Disinfecting Surfaces Against Coronavirus
A little good news on the COVID-19 front: yes, you can kill the virus on surfaces, with easily available disinfectants.
Copper surfaces, silver particles, alcohol-based disinfectants, and UV light will kill the virus. Frequently touched items, especially in public places, should probably just be irradiated with UVC light and/or coated with copper as a routine prevention measure.
(Regular UV light is an effective disinfectant but can also blind people and burn skin; UVC is a shorter wavelength, equally effective against microbes but not harmful to eyes or skin.)
Do Copper Surfaces Kill/Inactivate Coronaviruses?
In an experiment with aerosolized SARS-CoV-2 and SARS-CoV-1, at 21-23 degrees C and 40% humidity, both reached undetectable levels within 8 hours exposure to copper; by contrast, they lasted 72 hours on stainless steel and plastic.
H1N1 influenza, which was another pandemic virus, though not a coronavirus, lasted significantly less time on copper than stainless steel; 10^5 viable viruses after 24 hours on stainless steel vs. 10^2 viable viruses after 2 hours on copper.
Human coronavirus 229E remains infectious on plastic, ceramic, glass, and stainless steel for at least 5 days, was inactivated in less than 5 minutes on copper and brass when applied dry, and inactivated in less than an hour when applied in solution to metal alloys containing >75% copper.
Using copper-coated surfaces in real-world environments reduces microbial contamination.
In 5 residential healthcare facilities, where half of the doorknobs and handrails were coated with copper alloys while half were not, the bacterial concentration was significantly (p < 0.0001) lower on the copper-coated doorknobs and handrails.
Similarly, when weights and grips in a gym were coated with copper alloy or left as rubber or stainless steel, the bacterial concentrations on the copper-coated surfaces were 94% lower than the controls.
Silver Ion Zeolites as Anti-Microbial Surfaces
Commercially available silver zeolite powder (AgION powder, manufactured by Sinanen Co.) completely inactivated SARS-CoV at concentrations above 375 mg/L.
Zeolites are fine, talc-like powders that can be incorporated into coatings to produce antimicrobial surfaces; the FDA has approved zeolites for use in food packaging.
In a study of the effect of 7 disinfectant liquids on the SARS coronavirus, including several with >80% ethanol as active ingredient, all of them significantly reduced SARS concentrations, by a factor of at least 1000.
70%+ ethanol was effective at reducing (by a factor of >1000) the infectivity of both SARS and MERS coronaviruses; so was 50%+ 2-propanol, hydrogen peroxide, glutaraldehyde, formaldehyde, and povidone iodine. Chlorhexidine was not effective.
In a study of human coronaviruses 229E and OC43, soap, bleach, and Betadine (povidone-iodine, the active ingredient is iodine) all completely inactivated the viruses.
Axe dishwashing detergent, sodium hypochlorite solution, and the disinfectant Virkon S, all killed SARS-CoV virus by a factor of at least 1000.
Against two coronaviruses, mouse hepatitis virus and transmissible gastroenteritis virus, a solution of 70% ethanol reduced viral infectivity by a factor of >1000; phenolic, sodium hypochlorite, and orthopthalaldehyde did not.
Exposure of SARS virus to UVC radiation for six minutes results in a 400-fold reduction in infectivity. UVA and gamma radiation did not affect infectivity.
Another study of SARS found 1000-fold inactivation from 15 minutes of exposure to UVC.
A study of Ebola virus and MERS virus found that UVC light at >0.1 J/cm^2 reduced infectivity more than 5000-fold in both. Methylene blue plus light at >30 J/cm^2 also reduced infectivity 2000-fold in both.
Far-UVC light (207-222 nm) inactivates bacteria without harm to human skin. It also reduces H1N1 infectivity by 100-fold at low doses: 2 mJ/cm^2.
222-nm far-UVC light applied to a mouse wound where MRSA bacteria had been spread reduced skin bacteria concentrations by >1000-fold, just like 254-nm conventional antimicrobial UV irradiation, but only the 254-nm light increased skin thickness significantly ( a measure of skin damage.)
Written by Sarah Constantin
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