Disinfection of diving equipment and COVID-19
The novel coronavirus, also known as SARS-CoV-2, is the cause of the disease COVID-19, which killed 87,987 people worldwide at the time of this article (1). SARS-CoV-2 belongs to the viral group known as “corona” (Latin for “crown” or “halo”) due to the pattern of proteins that study its surface area (2). It is estimated that this group of viruses is responsible for 15 to 30 of the acute respiratory infections each year (3). However, these figures may change rapidly due to the current pandemic.
COVID-19 spreads through respiratory secretions in various ways, including aerosolized droplets emitted by coughing or sneezing, touching surfaces contaminated with the virus, or having close contact with someone who has the virus (2). The incubation period of the virus ranges from 2 to 14 days (2). One study identified median incubation as 5.1 days, with 97.5 of patients showing symptoms within 11.5 days (3).
The Divers Alert Network has received questions about the virus entering a submersible bottle because contaminated air has been sucked into the compressor.
Coronaviruses belong to a group of enveloped viruses, i.e. virion (the form that the virus takes outside the host cell) is protected by an oily layer of lipid (4). As with most enveloped viruses, the virus is inactivated by inactivating or destroying this layer of lipid. Studies on other coronaviruses have shown that their infectivity can be reduced by heat, UV light and alkaline or acidic conditions (5). Due to this and the fact that enveloped viruses can generally be easily inactivated, surfaces can be disinfected with household cleaning agents (6).
As research on SARS-CoV-2 is not yet complete, discussions are underway on how long it can survive on surfaces. Recent studies have shown that it can survive up to 3 hours in an aerosol droplet (e.g. by sneezes), in copper 4 hours, in cardboard 24 hours and in plastic and stainless steel 2-3 hours (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 waters (lakes, rivers, wetlands, etc.) and previously pasteurized wastewater at both low levels and ambient temperatures (8). In chlorinated or brominated pools and hot tubs, the CDC states that SARS-CoV-2 is inactivated (9).
There is very little data on SARS-CoV-2, and many of them are preliminary. In times like these, scientists will look for 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 its infectivity after being heated to 56 ° C for 15 minutes (5), and the World Health Organization also specifies this temperature and time (10). Another study found that the SARS-CoV-1 virus remains stable between 40° F (4°C) and 98°F (37°C) and loses infectivity after 30 minutes at 133°F (56°C) (11). .
The Divers Alert Network has received questions about the virus entering a submersible bottle because contaminated air has been sucked into the compressor. During the compression process of air, we can calculate, using the ideal gas equation T2 = T1 x (P2 / P1) (n-1) / n, that a four-stage compressor with 1 bar input pressure and an ambient temperature of approx. 26° C when compaction of air to approx. 275 bar/ 4000 psi a temperature between the steps in the cylinder of approx. 170. This calculation is very simple and does not take into account anything outside the ideal conditions. However, it indicates the current temperature at the time of peak pressure.
In reality, the outlet valve temperature will probably be about 75°C to 80°C and the gas temperature will be about 65°C, which occurs during each stage of the compressor (i.e. four cycles for a four-stage compressor, provided the outlet temperature of each stage is the same). Since this is definitely hot enough to kill SARS-CoV-2, it is therefore unlikely that COVID-19 will survive this process if an infected person coughs into the compressor intake. It is important to note that infected droplets exhaled by a person can be only 0.5 microns; The filtering systems alone would not remove them, but the virus should already be dead at this time.
However, it should be noted that the virus may enter the cylinder if a person carries the virus on their hands. Either as a result of an infection or if it unknowingly touches an infected surface and the bottle valve or the filling whip touches the route. It has been shown that some viruses are extremely pressure-resistant – an order of magnitude above the storage pressure of submersible gases. However, these studies were carried out on noroviruses, a non-enveloped group of viruses that are generally more difficult to kill than enveloped viruses (12, 13). Other studies conducted on enveloped viruses such as influenza only investigated the efficacy of high hydrostatic pressure at 289.6 MPa (42.003 PSI) (14). It is therefore very important to practice hand washing and disinfecting areas with high contact, including bottles and gas stations, as it is likely that a virus can survive at submersible gas storage pressure.
Quaternary ammonium compounds
Quarterary ammonium compounds or quats are a group of chemicals that are extremely common as active ingredients in cleaning solutions. These agents are hydrophobic and as such effective against enveloped viruses. Quats are thought to react with the virus envelope and “disorganize” it, causing the contents of the virus to leak and deteriorate. In addition, there is little evidence of virus resistance to 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 detergents containing these compounds in their laboratory biosafety guidelines for coronavirus disease 2019 (17).
There are quaternary ammonium-containing products that are commonly used in the diving industry to disinfect equipment. However, these compounds are harmful to the environment and caution should therefore be exercised when using and disposing of them (18).
Bleaching agent or sodium hypochlorite has been studied in many different concentrations and its effectiveness against viruses has been proven. It is a powerful oxidizing agent that damages the viral genome (19). According to the WHO, the recommended bleaching solution for general disinfection is a 1: 100 dilution of 5 sodium hypochlorite. (Note that some bleach marks have different concentrations of the active substance, such as those that are thickened and marketed to reduce spraying.) This dilution yields 0.05 or 50 ppm of the active ingredient and requires a soaking time of 30 minutes for objects to be immersed in the solution or at least 10 minutes when sprayed on to a non-porous surface (20). In a study specifically examining SARS-CoV-2, it was found that a bleaching concentration of 0.1 or 1,000 ppm was required to reduce infectivity when spraying on to a hard, non-porous surface (21). A second study with the same virus found that 0.1 sodium hypochlorite would inactivate the virus within 1 minute. A study of SARS-CoV-1 found that both 1:50 (0.1) and 1:100 (0.05) inactivated the virus after immersion for 5 minutes (22).
When using bleach, the use of gloves, a mask and eye protection is recommended. Mix the solutions in well-ventilated areas and use cold water as hot water decomposes the active ingredient. It is important never to mix bleach with other chemicals and to remove all organic matter from objects to be disinfected, as this also inactivates the active ingredient (21). Objects disinfected with bleach must be thoroughly rinsed with fresh water and left to dry before use, as they are corrosive for stainless steel (in higher concentrations) and irritate mucous membranes, skin and eyes (20, 23). It was also found that highly concentrated bleaching solutions are harmful to life-sustaining devices and cause metal fatigue and, in some cases, hose failure during the hart-anthrax attack. Therefore, these solutions are not used by EPA units for diving equipment if effective alternatives exist.
Soap and water
Washing hands and surfaces with water and soap is one of the most effective methods of protecting against the virus. The type of soap used is not important. Washing with water in connection with soap does not kill microorganisms, but physically removes them from a surface. Running water alone can help remove unwanted material from surfaces. The soap physically pulls any material from the skin into the water (24).
Divers Alert Network was asked why soap and water don’t work for diving equipment when recommended for hands. Soap and water must be combined with mechanical action as indicated above in order to be fully effective. Soaking the diving equipment in soapy water alone is not an effective method of disinfection. Combining soapy water with mechanical effect would theoretically prove more efficient. However, there are some parts of the diving equipment that are not easy to reach without disassembly, such as the inside of a regulator. Since an exhaled breath passes through the interior of a regulator and has contact with the membrane, the lever arm and other inner surfaces, it may be better to place the controller in a disinfection solution.
Irrespective of the active substance or the method for disinfecting the diving equipment, the proven efficacy against the novel coronavirus is of the utmost importance. The EPO’s “List N” is a collection of products that have proven effective against SARS-CoV-1 and will therefore also contribute to the killing of SARS-CoV-2. Outside the U.S., local government agencies may also have registered disinfectants. Following the instructions for use for each individual product ensures its effectiveness.
When product manufacturers register their products with the EPO, they must submit a list of uses for the product. It is unusual for registered products to include “Diving” on list N. Respiratory masks or materials that make up the diving equipment are more likely. When selecting a disinfection solution from list N, it is important to verify that the Epa registration of the product indicates the use for the materials concerned.
Some products that are usually recommended by manufacturers of underwater breathing apparatus are classified as quaternary ammonium disinfectants registered with the EPA only for use in the food sector and are not currently on the EPA’s List N. The EPA does not consider them to be effective against SARS-CoV-2 when applied to these materials and surfaces.
When selecting a disinfectant, it is extremely important to use a product that has proven to be effective against SARS-CoV-2 or the hard-to-kill SARS-CoV-1. The list of registered disinfectants can be found in your local authority’s pesticide registration system if the products listed in EPA List N are not available in your region. When using these products, be sure to follow the instructions and use the specified personal protective equipment (e.g. gloves or eye protection) when disinfecting. If registered products cannot be found, be sure to use the disinfection logs described by the CDC.
After disinfection of the devices, care must be taken to ensure that the devices are not re-infected, e.g. by handling them during storage. The staff of the dive shop should ensure that hygiene is disinfected by frequent hand washing and regular disinfection of areas of high contact, including petrol stations (as described in the “Heat” section of this article).
Finally, consider upgrading your existing contingency plan to include a potential COVID-19 infection by employees or customers. Make sure that you outline all disinfection logs and ensure that they are carefully followed by all employees. The most important consideration is the health and safety of your employees and customers.
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