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How to disinfect surfaces correctly

Disinfecting surfaces – the right way to do it

| von Julia

For various reasons, it may be necessary to carry out thorough disinfection – both on surfaces remote from the patient and on surfaces close to the patient. We have compiled a compact summary of the methods available for disinfection, how to effectively disinfect surfaces, and what to look out for in various surface disinfection procedures.

Cleaning or surface disinfection?

Although surface disinfection is not infrequently referred to as a step in the cleaning process, the two processes differ significantly from each other. When the term cleaning is used, it refers to the removal of visible soiling and invisible organic material. However, between 10 percent and 90 percent of the germs remain, so that viruses, bacteria and co. can continue to multiply.

Disinfection, on the other hand, ensures that also germs and pathogens are killed and/or inactivated. This can prevent infections in humans. In the case of disinfection, germ reduction is between 84 percent and 99.9 percent, which can apply to surfaces, materials and objects as well as to hands and skin.

In addition, a distinction can also be made between sterilization and disinfection. Sterilization goes one step further and leads to germ reduction or even complete sterility (DIN EN 556). For this reason, sterilization, in contrast to disinfection, can also be referred to as sterilization.

Why is the disinfection of surfaces so important?

Undetected, pathogens can survive for months on surfaces. Not least for this reason, it is elementary in many areas to carry out regular and thorough disinfection.

By the way, according to § 18 of the Infection Protection Act, this necessity is also regulated by law in care facilities and hospitals. The correct interval and optimal procedure depend mostly on whether the surfaces are near or far from the patient.

Patient-remote surfaces

We speak of non-patient surfaces when we are talking about risk areas with no or infrequent hand and skin contact. These include, for example, surfaces with a low probability of contact, low potential contamination with pathogens, and a low degree of clinically relevant susceptibility to infection in relation to patients.

For such surfaces, the required cleaning and disinfection intervals are less frequent, which can be regulated with the help of an individual cleaning and hygiene plan. Typical examples include stairwells, corridors, monitors and chair backs.

Patient-facing surfaces

On the other hand, there are areas close to patients, where there is a significantly higher risk of contamination – which is why stricter regulations and disinfection plans must take effect here to ensure proper disinfection. These areas are defined by frequent skin and hand contact. They are also often the place where aseptic work is performed.

Examples of these are: Examination couches, door and cabinet handles, sanitary areas, bedside tables and work surfaces for preparing syringes and infection solutions, and instrument tables and dressing carts.

Methods of surface disinfection

Not all surface disinfection is the same: When disinfecting surfaces, in addition to different agents, several methods can be used, which are accordingly associated with different advantages and disadvantages.

Wipe or scrub disinfection

Wipe and scrub disinfection now represents the gold standard for disinfecting surfaces. This involves the use of wipes with which the disinfectant can be uniformly distributed over the surface. Since there is no fine atomization of the active ingredient, personnel hazards are reduced to a minimum.

Advantages include thorough and precise work as well as low material consumption, since some cloths and wiper covers can be reprocessed either chemothermally or mechanically thermally. On the other hand, it can be mentioned as a disadvantage that the preparation of the disinfection solution can be associated with more effort and the process is thus generally more labor-intensive.

Spray disinfection

In addition, there is so-called spray disinfection, which is fundamentally inferior to scrub-wipe disinfection, according to the Robert Koch Institute (RKI). Here, the disinfectant is simply applied to the surface with a spray bottle -a convenient and easy application. Due to the high alcohol content, the disinfected surface dries quickly, which can also save time.

A disadvantage, however, is that the high alcohol content can lead to discoloration or a change in the surface of the materials – acrylic glass, for example, quickly becomes milky. In addition, aerosol formation through inhalation can be harmful to health and should be prevented at all costs. This type of application is also quite untargeted.

If spray disinfection is nevertheless applied, although this is no longer so popular, appropriate protective measures must be taken. This always includes personal protective equipment (PPE), which consists of mouth and nose protection, safety goggles and gloves.

Alcohol-based rapid disinfection

In addition, alcohol-based rapid disinfection can also be used. However, this requires that the surfaces to be disinfected are free of impurities and visible contamination: This is because these disinfectants generally tolerate only low levels of soap and protein contamination.

To properly disinfect with this approach, the surface must be kept moist throughout the alcohol’s exposure time and must not be wiped dry. This can sometimes have a negative effect on sensitive surfaces. Alcohol-based rapid disinfection is also not suitable for damp or wet areas, as dilution of the disinfectant could occur.

How do I disinfect correctly?

In order to be able to disinfect surfaces properly and reduce the number of germs and pathogens to a minimum, the correct procedure is particularly important in this process. Thus, attention should be paid to various things in the procedure, ranging from classification of the risk area to the choice of cleaning agent and dosage to the exposure time and storage of the disinfectant.

Determining surfaces to be disinfected: risk areas

Before disinfection can begin, the surfaces to be disinfected must be determined. For this purpose, a list is ideally drawn up that specifies the surfaces and workplaces and makes it possible to document them. Priority should be given to areas that are either exposed to frequent hand and skin contact or are used by a changing group of people.

The RKI also recommends a division into risk areas. This shows how urgent the need for cleaning and disinfection is. This also makes it easier to determine the frequency and scope of these measures. The classification looks as follows:

Risk Location Measures
Without risk of infection e.g. staircases, corridors, technical areas, lecture halls, dining rooms and offices No routine surface disinfection is necessary, so surface cleaning is sufficient
possible risk of infection e.g. treatment rooms in general wards, outpatient clinics, radiology paramedic rooms and rooms for intensive care monitoring While floors and other surfaces must be cleaned, surfaces with frequent hand and skin contact should undergo routine surface disinfection
particular risk of infection e.g. procedure rooms, special intensive care units, neonatology wards and operating rooms Routine disinfection of surfaces should be extended to floors and walls
Risk of infection for personnel e.g. disposal areas or microbiological laboratories Creation of a special cleaning and disinfection plan that is specific and binding for the corresponding areas
Danger of proliferation e.g. isolation and functional areas for the treatment of patients who have certain diseases Proper disinfection is necessary on all surrounding surfaces, which may also extend to the area outside the room

Choice of cleaning utensils

The choice of cleaning utensils should be adapted not only to the area, but also to the disinfection measure. It is important that the removal of the cleaning utensils, e.g. wipes and mop covers, is only done from containers with fresh wiping utensils.

In addition, the so-called cover change procedure must be applied. This means that the cloths or mop covers must not be immersed in the disinfectant solution again after a wiping operation. Otherwise, there would be a risk of contaminating the disinfectant, so that it would have to be poured away completely and used again.

In most cases, a distinction can be made between reusable wipes and those for single use. For routine disinfection procedures, the first variant is to be preferred, since the utensils can be processed mechanically thermally or chemo-thermally – it is sustainable.

For visibly soiled or heavily contaminated areas, on the other hand, disposable wipes are more suitable for preliminary work. The same also applies if the prepared cleaning utensils cannot be stored in a way that prevents microorganisms from multiplying.


Dosage is one of the most important factors when dealing with a disinfectant. If it is chosen too low, effectiveness may be limited. It also increases the risk of microorganism adaptation. Overdosing can not only increase costs, but also attack the material of the surfaces. This is particularly true if there is no compatibility between the disinfectant and the material – this must also be taken into account when dosing and selecting.

In order to ensure exact dosing, disinfectant dosing devices are used in practice. These are decentrally type-tested and can be set very precisely. This also increases the reproducibility of dosing, which would not be as accurate “by hand.” The ideal ratio of water to disinfectant can be found in the manufacturer’s instructions for the agent.

Distribute disinfectant

The procedure for distributing the disinfectant depends largely on whether it is a spray disinfection or a wipe-scrub disinfection. The work steps can be stated as follows for spray disinfection:

  • Donning PPE: Since there is a risk of inhaling aerosols during spray disinfection, care must be taken to wear suitable protective clothing before starting. Especially a mouthguard should be included.
  • Spraying the disinfectant: The disinfectant is applied to smaller surfaces with a spray bottle, working as close to the surface as possible. Likewise, a suitable ventilation is to be ensured.
  • Distribution: If possible, the surface should be wiped until it is completely wetted. Only then can it be ensured that all areas have been covered.

For a wipe-scrub disinfection, on the other hand, the optimal procedure is as follows:

  • Donning PPE: For a wipe-scrub disinfection, gloves are usually sufficient to protect against the disinfectant.
  • Preparation of the use solution: The use solution should be freshly prepared before each surface disinfection. Both material compatibility and the correct dosage must be observed.
  • Application of the disinfectant: The wipe must then be soaked in the disinfectant, for which it can be quite simply immersed. This is followed by an even mechanical distribution on the surface. After that, the wipe must not be dipped again to prevent contamination of the solution of use. Instead, the reference change procedure must be used. In addition, it must be ensured that the surfaces are completely wetted.

Procedure in case of massive contamination

If, on the other hand, massive contamination has occurred, a simple wipe-scrub disinfection is usually no longer sufficient. This may be the case, for example, if blood, pus or other bodily fluids have come into direct contact with the surface.

In such cases, the visible organic material must first be absorbed with a disposable cellulose cloth. This must be soaked with a suitable disinfectant. Only after this cellulose cloth has been disposed of can the usual disinfection be carried out according to a known scheme. This prevents the contamination from being spread further – instead of being banished directly.

Reaction time

In order for pathogens and germs to be sustainably killed or inactivated, the selected disinfectants must act for a certain time. The exposure time can vary greatly and depends on both the manufacturer and the ingredients of the agent.

Therefore, the manufacturer’s information or the information on the product packaging should always be taken into account when using the product. According to the RKI, the dosage in areas close to the patient and in the operating room must be selected in such a way that the 1-hour value can be adhered to – the dilution and concentration must be selected in such a way that they can develop their full effect within one hour of exposure time.

Reuse of surfaces

According to the RKI, surfaces can be reused once the disinfectant has visibly dried. It follows that many areas may be walked on or touched again even if the actual exposure time has not yet completely elapsed. But even here there are exceptions to the rule – so changed specifications apply if one of the following cases have occurred:

  • The disinfection was carried out as part of an officially ordered decontamination.
  • It concerns surfaces close to the patient, where a transition of the microorganisms into a wound would be possible (such as the bed of a wound patient).
  • Disinfection could be terminated by water running in (for example, bathtubs used in obstetrics or used by patients with wounds).
  • The surfaces must be rinsed with drinking water after disinfection, as they may come into contact with food, for example.

Tip: Note incompatibilities

Not every disinfectant is the same. Thus, different disinfectant ingredients are used, which may also differ between types of disinfectants. Therefore, it is elementary to look for any incompatibilities before use.

As a good example, the two groups of active ingredients amines and aldehydes do not get along with each other. The combination leads to a chemical reaction that can result in irreversible brown stains and discoloration. While disinfectants containing aldehydes are used for surfaces and instruments, amines are found in agents for floor disinfection.

If both variants are used in the same area, it is likely that one agent will drip onto the floor and come into contact with the other, activating the chemical reaction. Therefore, it is recommended to rely on a suitable combination of the active ingredients of both disinfectants or on intermediate cleaning with a suitable detergent to prevent corresponding damage. The same also applies to chlorine disinfectants.

Disinfectant storage

Every disinfectant comes with an expiration date, so disinfectant may well expire. Once this date is reached, effectiveness can no longer be guaranteed. The same also applies if the agent has not been stored properly.

Therefore, care should be taken during storage to prevent both strong heat and direct sunlight. Frost must also be excluded. For storage, only suitable and labeled containers should be used, which can be closed again airtight after each use.

Surface disinfection: central terms and measures

Which procedure and which interval are most useful for disinfection always depends directly on the situation in question. Consequently, at the beginning there is the question – what should be disinfected? In principle, routine disinfection can be distinguished from targeted surface disinfection and final disinfection. In addition, disinfection ordered by the authorities is a special case.

Routine disinfection

Routine disinfection can always be said to be a preventive or prophylactic measure. In particular, surfaces close to patients must be disinfected at regular intervals in order to significantly contain the spread of pathogens and germs.

Routine disinfection focuses on surfaces with frequent skin and hand contact as well as those that come into contact with a potentially contaminated material, such as door handles, bedside tables, and bed frames. Typically, wipe disinfection or wipe-scrub disinfection is used for this purpose so that surfaces can be reused immediately after drying.

Targeted surface disinfection: when pathogenic viruses occur

It becomes somewhat more targeted when contamination with pathogenic viruses has occurred or the contamination becomes directly visible. This may be the case, for example, if the surface has come into contact with blood, pus, and/or other body fluids or the occurrence of viruses cannot be ruled out.

In such cases, all contaminated areas are cleaned by wiping or wipe-scrub infection, and the disinfectant selected must be matched to the effect spectrum of the pathogenic virus. For example, if it is the well-known norovirus (Clostridioides difficile), the disinfectant must be appropriately virucidal. Soaked disposable wipes are used as the cleaning agent.

The disinfected surface may be used again once the contact time specified by the manufacturer has elapsed. Drying is also permitted as long as this does not result in renewed contamination.

Final disinfection

Final disinfection or final disinfection refers to the preparation of areas and/or rooms after a patient care or treatment has been performed there. This refers in particular to patients with known infections or diseases or pathogens. This disinfection can ensure that there is no longer a risk to subsequent uses of the premises.

Final disinfection is performed on all those areas that are or could be contaminated, which is why it also includes the floor and walls. Again, wipe disinfection with bactericidal, levurocidal and virucidal disinfectants is used. Depending on the type of infection or disease, an extended spectrum of activity should be used.

Disinfection in case of decontamination (ordered by authorities)

Disinfection during decontamination is a special case, because it is ordered by the authorities according to § 18 paragraph 1 of the Infection Protection Act (IfSG). It serves both to prevent and to contain outbreaks of notifiable and communicable diseases.

If such a disease is suspected and/or detected, all surfaces must be treated in the same way as for final disinfection. In addition, areas outside the patient’s room or the treatment room should also be included – in other words, practically all surfaces that are to be classified as possibly contaminated. Only agents and procedures on the Disinfectant List of the RKI may be used in such disinfection.

Visible organic material must be removed with a soaked disposable wipe before wipe-scrub disinfection can begin. The IfSG regulates the specified exposure time and the earliest possible reuse of surfaces.

Disinfecting surfaces is essential in many areas

To prevent the spread of pathogens and germs, appropriate disinfection is not only sensible but also mandatory in many areas. Both the selection of a suitable agent and the correct procedure are elementary. Optimal disinfection of surfaces increases protection and safety for all involved.

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