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Animal and Plant Health Inspection Service
U.S. Department of Agriculture
USDA FAQ's and resources about coronavirus (COVID-19).  LEARN MORE


Cleaning involves the removal of visible organic and inorganic matter (e.g., soil, dirt, debris, salts, oils, blood) from objects or surfaces. Cleaning is one of the most important steps in the C&D process! When done appropriately, cleaning alone can remove a large percentage of microorganisms. This step also helps improve disinfection efficacy since many chemical disinfectants have reduced effectiveness in the presence of organic material. The cleaning process should be conducted prior to the application of all EPA-registered disinfectants.

The cleaning process can be broken down into four basic steps: dry cleaning, washing, rinsing, and drying.

  1. Dry Clean: Dry cleaning involves the removal of gross contamination and organic material (e.g., soil, manure, bedding, feed) from equipment, objects, or animal areas. Use brooms, brushes, shovels, and manure forks to sweep, scrape, and remove organic material and debris from surfaces. To ensure thorough cleaning, use a systematic approach beginning at the top of the structure and continuing down to the bottom or floor. Pay special attention to corners, crevices or other areas where debris may accumulate. Remove as much gross debris as possible. Air blowers should not be used for dry cleaning due to the risk of spreading pathogens. Suitable personal protective equipment (e.g., masks) should be worn by cleaning personnel if significant dust generation is anticipated during the process. Moistening the areas or items with water may be helpful for controlling dust and minimizing aerosolization of pathogens. The cleaning process may require considerable time and effort, but it is an essential step as debris can harbor microorganisms, reduce disinfection efficacy, or even inactivate some disinfectant products. Disposal of all material should be in a manner that minimizes further spread of microorganisms and is compliant with any Federal, state, or local requirements and policies.

  2. Wash: The second step in the cleaning process is washing. This is one of the most overlooked steps in the C&D process. The physical action of scrubbing with detergents and surfactants helps to further reduce the number of microorganisms as well as removes any oil, grease, or exudates that may inhibit the action of disinfection. Prior to washing, any electrical equipment should be turned off and removed or covered tightly. Contacting an electrician may be necessary for the removal or protection of thermostats, timing devices, motor controls, and remote sensing equipment prior to washing. Wash the item or area by wiping or scrubbing. In larger areas, pressure spraying may be an option; however, in cases of highly infectious or zoonotic pathogens, high pressure systems should be avoided to avoid further dispersal of the pathogen or risk to the applicator. Whenever possible, warm to hot water (90-130°F [32-54°C] or higher) should be used. This can increase washing efficacy; heat may also aid in inactivating some pathogens. Hot water and steam can be effective for cleaning cracks, crevices and the inside of pipework where pathogens are likely to linger. Areas and items with organic material adhered to the surfaces should be pre-soaked for several hours. Rough surfaces should be scrubbed with a stiff brush to ensure that they are cleaned as completely as possible. Deep cracks, crevices, pits, pores, or other surface irregularities should be given particular attention to dislodge accumulated grime; these areas can serve as reservoirs for pathogens.

  3. Rinse: After washing, all surfaces should be thoroughly rinsed, as residues from cleaners and detergents can inactivate certain chemical disinfectants. Rinsing should be done at low pressure with cold water. When the rinsing process is completed, surfaces should be carefully inspected to ensure they are visibly clean. Moisture should spread evenly over surfaces and no “beading” should occur as this would indicate the presence of oil or grease.

  4. Dry: Whenever possible, surfaces should be allowed to dry completely (if possible overnight) before application of a disinfectant. Excess moisture, especially on porous surfaces, may dilute and reduce the efficacy of the disinfectant applied to the surface; it may also harm equipment. Fans or blowers can be helpful to the drying process but should not be used if dealing with highly infectious or zoonotic pathogens.
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