Collingwood Hospital first in Canada to have self-sanitizing Patient Rooms

BradfordToday reports on Collingwood hospital first in Canada to have self-sanitizing patient rooms

By Erika Engel

UV light, ozonated water, copper-infused surfaces, and titanium dioxide have all come together to make Canada’s first self-sanitizing patient room and bathroom at Collingwood General and Marine Hospital.

There’s copper in them there walls.

Collingwood General and Marine Hospital (CGMH) has opened the first of five self-sanitizing rooms, and will be the first hospital in Canada to use copper-infused panels on the walls in its hallways and patient rooms to prevent bacteria growth. 

Copper is naturally anti-bacterial and copper surfaces prevent bacteria growth.

The made-over patient room is located on the medical floor, and it’s packed with the latest technology in sanitization from the UV lights on the ceiling to the copper-infused toilet seat in the bathroom.

Norah Holder, CGMH president and CEO, said Collingwood’s hospital is the first in Canada to combine all of the self-sanitizing elements into one patient room and bathroom.

The bacteria-fighting technology includes copper-infused high touch surfaces like the bed rail, the door handles and pulls, the toilet seat, and the toilet handle. There’s UV lights on the ceiling that run on a disinfecting cycle when the patient is in the bathroom or outside the room, and there are plastic panels on the bottom half of the wall coated in titanium dioxide, which reacts with UV light to kill bacteria. In the bathroom a no-touch sink is engineered to prevent splashing and delivers ozonated water. Ozone has been proven to have an oxidizing, antiseptic, and germicidal effect. More UV lights in the bathroom activate after every use, bathing the room in UV light, which destroys the cell wall of bacteria, spores, and fungus.

The next rooms completed will have copper-infused panels covering the bottom half of the walls.

According to John Widdis, manager of operations and maintenance at CGMH, Collingwood will be the first hospital to use these panels as they are new to the market.

He said the technology doesn’t take away the need for cleaning, rather it mitigates the bacteria load on surfaces in the room. Rooms will still be cleaned once every 24-hours at minimum.

Swab tests showed bacteria counts in the range of 7,000 to 8,000 in a typical room. After the self-sanitizing technology was installed, the same swab tests are showing bacteria counts in the range of 30-50.

Dr. Michael Lisi, chief of staff at CGMH, said he’s “thrilled” to see CGMH become a leader in infection control technology locally, provincially, and nationally.

“This technology is really going to provide benefits in terms of patient safety, and safety of staff and visitors,” said Lisi. “I can have faith in such technology to provide the best level of care for our patients. This will help with improving outcomes and getting patients back to their families safely.”

CGMH has been testing some of the technology in its emergency department already. Widdis said he wanted to start with the one public washroom in the department once he watched the constant flow of people using the facility. The bathroom was cleaned once every 1.5 hours, but in between there would be eight or so people using it.

When the emergency department was renovated in 2016, Widdis had an ozone sink and some other self-sanitizing technology installed in the bathroom. Staff sinks were also replaced with models that delivered ozone water.

Since then, the hospital has seen the lowest rates of C-Difficile occurrences in recent history.

Lisi said the rates are the lowest they’ve been in six years. Widdis said the rates went down almost as soon as the changes were made in the emergency department.

“[Infection control] is a very significant component,” said Lisi. “It’s something all hospitals struggle with … C-Difficile can be life ending in elderly and those whose immune systems are not strong enough.”

Widdis has been at CGMH for 29 years and he’s seen hospitals and researchers work to battle hospital acquired infection rates over the course of his career.

In the beginning, said Widdis, it was done with chemicals, later it was bleach and hydrogen peroxide on surfaces. Before the UV lights, copper infused materials, and ozone water sinks, the last innovation was a “bomb” that would vaporize hydrogen peroxide to sanitize surfaces.

“We still use some of them,” said Widdis, adding the chemicals have moved to more earth-friendly compounds. “These are just more weapons we use in our fight against hospital acquired infections.”

The technology now installed on the medical floor will also continue to work against mutating strains of bacteria.

Widdis said staff decided to start installing the technology on the medical floor because it’s where patients would be isolated in cases of infection.

“If we have an outbreak, which we haven’t in years, this is the floor where we run into the most trouble,” said Widdis.

Work is continuing to outfit four more patient rooms and renovate hallways to include fresh paint and copper-infused panels on the walls. There are also plans in the works to outfit all hospital bathrooms with copper-infused toilet seats, high touch areas, ozone sinks and UV light.

For rooms not equipped with UV lights yet, the hospital has two portable towers with UV lights that can be used to disinfect any room.

Holder is looking forward to using this and even newer self-sanitizing technology in the future hospital build.

The CGMH foundation raised $1 million for the project through the Tree of Life campaign held at Christmas and other initiatives.

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Root Cause of the Odor Generated by Germicidal UV Disinfection with Mobile Units

Root Cause of the Odor Generated by Germicidal UV Disinfection with Mobile Units

By Normand Brais, P.Eng., M.A.Sc., Ph.D. and Benoit Despatis, Eng. ASHRAE Member

INTRODUCTION

It has been often noticed by many users over the years that whenever a germicidal UV surface disinfection is performed in a room, there is almost always a strange odor left afterward. It is not the smell of ozone, which can be easily identified and measured. It is more like a slightly pungent smell similar to rotten eggs or burnt hair. It is actually easier to recognize the smell than to describe it. Up to now, no satisfactory explanation as to the origin of this peculiar odor has been provided.  Several working hypothesis have been explored to explain this awkward phenomena:

1) Off-gassing of wall surfaces such as paint or other volatile materials.

2) UV lamps end caps glue off-gassing.

3) UV lamps connectors or end rubber boots overheating.

4) Interaction of UV with airborne and surface-borne dust.

After several tests and experiments, the first three hypotheses were quickly ruled out as a potential root cause. Off-gassing of paint was eliminated after testing in a bare metal aluminum enclosure and witnessing the same odor.

The UV lamps end caps were completely removed and all the glue removed with no effect. The same was done for the lamps connectors and also showed no impact on the odor. However, while we were performing these tests, it was noticed that when the disinfection cycles were repeated several times in the same enclosure, the perceived odor level after each cycle seemed to be diminishing. This was the hint that leads us to focus our attention on the presence of dust particles in the air, what these particles consist of, and how UV can potentially alter them into perceptible odorous compounds.

COMPOSITION OF AIRBORNE DUST

Airborne dust in homes, offices, and other human environments typically contains up to 80% of dead human skin and squamous hair, the rest consists of small amounts of pollen, textile fibers, paper fibers, minerals from outdoor soil, and many other micron size materials which may be found in the local environment1,2. In a typical indoor environment, the airborne dust volumetric load is somewhere between 100 and 10,000 μg/m3 (0.000044 to 0.0044 grain/ft3) order of magnitude. The dust load depends upon the occupancy rate, type of human activity, air filtration system efficiency, etc. It is worth noting that the maximum acceptable ASHRAE level for total dust is 10,000 μg/m3 (0.0044 grain/ft3) and 3,000 μg/m3 (0.0013 grain/ft3) for PM10.

Since airborne dust is essentially dead human skin and squamous hair pieces, it is worth taking a closer look at the fundamental material they are made of. The main constituent of human skin is a molecular group called keratin. Keratin is a family of fibrous structural proteins. Keratin is the key structural material making up the outer layer of human skin. It is also the key structural component of hair and nails. Keratin monomers assemble into bundles to form intermediate filaments, which are tough and insoluble. Keratins encloses large amounts of the sulfur-containing amino acid cysteine, required for the disulfide bridges that confer additional strength and rigidity by permanent, thermally stable crosslinking; a role sulfur bridges also play in vulcanized rubber. Human hair is approximately 14% cysteine. Cysteine3 is an amino acid with the chemical formula HO2CCH(NH2)CH2SH. The pungent smell of burning hair and rubber is due to the sulfur by-products. The average composition of human hair consists of 45.2 % carbon, 27.9% oxygen, 6.6% hydrogen, 15.1% nitrogen and 5.2% sulphur.4

INTERACTION OF UVC WITH KERATIN AND CYSTEINE

When high energy UV-C light photons hit a keratin/cysteine molecule, they have enough power to break their internal chemical bonds and shatter them into many smaller molecules. The energy of germicidal UV photons at 254 nm wavelength is 470 kJ/mole, a value greater than the energy of chemical bonds listed in Table 1. It is therefore quite clear that proteomic molecules such as keratin and cysteine can be broken up by germicidal UV irradiation but not by visible light, for which the average wavelength is 550 nm, and the maximum photon energy only 217 kJ/mol.

 

Table 1. Chemical Bonds Strength5

Chemical Bond

Chemical Bond Average Energy
(kJ/mol)

C – C

347

C – H

413

C – N

305

C – O

358

C – S

259

N – H

391

Therefore, some of the chemical bonds between carbon atoms and hydrogen, nitrogen, oxygen and sulfur atoms will be broken by germicidal ultraviolet photons. Some of the resulting broken pieces of molecules following a sufficiently intense UV photon bombardment will contain sulfur and therefore fall into a category known as thiol molecules. Thiols are a family of sulfur compounds also called mercaptans. Their smell threshold is extremely low. The human nose can detect thiols at concentrations as low as 1 part per billion. The rotten egg-garlic smell is a dominant characteristic of mercaptans as shown in Table 2.

Burning skin emits a similar smell as thiols, while setting hair on fire produces a sulfurous odor. This is because the keratin in our hair contains large amounts of cysteine, a sulfur-containing amino acid. The smell of burnt hair can cling to nostrils for days.

 

Table 2. Reported Sensory Threshold for Thiol / Sulfur Compounds6

Compound Name

Chemical Formula

Sensory Description

Smell Threshold (ppb)

Hydrogen Sulfide

H2S

Rotten egg, sewage-like

0.5 – 1.5

Ethyl Mercaptan

CH3CH2SH

Burnt match, sulfidic, earthy

1.1 – 1.8

Methyl Mercaptan

CH3SH

Rotten cabbage, burnt rubber

1.5

Diethyl Sulfide

CH3CH2SCH2CH3

Rubbery

0.9 – 1.3

Dimethyl Sulfide

CH3SCH3

Canned corn, cooked cabbage, asparagus

17 – 25

Diethyl Disulfide

CH3CH2SSCH2CH3

Garlic, burnt rubber

3.6 – 4.3

Dimethyl Disulfide

CH3SSCH3

Vegetal, cabbage, onion-like at high levels

9.8 – 10.2

Carbon Disulfide

CS2

Sweet, ethereal, slightly green, sulfidic

5

CALCULATION OF RESULTING SULFUR COMPOUNDS CONCENTRATION IN AIR

In order to confirm the hypothesis linking the origin of the post-UV disinfection smell to the presence of keratin and cysteine in the air dust, a straightforward molecular concentration calculation was performed.

Given the dust loading, and assuming that this dust consists of 80% skin or hair, both of these containing around 5% sulfur that will end up being broken down by UV into the smallest thiol molecules such as Methyl Mercaptan, Ethyl Mercaptan or even Hydrogen Sulfide, the concentration of Thiol can be estimated as follows:

Where:

Dustload = dust weight per unit air volume in μg/m3 (lb/ft3)

SK = % Sulfur in Keratin/Cysteine = 5%

%Skin_Hair = Skin and Hair mass fraction in the dust = 80%

ρThiol = Methyl Mercaptan density at normal ambient temperature and pressure = 1.974 kg/m3 (0.1232 lb/ft3)

Equation (1) shows that when the airborne dust load gets above 75 μg/m3 (0.000033 grain/ft3), which is frequently the case in occupied spaces, the level of thiol generated by the shattering of keratin proteins exceeds the smell threshold of 0.5 to 1.5 ppb. It follows that even in the case of a relatively clean environment with dust loading as low as 100 μg/m3 (0.000044 grain/ft3), the aftermath of the UV disinfection process will leave behind a concentration of 2 parts per billion, which is greater than the smell threshold level, thus leaving behind a perceptible smell. Plotting a graph of equation 1 and allowing the dust loading to go up to 1,000 μg/m3(0.00044 grain/ft3) shows that unless the dust does not contain much dead skin or hair squames, the UV disinfection of a room will almost always leave behind a thiol concentration that exceeds the smell threshold.

Figure 1. Thiol Concentration in ppb vs. Dust Load

At maximum ASHRAE acceptable airborne dust loads of 10,000 μg/m3 (0.0044 grain/ft3), concentration of thiol could end up being as high as 200 ppb after UV disinfection. According to the US National Institute for Occupational Safety and Health7 (NIOSH), the IDLH (Immediate Danger to Life or Health) level for Methyl Mercaptan is 150 ppm i.e. 150,000 ppb. Also, according to CSST in Quebec as well as OSHA8 (Occupational Safety and Health Administration), the acceptable TLV-TWA (Threshold Limit Value-Time Weighted Average) level for 8hr exposure is 0.5 ppm i.e. 500 ppb. Consequently, the potential levels of thiol concentration generated by UV disinfection are safe even at the highest acceptable airborne dust level.

CONCLUSION

Given that human occupancy normally generates concentrations of dust well above 75 μg/m3 (0.000033 grain/ft3) and that this dust is mainly made of human dead skin and hair, which consist of keratin and cysteine molecules; and understanding that high energy UV-C photons can break-up these molecules into thiol molecules which have a very low smell threshold, this paper has revealed the root cause of the odor produced by UV disinfection9 of rooms. Given that the resulting potential concentrations of thiol molecules are negligible when compared to the published acceptable exposure limits, it is safe to enter a room after germicidal UV disinfection has been performed.

ACKNOWLEDGMENTS

The authors are grateful to Dr. Wladyslaw Kowalski for data and editorial assistance.

NOMENCLATURE

μg = micro gram

ppm = parts per million volumetric concentration

ppb = parts per billion volumetric concentration

nm = nanometer (10-9 m)

grain = lb/7,000

References

Spengler, Samet, McCarthhy, Indoor Air Quality Handbook. McGraw-Hill, 2001.

Fergusson,J.E.,Forbes,E.A.,Schroeder,R.J., The Elemental Composition and Sources of House Dust and Street Dust, Science of the Total Environment, Vol.50,pp.217-221, Elsevier, April 1986.

Pure Appl. Chem. 56 (5), 1984: 595–624, Nomenclature and symbolism for amino acids and peptides (IUPAC-IUB Recommendations 1983)”, doi:10.1351/pac198456050595.

C.R. Robbins, Chemical and Physical Behavior of Human Hair, DOI 10.1007/978-3-642-25611-0_2, # Springer-Verlag Berlin Heidelberg 2012.

UWaterloo, Bond Lengths and Energies. n.d. Web. 21 Nov 2010. http://www.science.uwaterloo.ca/~cch…20/bondel.html

EPA. Reference Guide to Odor Thresholds for Hazardous Air Pollutants Listed in the Clean Air Act Ammndments of 1990. EPA/600/R-92/047, March 1992.

Disinfecting Air & Reducing Ethylene in Cold Rooms

Disinfecting Air and Reducing Ethylene in Cold Rooms

Mold and bacteria can severely impact the quality of meat, chicken, fish, fruits and vegetables that may be stored or prepared in warehouses and cold rooms. Ethylene off-gassing causes fruits and vegetables to prematurely ripen and aged, dramatically shortening shelf-life.

Sanuvox UV IL-CoilCean systems installed facing the cooling coil are designed to bask the coil and air with ultraviolet energy destroying microorganisms including bacteria, mold and viruses while oxidizing and reducing ethylene off-gassing.

With its high efficiency patented air disinfection systems, Sanuvox offers the right solution when the objective is to destroy airborne bio-chemical contaminants (e.g. bacteria, viruses, mold) that may affect the storage and preparation of fish, chicken and meat, as well as destroy ethylene off-gassing that causes produce to ripen faster.

THE EQUIPMENT

Multi-IL CoilClean units are installed facing the cooling coils in the fan coil unit. Each IL unit includes a UV-C/UV-V lamp mounted in an anodized aluminum parabolic reflector. The ballast box incorporates LED status lights for providing lamp status and replacement and can be remotely monitored.

OPERATING THE EQUIPMENT

The fan coil unit recirculates the air where:
1. The UV-C germicidal section of the UV lamp destroys airborne biological contaminants (viruses, mold, bacteria and spores).
2. The UV-V oxidizing section of the UV lamp reduces ethylene, slowing down the ripening process of vegetables and fruits. Coils remain clean and more energy efficient.

SLOWING DOWN THE CONTAMINATION SPREAD WITH UV-C
Produce will degrade due to the rotting process that is caused by parasitic fungi and mold. Food deterioration begins with the breakdown of the cellular tissue by enzymatic action that allows the growth of microbes. Germicidal UV (UV-C) is extremely effective at preventing the reproduction of bio-contaminants because UV-C destroys airborne fungi, molds and spores, limiting the contamination spread from one fruit to another. Meat, fish and chicken are especially vulnerable to airborne biocontamination. UV-C sterilizes the air, destroying contaminants as they circulate within the cold room.

RETARDING THE RIPENING PROCESS WITH UV-V
Photo-oxidation with UV-V can be used to reduce chemicals that trigger the ripening of fruits and vegetables. The life stages of a plant are influenced by plant hormones. An organic compound involved with ripening is ethylene, a gas created by plants from the amino acid, methionine. Ethylene increases the intracellular levels of certain enzymes in fruit and fresh-cut products, which include:

  • Amylase, which hydrolyzes starch to produce simple sugars.
  • Pectinase, which hydrolyzes pectin, a substance that keeps fruit hard.

UV-V oxidizes and thus neutralizes the ethylene molecules released by the ripening process, slowing down the spread of ripening to the surrounding produce. This oxidation process breaks down ethylene into carbon dioxide and water vapor.
Ethylene C2H4 C2H4+ O* -> CO2 +H2O

WHERE TO INSTALL

Many buildings and facilities can be equipped with the IL-CoilCean systems, like cold storage rooms, groceries, meat, fish and chicken storage, preparation facilities, fruit and vegetable retailers, warehousing and transportation.

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Fruits & Vegetables Surface Disinfection

Fruits and Vegetables Surface Disinfection

Surface contamination of fruits and vegetables is a problem for growers, distributors and retailers. Mold and bacteria can have severe effects causing produce to spoil.

Sanuvox UV IL Food Safe purifiers for food products and their packaging are exceptionally safe and versatile disinfection systems for surface, packaging and conveyor applications designed to bask meat, fish, poultry, fruits and vegetables, baked goods and packaging with UV-C germicidal light. The UV system is extremely effective at destroying surface contamination while extending product shelf-life. Only a few seconds of exposure can achieve up to 99.9999% destruction of common biological contaminants that are problematic in the food industry.

Incorporate the UV fixtures into the production line (i.e. over the conveyor belts) to bask the products and surfaces prior to packaging, maintening a sterile product ready for distribution and consumption.

As the system is incorporated into the production line, the lamps are covered with Teflon, that will trap pieces of grlass in the event of breakage.

When the objective is to prevent and destroy microbial contamination, such as bacteria and fungi that occur naturally on fruit and vegetable surfaces, and are responsible for premature decay, Sanuvox offers the right solution with its high efficiency patented air purification system. The process will leave no residue as is found using chlorine or irradiation treatments with gamma rays. At the producer level, sterilization of fruits and vegetables could reduce the use of pesticides.

THE EQUIPMENT

IL Food Safe purifier for food products equipped with parabolic reflectors and Teflon coated lamps will be positioned equidistant across the conveyor, parallel to it. Computerized sizing programs taking into account the speed of the conveyor and the contaminant(s) to be treated will determine the size of the lamps.

Typical installation:

OPERATING THE EQUIPMENT

The end user will determine the location and design of the lamp assembly enclosure that will attach to
the conveyor guaranteeing there is no direct UV exposure to employees. Fruits and/or vegetables will be exposed for a predetermined period of time to UV light as they move through the enclosure on the conveyor. This predetermined time will be sufficient to sterilize the fruit and/or vegetable pathogens and slow down ripening process.

RESEARCH ON STRAWBERRIES
Researchers from the Department of Food, Science and Nutrition (Laval University, Quebec, Canada) demonstrated that exposing strawberries to ultraviolet light prolongs their shelf life. Freshly picked strawberries exposed to germicidal ultraviolet (UV-C) have retained their freshness for 14 to 15 days, while untreated freshly picked strawberries were “almost done” on the tenth day.

The conclusions from this research have been published in the Food Science Journal. Refrigeration, which slows the growth of microorganisms and fruit ripening, allows a limited but effective mean regarding conservation of strawberries.

“Exposure to UV-C is a very interesting approach to facilitate the marketing and distribution of fresh fruits and vegetables”, says researcher Joseph Arul. This treatment slows the ripening of strawberries: they remain firm longer, their respiratory rate is lower, their color is more attractive and the taste is not altered. “It is believed that exposure to UV-C would kill some mold on the surface of the fruit or, more likely, the treatment would stimulate the defense mechanisms of the produce,” suggests the researcher.

Arul’s team has already demonstrated the benefits of UV-C exposure for the conservation of carrots, broccoli, tomatoes and blueberries.

Arul does not anticipate negative reactions from consumers, unlike gamma irradiated food, or more recently, genetically modified organisms. “The technique is more acceptable to a consumer. In low doses, UV is beneficial. It is a light source and I do not think people have problems with that.”

WHERE TO INSTALL

Many facilities can be equipped with the IL Food Safe, like vegetable growers, fruit and vegetable importers, hydroponic producers, and value-added packagers.

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Sterilizing Air in Facilities

Sterilizing Air in Facilities

New buildings are built tighter to save energy, while older buildings are implementing new measures to reduce heating and cooling loss. Reduced fresh air also prevents dilution of contaminated air resulting in an increase of contaminants as they are now trapped inside and are continually recirculated throughout the space.

Indoor Air Quality (IAQ) applications in hospitals, schools, commercial buildings and offices vary. From Hospital Acquired Infection (HAls), sick building syndrome, absenteeism and work place productivity, Indoor Air Quality influences these facilities in many differents ways.

When the objective is to eliminate up to 99.9999% of airborne bio-contaminants, including viruses and bacteria that circulate through the ventilation system without increasing the pressure drop resulting from high efficiency filtration, Sanuvox offers the right solution with its high efficiency patented air purification system.

THE EQUIPMENT

The BioWall air purification unit is installed in the ventilation duct parallel to the airflow, allowing sufficient contact time that is required for airborne sterilization. The UV-C intensity of each lamp can be measured in “realtime” with an optional UV-C sensor, ensuring the required inactivation intensity will be delivered to the contaminant.

OPERATING THE EQUIPMENT

To create the sterilization chamber in the existing duct (up to 5 feet deep per unit), the walls are covered with an aluminum reflective material. The proprietary sterilization sizing calculations take into account: air velocity, dimensions of the duct, the UV lethal dose needed to sterilize the microorganism for the desired inactivation rate. The sizing calculations will determine the number and length of the BioWall unit(s) required. The optional UV-C sensor will guarantee that the UV-C emitted from the lamp will exceed the amount of UV-C that is required at all times.

UVC GERMICIDAL PRINCIPLE

The 254nm UV-C germicidal wavelength has been used for decades for sterilization and its effect on microorganisms is well documented. UV germicidal process inactivates microorganisms by damaging their DNA structure, making it incapable of reproducing. The germicidal efficiency can deliver virtually a 100% disinfection rate. The system can achieve exceptionally high disinfection rates as a result of the BioWall unit being mounted parallel to the airflow and the desired intensity is sized for each particular application.

WHERE TO INSTALL

Many buildings and facilities can be equipped with the BioWall unit, like hospitals, private clinics, veterinary clinics, as well as fertility centers. It can also be installed in schools, universities, offices towers and commercial buildings.

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UV Disinfection: A Comparative Technology Review of Continuous UVC & Pulsed Xenon UV

Infection Prevention: Environmental Cleaning and Practical Infection Control

By Barry Hunt, Class 1 Inc., Canada

Recent events in the US healthcare industry have combined to create a rush by healthcare facilities toward the adoption of technology for total room disinfection. Events include: 1) changes to the Affordable Care Act that reduced CMS and insurer compensation to hospitals due to high rates of Healthcare Acquired Infections (HAIs); 2) elimination of CMS and insurer reimbursements to hospitals for individual patient healthcare costs if and when a patient develops an HAI; 3) a number of peer-reviewed publications of total room disinfection systems used at terminal discharge demonstrating successful reductions of either bioburden or HAIs or both; 4) presenter advocacy at recent infection prevention professional conferences including American Prevention and Infection Control (APIC) and Society of Healthcare Epidemiology of America (SHEA); 5) industry innovation; and 6) industry promotion.

In the ensuing market competition between hydrogen peroxide vapor (HPV) fogging and UV total room disinfection systems, UV appears to be the leader in the U.S., likely for reasons of speed, safety and ease of use19. Well-trained housekeeping staff can completely disinfect 20 to 50 patient rooms per day depending on the speed of the mobile UV system chosen. The faster the disinfection system, the faster the room turnaround, and the greater the improvement in hospital revenue; the less EVS staff time required, the lower the hospital operational costs; and there is no risk to staff or patients of exposure to residual aerosol disinfectant.

Of the two types of energy-based disinfection systems being marketed today, UVC has been a proven technology for disinfecting air, water and instruments for over a century2,3. UVC is a narrow spectrum technology operating at a frequency of 254 nm, very close to the optimal germicidal frequency (263 nm to 266 nm) for bacterial and viral disinfection.

PX light is a broad-spectrum technology developed in the 1950s primarily for flash photography. PX does however include some germicidal UV in its range of emitted light frequencies.

Efficiency

Narrow spectrum UVC emitters are relatively efficient at generating germicidal UV with a known range of efficiency from 24% to 38%. That means a bulb rated for 100 W input power from one manufacturer may emit 24 W of germicidal UV, while a 100 W bulb from another device manufacturer may produce as much as 38 W of germicidal radiation. Technologies known to impact this range include tubing materials, and temperature management. Further optimization of emission of UV energy onto surfaces can be accomplished with reflectance technology.

By contrast, PX bulbs are relatively inefficient at generating germicidal UV with a published efficiency of just 9%. Much of the input energy is wasted as heat and visible light, rather than being converted to germicidal UV. Consequently, for any given input power, a UVC lamp will emit approximately 4 times more germicidal UV than its PX counterpart.

Given the example of a typical US hospital receptacle that supplies up to 2000 watts of electrical power, the maximum germicidal UV output of a PX device can only be 180 Watts (9 % x 2000 watts = 180 watts), whereas a UVC device can generate 760 Watt of germicidal UV (38% x 2000 watts = 760 watts).

Disinfection efficiency is a direct function of the delivered germicidal UV power and exposure time. Therefore, it becomes quite clear that UVC can disinfect up to 4 times faster, or 4 times more, than a PX device from a single emitter using the same power (760 watts / 180 watts = 4.2X).

Efficacy

UVC constants have been published for all bacteria and viruses allowing easy calculation of time and power required for deactivation with germicidal UV. Disinfection constants vary greatly with the organism. In general, vegetative bacteria are deactivated very quickly, spores require a lot more time.

 

At a UVC energy dose of 400 mJ/cm2, all known epidemiologically important pathogens (EIP), including Clostridium difficile spores, are rendered inert. Germicidal UV creates thymine-thymine dimers and thymine-cytosine dimers of neighboring molecules on strands of DNA and RNA, preventing organism replication.

The higher the emitted energy of the device, the faster the target energy dose is reached, and the faster the disinfection cycle. For example, if the device emitted 400 mJ/cm2/minute at the target distance, only one minute of operation would be required for disinfection. If the device emitted 40 mJ/cm2/minute (more commonly expressed as 0.667 mJ/cm2/s i.e. 0.667 mW/cm2) at the target distance, then 10 minutes would be required to achieve the same disinfection dose.

 

Life Cycle / Maintenance:

The life of a PX bulb is counted by the number of pulses it can sustain before the electrodes are destroyed. Typical published values for PX life-cycle range from 1 to 10 million pulses. Assuming an average life cycle of 5 million pulses, and a flash rate of 3 times per second, (the value reported by one PX manufacturer), this will only result in an expected life of 463 hours. (5 million / 3 = 1.67 million seconds = 463 hrs.) Given that a typical disinfection cycle lasts 15 minutes according to one PX manufacturer, this means that the PX lamp will need to be replaced after 1,852 cycles. Assuming the PX unit is used 20 times per day, then the PX lamps will need to be replaced every 3 months.

By comparison, the published life expectancy of a typical UVC lamp is between 10,000 and 17,000 hours. For at least one manufacturer, that could mean bulb replacement as little as every 5 years.

Operational & Proximity Safety:

Because of their inherent high temperature flash operating mode, PX lamp surfaces become extremely hot (1000 oC) and may become a fire hazard or cause severe injuries if accidentally touched after discharge (similar to a burnt flash bulb from a 1950s flash camera). In addition, the gas pressure that builds up inside the hot lamp becomes pressurized to several atmospheres and can explode violently projecting glass debris. This may be the reason at least one PX manufacturer retracts the PX lamps into a protective canister immediately after discharge.

Viewing Safety:

UVC can be safely and comfortably viewed from behind glass. UVC does not penetrate glass or plastics. This allows high visibility of the disinfection process in glass-walled areas like ICU.

Conversely, PX devices discharge an intensely bright fast-paced strobe of visible light. Staff need to be trained to protect patients, visitors and staff from accidentally viewing the device through glass while in operation. This may require installation of additional curtains or blinds, as well as training of EVS staff and clinical staff working in commonly glassed areas such as ICU. Even casual contact walking beside partially covered glass can subject passersby to discomfort from the intense white light flash.

Mercury:

At least one PX manufacturer promotes the fact their product does not contain mercury. True. Conversely, UVC lamps do contain a tiny amount of mercury, the same as every fluorescent lamp used throughout hospitals, commercial and industrial buildings and residences all over the world. The amount of gaseous mercury that could be released from a broken UVC lamp in a hospital is much too low to create a health risk. Many manufacturers also encapsulate their lamps in a protective Teflon sleeve that both eliminates any possible release of mercury vapor and serves to protect occupants from exposure to fragments of broken glass in the event of breakage.

Discussion

Optimization:

All light energy, whether visible or invisible, UV or non-UV, UVC or PX, follows an inverse square law. If the distance from the point source to the target doubles, the energy decreases to 25%. Conversely, if the distance to target is halved, the energy density quadruples. Thus whether using 9% efficient PX or 38% efficient UVC, using two emitters instead of one would cut the distance to target for all surfaces in half and would reduce the room disinfection time by 75%.

A further effectiveness optimization strategy would be to locate the two emitters equidistant on either side of the patient bed with an overlap pattern of UV emission and set to achieve a Log6 reduction on the most distant outer wall surface. This would double the germicidal UV in the vicinity of the patient bed between the emitters, the most critical area in the room, and provide up to a Log12 reduction. Adding additional emitters would shorten room disinfection time even further but the law of diminishing returns would suggest two to three emitters is optimum.

Conclusion

Both UVC and PX have been shown to dramatically reduce bioburden and HAIs. However, UVC appears to be 4 times more energy efficient than PX, and 4 times faster or more effective than PX. UVC appears to provide 10 times longer lamp life and dramatically lower life cycle costs than PX. UVC does not expose staff to the risk of contact with excessively high temperature, or exploded lamps that PX may. UVC can be safely and comfortably viewed while in operation from behind glass or plastic whereas PX presents a risk of temporary blinding or discomfort for passersby.

All germicidal UV systems can substantially shorten room disinfection times and optimize room turnaround using two or three emitters.

UVC appears to offer significant technological, operational, safety and cost advantages over PX. Perhaps that is why UVC is the predominant air, water and surface disinfection technology used in all other industries. There are millions of UVC installations worldwide and no apparent movement afoot in any industry to switch from UVC to PX. The market share for UVC in other industries is likely in the order of 99.99%. Perhaps we should pause to consider that context, as well as the safety, operation, efficiency, efficacy, life-cycle and maintenance costs, when we consider our options for germicidal UV surface disinfection for healthcare.

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New Sanuvox Mobile UV Sterilization System for Hospitals

New Sanuvox Mobile UV Sterilization System for hospitals

Sanuvox releases the ASEPT.2X mobile UV sterilization system to help reduce nosocomial infections in hospital environments.

The ASEPT.2X mobile UV sterilization system uses a primary and secondary unit to sterilize high-touch surfaces with ultraviolet ‘C’ energy controlling (6 log reduction) drug-resistant microorganisms, such as MRSA and C. diff. in less than 10 minutes in a standard patient hospital room. The two-unit operation dramatically lowers the sterilization time typically associated with UV sterilization, while achieving exceptional deactivation rates by minimizing shadow areas through the use of the two-unit system.

Studies show that even with the best terminal cleaning practices, an operating or patient room can remain the source of many potential harmful drug-resistant microorganisms as manual cleaning effectively cleans less than 50% of surfaces. In the US it is estimated that HAIs (Hospital Acquired Infections) result in 1.7 million infections and 99,000 deaths costing the healthcare system between 28 to 33 billion dollars annually. Statistics show that one in every 20 patients admitted to a US hospital falls victim to an infection they contracted while there.

UV sterilization (UVC 254nm wavelength) has been used in hospitals for decades. Commercially available mobile UV systems are used to sterilize the patient room in the terminal cleaning process. However, the limitation to UV sterilization is that it is a “line-of-sight” technology. UV sterilization is ineffective in shadowed areas where the light cannot reach. This can include the other side of high-touched areas, such as a remote or call button or the other side of a bed or bed rail. As such, conventional UV systems require multiple positioning within a room to lessen the chances of shadow areas that block the sterilizing ability of the UV light. In doing so, time and resources are spent moving the system around the room and preparing the room for additional treatments.

The ASEPT.2X mobile UV sterilization system has been tested by ATS Labs in Minnesota (USA) to show a 99.9999% reduction in MRSA and C. diff. in less than 5 minutes around high-touched areas close to the patient bed, and under 10 minutes throughout the rest of the room. The ASEPT.2X is also being evaluated in one of the nation’s leading teaching hospitals.

The now readily available ASEPT.2X includes many firsts incorporated into a mobile system. Some features include a total of eight infrared motion detectors (360 degree protection around each of the two units) that will shut the units down should any personnel enter the room during the sterilization process. Wi-Fi communication between both primary and secondary units controlled and monitored by any smart device while logging all sterilization cycles.

According to Normand Brais, Ph.D., Founder and VP Engineering at Sanuvox, “The ASEPT.2X UV system helps eliminate the one limitation in UV sterilization, shadows. By maintaining a closer proximity to high-touched areas and reducing shadow areas by treating both sides of the patient bed and surrounding areas, Sanuvox is able to deliver an elegant solution in reducing HAIs while increasing productivity.” The idea is to make the ASEPT.2X easily accessible to virtually any medical facility looking to implement the system.

Although single UV systems can sell for well over US$100,000, Sauvox believes that with every unit in operation, it can save lives and wanted the systems priced right to do so. As such, a fully equipped two-unit ASEPT.2X system will sell for considerably less, making the unit readily available to most who are looking into the technology.”

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