Guidance for Decontamination of the Built Environment:
Cleaning, Disinfection, Worker Protection, and Post Cleaning and Remediation Assessment
INTRODUCTION AND PURPOSE
The mission of The Cleaning Industry Research Institute (CIRI) is to communicate science-based technical information and peer-reviewed research findings about cleaning and restoration of the indoor environment to all interested stakeholders. Toward that end, CIRI provides this resource guidance document to assist those cleaning professionals currently dealing with building cleanup and worker and occupant protection in the midst of the COVID-19 pandemic, in non-healthcare environments, utilizing targeted health-based cleaning and disinfection practices.
BACKGROUND AND SCOPE
Whether conducting business of a routine nature, or dealing with the challenges of a pandemic, professional cleaners and restorers are responsible for ensuring healthy environmental quality in those indoor places where people spend the vast majority of their time. As professionals, they exhibit: a) a commitment to create a healthy condition; b) the knowledge-based ability and skill to deliver specialized cleaning and restoration services and processes that create a healthy condition; and c) the delivery of effective, health-essential cleaning activities. Such commitment therefore requires the following:
- A well-defined cleaning management structure.
- An effective communications policy and strategy.
- Focused training and reinforcement for cleaning personnel.
- Use of products, equipment, and technology tested for effectiveness and safety.
- Decontamination of all equipment at conclusion of the project.
- The inclusion of cleaning effectiveness measurements.
While the scope of this document focuses on the cleaning and restoration of an indoor environment contaminated with the recently emerged COVID-19 coronavirus, it should be remembered that the core approach to successful decontamination of any environment from any pollutant is an understanding of the definition of Clean: a condition free of unwanted matter, and Cleaning: the process of achieving the clean condition, so human activities can take place in a healthy environment. Thus, a systematic process of cleaning includes: a) understanding the environment to be made free of unwanted matter; 2) identification of the unwanted matter; 3) separation of the unwanted matter from the environment; 4) containment of the unwanted matter; and 5) safe transport and disposal of the unwanted matter.
Epidemiology. This respiratory virus is the 7th Coronavirus to infect humans. Of the other six, four are cold viruses (OC43, HKU1, 229E, NL63), and the other two have caused widespread epidemics: SARS (Sudden Acute Respiratory Syndrome) virus in 2003 and MERS (Middle Eastern Respiratory Syndrome) virus in 2012. Both SARS and MERS originated in wild animals in Asia and the Middle East respectively, mutated and jumped to humans, and were able to continue sustained human to human transmission, resulting in severe lung disease. With both viruses, those most affected were those in close contact with persons exhibiting serious illness. SARS had a case-fatality rate of 15%, while MERS rose to 35%. Similarly, COVID-19 emerged from animals and jumped to humans, with sustained person-to-person transmission, in the fall of 2019 in China.
Biology. Genetically, COVID-19 is closely related to the SARS virus, and almost identical to some animal coronaviruses. It is an enveloped, single-stranded RNA virus, 60-120 nm in diameter, and very efficient at replication inside human lung epithelium cells, especially in the alveolar region deep in the lungs, producing mild to severe respiratory disease, to include fatal pneumonia. While the virus has mutated since emerging in late 2019, there is yet no indication the mutation has led to increased infectivity or more deadly outcomes.
Pathology. The incubation period from infection to disease symptoms is 2-7 days, with some persons exhibiting a longer timeframe, perhaps up to 14 days. COVID-19 disease symptoms include fever (85-90%), dry cough (65-70%), fatigue (35-40%), sputum production (30-35%), and shortness of breath (15-20%). In some individuals, illness may progress to serious disease with extreme shortness of breath, severe chest symptoms, and pneumonia in both lungs. The current case-fatality rate, based upon confirmed cases and deaths, as of early December 2020 is 2.0% for the USA, and 2.3% globally. This is a reduction of rates from earlier in the year. Also, some infected individuals may remain asymptomatic, showing no symptoms, and never become ill. Others may show only mild symptoms, seek no medical help, and fully recover. With both of these groups, there is insufficient data to determine how many of such persons may transmit the virus to others. With those persons who show significant symptoms and seek medical help, it is presumed that each will infect 2-4 other people with whom they come in close contact.
Those persons who are most susceptible to infection and serious resultant disease are those with predisposing risk factors or comorbidities, to include older age (>65), being male, obesity, chronic lung disorders, diabetes, heart conditions, or those who are immunocompromised.
Transmission. Presently, while what is known specifically about mechanisms of COVID-19 transmission is limited, there is a wealth of information available from studies of other respiratory viruses that is applicable to the COVID-19 virus. That includes studies on the transmission of influenza viruses, respiratory syncytial virus (RSV), measles virus, adenoviruses, and perhaps most importantly, the SARS and MERS coronaviruses.
Transmission of the COVID-19 virus from one person to another can occur by the aerosol (inhalation) route, direct contact with respiratory secretions (as in the healthcare environment), or through skin contact transmission via inanimate surfaces (fomites).
- Airborne transmission. Viral aerosols, in the form of droplets expelled by coughing or sneezing, typically consist of a mixture of aggregate viruses, and some mono-dispersed (single) viruses, carried by other materials such as respiratory secretions and/or inert particles, such as airborne dusts. Aerosol size changes as the droplets are aerosolized and exposed to environmental factors (relative humidity, temperature) that favor desiccation or hygroscopicity. Desiccation results in droplets becoming smaller as they dry, and thus are more likely to stay suspended longer in the indoor air flow. Thus, a forceful sneeze may generate as many as 40,000 droplets, most of which can evaporate to particles (droplet nuclei) in the 0.512 µm range (droplet nuclei). Those can be deposited in the upper respiratory region where they may infect epithelium in the nasal passages or mouth. If enough numbers of the virus infect cells and/or an individual has a weak immune system, this infection may proceed to disease in the lungs. In high humidity environments, droplets can become larger and thus fall out faster due to gravity onto surfaces and materials, where they can become airborne again due to various disturbances of those areas, such as someone walking across a hard or carpeted floor, or using a table or desk.
- Fomite transmission. While aerosol infection via droplet nuclei is recognized as a major route of transmission, contact transmission via skin contact with inanimate contaminated surfaces and materials (fomites) may be more significant in the infection process. Infection may occur as hands contact viruses that survive on surfaces or materials, and then fingers touch the nose, eyes or mouth. This raises the question of COVID-19 survival on surfaces, especially as the virus can be protected while embedded in a matrix of respiratory secretions. A 2010 study showed that animal coronaviruses could survive from 5-28 days on hard surfaces, depending upon air temperature and relative humidity (RH). And a recent 2020 study has confirmed that COVID-19 can survive up to 2-3 days on plastic and stainless steel, 4 hours on copper, and up to 24 hours on cardboard. While studies on coronavirus survival on fabric are scant, data has shown survival on cotton cloth for just one hour. Also, it has been established that COVID-19 can survive the typical range of indoor temperatures and relative humidities.
Restoration workers and cleaning personnel engaged in remediation/cleaning activities in nonhealthcare indoor environments where COVID-19-infected persons have been confirmed or suspected, should follow recommended and required protective practices, as put forth in guidance resources of federal agencies such as OSHA and NIOSH, and recognized professional organizations, such as AIHA and ACGIH. Such resources provide the critical guidance and information necessary to reduce exposure risk to cleaning and restoration personnel relative to personal protective equipment (PPE), specific work protocols and practices, and related health and safety training and management. For example, doffing of protective gear following completion of indoor cleaning and decontamination should be done outside of the indoor environment in order to prevent recontamination of cleaned surfaces. And likewise, all equipment used in the remediation process must be appropriately cleaned and decontaminated prior to use in another environment. Adherence to accepted practices and protocols will ensure the protection of cleaning and restoration workers and their families, as well as building occupants.
Principles. Whether the challenge is to decontaminate an indoor environment where confirmed or suspected COVID-19-infected persons were occupants, or as a preventive approach by custodial personnel to reduce potential risk, the approach to both is the same. The effective decontamination of key surfaces associated with infectious agent transmission requires the implementation of two well-defined processes: health-based cleaning, and the application of an antimicrobial pesticide. The premise of health-based cleaning is to clean for health first and appearance second, with the goal to maximize the physical removal of contaminants from surfaces, and reduce the risk of human exposure. When those contaminants are recognized human pathogens, cleaning prepares those surfaces for the application of an appropriate disinfectant to kill or inactivate any residual organisms. Cleaned surfaces are imperative and required for successful disinfection. Effective health-based cleaning reduces the bioburden of microorganisms, as well as removes the bulk of soil and organic matter than may compromise the effectiveness of the disinfection process. Thus, this may involve the traditional two-step approach of cleaning followed by disinfection, or the use of a combined cleaner-disinfectant in a single process. And in all cases, cleaning needs to maintain and preserve the integrity of the surface or material being treated.
Targeted hygiene. For both restoration and custodial personnel, the identification of key high contact touch points as vehicles of transmission, and thus priority targets for cleaning and disinfection, is crucial to the health-based cleaning approach. Such touch points are ones that are frequently touched by human hands, wherein viruses in particular can be deposited by human “carriers”, and maintained until transferred to the non-infected hands of others. Primarily, these are hard surface materials commonly found and touched in everyday life in indoor environments. Typically, these include tabletops, desktops, countertops, door and drawer handles and knobs, elevator buttons, appliance handles and doors (microwaves, refrigerators), vending machine surfaces, copy machines, water fountains, etc. All restroom surfaces may be considered critical, both those that are touched and those that may be contaminated from aerosols, such as those emanating from high pressure toilets and sinks.
Other surfaces, such as walls and floors are lower risk for contact transmission, yet should not be overlooked, especially by restoration personnel, for cleaning and disinfection during a COVID-19 remediation. Fabric materials, such as drapes and curtains should be laundered as appropriate, or otherwise cleaned by HEPA vacuuming, along with upholstered furniture, with additional methods according to established restoration industry standards.
Cleaning of surfaces. Manual cleaning is the most important determinant of quality cleaning, as it combines the effectiveness of a detergent cleaner to emulsify soils and debris and associated microbes, with the physical friction necessary for removal. Fortunately, in regard to COVID-19, it’s a virus with a lipid envelope that renders it very susceptible to dissolution by detergents, which contributes to the virus’s inactivation directly, or by making it very susceptible to the actions of all classes of disinfectants. Cleaning must ensure removal rather than mere shift of microorganisms, as can happen as the cleaning cloth is removed from a surface prematurely, or areas of a surface are missed, or contamination is smeared over a surface due to failure to change cloths frequently. This is critical regardless of whether cotton cloths, microfiber cloths, or other cloths are used, and whether they are disposable or reusable. It is worth noting, however, that an investigation of the ability of 10 different microfiber cloths to remove microbial contamination from three common hospital surfaces (stainless steel, furniture laminate and ceramic tile) under controlled laboratory conditions (microbial suspensions, automated cleaning device) concluded that microfiber cloths are an effective way to reduce levels of nosocomial pathogens in the hospital environment.
Disinfection. Disinfection is the process of killing the majority of human microbial pathogens, or inactivating them so their reproductive capability is disabled. It is a chemical or physical process that reduces the microbial burden by 99.9% (3 log10) or more. Chemical germicides are regulated by the USEPA through an evaluation of product efficacy, and approval of relevant label claims. Such products span a wide berth of disinfectant classes and are required to be used per label directions as to concentration and dwell or contact time. Most have comprehensive microbiocidal claims, such as approval for use against specific viruses, to include a number of human respiratory viruses (e.g. Influenza A, Adenovirus, RSV), appropriate animal surrogate viruses similar to human viruses, or an emerging pathogen claim, that indicates the product can be used against the SARS-CoV-2 (COVID-19) coronavirus. The emerging pathogen claim confirms that the product has: 1) demonstrated efficacy against a harder-to-kill virus (non-enveloped ones such as Adenovirus, Hepatitis A virus, Norovirus); or 2) demonstrated efficacy against another type of human coronavirus, similar to the SARS-CoV-2 virus. The EPA’s List N: Products with Emerging Viral Pathogens AND Human Coronavirus claims for use against SARS-CoV-2, can be found on the agency’s website.
Saturated steam vapor disinfection technology can be utilized in place of chemical germicides for specific applications, such as restroom surfaces, and other non-uniform surfaces whose material integrity won’t be compromised by the high temperature (100ºC). For human pathogenic viruses, research has shown that as temperature increases, the time for viral kill decreases significantly, as shown by complete inactivation of influenza A virus (H1N1) in 14 seconds at 70°C, Coxsackievirus B4 (CVB4) in 5 seconds at 70°C, and both in 1 second at 100°C. Similarly, Herpes simplex virus type 1 (HSV-1) was totally inactivated in 7 seconds at 70°C and in 1 second at 100ºC. Such thermal kinetic data were generated using virus cultures containing various serum/protein elements, which simulates respiratory and other human pathogenic viruses in the indoor environment that are often contained in a similar matrix of saliva and nasal secretions.
Studies have shown that cleaning and disinfection with classically used chemical germicides is often inadequate, and may leave environmental surfaces contaminated with residual pathogens. Thus, if desired, especially as a terminal approach to decontamination in healthcare environments, the use of ultraviolet radiation (UV) or vaporized biocide treatment may be used, both systems of which are commercially available. Modern UV devices provide a means of disinfection that is heavily supported in the literature. The units emit ultraviolet radiation in the C spectrum between the wavelengths of 200 and 320 nm (the biocidal spectrum). And of particular note, are Pulsed Xenon Ultraviolet Light (PX-UV) devices, which have been shown to effectively reduce nosocomial bacterial pathogens in the absence of cleaning. The utility of UV devices is especially useful when disinfecting areas not routinely cleaned, or in disinfecting special areas such as a laboratory or patient room post-occupancy. It can also be useful for an area difficult to clean with a disinfectant, with one study finding that UV light was able to reach and effectively treat many such surfaces, both hard and soft. And the efficacy of a multiple-emitter automated UV-C system was confirmed in a recent study that showed the kill of 5.9 log10 of MERS-CoV human coronavirus in droplets on glass in five minutes of exposure time.
Hydrogen peroxide (H2O2) is an oxidizing agent that produces highly reactive hydroxyl radicals that attack DNA, membrane lipids, and other essential microbial components. As such, gaseous hydrogen peroxide (as an aerosol [aHP] or a vapor system) has been shown to be effective in the decontamination of nosocomial bacterial pathogens. The ideal H2O2 concentration for vaporized hydrogen peroxide (VHP) systems is 35%, while aHP uses a concentration of 5%-7%. The effectiveness of VHP has been confirmed in a number of laboratory studies, and found to be very effective against human influenza A virus, human adenovirus type 2, and transmissible gastroenteritis coronavirus of pigs, a SARS-CoV surrogate. Finally, it is worth emphasizing that alternative treatment modalities such as UV-C and VHP, while shown to be effective for special applications, are typically not feasible for use in routine COVID-19 cleanup situations, especially in non-healthcare environments.
Lastly, any discussion of disinfection must address the fogging or misting of chemical germicide products as an intervention to curb infectious agent transmission via air or surfaces in an indoor environment. In April, 2013 the Director of EPA’s Office of Pesticide Programs sent a letter to all EPA registrants of antimicrobial pesticide products which made claims to provide control of public health microorganisms when applied by fogging and/or misting. The issue was efficacy. The letter then explained why the EPA believes that fogging/misting methods of application may not be adequately effective, and afforded the following rationale:
“Application by fogging/misting results in much smaller particle sizes, different surface coverage characteristics, and potentially reduced efficacy when compared to sanitization or disinfection product applications by spraying, sponging, wiping or mopping.
The absence of pre-cleaning in the presence of soil contamination, potential reaction with or absorption of the active ingredient for different surfaces, and humidity/temperature fluctuations can also impact distribution and efficacy of the product.
A surface treated by fogging/misting does not receive the same amount of active ingredient per unit area as the standard methods of application and, as a result, the level of efficacy actually achieved may not be the same level claimed on the label.”
POST- CLEANING ASSESSMENT
Presently, no methods exist to conduct clearance testing for COVID-19 or any other viruses. However, for some measure of assurance, it is possible to randomly sample hard surfaces to assess whether cleaning and disinfection has achieved an acceptable level of decontamination (to include microbes and associated residues), and determine whether additional cleaning is necessary. This testing can be done using ATP sampling to test random areas of a cleaned structure and compare results with an established baseline of acceptable post-cleaning ATP values previously generated by large numbers of samples across a variety of surface materials common to the indoor environment. If areas are identified that indicate incomplete cleaning, those surfaces would require recleaning. The technology is feasible for post-cleaning assessment, as it is convenient, rapid, and economical, with each sample yielding results in less than one minute.
Background. Adenosine triphosphate (ATP) has historically been used successfully as an important marker for the detection and quantification of pollutant loads of biological origin and overall cleanliness in the food production and food service industries, and has been confirmed as a representative marker for detection of levels of surface contamination in hospital settings. Previous research has also identified the use of ATP marker as a feasible, rapid, real-time, quantitative, and economical approach to the measurement of cleaning effectiveness on a variety of surfaces and materials in school buildings. ATP is the energy driver for biological systems and can be measured through an enzymatic luciferin/luciferase reaction detected and quantified as bioluminescence. The method converts ATP into a light signal that is measured by an instrument that provides a quantitative measurement of ATP from biomass in relative light units (RLUs). Thus, after cleaning and a drop in biomass, there is a corresponding decrease in measurable ATP.
CIRI was established to raise awareness of the importance of cleaning through scientific research, and remains a viable route for promoting and coordinating evidence-based research efforts, and communicating those findings to industry to address critical issues, and work toward the establishment of standard approaches to the achievement of health-based cleaning.
This Guidance is a living document and will be updated as new scientific information pertinent to the cleaning and disaster restoration industries becomes available.
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