Automatic Sanitization for Transportation Industry (part 2)

INTRODUCTION

In light of the recent events related to the spreading of the COVID-19 epidemic, one of the measures that all railway and metropolitan transport operators are facing concerns the sound public health management as well as the indoor spaces routine cleaning, disinfection and sanitizing of common areas.

As far as the latter is concerned, AYES is committed to render assistance and provide concrete guidelines for defining, developing and deploying suitable systems capable of performing effective sanitizing tasks.

MEASURES TO COPE WITH VIRUSES

As a follow up to our previous article on this topic, other measures considered as effective with regards to limiting virus spreading, according to Italian ISS COVID 19 Report n. 25/2020 of 05.15.2020 are:

-         Treatment with ozone;

-         Treatment with vaporized hydrogen peroxide;

-         Treatment with UV.

Below, we will focus on the latter two treatments, considering all the advantages and disadvantages of each. 

Sanitization with H202 V-Form

What is Hydrogen peroxide?

FIGURE 1 - HYDROGEN PEROXIDE

This substance was discovered in 1818 by Thénard and is found naturally in milk, honey, and ordinary tissues of normal cell function. Hydrogen peroxide kills by oxidation that occurs when an atom loses electrons.

Advantages: High efficacy, Rapid activity, Monitoring capability, Low cost.

Limitations: Material compatibility, Penetrability, Toxicity, Technique Sensitive, Storage.

The advantages of H2O2 are its relatively efficient application. It’s controllable usage and residue-free decomposition a give it a positive environmental balance and its chemical properties make it a powerful decontaminant.

Potential risk is that contact with increased concentrated levels of H2O2 can lead to skin burns and is particularly harmful when inhaled as vapour, which can lead to long-term damage to the respiratory organs. All these disadvantages and risks must be considered. Limit of exposure is 1ppm in the short term.

Overall good compatibility with all materials used in train interior: this helps the product to maintain a perfect functionality during all product life.

FIGURE 2 - H202 V-FORM MATERIAL RESISTANCE

Sanitization with UV-C

UV light is a concrete alternative to chemical disinfection products.

Ultraviolet (UV) light decontamination system is a novel technology that may supplement standard cleaning practices and potentially further reduce the transmission of pathogens.

UV light covers a wavelength spectrum from 100 to 380 nm and is subdivided into three regions by wavelength: UVA (320 to 400 nm), UVB (280 to 320 nm), and UVC (200 to 280 nm). Among them, UVC has the strongest germicidal effect and is widely used in the form of mercury lamps to disactivate microorganisms.

FIGURE 3 – THE SPECTRUM OF LIGHT

The radiation warps the structure of the pathogen’s genetic material and prevents the viral particles from making more copies of themselves.

To achieve maximal efficacy, it is suggested that UV light devices should be utilised in multiple locations within public transportation. To ensure staff and patient safety, it is recommended that all personnel should be cleared from the room before use and that the room be closed to entry for the duration of the UV light application.

FIGURE 4 – UV-C TRAIN USE CASE

UVC light, when used in appropriate environments and according to UV-C dose & log reduction, can reduce the growth of the coronavirus and take the pressure off employees who currently disinfect rooms and surfaces manually.

FIGURE 5 – UV-C DOSE AND LOG REDUCTION

To complete a discussion about innovative systems of sanitization special attention must also be given to other forms of sanitization. Such a strategy should provide for the following treatments:

Sanitization with Dry Vapor Steam

Using temperatures of 80 °C (176 °F) or higher on contact surfaces is known to remove most bacteria and inactivate most viruses. With extended exposure times from a few seconds to 30 minutes (depending on the pathogen) even at 60 °C (140 °F), temperature is able to remove or inactivate pathogens.

The World Health Organization recognizes viral inactivation by heat and recommends boiling drinking water in regions where communicative diseases are common.

Dry vapor steam is proven to both clean and sanitize and is capable of disinfecting in controlled environments where lethal temperatures can be guaranteed.

FIGURE 6 – DRY VAPOR STEAM PENETRATION

Electrostatic Spray Technology

Electrostatic spray technology is a new way to apply cleaners, sanitizers, and disinfectants to help facilities treat surfaces, often in less time and with better coverage than traditional cleaning methods. Air and liquid enter the rear of the nozzle separately. The air moves through the nozzle under pressure and meets the liquid at the nozzle tip, causing the formation of spray droplets that are 30 to 60 microns in diameter. At the tip of the nozzle is a tiny electrode which applies an electrical charge to the spray.

The electrical charging causes a natural force of attraction between the spray droplets and target surface, similar to the attraction between items of clothing created by the tumbling of a clothes dryer.

FIGURE 7 – DRY VAPOR STEAM PENETRATION

Finally, to account for the blind spots where a standard system is not able to provide a high level of sanitization, it would be advantageous to use a COMBINED ACTION of the above described treatments.

For instance, South Korea has been using dry vapour steam in conjunction with sodium hypochlorite based chemical treatments in disinfecting “phone booth-style” COVID-19 testing stations inside hospitals.

Seoul Metro has been disinfecting subway trains with hydrogen peroxide based electrostatic misting systems and dry vapour steam for upholstery and human contact surfaces.

FIGURE 8 – COMBINED ACTION: PRATICAL EXAMPLE

CONCLUSIONS

AYES is investing in exploring new options as large scale cleaning and disinfecting treatments are necessary. We are strongly committed to finding innovative ways to contribute to improving the sanitization and treatments applications for public transportation.