The current standard practice for disinfecting surfaces in healthcare and clean manufacturing facilities is chemical disinfection. It comprises manually wiping surfaces with a chemical solution, such as alcohol, chlorine, or quats.
When performed properly, chemical disinfection is often a very effective way to eliminate microbes from inanimate surfaces. While new chemical disinfectants have been developed over the years, the basic principles have remained somewhat unchanged in the last decades.
However, with the proliferation of multi-resistant hospital bacteria as well as the increasing demands for environmentally sustainable operations, the common old practices are facing a need for change.
This article discusses the weaknesses and limitations of chemical disinfection. We also show how the traditional practice can be complemented with new technology and automation, allowing us to defeat multi-resistant microbes and to reduce the use of toxic chemicals and associated health and environmental burden in many areas.
What is automatic and continuous disinfection?
Automatic disinfection refers to microbial decontamination processes and systems where the need for human input has been brought to a minimum.
The degree of autonomy and necessary maintenance can vary between solutions. Automatic disinfection can comprise automatic chemical dispensing systems, self-disinfecting surface coatings, or different physical methods, such as UVC radiation and visible blue light.
Continuous disinfection means the capability to keep surfaces clean around the clock as opposed to episodic, once per day operation. Examples of continuous disinfection are visible blue light that is either continuously on or switched on and off with a presence sensor. A method that can provide several disinfection cycles during the working day can be considered continuous.
The Spectral Blue by LED Tailor is a continuous disinfection system that uses Multi-Wavelength, High-Intensity (MWHI) antimicrobial blue light (aBL) to decontaminate indoor air and surfaces.
Read here in more detail how the MWHI technology works.
Weaknesses of Manual Chemical Disinfection
Chemical disinfection often works flawlessly in laboratory conditions but falls short in practical use. This is true even in healthcare and hospital environments, where standards for cleanliness are very rigorous.
Its performance suffers from two main problems: human error and long intervals between disinfections.
“Multiple studies have shown that manual cleaning and disinfection of surfaces in hospitals is suboptimal.” (Boyce 2016, pp. 2)
The human error includes factors such as insufficient time for proper work, inadequate staff training, insufficient attention to detail, disregard for contact times with liquids, high staff turnover, and inappropriate handling and storing of supplies. There can be significant individual and organizational differences in how cleaning and disinfection staff can cope with the demanding workload.
Human error can lead to subpar disinfection results and contamination of disinfection equipment and supplies. Some difficult to reach surfaces and spaces can be missed altogether. Chemical disinfectants can be used in insufficient dilutions, or they may not be allowed sufficient time to eliminate microbes. Proper contact times for different chemical disinfectants can range from several minutes to half an hour – times that are often impossible to meet outside laboratory conditions. If not stored and cleaned properly, cleaning equipment like clothes can end up just spreading microbes across surfaces and rooms.
The second problem is that the effect of episodic chemical disinfection does not last. Even if disinfection is performed in the most rigorous way and most microbial contamination is successfully removed, microbial growth resumes immediately afterwards. A quantity of microbial life often survives, and their reproduction continues uninterrupted and at an exponential rate. Also, when people return to the disinfected room, they bring new microbes with them. As a result, it does not take long for the microbe population to reach pre-disinfection levels.
Other problems of chemical disinfection include the leaving of chemical residues on surfaces, which in turn can become a good growth platform for microbes. Additionally, chemical disinfectants often have only one mechanism of action, which means that a certain chemical is good at killing certain kinds of microbes but not all. Chemicals are therefore selective, and you must keep in your arsenal several different chemicals to combat different microbes. The tricky part then is to know which one to use and when.
Because of these weaknesses in chemical disinfection, hospitals and clean manufacturing facilities relying solely on them are under the risk of costly hygiene failures. Especially multi-resistant bacteria are causing difficult infections across European hospitals. These infections could often be prevented with better environmental decontamination. But more chemicals are clearly not the solution.
Health and environmental aspects of chemical disinfection
Another negative aspect with chemical disinfectants is that they are often toxic substances that cause harm to their users and the environment.
Hospital staff with long-term exposure to strong chemicals and fumes have been shown to be more susceptible of developing health issues such as asthma, allergies, skin or lung irritation and COPD. Such health issues can lead to long absences or early retirement, which becomes very costly for our healthcare system.
The production and use of toxic chemicals also negatively impacts the environment. Toxic wastewaters can damage aquatic ecosystems, disturbing the hormonal activity of many species. The regulation of toxic chemicals is also tightening, meaning that organizations must constantly keep up with new rules and maintain documentation of the substances they are purchasing and using.
What benefits can automatic and continuous disinfection bring?
Continuous disinfection of surfaces and spaces addresses both main issues of chemical disinfection. It eliminates the risk for human error and prevents microbial populations from growing back to pre-disinfection levels.
Refer to our science section for peer-reviewed articles on the efficiency of antimicrobial blue light here.
A continuous disinfection system like Spectral Blue provides constant performance and quality 100% of the time, with no user input required. Spectral Blue devices are designed to be installed and forgotten, requiring no maintenance, and keeping your working spaces safe and microbe-free automatically.
Spectral Blue does not miss corners, it does not forget to wash cloths between disinfections, and its efficiency does not vary from day to day.
Continuous disinfection also removes the issue of microbial re-growth between disinfection rounds. As disinfecting action is taking place either regularly or all the time, microbial growth is constantly being interrupted and prevented. Spectral Blue disinfection systems are meant to be used always when the spaces are left vacant, making sure microbes are never being given a chance to grow.
The below graphs show the effect visually. Automatic disinfection with Spectral Blue turns the microbial life curve upside down: With episodic chemical disinfection you get one moment of high hygiene, but re-growth happens fast after the job has been done. With Spectral Blue, microbes are constantly being suppressed with several daily cycles of blue light treatment. Blue light is not as fast as a chemical disinfectant in killing microbes; it might not get everything in one go, but it will first gradually bring the levels down and then keep them down permanently.
Continuous disinfection as complementary strategy
Proper cleaning is always a precondition for any kind of disinfection to work. This is true for chemicals, fogging systems, and light-based systems alike. So far, no automatic system can replace the manual cleaning of surfaces.
For regulatory reasons, automation also cannot yet replace traditional disinfection methods completely. In hospitals, ambulances, laboratories, and cleanrooms, where meticulous cleanliness is rigorously applied, there are rules that mandate the use of certain chemicals.
However, an automatic solution with low operation costs and low maintenance requirements can complement these existing manual routines. Such system can maximize disinfection efficiency by addressing the most serious shortcomings of manual processes. Together, regular disinfection with chemical agents and automatic continuous disinfection with antimicrobial blue light can keep your workspace cleaner and safer than ever before.
Where possible, organizations can also reduce the use of chemicals; often it is enough to clean the surfaces with a detergent, and let blue light do the disinfection. Strong chemical disinfectants can be left as a backup for situations where an instant, strong effect is required, such as disinfecting a hospital room after a patient with a highly infectious disease.
Spectral Blue disinfection system is based on LED devices that emit antimicrobial blue light, which is a proven and safe method of microbial decontamination. The systems can be operated in a completely automatic mode and used continuously without any user input. Antimicrobial blue light can be further complemented with titanium dioxide (TiO2) coating of critical touch surfaces. The coating makes surfaces easier to clean and increases the efficiency of blue light. The coating also allows eliminating an even broader range of microbes, including microbial spores.
Boyce, J.M. Modern technologies for improving cleaning and disinfection of environmental surfaces in hospitals. Antimicrob Resist Infect Control 5, 10 (2016).
Leanse, L.G., dos Anjos, C., Mushtaq, S. Dai, T. Antimicrobial blue light: A ‘Magic Bullet’ for the 21st century and beyond?, Advanced Drug Delivery Reviews, 180, 2022,