The novel coronavirus, also known as SARS-CoV-2, is the cause of the disease COVID-19, which has killed 408,025 people worldwide. SARS-CoV-2 is part of the viral group known as “corona” (Latin for “crown” or “halo”) because of the pattern of proteins that stud its surface2. It is estimated that this group of viruses is responsible for 15%-30% of acute respiratory infections each year3. These numbers, however, are subject to rapid change as a result of the current pandemic.
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 virus2. The incubation period of the virus ranges from 2-14 days2. One study identified the median incubation as 5.1 days with 97.5% of patients showing symptoms within 11.5 days3
Bleach 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 genome20. In a study that examined SARS-CoV-2 specifically, it was found that a sodium hypochlorite concentration of 0.1% or 1,000 ppm in water was needed to reduce infectivity when sprayed onto a hard-non-porous surface21. A second study on the same virus found that 0.1% sodium hypochlorite would inactivate the virus within 1 minute. A study on SARS-CoV-1 found that bleach:water concentrations of 1:50 (0.1% sodium hypochlorite) and 1:100 (0.05% sodium hypochlorite) inactivated the virus after an immersion of 5 minutes.
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. 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. 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.
The CDC recommends a solution of 1/3 cup bleach per gallon of water (22mL bleach per L water) with a soaking time of 1 minute for hard, nonporous surfaces. This relatively weak 2% bleach solution and short contact time should not cause damage to scuba regulators.
Soap and Water Washing hands and surfaces with soap and water is one of the most effective ways to protect against the virus. The type of soap used is not important. Washing with soap and water does not necessarily kill microorganisms but physically removes them from a surface. Running water by itself can be effective in removing some unwanted material from surfaces, however, soap will physically pull material from the skin and into the water.
You may ask why soap and water will not work for scuba equipment if it is recommended for hands. Soap and water, as stated above, must be combined with mechanical action to be completely effective. Soaking scuba equipment in soapy water alone is not an effective disinfection method. If soapy water was combined with mechanical action, it would theoretically prove to be more efficient. However, there are some parts of scuba equipment that are not easily reached without disassembly, such as the inside of a regulator. Since an exhaled breath will travel through the inside of a regulator and contact the diaphragm, lever arm, and other internal surfaces, soaking the regulator in a disinfectant solution may be a better option.