Le nouveau coronavirus, également connu sous le nom de SRAS-CoV-2, est à l'origine de la maladie de la COVID-19, qui a tué 87 987 personnes dans le monde au moment de la rédaction de cet article.1Le SRAS-CoV-2 fait partie du groupe viral connu sous le nom de « corona » (couronne ou halo en latin) en raison du motif des protéines qui ornent sa surface.2 On estime que ce groupe de virus est responsable de 15 à 30 % des infections respiratoires aiguës chaque année.3 Ces chiffres sont toutefois susceptibles d'évoluer rapidement en raison de la pandémie actuelle.
COVID-19 spreads via respiratory secretions in a variety of ways including aerosolized droplets expelled by coughing or sneezing, touching surfaces contaminated with the virus, or close contact with someone who has the virus.2 The incubation period of the virus ranges from 2-14 days.2 One study identified the median incubation as 5.1 days with 97.5 percent of patients showing symptoms within 11.5 days.3
Coronaviruses belong to a group of enveloped viruses, which means the virion (the form that the virus takes while outside the host cell) is protected by an oily lipid layer.4 As with most enveloped viruses, damaging or destroying this lipid layer will inactivate the virus. Studies of other coronaviruses have shown their infectivity can be reduced by heat, UV light and alkaline or acidic conditions.5 Because of this, and the fact that enveloped viruses are generally easily inactivated, surfaces can be disinfected using household cleaning products.6
Because research into SARS-CoV-2 is ongoing, there is debate about how long it can survive on surfaces. Recent studies have shown that it can survive up to 3 hours in an aerosol droplet (such as from a sneeze), 4 hours on copper, 24 hours on cardboard, and 2-3 days on plastic and stainless steel.7 In water, however, it is unclear how long SARS-CoV-2 survives. Studies on the SARS virus, called SARS-CoV-1 and the cause of an epidemic in 2003, have shown that it remained infectious for long periods in surface water (lakes, rivers, wetlands, etc.) and previously pasteurized sewage at both low and ambient temperatures.8 In chlorinated or bromated pools and hot tubs, the CDC specifies that SARS-CoV-2 would be inactivated.9
Calor
There is very little data on SARS-CoV-2, and much of it is preliminary. In times like these scientists will look to related but slightly harder-to-kill viruses. In the case of the novel coronavirus, some data reports are based on the SARS-CoV-1 virus because it is more difficult to kill than the novel coronavirus. One study found that the SARS-CoV-1 virus loses infectivity after being heated to 133°F (56°C) for 15 minutes,5 and the World Health Organization specifies this temperature and timing as well.10 Another study found that the SARS-CoV-1 virus remains stable between 40°F (4°C) and 98°F (37°C) and would lose infectivity after 30 minutes at 133°F (56°C).11
Divers Alert Network has received questions about the virus entering a scuba cylinder as a result of contaminated air being drawn into the compressor. During the process of compressing air, using the ideal gas equation T2 = T1 x (P2/P1)(n-1)/n we can calculate that a four-stage compressor with 1 ATA inlet pressure and an 80°F environment pumping air up to 29 ATA or around 4000 psi, would have an inter-stage temperature inside the cylinder of 224 °F. This calculation is very basic and does not account for anything outside of ideal conditions. However, it does indicate the instantaneous temperature at the moment of peak pressure.
En realidad, la temperatura de la válvula de salida probablemente será de 170°F-190°F, y la temperatura del gas alrededor de 150°F, que se producirá durante cada etapa del compresor (es decir, cuatro ciclos para un compresor de cuatro etapas, suponiendo que la temperatura de salida de cada etapa sea la misma). Debido a que esto es definitivamente lo suficientemente caliente como para matar el SARS-CoV-2, por lo tanto, es poco probable que COVID-19 sobreviva a este proceso si una persona infectada tose en la toma de aire del compresor. Es importante tener en cuenta que las gotitas infectadas exhaladas por una persona pueden ser tan pequeñas como 0,5 micrones; los sistemas de filtro por sí solos no las eliminarían, pero el virus debería estar muerto en esa etapa.
It should be noted, however, that if an individual carried the virus on their hands, either as a result of being infected or unknowingly touching an infected surface, and touches the cylinder valve or fill whip, the virus could potentially enter the cylinder through this route. It has been shown that some viruses are extremely pressure resistant — an order of magnitude above diving gas storage pressures. These studies, however, were conducted on noroviruses, a non-enveloped group of viruses that are generally harder to kill than enveloped viruses.12, 13 Other studies conducted on enveloped viruses such as the flu only explored the efficacy of high hydrostatic pressure at 289.6 MPa (42,003 PSI).14 It is therefore very important to practice hand washing and disinfection of high-touch areas including cylinders and fill stations, as it is likely that a virus could survive at diving gas storage pressures.
Compuestos de amonio cuaternario
Quaternary ammonium compounds, or quats, are a group of chemicals that are exceedingly common as active ingredients in cleaning solutions. These agents are hydrophobic and as such are effective against enveloped viruses. Quats are thought to react with the viral envelope and “disorganize” it, leading to the contents of the virus leaking out and degrading. In addition, little evidence exists to support viral resistance against these compounds.15 Studies have shown that quats are effective against SARS-CoV-1,16 and the World Health Organization (WHO) recommends the use of cleaning products containing these compounds in their laboratory biosafety guidance related to coronavirus disease 2019.17
Existen productos que contienen amonio cuaternario comúnmente utilizados en la industria del buceo para desinfectar equipos. Sin embargo, estos compuestos son perjudiciales para el medio ambiente, por lo que se debe tener cuidado en su uso y eliminación.18
Blanqueador
Bleach, or sodium hypochlorite, has been studied in many different concentrations, and its effectiveness against viruses has been proven. It is a strong oxidant that works by damaging the viral genome.19 According to the WHO, the recommended bleach solution for general disinfection is a 1:100 dilution of 5 percent sodium hypochlorite. (Note that some brands of bleach have different concentrations of the active ingredient, such as those that are thickened and marketed to reduce splashing.) This dilution yields 0.05 percent or 500 ppm of the active ingredient and requires a soaking time of 30 minutes if objects are immersed in the solution or at least 10 minutes if sprayed onto a nonporous surface.20 In a study that examined SARS-CoV-2 specifically, it was found that a bleach concentration of 0.1 percent or 1,000 ppm was needed to reduce infectivity when sprayed onto a hard-non-porous surface.21 A second study on the same virus found that 0.1 percent sodium hypochlorite would inactivate the virus within 1 minute. A study on SARS-CoV-1 found that both 1:50 (0.1 percent) and 1:100 (0.05 percent) inactivated the virus after an immersion of 5 minutes.22
When using bleach, the use of gloves, a mask and eye protection is encouraged. Mix the solutions in well-ventilated areas, and use cold water, as hot water will decompose the active ingredient. It is important to never mix bleach with other chemicals and to remove all organic matter from items to be disinfected, as this too will inactivate the active ingredient.21 Items disinfected with bleach must be thoroughly rinsed with fresh water and allowed to dry before use, as it is corrosive to stainless steel (in higher concentrations) and irritating to mucous membranes, skin and eyes.20, 23 Highly concentrated bleach solutions have also been found to be harmful to life-support equipment, causing metal fatigue and in some cases hose failure during the Hart building anthrax attack. As such these solutions are not used by EPA units for dive equipment when effective alternatives exist.
Agua y jabón
Lavarse las manos y las superficies con agua y jabón es una de las formas más efectivas de protegerse contra el virus. El tipo de jabón utilizado no es importante. Lavar con agua y jabón no mata los microorganismos, sino que los elimina físicamente de la superficie. El agua corriente por sí sola puede ser efectiva para eliminar material no deseado de las superficies, sin embargo, el jabón extraerá físicamente el material de la piel y lo introducirá en el agua.24
Nos han preguntado por qué el agua y jabón no funcionan para el equipo de buceo pero sí se recomienda para las manos. Como se indicó anteriormente, el agua y jabón deben combinarse con una acción mecánica. Remojar el equipo de buceo solo en agua jabonosa no es un método de desinfección efectivo. Si el agua jabonosa se combinara con la acción mecánica, teóricamente sería más eficiente. Sin embargo, hay algunas partes del equipo de buceo que no se pueden alcanzar fácilmente sin desarmar, como el interior de un regulador. Dado que una respiración exhalada viaja a través del interior de un regulador y tiene contacto con el diafragma, el brazo de palanca y otras superficies internas, sumergir el regulador en una solución desinfectante puede ser una mejor opción.
Directrices de EPA (Environmental Protection Agency)
No matter the active ingredient or method of disinfecting scuba equipment, proven efficacy against the novel coronavirus is of utmost importance. The EPA’s “List N” is a compilation of products that have proven efficacy against SARS-CoV-1 and will therefore also work to kill SARS-CoV-2. Outside of the United States, local governing bodies may also have registered disinfectants. Following the directions for use for each individual product will ensure its efficacy.
Cuando los fabricantes de productos registran sus productos con EPA, deben enviar una lista de usos para el producto. Es poco común que los productos registrados en la Lista N contengan "buceo"; es más probable que aparezcan en la lista los respiradores o materiales de los que está hecho el equipo de buceo. Al elegir una solución desinfectante de la Lista N, es importante verificar que el registro del producto en EPA especifique su uso para los materiales en cuestión.
Algunos productos comúnmente recomendados por los fabricantes de equipos de buceo se clasifican como desinfectantes de amonio cuaternario registrados con EPA para uso exclusivo en el servicio de alimentos y actualmente no están en la Lista N de EPA. EPA no considera que sean efectivos contra el SARS-CoV-2 cuando se aplica sobre esos materiales y superficies.
Buenas prácticas
When selecting a disinfectant, it is of utmost importance to use a product that has proven efficacy against either SARS-CoV-2 or the harder-to-kill SARS-CoV-1. Consult your local governing body’s pesticide registration system for its list of registered disinfectants if the products specified in the EPA’s List N are unavailable in your area. When using these products, be sure to follow the directions and use the specified personal protective equipment (such as gloves or eye protection) when disinfecting. If registered products cannot be found, be sure to use disinfection protocols outlined by the CDC.
Después de desinfectar el equipo, se debe tener cuidado de no volver a infectarlo, por ejemplo, al manipularlo durante el almacenamiento. Los empleados de las tiendas de buceo deben tener cuidado de mantener una buena higiene al lavarse las manos con frecuencia y desinfectar regularmente las áreas de alto contacto, incluidas las estaciones de llenado (como se describe en la sección "calor" de este artículo).
Finalmente, considere actualizar su plan de acción de emergencia existente para incluir una posible infección COVID-19 por parte del personal o los clientes. Asegúrese de describir todos los protocolos de desinfección y asegurarse de que todo el personal los siga diligentemente. La consideración más importante es la salud y seguridad de su personal y clientes.
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Referencias
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