Operational Considerations for Schools | CDC

Cleaning and Disinfection

Personal controls: General recommendations for cleaning and disinfection in schools

Intensify cleaning and disinfection by cleaning staff. Frequently touched surfaces should be cleaned and disinfected at least once a day (i.e., before or after school day), and more frequently when possible. Railings, desks and tables, door and window handles, sanitation (restroom/toilet/latrine) surfaces, toys, teaching/learning aids, and materials used/shared by students (e.g., pens, pencils, art supplies, books, electronics) are examples of frequently touched surfaces.

Cleaning refers to the removal of germs, dirt, and impurities from surfaces. It does not kill germs, but by removing them, it lowers their number and the risk of spreading infection. Removing dirt and impurities also helps disinfectant be more effective.

Disinfecting refers to using chemicals, for example, diluted sodium hypochlorite (bleach), to kill germs on surfaces. This process does not necessarily clean dirty surfaces or remove germs, but by killing germs on a surface after cleaning, it can further lower the risk of spreading infection.

Use a 0.1% solution made from bleach and water (using non-turbid water source) for disinfection. To mix, use the percentage found on the bleach bottle (for example, 5%) and follow these instructions:

Example of making 0.1% solution with 5% liquid bleach:
[5% chlorine in liquid bleach / 0.1% chlorine solution desired] – 1 = [5 / 0.1] – 1
= 49 parts of water for each part liquid bleach
If you are using a 20 L jerry can or bucket to mix, you will need 400 mL of bleach and should fill the rest of the jerry can with water.
20 L / 50 parts = 0.4 L, or 400 mL

[% chlorine in liquid bleach ∕ % chlorine desired] − 1 = Total parts of water for each part bleach

See instructionspdf icon for making 0.1% solution from 0.5% disinfecting solution, 70% high-test hypochlorite (HTH), or 35% chlorine powder.

Cleaning and disinfection procedures:

1) Put on personal protective equipment (rubber gloves, thick aprons, and closed shoes).

2) Mix 0.1% bleach solution using the procedures described above in well-ventilated area.

3) Clean with detergent or soap and water to remove organic matter.

4) Apply the 0.1% solution to the surface with a cloth and allow for a contact time (the amount of time that the disinfectant should remain wet and undisturbed on the surface) of at least 1 minute. Additional disinfectant may need to be applied to ensure it remains wet for 1 minute. After 1 minute has passed, rinse residue with clean water (this will also protect the surface or item from damage).

5) After cleaning and disinfection, carefully remove personal protective equipment (PPE) and wash hands immediately. Re-usable PPE (e.g., aprons) should be laundered immediately.

Cleaning and disinfecting should not take place near children or people with asthma.

Procedures for cleaning and disinfecting various surfaces (hard surfaces, soft surfaces, electronics, and laundry) can be found here.

Administrative and engineering controls: Possibilities for schools

  • Cleaning staff should clean and disinfect frequently touched surfaces at least once a day, or more frequently if possible. If once daily, cleaning and disinfecting can take place either before the school opens or after it closes.
  • School administrators, cleaning staff, and select students should walk through the school together and decide which surfaces are touched frequently by students and staff and therefore should be the target of cleaning and disinfection efforts.
  • Increase ventilation and air flow. Ensure ventilation systems (when present) are working properly. Increase circulation of outdoor air within buildings by opening windows and doors if it is safe to do so.
  • Provide the cleaning staff with cleaning supplies (soap/detergent, bleach, buckets) and PPE specific for the disinfectant to wear when mixing, cleaning, and disinfecting (for example, rubber gloves, thick aprons, and closed shoes). PPE should be used for COVID-19-related disinfection only (cleaning staff should not bring home PPE – it should be stored at the school in a secure, designated area).
  • Provide cleaning staff with information (e.g., written or pictorial instructions) about when and how to clean and disinfect and how to safely prepare disinfectant solutionspdf icon, as described in the leftmost column.
  • If someone becomes sick at school, close off spaces used by the sick person until after they can be cleaned and disinfected. Cleaning staff should wait 24 hours before cleaning and disinfecting, or if 24 hours is not feasible, wait as long as possible.

Materials, activities, and personnel needed for implementation

  • Stocks of soap, bleach, buckets, and other cleaning supplies (e.g., mops, cloths).
  • Designated cleaning staff.
  • PPE for designated cleaning staff (rubber gloves, thick aprons, and closed shoes).
  • Sufficient access to non-turbid water to meet all cleaning and disinfection needs.
  • Instructional materials describing the cleaning and disinfection process, including proper mixing of solutions, for use by designated cleaning staff.
  • Written schedule for increased routine cleaning and disinfection.

Considerations and challenges for schools

If schools use an expanded timetable (e.g., one group of students attends in the morning and another in the afternoon and/or evening), cleaning and disinfection must occur between each session.

There will be costs associated with purchasing the bleach, soap, cleaning supplies, and PPE; printing instructional materials; and possibly having to pay additional staff to clean.

If no rubber gloves are available for cleaning staff, any kind of gloves can be used. If no aprons are available, cleaning staff can wear protective clothing (such as long pants and long-sleeved shirts) that are laundered after each use.

There could be further supply chain constraints on soap, chlorine products, and PPE as demand increases as COVID-19 spreads. Calcium Hypochlorite (HTH) powder or bleaching powder can also be used to mix disinfection solutions if available.

If water supply is not available on site, it will be more challenging and costly to clean and disinfect daily. Water-scarce schools may consider temporary solutions for water provision, such as water trucking.

There is potential for harm to users when making and using disinfection products, so it is important for cleaning staff to be adequately protected when mixing and using disinfectant and trained on how to mix and disinfect.

Note: Large-scale spraying of disinfectant in schools or on school buses is not recommended. There is limited evidence that it is effective. To be effective, disinfectants need to have sufficient contact time and coverage, which is difficult to get when doing large-scale spraying. There is also limited ability to prevent people nearby from the hazards of inhaling disinfectants during large-scale spraying. Additionally, organic matter, like that which is often found on the ground in public places, would need to be removed by cleaning before disinfectants would work effectively

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