25. 03. 2020
Prague, 25 March 2020 – The Prague Public Transit Company (DPP) has started the process of cleaning and coating the interiors of its metro trains running on line B with the “CleanShield Indor Coating TiO2” broad-spectrum disinfectant, which effectively kills 99.9% of viruses, bacteria, fungi and molds. The key active ingredient is the chemical titanium dioxide (TiO2) and the declared effectiveness of the protective polymer layer is for up to two years. DPP will also progressively disinfect trains running on metro lines A and C. Tonight, DPP will simultaneously start to apply this polymer disinfectant to its buses and trams. All 146 DPP metro trains are expected to have been disinfected by mid-April, with the disinfection of the other vehicles that make up the public transport system expected to be completed by the end of April at the latest. DPP will thus be one of the first transport companies in the former Czechoslovakia to have its entire vehicle fleet fully disinfected with this latest nano-technology product, using TiO2 polymers with long-lasting antibacterial, antiviral and antifungal effects.
This titanium-dioxide nanopolymer disinfectant is systematically applied to all interior surfaces of the vehicle in aerosol form, treating ceilings, side walls, glass, doors, seats, handrails and restraint systems, i.e. all areas that people touch or where microorganisms could settle. Thanks to the natural fallout of the aerosol, the car floor is also disinfected. It takes at least an hour to treat the inside of a 100-meter long metro train consisting of 5 carriages. The vehicle must be first cleaned conventionally and free of graffiti prior to the application of the nanopolymer. After disinfection, the vehicle must stand and be allowed to vent into the atmosphere for at least another two hours to form the thin, hydrophobic layer of titanium dioxide polymers, which cures into its final, and fully effective form, over the next two days.
By both regular cleaning and the use of these 21st century technologies for long-term disinfection purposes, DPP will be able to maintain the cleanliness of all public transportation vehicles. These latest trends in cleaning and disinfection are both efficient and long-lasting. They are designed to be both effective and to increase our passengers feeling of safety and well-being, important quality parameters not only in these current difficult times but also in looking ahead into the future. In its selection process for this new technology, DPP considered the long-term effectiveness of the product itself, its good international reputation and the fact that it was now being used by other transportation companies. It was also impressed by the speed and ease-of-use characteristics of the product. Other considerations included the benefits of the new product to both passengers and DPP employees. And, in terms of its impact on existing cleaning procedures, this new technology should be able to streamline and simplify requirements and ultimately reduce overall costs. The effectiveness of the new technology will be verified by means of control swabs, which will be taken every 6 months from 10 randomly selected trams, 10 buses and 10 metro cars. If it is found that the product fails to meet its declared warranties, DPP will require repeated disinfection of the cars at the manufacturer’s expense.
This nanopolymer disinfection process will be taking place through the end of this week at the Zličín depot; and, starting next week, DPP will begin using it on line A trains at the Hostivař depot.
As the last, the M1 trains, which are operated on line C, will be both ozone disinfected, as well as conventionally cleaned, at the Kačerov depot. All 146 metro trains are expected to have been protected with this CleanShield titanium dioxide disinfectant by about mid-April. Once a train has been disinfected with these nanopolymers, passengers will be able to recognize it by the circular sticker with the words, “Zdravé prostředí – Vyčištěno technologií TiO2” (Healthy Environment - Cleaned with TiO2 technology). In addition to the disinfecting of the interior of the metro trains, DPP plans to apply this new technology to all escalator handrails.
On 25.3.2020, DPP will also begin a parallel effort at the tram Žižkov depot and in the bus Vršovice garages with the application of this polymer-based disinfectant to buses and trams. Unlike the disinfection process being used on the metro trains, the buses and trams will only be disinfected at night, starting around 10:00 p.m. – i.e. after returning to their depots. Here the process involves PolyHMG fogging of the vehicles with the cationic polymer polyhexamethylenguanidine. By use of this thick fog, the entire interior surface of the vehicle is coated with the active disinfectant. After the moisture (water) has been vented and evaporates, an ultra-thin polymer protective layer is formed on the surface. It takes about 10 minutes to treat a single vehicle with this technology.
According to the provided certifications, PolyHMG has a biocidal activity life of 21 days, after which time, it needs to be reapplied. DPP decided to use this shorter duration on its trams and buses in order to have its entire fleet (metro, trams and buses) nanopolymer disinfected as quickly as possible. The previous means of disinfecting by conventional means, e.g. using chlorine, lasted only a matter of tens-of-minutes and cleaning using ozone lasted just a few days, depending on the number of passengers. On completion of the disinfection of the metro trains and the expiration of the 21 days of PolyHMG protection of its buses and trams, DPP plans to treat all of its surface transport vehicles with the same titanium dioxide nanotechnology it has used on its metro trains. This should provide its entire vehicle fleet with the declared 2-year biocidal protection.
How does the titanium dioxide protective layer work?
CleanShield contains, in addition to water and alcohol, a 2% solution of titanium dioxide nanoparticles and other additives. It is produced in Denmark. Upon evaporation of the water and alcohol, the active ingredient forms a hard, colorless, hydrophobic polymeric coating on the treated surfaces. It forms an irregular lattice structure that repels water and all aqueous solutions. Its thickness is about 1/20th of that of a human hair. The active substance on the treated surface prevents the formation of deposits, resists pollutants and colonization by microorganisms, molds and fungi. At the same time, it has a biocidal effect on all microorganisms, eliminating gram-negative and gram-positive bacteria, fungi, molds and yeasts, including their spores, and 99.9% of viruses. It destroys Streptococcus strains, breaks down endotoxins and removes odors. The manufacturer states that this antimicrobial activity continues for up to two years with abrasion resistance at 150,000 repetitions. The product is certified for safety and efficacy by authorities from Denmark, Germany, Italy and other countries and it complies with all European directives and regulations on safety and health protection.
Advantages of Titanium-Dioxide Polymer Protection
Unlike ozone or chlorine-based products, CleanShield titanium dioxide is non-corrosive, non-toxic to higher organisms (plants, animals or humans), non-volatile, non-mutagenic and non-carcinogenic. It is odorless and tasteless. It has the ability to break-down and decompose bio-films and, thanks to its self-cleaning properties, it reduces cleaning time, respectively by 30 - 50%, depending on the type of surface. Due to its declared efficacy, it significantly reduces the risk of biological contamination of surfaces. Last but not least, it is a natural product.
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