An Overview of Disinfection Methods

By: Dr. Richard Wade, PhD, MPH, R-Zero Chief Scientist

Long-term prevention for COVID-19 and beyond

Since the World Health Organization (WHO) declared COVID-19 to be a global pandemic March 11, 2020,1 organizations have grappled with how–or if–to operate safely going forward. This highly contagious and transmissible disease is unlike anything the United States has experienced in over a decade. While older adults and those with severe underlying medical conditions are at greater risk, a wide range of symptoms from mild or no effects to severe respiratory and cardiovascular illness makes it sometimes hard to detect, but essential to contain. How we’ve dealt with prevention and treatment of the virus has also evolved as new information has come to light. With nearly 8 million cases and 200,000+ deaths  in the U.S. attributed to COVID-19 and no proven vaccine or antiviral therapy, industries must prepare and implement long term infection prevention programs in schools, businesses, and workplaces across the country.

Virus Viability
Understanding how the virus is transmitted is essential for developing a plan for controlling transmission. The viability of COVID-19 differs greatly in air, on various surfaces, and in water. Viral particles have been detected on smooth surfaces such as glass, stainless steel, and plastic up to 6 days after inoculation.2 Airborn (aerosol) viral particles have been detected for up to 3 hours. Previous studies have indicated that the virus has low stability in water and is unlikely to be transmitted through contaminated drinking water3.

How we Pass the Virus 
The primary way COVID-19 is transmitted is through direct, indirect, and close contact with an infectious person coughing, sneezing, talking, or singing and inhaling their respiratory secretions or droplets.4,5,6 Lighter, airborne droplets may remain suspended in the air for up to 3 hours, travelling distances greater than 1 meter.7

The secondary means to catch the virus is by coming in contact with contaminated objects or surfaces and touching your nose, mouth, or eyes.8 The COVID-19 virus can be viable for hours to days depending on the surface they land on. 

Returning to Normalcy Requires Vigilance
Reducing the risk of exposure to COVID-19 in schools, workplaces, and businesses depends on maintaining a vigilant protocol of cleanliness and sanitation. We’ve included a list of the most common methods of disinfection for interior spaces. These, along with proper personal hygiene and the use of PPEs (when necessary) will help control virus transmissions and help the world move forward. 

Cleaning and Disinfection Protocols
Before disinfecting, a routine cleaning with soap and water is recommended in order to remove bulk dirt and germs from surfaces.9 Daily cleaning should be performed on high contact surfaces such as light switches, doorknobs, handrails, desktops, faucets, toilets, and shared equipment. 

Following cleaning, it’s recommended that you disinfect high touch surfaces and objects to kill any remaining viral particles. The EPA keeps a list of hundreds of disinfectant products verified to eradicate the virus when used properly. Surfaces and objects that are infrequently touched do not warrant daily disinfection after cleaning. 

Here’s some of the most commonly used methods of disinfection:

1. Hand wiping with disinfectant

The method:

The most widely accessible method of disinfection is by hand wiping with a disinfectant from the EPA’s approved list. Effective solutions include diluted bleach, ethanol, and other chlorine-based products. Chemical-based disinfection is an effective method that has demonstrated a high rate of success when used properly, breaking the virus’ lipid envelope which surrounds its genetic material. 

Best for:

Smaller areas where attention to detail can be paid and timing is not of the essence.

Considerations: 

  • Hand-applying disinfectants requires adequate contact time on surfaces.
  • Many products are highly toxic when ingested and shouldn’t be used on surfaces where children will be exposed. 
  • Some disinfectants require dilution, mixing, pouring into spray bottles, and aerosolization using sprayers. 
  • Proper training is imperative for the proper application techniques and safe handling of chemicals. 
  • Wearing adequate personal protective equipment (PPE) including masks, respirators, and gloves, may be required when handling certain disinfectants. 
  • Hand-application of disinfectants can be time-consuming and is difficult to conduct in large spaces or in areas with large surface areas. 

2. Fogging or spraying disinfectants

The Method:

Conventional or electrostatic sprayers are a common way to apply disinfectant solutions on surfaces in a large setting. Electrostatic sprayers are handheld machines that apply a positive charge to liquid disinfectants as they are sprayed, which are then attracted to and spread across negatively charged surfaces. So the disinfectant can cover surfaces not normally reached, including the undersides and backs of furniture, stadium chairs, and more. Electrostatic sprayers have been proven more effective than conventional sprayers against a variety of pathogens.10 

Best for: 

An effective solution for sterilizing surfaces in large areas or for many surfaces. 

Considerations:

  • This application method is widely used with hydrogen peroxide (H2O2)-based solutions which have lower toxicity than other widely used disinfectants, but still requires adequate PPE.11 
  • Like hand-application, the efficacy of spraying disinfectants is dependent upon the proper contact time and dilution strength of the individual chemical used.
  • Not as easy to pinpoint smaller areas or surfaces.

3. Ultraviolet Light Disinfection

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The Method:

Used for decades in healthcare settings, ultraviolet (UV-C) irradiation is an efficient disinfection option against viruses, bacteria, fungi and more. Increasingly popular due to its low environmental impact, UV-C irradiation acts against viruses by disrupting their genetic material and rendering it inert. In addition to surface disinfection, UV-C light has been demonstrated to eradicate airborne human droplets at a rate of 99.9% under experimental conditions.12

Best for: 

Spaces of 1,000 square feet or less requiring a fast, easy and non-toxic disinfecting solution

Considerations:

  • UV-C has a very high efficacy rate and can disinfect both surfaces and air. 
  • Minimal application time and effort required. 
  • No chemicals are used, so there are no hazards of chemical residue toxicity, recurring material costs, or disposal requirements.
  • UV-C disinfection does not cause damage to materials or food items, unlike many chemical disinfection methods.  
  • UV-C acts by direct exposure, so infectious viral particles not in the direct line of sight of the UV-C device will not be disinfected. 
  • Additionally, UV-C is only effective at sufficient dose, duration, and distance of application. 
  • UV-C does poses a risk to human health, so UV-C lamps must be used in vacant rooms to avoid exposure and damage. 

4. Other chemical disinfection methods

Several lesser-used disinfection chemicals and methods exist with respective strengths and weaknesses. One method is Ozone (O3) disinfection, which acts by forming reactive hydroxyl (OH) radicals which can destroy viral cell walls and damage viral genetic material.14 Requiring high concentrations to be effective, this solution is highly irritating and toxic to humans, therefore its uses with available technology are limited.15 

5. Additional infection prevention protocols

In addition to thorough cleanings and disinfection regimens, other protocols can be used to further reduce the transmission of COVID-19. The CDC recommends the following: 

  • Occupant density controls, achieved through full or partial tele-work/school schedules, flexible scheduling, and the extension of building operating hours to accommodate staggered work or school shifts. 
  • Physical distancing between building occupants by at least 6 feet limit the spread of potentially infectious respiratory droplets. 
  • Seating arrangements with adequate shielding and distance between people. 
  • Barrier construction or PPE usage should also be implemented. 
  • Detailed communications and enforcement for employees or students about policies and actions to aide in infection prevention (including the above). 
  • The implementation of engineering controls to reduce the transmission of COVID-19 including adjustments to indoor ventilation systems to increase outside air and thereby reduce indoor contaminant concentrations .

Looking forward 

The COVID-19 pandemic continues to pose a major threat around the world. While we all look forward to a time when the threat of the virus has subsided, governments and administrative officials understand the importance of developing and maintaining a comprehensive cleaning and disinfection protocol even after its gone. 

The highest standards for cleanliness will not only help prevent the spread of major viruses such as COVID-19, but also milder agents responsible for yearly cold and flu infections. The fact is, a single recommended solution does not exist by itself, and  methods will vary between industries and settings depending on requirements and circumstances. However, one when combined with a cleaning regimen and administrative controls, including health screenings, daily temperature checks, and proper hand and respiratory hygiene, you will have a good plan to move forward. 

Sources



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Sources:

(1)World Health Organization. (2020, March 11). Coronavirus Disease (COVID-19) – events as they happen. Retrieved September 10, 2020, from https://www.who.int/emergencies/diseases/novel-coronavirus-2019/events-as-they-happen

(2) Chin, A., Chu, J., Perera, M., Hui, K., Yen, H., Chan, M., . . . Poon, L. (2020). Stability of SARS-CoV-2 in different environmental conditions. The Lancet Microbe, 1(1), 10th ser. doi:10.1101/2020.03.15.20036673

(3) Rosa, G. L., Bonadonna, L., Lucentini, L., Kenmoe, S., & Suffredini, E. (2020). Coronavirus in water environments: Occurrence, persistence and concentration methods – A scoping review. Water Research, 179, 115899. doi:10.1016/j.watres.2020.115899

(4) Liu J, Liao X, Qian S, Yuan J, Wang F, Liu Y, et al. Community Transmission of Severe Acute Respiratory Syndrome Coronavirus 2, Shenzhen, China, 2020. Emerging Infect Dis. 2020;26:1320-3.

(5) Kumar, M., Taki, K., Gahlot, R., Sharma, A., & Dhangar, K. (2020). A chronicle of SARS-CoV-2: Part-I – Epidemiology, diagnosis, prognosis, transmission and treatment. The Science of the total environment734, 139278. https://doi.org/10.1016/j.scitotenv.2020.139278

(6) Report of the WHO-China Joint Mission on Coronavirus Disease 2019 (COVID-19) 16-24 February 2020. Geneva: World Health Organization; 2020 (available at https://www.who.int/docs/default-source/coronaviruse/who-china-joint-mission-on-covid-19-final-report.pdf).

(7) How Coronavirus Spreads. (2020, June 16). Retrieved September 15, 2020, from https://www.cdc.gov/coronavirus/2019-ncov/prevent-getting-sick/how-covid-spreads.html

(8) Report of the WHO-China Joint Mission on Coronavirus Disease 2019 (COVID-19) 16-24 February 2020. Geneva: World Health Organization; 2020 (available at https://www.who.int/docs/default-source/coronaviruse/who-china-joint-mission-on-covid-19-final-report.pdf).

(9) United States, Centers for Disease Control and Prevention. (2020). Guidance for cleaning and disinfecting public spaces, workplaces, businesses, schools, and homes. CDC.

(10) Jiang, W., Etienne, X., Li, K., & Shen, C. (2018). Comparison of the Efficacy of Electrostatic versus Conventional Sprayer with Commercial Antimicrobials To Inactivate Salmonella, Listeria monocytogenes, and Campylobacter jejuni for Eggs and Economic Feasibility Analysis. Journal of Food Protection, 81(11), 1864-1870. doi:10.4315/0362-028x.jfp-18-249

(11) NIOSH. (2019, June 21). Hydrogen Peroxide. Retrieved September 16, 2020, from https://www.cdc.gov/niosh/topics/hydrogen-peroxide/default.html

(12) Buonanno, M., Welch, D., Shuryak, I., & Brenner, D. J. (2020). Far-UVC light efficiently and safely inactivates airborne human coronaviruses. Nature, 10, 1-8. doi:10.21203/rs.3.rs-25728/v1

(13) Venkata Mohan, S., Hemalatha, M., Kopperi, H., Ranjith, I., & Kiran Kumar, A. (2020). SARS-CoV-2 in Environment Perspective: Occurrence, Persistence, Surveillance, Inactivation and Challenges. Chemical engineering journal (Lausanne, Switzerland : 1996), 126893. Advance online publication. https://doi.org/10.1016/j.cej.2020.126893

(14) EPA. (1998). Wastewater Technology Fact Sheet Ozone Disinfection. Retrieved September 14, 2020, from https://www3.epa.gov/npdes/pubs/ozon.pdf

(15) ASHRAE. (2020, May). Guidance for Building Operations During the COVID-19 Pandemic. Retrieved September 14, 2020, from https://www.ashrae.org/news/ashraejournal/guidance-for-building-operations-during-the-covid-19-pandemic

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