El Periódico reports on a new method of disinfection (article in Spanish)

El Periódico reports on a new method of disinfection (article in Spanish)

Utilizando la combinación de la luz UV, la nebulización o microdifusión molecular, la pulverización y la aplicación directa para la eliminación del SARS-Cov-2.

Equipos UV EULEN Limpieza Hospitalaria. / EPDA

EULEN Limpieza, actividad del Grupo EULEN, líder en nuestro país en el diseño de servicios a empresas y siguiendo con su objetivo de ofrecer a la sociedad servicios innovadores que aportan soluciones útiles, de calidad y sostenibles, ha concluido -tras multitud de ensayos realizados por su departamento Técnico de higienistas exclusivo para el entorno Hospitalario y de un equipo de I+D+I- que la mejor técnica para eliminar virus, bacterias, hongos y agentes contaminantes orgánicos similares en entornos sanitarios es una combinación de diferentes técnicas aisladas.

La efectividad que cada una de ellas tiene en diferentes aspectos, hace que dicha combinación de técnicas específicas como laluz UV, la nebulización o microdifusión molecular, la pulverización y la aplicación directa sea la técnica definitiva en la limpieza hospitalaria frente al SARS-Cov-2.

Tecnología puntera

Actualmente la compañía dispone de los equipos más avanzados a nivel mundial y que otorgan una máxima seguridad de utilización tanto para los operarios que los manejan como para cualquier usuario del espacio tratado, especialmente en el ámbito hospitalario.

Destacan las unidades del equipo Asept.2x de Sanuvox Technologies, empresa canadiense líder de su sector. Este dispositivo puntero en desinfección por luz ultravioleta se utiliza tanto en quirófanos como en habitaciones. La luz UVC y la luz UVV del equipo tienen la misma longitud de onda que la producida por el Sol y ataca a los microorganismos a nivel molecular, desactivando y destruyendo los contaminantes, así como degradando los agentes químicos y olores. A diferencia de las lámparas convencionales, los sistemas de purificación UV que utiliza EULEN Limpieza usan un proceso patentado diseñado para entregar la máxima cantidad de luz UV.

Para complementar el sistema de desinfección por UV, la compañía emplea la última tecnología en nebulización y pulverización de generación de niebla nano y micrométricacon dinámica inductiva. Es la misma tecnología que en la actualidad está siendo usado también por las Unidades Tecnológicas de Cuerpos de Seguridad del Estado en la lucha contra el Sars-COV-2. Dotado con la última tecnología de desinfección mediante chorro regulable que permite desinfectar las estancias en un corto tiempo, minimiza tanto el desinfectante utilizado como los residuos y posibles daños a personas e infraestructuras. Asimismo, permite tratar grandes áreas en cortos periodos de tiempo, accediendo a todas las superficies y zonas de difícil acceso, realizando el perfecto mojado de todas las superficies a desinfectar.

Por último, de acuerdo a su política de utilización de los mejores biocidas del mercado, desarrollados por las empresas líderes, junto a los profesionales formados y acreditados acorde con la normativa establecida por el Ministerio de Sanidad en cuanto a la aplicación de Biocidas,se selecciona en cada momento el más conveniente para aplicar por el método óptimo en función de las necesidades. Por ello, es importante distinguir entre los de un espectro más específico de los de amplio espectro.

En definitiva, la combinación de todas estas técnicas y tecnología se convierten en la mejor solución frente a la COVID-19 en espacios hospitalarios y aseguran un resultado óptimo en desinfección en el menor tiempo posible.

En la actualidad, numerosos hospitales de la Generalitat Valenciana y otros de referencia en la geografía española confían en las soluciones de EULEN Limpieza cuya estructura y forma de trabajo propia asegura el mejor resultado en un entorno como el sanitario.

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El Mundo reports on ASEPT.2X in Spain (article in Spanish)

El Mundo reports on ASEPT.2X in Spain (article in Spanish)

Para Héctor Atienza

La Clínica Universidad de Navarra emplea un máquina pionera en España que desinfecta de COVID-19 las habitaciones del hospital en poco más de cinco minutos con rayos UV. Estos modelos se fabrican en Canadá y cada equipo cuesta hasta 160.000 euros.

Dos máquinas UVR desinfectando un quirófano en la Clínica Universidad de Navarra.

La lucha contra el Covid-19 también se pelea estos días al milímetro en cada rincón de los centros hospitalarios por los equipos de limpieza. El coronavirus ha demostrado tener una alta capacidad de transmisión y fácil apego a todo tipo de materiales de forma invisible. Su resistencia complica las labores de desinfección de las salas en plena crisis sanitaria.

Una de las técnicas más innovadoras en esta particular batalla contra el virus son las lámparas germicidas de irradiación ultravioleta (UVGI). Con esta tecnología tanto las estancias de los hospitales como los quirófanos quedan libres del bicho tras su paso en un corto periodo de tiempo.

“Son muy efectivas porque destruyen tanto el ADN como el ARN, donde está la programación genética de los virus y las bacterias. Una destrucción total en poco tiempo que permite el acceso casi inmediato a las estancias”, destaca el doctor de la Clínica Universidad de Navarra, Francisco Guillén Grima, cuyos centros en Madrid y Pamplona aplican esta técnica pionera de trabajo.

Se trata de una tecnología relativamente novedosa en España. Con las técnicas tradicionales de esterilización de espacios, como el peróxedo de hidrógeno y las botellas de gas o vapor, los pacientes deben esperar entre una y tres horas para poder acceder a la habitación. Mientras que los equipos ASEPT-2x UV permiten su entrada en poco más de 10 minutos después de la salida del último paciente.

El médico Guillén Grima posando junto a un modelo ASEPT-2X UV.

“Las recibimos hace justo ahora dos años. La primera vez que las utilizamos fue porque se había intervenido quirúrjicamente a un paciente infeccioso, pero el quirófano se necesitaba urgente para un transplante cardiaco. En estos casos, te avisan cuando hay una posible donación y se debe actuar de inmediato. Metimos las dos torres y en 20 minutos el quirófano estaba operativo“, añade Guillén Grima que también fue uno de los 70 científicos que firmaron el manifiesto enviado en marzo a Pedro Sánchez solcitando el confinamiento de la población.

Fabricados por la firma canandiense Sanuvox, los equipos tienen una altura de 1,60 metros y poco más de 71 centímetros de ancho. Con apenas 45 kilos de peso, su transporte se realiza de forma sencilla con sus ruedas guía por todas las dependencias del hospital.

El único inconveniente que pueden tener estos equipos son las zonas de sombra que genera la lámpara UV cuando actúa. Para contrarrestar este hándicap, el personal técnico sitúa la máquina en varios puntos de las habitaciones evitando así cualquier recoveco con virus.

“Uno de los equipos se compone de dos torres que trabajan simultáneamente y cada lámpara se activa cinco minutos. Pero ahora con el tema de coronavirus hemos subido a seis minutos para asegurar la desinfección como un margen de seguridad total. Con la crisis del coronavirus también hemos alquilado cuatro torres más porque no dábamos a basto“, añade el especialista.

Son equipos caros. Según ha podido confirmar EL MUNDO, cuestan entre 60.000 y 140.000 euros, en función de las características del modelo. Algunos fabricantes ya ofrecen versiones que se mueven de forma autónoma por las instalaciones hospitalarias. Sin embargo, la clave del equipo está en el software que registra la máquina vía Wifi en el servidor del hospital. Pueden ofrecer diferentes soluciones tanto de servicios como de control de salud.

“Al quemar el polvo, también se produce cierto olor que se va enseguida. Si quieres que no huela a ozono, hay modelos que llevan unos filtros, pero la máquina cuesta más cara”, destaca el doctor Guillén Grima.

Estos equipos, que en España son distribuidos por la empresa tecnológica Alfatec Sistemas, también están presentes en los centros de la Fundación Jiménez Díaz en Madrid, del grupo QuirónSalud, y en la empresa de servicios generales Eulen.

LÁMPARA PARA UTENSILLOS

La técnica de desinfección ultravioleta, con una lámpara de pequeñas dimensiones, también se utiliza en los hospitales para limpiar de gérmenes en equipos de uso habitual entre pacientes y en parte del material médico. Sin embargo, este equipo también hace una especial labor desesterilizando los mandos a distancia de las televisiones.

“Es un equipo que se toca mucho por pacientes y acompañantes. Nosotros ahora los metemos en la máquina y salen dentro de una bolsa precintada. También los usamos con los termómetros, endoscopios… Es una técnica nueva que tendrá mucho futuro en España”, añade el médico.

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Sanuvox UV air purifiers capabilities against viruses

Sanuvox UV air purifiers capabilities against viruses

Sanuvox corporation, a North American leader in UV disinfection of air and surfaces, would like to warn people tempted to purchase air purifiers or other devices against potential claims that would find themselves misleading.

UV air purifiers installed in the HVAC system, with an adequate germicidal dosage sized for the air flow, will destroy airborne viruses, but cannot guarantee anyone from becoming infected.

Air purifiers inside HVAC cannot disinfect frequently touched surfaces such as door handles and light switches, which are common disease transmission path. So good hygiene practice and frequent wash of hands continue to be the safest way to protect ourselves against any airborne or surface contaminants that can be introduced by other occupants and dispersed by the HVAC system in the house.

In other words, a powerful UVC air purifier can reduce the possibility of spreading the contaminants through the HVAC system, but it does not eliminate the necessity of safe hygiene practices.

 
Because the susceptibility to germicidal UV of any microorganism is determined by its genome sequence, the germicidal UV dose required to kill the CoVid-19 is practically the same as for the SARS-CoV (2003) within less than 1.6% variance.
 

For additional technical information regarding Covid-19, please visit https://bit.ly/38t12Mo.

Cannabis Producer in Rigaud, May 2018

The case

This grower has 3 grow rooms in which he produces cannabis. The air system in each room is 5 tons (2,000 cfm). There are also fans all over the peripheral of the rooms to move the air around.

The Problem

Production was always infected with powdery mildew, botrytis and fusarium. These spores would spread on a few plants, therefore contaminating the rest of the plants through air flow.
It was becoming an issue with profitability, as the infected cannabis plants had to be discarded of.

Indoor Cannabis Facility

Fans

GC-Quattro UV Air Purifier

Sanuvox Customized Solution

After sizing calculation, it was proposed to install a GC QUATTRO unit in each return of each air handler. Because one of the owners was an HVAC contractor, the installation was a pretty simple task. Low maintenance of the units was also considered. In between production, the rooms were cleaned thoroughly, and the fans blades disinfected from all the dust settlings.

Conclusion

Two months later, the owner reported a full harvest in his 3 rooms, with almost no powdery mildew. He also noticed that all the fans alongside the walls no longer contained a sticky film build up on the blades. So they no longer require to be wiped down with alcohol.

The grower has launched a new larger facility in the northern part of Ontario: every unit will be equipped with SANUVOX technologies.

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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Reducing Odors in Waste Rooms

Reducing Odors in Waste Rooms

Facilities, apartments and condominiums often suffer from odors from the garbage rooms that migrate from the holding area to the garage or on the floors through the chute system.

Different stand-alone systems can be used to eliminate these problems by destroying bacteria and removing chemical and biological odors. The objective is to rapidly recirculate the air in the room in front of UV-C to break down bacteria’s DNA, and in front of UV-V to oxidize the chemical decay molecules while minimizing the residual ozone.

MANUAL SETTING EQUIPMENT

The Sanuvair® S600:
This stand-alone UV air purifier incorporates a variable blower of 300 to 600 cfm, an aluminum mesh washable prefilter to capture particulates and 3 full UV-V oxidizing lamps. According to the customer’s needs, one, two or three UV-V 6.5’’ U shaped  lamps are lighted up.

Room size:  up to 8,000 cubic feet

Suggested installation Sanuvair® S600:

AUTOMATIC SETTING EQUIPMENT

The Sanuvair® S300 OZD:
This stand-alone UV air purifier incorporates a two-speed blower of 220/300 cfm, a 2” pleated prefilter to capture particulates, 1 UVC/UVV lamp and 1 full UV-V oxidizing lamp tied with 20 ft of wiring to an ozone controller set at 0.025 ppm. The controller will sample the air every minute and trigger off the UV-V lamp if more than the set point of ozone is detected. It also comes with 2 extra prefilters.

Room size:  up to 3,000 cubic feet

Suggested installation Sanuvair® S300 OZD:

The Sanuvair® S1000 OZD:
This stand-alone UV air purifier incorporates a blower of 1,000 cfm, 2 x 1” pleated prefilter to capture particulates, 1 UVC/UVV “J” shaped 16” lamp and 1 full UV-V “J” shaped 16” oxidizing lamp tied with 20 ft of wiring to an ozone controller set at 0.025 ppm. The controller will sample the air every minute and trigger off the UV-V lamp if more than the set point of ozone is detected. It also comes with 2 extra prefilters.

Room size:  up to 10,000 cubic feet

Suggested installation Sanuvair® S1000 OZD:

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About PCO: Photocatalytic Oxidation

About PCO: Photocatalytic Oxidation

By Normand Brais, P.Eng., M.A.Sc., Ph.D.

Common Titanium oxide base catalyst: TiO2

In chemistry, PCO is the acceleration of a photoreaction in the presence of a catalyst. In catalyzed photolysis, light is absorbed by an adsorbed substrate. The photocatalytic activity depends on the ability of the catalyst to create electron–hole pairs, which generate free radicals (hydroxyl radicals: OH) able to undergo oxidation reactions. Its comprehension has been made possible ever since the discovery of water electrolysis by means of the titanium dioxide. Commercial application of the process is called Advanced Oxidation Process (AOP) and is used for water treatment.

Titanium dioxide, particularly in the anatase form, is a photocatalyst under ultraviolet light. Recently it has been found that titanium dioxide, when spiked with nitrogen ions, or doped with metal oxide like tungsten trioxide, is also a photocatalyst under visible and UV light. The strong oxidative potential of the positive holes oxidizes water to create hydroxyl radicals. It can also oxidize oxygen or organic materials directly. Titanium dioxide is thus added to paints, cements, windows, tiles, or other products for sterilizing, deodorizing and antifouling properties and is also used as a hydrolysis catalyst.

Although this technology looks perfectly transposable to air, there is one main practical caveat that recently came to light: the titanium oxide is being “poisoned” by silica and its useful service life is severely impaired. After some longer time experience of this technology in the air, it was observed that the PCO would gradually decay and lose most of its oxidative potential within a year or less.

The effect of silica as a titanium oxide neutralizer is well known in the sunscreen industry. Every sunscreen with a physical blocker contains titanium dioxide because of its strong UV light absorbing capabilities, thus preventing UV from reaching the skin. Sunscreens designed for infants or people with sensitive skin are often based on titanium dioxide and/or zinc oxide, as these mineral UV blockers are less likely to cause skin irritation than chemical UV absorber ingredients, such as avobenzone.

However, to avoid the creation of carcinogenic radicals on the skin due to the activity of photocatalytic reaction, the titanium dioxide particles used in sunscreens are intentionally coated with silica. The addition of silica effectively neutralizes the photocatalytic properties of the titanium oxide, making the sunscreen harmless.

Because silica is commonly found in household applications such as caulking and many other materials, the PCO titanium oxide is contaminated with silica and will lose half of its activity within three months. This means that after 6 months, it will be down to 50% efficiency, after 9 months down to 25% efficient, and after a year down to 12.5% only. It will then cease to provide adequate performance as an air purification device. This is the main reason why serious companies are now taking a step back and even walking away from the marvelous promises of common titanium oxide based PCO as a solution for odor removal.

New Cobalt Photocatalytic Oxidation (Co-PCO)

Using UV light to achieve clean air and water resources through photocatalytic oxidation is a goal of scientists worldwide(1,2,3) over the last two decades. Photocatalysis is a widely generic term that applies to chemical oxidation reaction enabled by photon activated catalyst, commonly called PCO in the air purification industry.

PCO catalyst consists of a metal oxide semiconductor, usually titanium oxide (TiO2), with a band gap energy that allows the absorption of ultraviolet photons to generate electron hole pairs called “active sites” that can initiate the chemical reaction. For titanium oxide PCO, the energy band gap is centered on 360 nm photons, which is in the middle of the UV-A range (315-400 nm). This is quite far away from the UV-C range of common germicidal lamps emitting most of their photon energy at 254 nm wavelength and as such partially explains the rather deceiving efficiency of current titanium oxide based PCO air purifiers using low pressure mercury lamps. This low efficiency is mainly responsible for hazardous by-product formation such as formaldehyde. Another important barrier to the implementation of actual PCO is its short lifetime due to silica poisoning of the catalyst. Silica which is the main constituent of common sand is omnipresent in our daily environment. Siloxanes have been identified as the root cause of current PCO deactivation(4). As deactivation reduces the number of active sites available, incomplete oxidation becomes prevalent, promoting the production of by-products.

The fundamental effect of the addition of cobalt oxide is to shift the energy band gap of the catalyst toward higher energy photons closer to the 254 nm photons emitted by low pressure mercury lamps. With a capacity to absorb at higher energy, the cobalt enhanced catalyst provides enough photocatalytic activity to completely oxidize household VOCs(5,6) and avoid the transient formation of formaldehyde, acetaldehyde, and other incompletely oxidized by-products. It is worth noting that the higher energy active band gap of the Cobalt catalyst is much wider than the actual titanium oxide and was found to be almost insensitive to silica poisoning. Actual testing has shown no significant decline in the Cobalt catalyst activity after a full year in service.

References

  1. Peral,J.; Ollis, D.F. Heterogeneous photocatalytic oxidation of gas-phase organics for air purification: acetone,1-butanol, butyraldehyde,formaldehyde,and m-xylene oxidation. J.Catal. 1992, 136, 554-565.
  2. Dibble, L.; Raupp, G. Kinteics of the gas-solid heterogeneous photocatalytic oxidation of trichloroethylene by near UV illuminated titanium oxide. Catal. Lett., 1990,4, 345-354.
  3. Pichat,P.; Disdier, J.; Hoang-Van, C.; Mas, D.;Goutallier, G.; Gaysee, C. Purification/deodorization of indoor air and gaseous effluents by TiO2 photocatalysis. Catal today 2000, 63, 363-369.
  4. Warner, N.A.; Evenset, A.; Christensen, G., Gabrielsen, G.W.; Borga, K.; Leknes, H. Volatile siloxanes in the European arctic: Assessment of sources and spatial distribution. Env iron. Sci. Technol., 2010,4,7705-7710.
  5. Building Assessment Survey and Evaluation (BASE) study. Available online: http://www.epa.gov/iaq/base/index.html
  6. Hay, S.; Obee, T.; Luo, Z.; Jiang, T.;Meng, Y.; He, J.;Murphy, S.; Suib,S. The viability of photocatalysis for air purification. Molecules, 2015, 20, 1319-1356.

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.

Odor Remediation of Environmental Tobacco Smoke

Odor Remediation of Environmental Tobacco Smoke

By Normand Brais, P.Eng., M.A.Sc., Ph.D.

INTRODUCTION

Environmental Tobacco Smoke or ETS is a technical term which describes the contaminants released into the air when tobacco products burn or when smokers exhale. At room temperature, many of these compounds are gaseous but most are solid ash particulate and liquid droplets called aerosol.

Particles in tobacco smoke are especially problematic to remove not because of their small size (0.1 to 1 micron), but because they are coated with tar, nicotine, phenols, and many other pungent odorous compounds. They can remain airborne for hours after smoking stops.

Due to their aerosol coating, tobacco smoke particles are not dry but rather sticky and will inevitably clog the surface of any types of air filters, making them quickly wasted and thus ruling out the solution of simple filtration. Their stickiness makes them cling to walls, carpets, fabrics, and clothing, thus impregnating the environment with a lasting nasty smell.

This article describes those technical challenges and explores from a fundamental point of view the proper use of ultraviolet photo-oxidation process as a solution to remediate the odors caused by environmental tobacco smoke.

COMPOSITION OF CIGARETTE SMOKE

Studies have shown that cigarette smoke contains over 3,800 chemical compounds. Some of these compounds are shown in Table 1 below. Cigarette smoke aerosols are essentially condensable gases resulting from incomplete combustion. Combustion being an oxidation process, those aerosols can be rendered less sticky and turned into dry ash by completing their oxidation. Their odors would even disappear if they could be fully oxidized down to water vapor and carbon dioxide, which are odorless compounds. If one could draw the smoke cloud directly into the combustion chamber of an industrial fume incinerator at 850 Celcius for two seconds, the odorous molecules cocktail listed in Table 1 would be completely oxidized and consequently odorless. Although it would work perfectly, this solution is obviously not economically sound.

 

Table 1. Chemical composition of cigarette smoke

Duration of smoke production (sec)

20 sec

550 sec

Characteristics or compound

Mainstream Smoke

Sidestream smoke

Particles (number per cigarette)

1.05E+12

3.50E+12

a) Solid particles and aerosols

(mg/cigarette)

(mg/cigarette)

Tar

20.80

44.10

Nicotine

0.92

1.69

Benzo (a) pyrene

3.50E-05

1.35E-04

Pyrene

2.70E-04

1.01E-03

Fluoranthene

2.72E-04

1.26E-03

Benzo (a) fluorene

1.84E-04

7.51E-04

Benzo (b/c) fluorene

6.90E-05

2.51E-04

Chrysene, benz (a) anthracene

1.91E-04

1.22E-03

Benzo (b,k,j) fluorenthrene

4.90E-05

2.60E-04

Benzo (e) pyrene

2.50E-05

1.35E-04

Perylene

9.00E-06

3.90E-05

Dibenz (a,j) anthracene

1.10E-05

4.10E-05

Dibenz (a,h) anthracene, ideno-(2,3) pyrene

3.10E-05

1.04E-04

Benzo (g,h,i) perylene

3.90E-05

9.80E-05

Anthanthrene

2.20E-05

3.90E-05

Phenols (total)

2.28E-01

6.03E-01

Cadmium

1.25E-04

4.50E-04

Polonium 210, pCi

7.00E-02

1.30E-01

b) Gases and vapors

(mg/cigarette)

(mg/cigarette)

Water

7.50

298.00

Carbon monoxide

18.30

86.30

Ammonia

0.16

7.40

Carbon dioxide

63.50

79.50

NOx

0.014

0.051

Hydrogen Cyanide

0.240

0.160

Acrolein

0.084

0.000

Formaldehyde

0.000

1.440

Toluene

0.108

0.600

Acetone

0.578

1.450

Source: Introduction to indoor air quality: a reference manual, EPA/40013-91/003

 

AIR FILTRATION AND IONIZATION LIMITATIONS AGAINST TOBACCO SMOKE

Inspection of Table 1 shows that filtration alone could not handle cigarette smoke aerosols. Past experience has shown that the very small sub-micron size of the particles requires expensive HEPA filters that become tar coated and consequently clogged very quickly.

Besides classic filtration, there is another well-known way to remove sub-micron particulates from the air. Electrostatic air filters also called air ionizers have this capability. Instead of capturing particles mechanically like classic filters, the idea behind electrostatic or electronic filtration is to electrically charge the particles so that they will migrate due to electrical forces toward nearby surfaces. The same effect is obtained by rubbing a balloon on one’s hair and then sticking it to a wall. Eventually, the balloon loses its charge and falls back to the floor.

Many of the popularly called “smoke eaters” use the electrostatic principle to collect smoke particles on metal plates. The effect of ionizers on the smoke particles in the air is the same, except that they have no collecting plates and the charged particles end up sticking on the walls and surfaces of the room. It is worth noting that since the cigarette particles are sticky with tar, they will overtime coat all the room surfaces with pungent smelly yellow-brown tar extract.

Experiences with ionizers into small volumes like a hand jar is quite conclusive where the smoke particles of one cigarette can be easily dispersed toward to jar walls within 15 to 20 seconds. However when repeating the same experience in a larger volume like a 3m x 3m x 3m room, the time required to clear the air from the same amount of smoke goes up to several hours!

The explanation for this loss of effectiveness as the room size increases is rooted into basic fundamental physics of electrostatic forces: the Coulomb Law, which states that the electrical forces between charged particles decreases with the square of their distance. The Coulomb Law implies that when the distance is doubled, the electrical force is reduced by a factor of 4. When comparing the electrical forces in the small jar where the particles are within less than a few centimeters from one another and from a nearby wall with that of a room of a few meters wide, the electrostatic forces responsible for the dispersion of the smoke particles are down by the square of the ratio of 1 meter to 1 centimeter i.e. the square of 100 or 10,000 times less electrical force !

This fundamentally explains why experiment based on removing the same number of smoke particles in a normal size room takes several hours (10,000 + seconds) whereas the old sales-pitch demonstration videos performed in a hand size container takes seconds. Not only air ionization does not remove the odors due to the walls and surface tar coating effect, but their electrostatic actions are way too slow to have any significant cleaning effect except in a small jar. On top of their ineffectiveness, the fact that room surfaces will get gummy as they accumulate the electrically charged tar particles instead of using some internal cleanable capture plates like in all electrostatic smoke eater units, the air ionizers are in fact an ill-conceived version of an electrostatic smoke eater and an overall bad idea.

EFFECT OF ULTRAVIOLET LIGHT ON CIGARETTE SMOKE

When ultraviolet UV-C light photons hit a tar or nicotine molecule, they carry enough impact energy to break the interatomic chemical bonds and shatter the molecule into many smaller molecules. The energy of germicidal UV photons at 254 nm wavelength is 470 kJ/mole, an energy greater than the energy of all the chemical bonds listed in Table 2. By comparison, visible light with an average wavelength of 550 nm has photon energy of only 217 kJ/mol.

It is therefore quite clear that some bonds within tar, nicotine and phenols molecules in the smoke can be broken down by UV-C irradiation but not by visible light.

Table 2. Chemical Bonds Strength4

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, the chemical bonds between carbon atoms and hydrogen, nitrogen, oxygen and sulfur atoms will be broken down by UVC ultraviolet photons, resulting broken pieces of molecules. Following this process, the broken molecules can now be further oxidized to complete their combustion and reduce their odor potential.

This oxidation can be accomplished by using a higher energy ultraviolet of 185 nm wavelength called UVV, where the second V stands for Vacuum. UVV photon have an energy of 645 kJ/mole but can only propagate into a vacuum because the dioxygen molecule in the air absorbs it and as a result gets broken up into monoatomic oxygen. At normal atmospheric pressure, UVV photons are almost totally absorbed within less than 5 mm away from a standard low pressure mercury quartz lamp UVV source. These free oxygen atoms generated by the UVV light are then able to react and complete the oxidation of the broken-down tar, nicotine, and phenols molecules.

The end products of this photo-oxidation process are then dry non-sticky ashes particles that can now be captured by adequate standard filters. This way the odors are eliminated by the oxidation process and the dry resulting particles removed by filtration.

The proper sizing to avoid oversizing of photo-oxidation system is of utmost importance. Should there be nothing to react with, the UVV generated oxygen atoms O* will react with dioxygen molecules O2 to produce ozone O3, another undesirable compound. Ozone is a not a stable molecule and will decompose naturally into normal dioxygen at ambient room temperature within 20 to 30 minutes depending upon relative humidity. The OSHA limit for 8 hours exposure is 0.05 ppm of ozone. Because the generation rate and the rate of decomposition of ozone in the absence of any smoke or other volatile contaminants in a given room size at an ambient temperature and ventilation rate can all be adequately calculated, it is possible to size an ultraviolet photo-oxidation system that will never exceed the OSHA safety limit.

CONCLUSION

This paper has described in detail the nature and composition of cigarette smoke and the consequential inherent shortcomings of classical filtration and electrostatic filters or air ionizers. Many years of experimental evidences backed by calculations based on cigarette smoke chemical composition show that the odor of cigarette smoke cannot be removed without altering the structure of the molecules responsible for the odors which are essentially tar, nicotine, and phenols. Besides thermal incineration, ultraviolet photo-oxidation has proven to be the most effective way to accomplish this by degrading and oxidizing those molecules. Their oxidation render the smoke particles dry and non-sticky which make them acceptable candidates for standard filtration. Care must be taken to adequately engineer the ultraviolet photo-oxidation system with respect to the room size and ventilation rates to keep the potential residual ozone well within the OSHA limit when the treated room becomes free from tobacco smoke.

 

ACKNOWLEDGMENTS

The author is grateful to Francisco Doyon P.Eng. and Grégory Clément P.Eng. for sharing their experimental data on the effect of air ionizers on environmental tobacco smoke inside rooms of various scale.

References

  1. C.N. Davies, Cigarette smoke: generation and properties of the aerosol, J.Aerosol Sci. Vol 19, No.4, pp463-469, 1988.
  2. Hays, Gobbell, Ganick, Indoor Air Quality, McGraw-Hill,1995, p.58.
  3. Spengler, Samet, McCarthhy, Indoor Air Quality Handbook. McGraw-Hill, 2001.
  4. UWaterloo, Bond Lengths and Energies. n.d. Web. 21 Nov 2010.
  5. 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 Ammendments of 1990.
  6. EPA/600/R-92/047, March 1992.

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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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