners and operators must look at treating the air in their buildings.

In reaction to the coronavirus pandemic, building owners and operators must now make certain they are doing everything they can to improve indoor air quality (IAQ) and suppress potential spread of the virus.

RecommendationsThroughout the article, we will discuss the following methods to ensure a safe indoor environment. . 1. Modify HVAC Operations

Includes increasing outside air, upgrading to higher MERV level filters, modifying schedules, etc.

2. Ultraviolet Germicidal Irradiation UVGI Includes at the coils, upper room, mobile, etc.

3. Bipolar Ionization Includes at the coils, in-duct, localized at fan inlet, etc.

Of all illnesses are caused by indoor air contaminates

Of our time is spent indoors

Indoor air quality is 2 to 5 times lower than outside air quality

50% 90%

Up to 5x

Indoor air quality is one of the top 5 most urgent risks for quality health

Top #5

Evolution Energy Partners - Methods and Effects of Mechanical Ventilation, Ultraviolet Light and Bipolar Ionization on Airborne and Surface Borne Pathogens- MAY 2020 (Coronavirus)

U.S. EPA

U.S. EPA

U.S. EPA

U.S. EPA

“Changes to building operations, including the operation of heating, ventilating, and air conditioning systems can reduce airborne exposure to SARS-CoV-2”ASHRAE – Position on Airborne transmission of SARS-CoV-2

Understanding the CoronavirusCOVID-19: SARS-CoV-2 is a coronavirus strain that causes COVID-19.

Particle SizeParticle sizes are measured in microns (1/1000 millimeter). SARS-CoV-2 is 0.125 microns, meaning that it is approximately 1/100 the size of a dust particle. The virus travels on respiratory droplets which are greater than 5 microns

Travel DistanceThe virus can typically travel 3 to 6 feet (further if propelled).

Survival TimeIt is believed that the virus can survive several hours in the air and several days on certain surfaces.

Recent CDC guidance indicates lowers transmissibility from surfaces.

The Johns Hopkins School of Medicine indicates there are many different kinds of coronaviruses. Some strains of the virus can cause colds or other mild respiratory (nose, throat, lung) illnesses, whereas others can cause more serious diseases, including severe acute respiratory syndrome (SARS) and Middle East respiratolry syndrome (MERS). Much is still unknown about the virus, but COVID-19 seems to spread faster than SARS while causing less severe illness.


HVAC Systems and Indoor Air QualityHow does your HVAC system relate to indoor air quality?

Heating, Ventilation, & Air Conditioning (HVAC)The goal of HVAC is to provide thermal comfort and acceptable indoor air quality. HVAC is an important part of a building’s structure because it regulates the condition of indoor air with respect to temperature, humidity, and minimum required outside air. Ventilation includes both the exchange of air to the outside as well as circulation of air within the building. Ventilation and filtration are two of the most important factors for maintaining indoor air quality in buildings.

Poor Indoor Air Quality (IAQ)Poor IAQ can lead to viral infections, bacterial infections, asthma, allergies, nausea, headaches, dizziness, and other maladies.

HVAC Systems and CoronavirusHVAC systems are critical components in suppressing the spread of the coronavirus from one

building occupant to another and causing potentially overwhelming spread of the disease.

The following information covers the latest HVAC operations recommendations as well as

supplemental technologies designed to disinfect indoor air and surfaces in tandem with the

HVAC system.


Operational ChangesUsing Dilution to Combat the Spread of Coronavirus

Outside AirMaintaining minimum recommended air exchanges (exhausting inside air and replacing it with fresh outside air) per hour is critical to maintain proper indoor air quality. However, the more outside air brought into a building means the more air that needs to be conditioned (heated or cooled) and the more money spent on electricity, gas, steam, maintenance, etc.

Traditionally, building operators ensure adequate IAQ by mixing indoor and outdoor air before recirculating it through the building. They also use demand controlled ventilation to measure CO2 levels in interior spaces and energy recovery systems to reuse sensible and latent heat, etc. Mixing indoor and outdoor air reduces the amount of outdoor air needed, reducing energy usage.

ASHRAE Guidance Dilution is the process of decreasing the concentrations of indoor contaminants by diluting interior

spaces with outside air. ASHRAE released the following recommendations regarding dilution

ventilation and COVID-19.

Increase Outdoor Air Ventilation:• Open outdoor air dampers to 100% (as indoor and outdoor conditions permit)

• Disable demand control ventilation and energy recovering systems

• Enable outside air economizer mode and increase minimum outside air settings

• Maintain relative humidity between 40% and 60%

• Check airflow to larger areas such as large office areas, conference rooms, lobbies

• Maintain proper pressurization (both building pressure and toilet exhaust)

• Air flush the building two hours before and post occupancy every day. This includes operating

the exhaust fans as well as opening the outside air dampers.


Operational ChangesIncreasing Filtration to Combat the Spread of Coronavirus

Air FiltrationAir filtration is the process of running outside air

and recirculated indoor air through filters within

the HVAC system.

Filter EfficiencyFilter efficiency, a filter’s ability to capture

particulate matter, is determined by its MERV

rating. Because the SARS-CoV-2 virus is 0.125

microns, we will focus on filter efficiency at the

0.03 to 1.0 microns level.

As indicated in the chart to the right, a MERV-8

filter (the minimum standard filter for commercial

office buildings) will trap less than 20% of air

particles size 0.03 to 1.0 microns. Whereas, a

MERV-16 filter, the common minimum standard

used by hospitals, will capture 95% or more.

ASHRAE Guidance• Increase HVAC AHU filtration to MERV-13 or

highest level achievable.

• Seal the filters to minimize bypass air.


Challenges and Potential IssuesAlthough upgrading to a higher MERV level will almost always help to improve and maintain general

overall IAQ, it is by no means a solution unto itself as there are additional considerations to factor:

• AHU filters are not in the occupied and potentially contaminated spaces of the building and can

only filter outside and recirculated air that gets back to the AHU.

• Even higher MERV filters can not filter out all virus-sized particles (as noted in the table above).

• Higher MERV filters can cause system pressure drop, require more frequent filter changes, may

not fit the current AHU’s filter rack, and may overwhelm fan capacity.

*The Federation of European Heating, Ventilation and Air Conditioning Associations recommends

“No use of recirculation” only 100% outside air.

Ultraviolet LightDisinfecting Surfaces and the Air

GUV and UVGIGermicidal UV (GUV) refers to using short-wave ultraviolet radiant energy to inactivate viral,

bacterial, and fungal organisms so they are unable to replicate and potentially cause disease.

When the process is applied in a given location, it is generally referred to as ultraviolet germicidal

irradiation (UVGI).


Three Primary UVGI ApplicationsAlthough UVGI can be applied in several different manners, we will focus on the three most

prevalent and applicable approaches to using UVGI.

Air Handling Unit (AHU) Coils

Upper Room UVGI (Upper Air)

Portable/Mobile “Robot” UGVI

UGVI for AHU Coil CleaningDisinfecting Surfaces and the Air

Air Handling Unit (AHU) CoilsIn brief, AHU’s move supply air via large fans. The air is pushed by the fans through the filter and

across the coils which heat or cool the air before it enters the ductwork. The air is then dispersed

throughout the building. Inside the coil is a hot or cold fluid, typically heated or chilled water,

refrigerant or steam, that warms or cools the air as it passes across the coils.

During normal operation, condensation that forms on the coils and the fins inside the system

can become polluted with microfilm (microorganisms such as fungi, bacteria, viruses, etc.). This

buildup can lead to indoor air contamination as well as lost system performance due to lost heat

transfer capacity and increased energy consumption needed to continue to move air through the

system.


UVGI for Coil CleaningUGVI is an alternative or adjunct to mechanical

and chemical coil cleaning options. UVGI systems

are typically installed near the primary AC coil

and proactively remove bio-films. Most

microorganisms that the UV light is concentrated

on or that pass within the UV bulb’s line of sight,

will be destroyed.

Benefits Limitations

• Proven as an effective inactivation method

for mold, bacteria, and viruses on the coils.

• Maintains system efficiency and airflow,

savings energy and money.

• Will not damage coils unlike other chemical

cleaning treatments.

• UV can only “kill” what it “sees”. The coil

depth and dry side will not be disinfected.

• Exposure to UVGI light can cause serious

harm to the eyes and skin.

• Poor disinfection performance in low

temperatures, high humidity, or when dust

and film build up on the UVGI bulbs.

• Efficacy decreases over time as the bulbs

lose light output.

Upper Room UVGI CleaningDisinfecting Surfaces and the Air

Upper Room UVGIIn an upper room UVGI system,

UV lamps are installed into fixtures

suspended from a ceiling or

mounted on a wall. Fixtures are

shielded with louvers or bafflers in

order to block radiation below the

horizontal plane of the fixtures.

The UV lights create, in the upper

portion of the room, a germicidal

zone where bacilli are killed (see

picture to right).


Careful and proper installation is critical to ensure that the occupants in the lower portion of the

room are not exposed. Good air mixing is needed to transport the air (and thereby the bacilli) to

the upper portion of the room. Disinfection is achieved through the rapid dilution of contaminated

lower room air with clean irradiated upper room air.


• Tested in a hospital-based field study

to be effective at killing or deactivating

tuberculosis bacteria and is presumed

effective against other bacteria and viruses

such as SARS-CoV-2.

• Low risk of exposure to UV light when

properly installed.

• Provides rapid dilution of the contaminated

air at breathing level.

• Can be implemented in just high-risk rooms

and areas or installed more expansively

• UV can only “kill” what it “sees”. Any area not

in line of sight will be unaffected.

• Needs to be implemented in every occupied

space to ensure expansive coverage to

mitigate spread.

• UV needs time to kill pathogens. Ventilation

rates exceeding 6 air changes/hour

reduces effectiveness because radiation

time is too short.

• Sufficient air mixing is essential.

• Efficacy decreases as humidity rises and as

lamps loose light output over time.

Portable UGVI Cleaning Disinfecting Surfaces and the Air

Mobile UVGI Room Sterilization Mobile or “Robot” UVGI is essentially multiple

UVGI lamps affixed to a mobile unit (either

pushed on wheels or driven by pre-programmed

robotics). The robotic units drive through

the operational environment completely

autonomously, disinfecting surfaces that are in

direct line of sight of the UV light.

UVGI robots have integrated functional safety

and navigation software to ensure a reliable

localization and the avoidance of people and

obstacles. The units have stainless-steel housing

with an antimicrobial coating to prevent the

transmission of germs by the robots themselves.

When finished, the unit returns to its charging

station and is ready for another sterilization run

after re-charging.



• Relatively quick sterilization (approximately

10 to 20 minutes for a regular size hospital

or hotel room).

• Can be directed to high risk areas only or

programmed to disinfect all areas.

• Low to moderate risk of direct or over-

exposure to UV light due to the unit’s safety

software.

• UV can only “kill” what it ”sees”.

• Does not provide continuous disinfection

because the units can ONLY be used during

unoccupied times.

• Some risk of UV exposure if safety protocols

are not adhered to.

• Multiple units would be needed to sanitize

all areas of a building in a reasonable

amount of time.

• UV lamps loose light output and efficacy

over time. Regular replacement is essential.

Biopolar Ionization What it is and how it works

About Biopolar IonizationBipolar Ionization (BPI) technology releases negatively and positively charged atoms that attach

to and deactivate harmful substances like viruses, bacteria, mold, allergens, and volatile organic

compounds (VOC’s). Ionization is considered nature’s air cleaning process and the positively and

negatively charged ions generated by bipolar ionization systems mimic the process that occurs in

nature. The technology first arrived In the US in the 1970s as a tool to control pathogens in food

manufacturing.

Types of Biopolar IonizationThe two primary methods of generating bipolar ions are Corona Discharge and Needlepoint. Corona

tube technology utilizes a dielectric such as glass, ceramic or composite and higher voltage at 12.07

eV to complete the electrical circuit and create bipolar ions. Needlepoint BPI utilizes lower voltage

A/C current to energize carbon fiber “needles”, creating positive and negative ions based on the

alternating current.


How Does it Work?Step 1: The BPI system in an AHU is placed

between the blower fan and the dry side of

the coils or at the fan inlet in VAVs, FCUs,

PTACs, WSHPs, etc.

Step 2: The system produces millions

of positively and negatively charged

oxygen ions.

Step 3: The charged ions continuously

flood the occupied spaces served by the

HVAC system. The oppositely charged ions

seek out particulate matter and trigger cell

oxidation at the molecular level, rendering viruses and bacteria inert while also destroying mold, allergens, VOC’s, etc.

Step 4: Other oppositely charged airborne particles conglomerate and grow large enough to be

carried by the return air to the AHU media filter and are thusly removed from the air flow.

BPI Research and Testing Findings regarding BPI’s impact on IAQ

Laboratory and Real World Testing of BPIBipolar ionization has been well tested by renowned testing laboratories and universities such

as ETL, EMSL, ATL, ATS, University of Syracuse, National Research Council of Canada, University

of Cincinnati, and several others. There are a significant number of case studies backed by

independent 3rd party air quality testing firms done for organizations employing the technology

such as Mayo Clinic, Seattle Children’s Hospital, Johns Hopkins Hospital, NYU Langone Medical

Center, University of Maryland, Valencia College, etc. The technology is used in facilities across

multiple industries including Google, The National Football League, Hilton, Cushman & Wakefield,

and even the White House.


BPI Test ResultsThere are many 3rd party IAQ verifications of the efficacy of BPI

in reducing VOC’s, allergens, mold spores, and other particulate

matter in the occupied spaces of buildings as well as its ability

to clean all sides and full depth of HVAC coils. However, similar

to how Upper Room UVGI testing in the “real world” is limited

to only one hospital-based field study on tuberculosis spread,

human-based field studies involving BPI and its effectiveness

against viruses like SARS-CoV-2 are not available. For this

reason, we will only focus on reputable laboratory study results.

The below chart shows results of tests performed on various

pathogens across different manufacturers’ BPI systems.

*Norovirus is not an enveloped virus and is thus harder to “kill” than SARS-CoV-2 which is an enveloped virus.

** The SARS-CoV-2 virus will be available to labs to test in June 2020 but the results of BPI’s effectiveness against other corona viruses is promising.

Additional Related BPI Information Findings regarding MERV level improvement

Improvement in MERV FiltrationResearch and testing has determined that the addition of BPI to the HVAC system increases filter

efficiency by 4 to 5 MERV levels.


“The combination of

the NPBI with MERV 12

has the same efficiency

as a MERV 16 filter for

size bin E2 (PM2.5), i.e.

a filter eff. ≥ 95%,”

- National Research Council of Canada

Improvement in Facepiece Respirator and Surgical Mask Filtering Efficiency Research and testing has

determined that the addition of BPI

to the indoor environment increases

N95 facepiece respirator and

surgical mask efficiency (48.4%, and

194% respectively).

BPI Benefits and Limitations Economic and health benefits

Economic BenefitsBefore listing the health related IAQ benefits of BPI, it is important to also note the potential

economic benefits. ASHRAE established Standard 62.1 - Ventilation for Acceptable Indoor Air

Quality. This standard governs ventilation rates and ASHRAE offers two compliance paths to

meet ventilation requirements; the Ventilation Rate Procedure (aka VRP method) and the Indoor

Air Quality Procedure (aka IAQ Procedure). Under the IAQ Procedure, the minimum required

rate of outdoor air (OA) can be reduced dramatically through engineered solutions (i.e. BPI) that

sufficiently reduce contaminant concentration. This reduction in OA intake and the improvement in

heat transfer, etc.. can lead to a significant reduction in energy consumption and costs.

Economic Benefits include:• 15% reduction in size of HVAC system for new construction.

• 20-40% reduction in ongoing HVAC energy expenditures (electric/gas/steam).

• Extended life of HVAC filters and equipment.


Benefits• Laboratory tested to be effective at killing or deactivating a myriad of viruses and bacteria

and is presumed highly effective against SARS-CoV-2.

• Validated to “hunt and kill” allergens, spores, VOC’s, and other particulates in the air and

on the surfaces within all spaces of the building served by the HVAC system. Presumed to

have the same effectiveness against pathogens in the indoor environment.

• No health risk as long as ozone is not created in the ionization process.

• Improves HVAC filter and facemask filtration efficiency.

• Saves energy and related costs and reduces GHG emissions.

Limitations• Some ionization technology produces ozone which is harmful to the lungs. BPI technology

must be UL 2998 Certified as “ozone free” to safely use.

• Although the body of reputable testing and studies regarding the efficacy of BPI against

viruses is significant, field testing under real-world infection conditions would be even

more conclusive validation.

Comparison of ApproachesIAQ method comparison


Cost Comparison(Costs vary by manufacturer and by application and are only one consideration amongst several in

determining necessity).

A Blueprint for Action The time is now

As stated, the advent of COVID-19 has fundamentally changed the way we need to look at treating

the air in our buildings. In reaction to the pandemic, building owners and operators must make

certain they are doing everything they can to improve indoor air quality and help suppress the

potential spread of the virus.

This article gives us a blueprint for action. The know-how to act decisively to implement the

solutions outlined. Doing so will ensure the best possible indoor air quality with the most effective

methods to combat the spread of SARS-CoV-2.

What can you do today?• Upgrade your HVAC filters to a higher MERV level and open your building’s outdoor air dampers

to 100%.

• Disable your demand control ventilation and energy recovery systems and maintain proper

building pressure.

• Make sure the relative humidity in your building is between 40% and 60% and consistently air

flush the building two hours before and post occupancy every day.

The aforementioned operational changes will go a long way in combating airborne pathogens

through dilution and filtration but there is more to be done. UV germicidal irradiation and bipolar

ionization have the ability to not just dilute the concentration of pathogens, but also destroy them.

Implementing Bipolar Ionization or Upper Room UGVI throughout your building will help ensure the

coronavirus is rendered inactive and harmless before it has the ability to infect more people.


The time is now to follow the blueprint.For more information on the methods and operational changes mentioned in this article,

contact the EEP team at [email protected] or 877.280.4655.

About EEPEvolution Energy Partners (EEP) is a full-service energy management, engineering, and

consulting firm offering best-in-class sustainability, energy efficiency, data analytics, and

procurement solutions.

ReferencesList of references

US EPA,ORD. (2017, November 2). Indoor Air Quality | US EPA. Retrieved May 24, 2020, from US EPA website: https://www.epa.gov/report-environment/indoor-air-quality

ASHRAE Position Document on Filtration and Air Cleaning. (n.d.). Retrieved from https://www.ashrae.org/file%20library/about/position%20documents/filtration-and-air-cleaning-pd.pdf Filtration / Disinfection. (2020). Retrieved May 24, 2020, from Ashrae.org website: https://www.ashrae.org/technical-resources/filtration-disinfection

Environmental control for tuberculosis: basic upper-room ultraviolet germicidal irradiation guidelines for healthcare settings. (2009). https://doi.org/10.26616/nioshpub2009105

Research aims to measure benefits of using UV light as an HVAC coil cleaner | Penn State University. (2017). Retrieved May 24, 2020, from Psu.edu website: https://news.psu.edu/story/469222/2017/05/23/research/research-aims-measure-benefits-using-uv-light-hvac-coil-cleaner

Filtration and Air-Cleaning Systems to Protect Building Environments from Airborne Chemical, Biological, or Radiological Attacks Department of Health and Human Services Centers for Disease Control and Prevention National Institute for Occupational Safety and Health. (2003). Retrieved from https://www.cdc.gov/niosh/docs/2003-136/pdfs/2003-136.pdf

COVID-19 and the Risk from Recirculated Air in Buildings | Green Building Law Update. (2020, April 30). Retrieved May 24, 2020, from Green Building Law Update website: https://www.greenbuildinglawupdate.com/2020/04/articles/environmental/covid-19-and-the-risk-from-recirculated-air-in-buildings/

ASHRAE Offers COVID-19 Building Readiness/Reopening Guidance. (2020). Retrieved May 24, 2020, from Ashrae.org website: https://www.ashrae.org/about/news/2020/ashrae-offers-covid-19-building-readiness-reopening-guidance

ASHRAE Issues Statements on Relationship Between COVID-19 and HVAC in Buildings. (2020). Retrieved May 24, 2020, from Ashrae.org website: https://www.ashrae.org/about/news/2020/ashrae-issues-statements-on-relationship-between-covid-19-and-hvac-in-buildings

Hagbom, M., Nordgren, J., Nybom, R., Hedlund, K.-O., Wigzell, H., & Svensson, L. (2015). Ionizing air affects influenza virus infectivity and prevents airborne-transmission. Scientific Reports, 5(1). https://doi.org/10.1038/srep11431

Mobile disinfection robot - MetraLabs. (2020, April 21). Retrieved May 25, 2020, from Metralabs.com website: https://www.metralabs.com/en/uv-c-disinfection-robot/ Mphaphlele, M., Dharmadhikari, A. S., Jensen, P. A., Rudnick, S. N., van Reenen, T. H., Pagano, M. A., … Nardell, E. A. (2015). Institutional Tuberculosis Transmission. Controlled Trial of Upper Room Ultraviolet Air Disinfection: A Basis for New Dosing Guidelines. American Journal of Respiratory and Critical Care Medicine, 192(4), 477–484. https://doi.org/10.1164/rccm.201501-0060oc

Hyun, J., Lee, S.-G., & Hwang, J. (2017). Application of corona discharge-generated air ions for filtration of aerosolized virus and inactivation of filtered virus. Journal of Aerosol Science, 107, 31–40. https://doi.org/10.1016/j.jaerosci.2017.02.004

US EPA,OAR. (2014, July 31). Building Air Quality Guide: A Guide for Building Owners and Facility Managers | US EPA. Retrieved May 24, 2020, from US EPA website: https://www.epa.gov/indoor-air-quality-iaq/building-air-quality-guide-guide-building-owners-and-facility-managers

US EPA,OAR. (2014, August 28). An Office Building Occupants Guide to Indoor Air Quality | US EPA. Retrieved May 24, 2020, from US EPA website: https://www.epa.gov/indoor-air-quality-iaq/office-building-occupants-guide-indoor-air-quality


ReferencesList of References

GPS Library - GPS. (2020, May 20). Retrieved May 24, 2020, from GPS website: https://globalplasmasolutions.com/gps-library/ US EPA,OAR. (2014, August 26). Indoor Air Pollution: An Introduction for Health Professionals | US EPA. Retrieved May 24, 2020, from US EPA website: https://www.epa.gov/indoor-air-quality-iaq/indoor-air-pollution-introduction-health-professionals

Plasma Air. (2020). Retrieved May 24, 2020, from Plasma-air.com website: https://www.plasma-air.com/resources/574 ASHRAE Standards. (2020). Retrieved May 24, 2020, from Ashrae.org website: https://www.ashrae.org/technical-resources/standards-and-guidelines/read-only-versions-of-ashrae-standards

Sherman, M. (n.d.). All Rights reserved. Retrieved from https://www.ashrae.org/File%20Library/Technical%20Resources/Standards%20and%20Guidelines/Standards%20Intepretations/IC-62.1-2016-2.pdf

Technology - AtmosAir Solutions. (2016, February 8). Retrieved May 24, 2020, from AtmosAir Solutions website: https://atmosair.com/technology/ Sustainability; Health and Safety; Ultraviolet Light; Bipolar Ionization. (2020, April). Retrieved May 24, 2020, from HPAC Engineering website: https://www.hpac.com/covid-19/article/21128399/sustainability-health-and-safety-ultraviolet-light-bipolar-ionization

Nardell, E. A., Bucher, S. J., Brickner, P. W., Wang, C., Vincent, R. L., Becan-McBride, K., … Wright, J. D. (2008). Safety of Upper-Room Ultraviolet Germicidal Air Disinfection for Room Occupants: Results from the Tuberculosis Ultraviolet Shelter Study. Public Health Reports, 123(1), 52–60. https://doi.org/10.1177/003335490812300108

Miller, S. L. (2015). Upper Room Germicidal Ultraviolet Systems for Air Disinfection Are Ready for Wide Implementation. American Journal of Respiratory and Critical Care Medicine, 192(4), 407–409. https://doi.org/10.1164/rccm.201505-0927ed

Anderson, D. J., Gergen, M. F., Smathers, E., Sexton, D. J., Chen, L. F., Weber, D. J., & Rutala, W. A. (2013). Decontamination of Targeted Pathogens from Patient Rooms Using an Automated Ultraviolet-C-Emitting Device. Infection Control & Hospital Epidemiology, 34(5), 466–471. https://doi.org/10.1086/670215

UV Light Can Aid Hospitals’ Fight to Wipe Out Drug-Resistant Superbugs | Duke Health. (2017). Retrieved May 25, 2020, from Dukehealth.org website: https://corporate.dukehealth.org/news-listing/uv-light-can-aid-hospitals%E2%80%99-fight-wipe-out-drug-resistant-superbugs

Kowalski, W. J. (2009, July 9). Upper Room UV Systems. Retrieved May 24, 2020, from ResearchGate website: https://www.researchgate.net/publication/303929036_Upper_Room_UV_Systems


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