Environmental surfaces are more likely to be contaminated with COVID-19 virus in health-care settings where certain medical procedures are performed. These surfaces, especially where patients with COVID-19 are being cared for, must be properly cleaned and disinfected to prevent further transmission.
This advice applies to alternative settings for isolation of persons with COVID-19 experiencing uncomplicated and mild illness, including households and non-traditional facilities.
Transmission of the COVID-19 virus has been linked to close contact between individuals within closed settings, such as households, health facilities, assisted living and residential institution environments.
Community settings outside of health-care settings have been found vulnerable to COVID-19 transmission events including publicly accessible buildings, faith-based community Centers, markets, transportation, and business settings, Although the precise role of transmission and necessity for disinfection practices outside of health-care environments is currently unknown.
Infection prevention and control principles designed to mitigate the spread of pathogens in health-care settings, including cleaning and disinfection practices, must be adapted so that they can be applied in non-health care setting environments.
In all settings, including those where cleaning and disinfection are not possible on a regular basis due to resource limitations, frequent hand washing and avoiding touching your face should be the primary prevention, to reduce any potential transmission associated with surface contamination.
Environmental surfaces in health-care settings include furniture and other fixed items inside and outside of patient rooms and bathrooms, such as tables, chairs, walls, light switches and computer peripherals, electronic equipment, sinks, toilets as well as the surfaces of non-critical medical equipment, such as blood pressure cuffs, stethoscopes, wheelchairs and incubators.
In non-healthcare settings, environmental surfaces include sinks and toilets, electronics (touch screens and controls), furniture and other fixed items, such as counter tops, stairway rails, floors and walls.
Like other coronaviruses, SARS-CoV-2 is an enveloped virus with a fragile outer lipid envelope that makes it more susceptible to disinfectants compared to non-enveloped viruses such as rotavirus, norovirus and poliovirus. 22 Studies have evaluated the persistence of the COVID-19 virus on different surfaces. One study found that the COVID-19 virus remained viable up to 1 day on cloth and wood, up to 2 days on glass, 4 days on stainless steel and plastic, and up to 7 days on the outer layer of a medical mask. Another study found that the COVID-19 virus survived 4 hours on copper, 24 hours on cardboard and up to 72 hours on plastic and stainless steel.
COVID-19 virus also survives in a wide range of pH values and ambient temperatures but is susceptible to heat and standard disinfection methods, Studies, however, were conducted under laboratory conditions in absence of cleaning and disinfection practices and should be interpreted with caution in the real-world environment.
Guidance is intended for health-care professionals, public health professionals and health authorities that are developing and implementing policies and standard operating procedures (SOP) on cleaning and disinfection of environmental surfaces within the healthcare environment.
Principles of environmental cleaning and disinfection
Cleaning helps to remove pathogens or significantly reduce their load on contaminated surfaces and is an essential first step in any disinfection process. Cleaning with water, soap (or a neutral detergent) and some form of mechanical action (brushing or scrubbing) removes and reduces dirt, debris and other organic matter such as blood, secretions and excretions, but does not kill micro-organisms.
Organic matter can impede direct contact of a disinfectant to a surface and inactivate the germicidal properties or mode of action of several disinfectants. In addition to the methodology used, disinfectant concentration and contact time are also critical for effective surface disinfection.
A chemical disinfectant, such as chlorine or alcohol, should be applied after cleaning to kill any remaining micro-organisms.
Disinfectant solutions must be prepared and used according to the manufacturer’s recommendations for volume and contact time. Concentrations with inadequate dilution during preparation (too high or too low) may reduce their effectiveness. High concentrations increase chemical exposure to users and may also damage surfaces. Enough disinfectant solution should be applied to allow surfaces to remain wet and untouched long enough for the disinfectant to inactivate pathogens, as recommended by the manufacturer.
Cleaning and disinfection techniques and supplies
Cleaning should progress from the least soiled (cleanest) to the most soiled (dirtiest) areas, and from higher to lower levels so that debris may fall on the floor cleaned last in a systematic manner to avoid missing any areas. Use fresh cloths at the start of each cleaning session (e.g., routine daily cleaning in a general inpatient ward).
Discard cloths that are no longer saturated with solution, for areas considered to be at high risk of COVID-19 virus contamination, use a new cloth to clean each patient bed. Soiled cloths should be reprocessed properly after each use and an SOP should be available for the frequency of changing cloths.
Cleaning equipment (e.g. buckets) should be well maintained. Equipment used for isolation areas for patients with COVID- 19 should be color coded and separated from other equipment. Detergent or disinfectant solutions become contaminated during cleaning and progressively less effective if organic load is too high; therefore, continued use of the same solution may transfer the micro organisms to each subsequent surface.
Detergent and/or disinfectant solutions must be discarded after each use in areas with suspected/confirmed patients with COVID-19. It is recommended that fresh solution be prepared on a daily basis or for each cleaning shift. Buckets should be washed with detergent, rinsed, dried and stored inverted to drain fully when not in use.
Products for environmental cleaning and disinfection
Follow the manufacturer’s instructions to ensure that disinfectants are prepared and handled safety, Wearing the appropriate personal protective equipment (PPE) to avoid chemical exposure.
Selection of disinfectants should take account of the micro organisms targeted, as well as recommended concentration and contact time, Compatibility of chemical disinfectants and surfaces to be tackled, toxicity, ease of use and stability of the product. Selection of disinfectants should meet local authorities’ requirements for market approval, including any regulations applicable to specific sectors, for example health-care and food industries
Spraying disinfectants and other no-touch methods
In indoor spaces, routine application of disinfectants to environmental surfaces by spraying or fogging (also known as fumigation or misting) is not recommended for COVID- 19. One study has shown that spraying as a primary disinfection strategy is ineffective in removing contaminants outside of direct spray zones, Moreover, spraying disinfectants can result in risks to the eyes, respiratory or skin irritation and the resulting health effects.
Spraying or fogging of certain chemicals, such as formaldehyde, chlorine- based agents or quaternary ammonium compounds, is not recommended due to adverse health effects on workers in facilities where these methods have been utilized Spraying environmental surfaces in both health-care and non- health care settings such as patient households with disinfectants may not be effective in removing organic material and may miss surfaces shielded by objects, folded fabrics or surfaces with intricate designs. If disinfectants are to be applied, this should be done with a cloth or wipe that has been soaked in disinfectant.
Some countries have approved no-touch technologies for applying chemical disinfectants (e.g. vaporized hydrogen peroxide) in health-care settings such as fogging-type applications, devices using UV irradiation have been designed for health-care settings. However, several factors may affect the efficacy of UV irradiation, including distance from the UV device; irradiation dose, wavelength and exposure time; lamp placement; lamp age; and duration of use.
Other factors include direct or indirect line of sight from the device; room size and shape; intensity; and reflection Notably, these technologies developed for use in health-care settings are used during terminal cleaning (cleaning a room after a patient has been discharged or transferred), when rooms are unoccupied for the safety of staff and patients. These technologies supplement but do not replace the need for manual cleaning procedures.
If using a no-touch disinfection technology, environmental surfaces must be cleaned manually first by brushing or scrubbing to remove organic matter, spraying or fumigation of outdoor spaces, such as streets or marketplaces, disinfectant is inactivated by dirt and debris and it is not feasible to manually clean and remove all organic matter from such spaces. Moreover, spraying porous surfaces, such as sidewalks and unpaved walkways, would be even less effective.
Non-health care settings environment
There is no evidence for equating the risk of transmission of the COVID-19 virus in the hospital setting to any environment outside of hospitals. However, it is still important to reduce potential for COVID-19 virus contamination in non-healthcare settings, such as in the home, office, schools, gyms or restaurants.
High-touch surfaces in these non-health care settings should be identified for priority disinfection. These include door and window handles, kitchen and food preparation areas, counter tops, bathroom surfaces, toilets and taps, touchscreen personal devices, personal computer keyboards, and work surfaces. Disinfectant and its concentration should be carefully selected to avoid damaging surfaces and to avoid or minimize toxic effects on household members or users of public spaces.
Environmental cleaning techniques and cleaning principles should be followed as far as possible. Surfaces should always be cleaned with soap and water or a detergent to remove organic matter first, followed by disinfection. In non-health care settings, sodium hypochlorite (bleach) may be used at a recommended concentration of 0.1%.
Personal safety when preparing and using disinfectants
Cleaners should wear adequate personal protective equipment (PPE) and be trained to use it safely. When working in places where suspected or confirmed COVID-19 patients are present, or where screening, triage and clinical consultations are carried out, cleaners should wear PPE: gown, heavy duty gloves, medical mask, eye protection (if risk of splash from organic material or chemicals), and boots or closed work shoes.
Disinfectant solutions should always be prepared in well- ventilated areas. Avoid combining disinfectants, both during preparation and usage, as such mixtures cause respiratory irritation and can release potentially fatal gases, in particular when combined with hypochlorite solutions.
Personnel preparing or using disinfectants in health care settings require specific PPE, due to high concentration of disinfectants used in these facilities and the longer exposure time to disinfectants during the workday. PPE for preparing or using disinfectants in health care settings includes uniforms with long-sleeves, closed work shoes, gowns and/or impermeable aprons, rubber gloves, medical mask, and eye protection (preferably face shield).
In non-health care settings, resource limitations permitting, where disinfectants are being prepared and used, minimum recommended PPE is rubber gloves, impermeable aprons and closed shoes. Eye protection and medical masks may also be needed to protect against chemicals in use or if there is a risk of splashing.