Electrostatic Sprayer vs. UV-C — Disinfection Comparison

The COVID-19 pandemic brought many problems to light. From highlighting deficiencies in our healthcare system to exacerbating already-stressed supply chain issues, a myriad of concerns was on full display. But one area that received a particularly increased level of scrutiny was our standards for cleanliness and disinfection. The general public began taking additional measures to protect their hygiene, such as more actively washing their hands and using various methods to disinfect everyday items, like groceries or delivered packages, that had long-been afterthoughts. In turn, businesses, hospitals, and schools made concerted efforts to ramp up their own, large-scale practices for disinfection, looking toward new technologies for better efficiency. One method that gained a notable surge in attention was the electrostatic sprayer.

By no means a new method for disinfection, but with everybody looking to provide cleaner, safer spaces, it was one that many turned to for help getting the job done. The global market size for electrostatic disinfectant sprayers is now expected to cross 2.5 billion AUD by 2025.

With that, it’s important to examine just how exactly electrostatic spraying disinfection works, explore the benefits of its use, as well as consider the potential drawbacks it presents – especially when compared to alternative methods for disinfection, such as autonomous UV-C.

The Science of Electrostatic Sprayer Disinfection

While the technology used in electrostatic disinfectant spraying is somewhat unique, its foundation is built on standard disinfectant protocols. Put simply, it disinfects surfaces using your customary set of chemical solutions — alcohol, chlorine, bleach, hydrogen peroxide, and so on. These solutions have been used for disinfection purposes for many years, typically having been applied with a standard spray bottle and then manually wiped with a clean towel.

Where electrostatic sprayers differ from the traditional method is that, during the application process, they send out positively charged droplets. This is accomplished by using a specialised disinfectant sprayer gun, perhaps similar in look to sprayers utilised for painting or fertilising.

Once discharged from the sprayer, the positively charged droplets will then bond with a negatively charged surface – such as a desk, door handle, or any other object. The idea behind using the electrically charged solution is that it will, in effect, “wrap” around surfaces. So, for instance, if you were to aim the sprayer at a chair, you could conceivably disinfect both the front side — where the sprayer is aimed — and the back side of the chair all in one instance of spraying, with no need to move around the chair and repeat the process on the opposite side.

From there, the chemical solution remains in contact with the applied surface for a set amount of time and the disinfection process runs its course.

Disadvantages of Electrostatic Sprayer Disinfection

All that can appear good in theory, but there are still questions about the efficacy of using electrostatic sprayers for disinfection. For one, their potency may not be as powerful when compared to other methods of disinfection. One study found that an application of electrostatic bleach saw a reduction of only 50% in SARS-CoV-2 RNA, whereas the virus saw a significantly larger reduction of 83% when exposed to UV-C.

Secondly, there are still concerns regarding whether the main selling point of electrostatic spraying — namely, the “wrap around” capability — is as accurate as promised. In fact, the Environmental Protection Agency performed a series of tests where an electrostatic sprayer was used on a trash can. While the section of the trash directly in front of the sprayer received a proper amount of disinfection, “The back side of the cylindrical trash receptacle shows little if any deposition, indicating minimal ‘wrap-around’ effect.”

Regardless of the soundness of the science behind electrostatic sprayers, the truth of the matter is that several other factors that could prevent it from being used for genuine disinfection.

Risk of Human Error with Electrostatic Sprayers

Even if the science surrounding electrostatic spraying disinfection was indisputable, the mechanism is only as effective as the application process allows. The manual labour component of electrostatic spraying is — as with any process that must be performed by hand — susceptible to human error.

For starters, in order to achieve a proper disinfection, the chemical solutions must be sprayed in a consistent manner. While the electrically charged particles could theoretically mask any inconsistent applications, that technology can only go so far. Despite our best efforts, humans are prone to mistakes. In fact, “The key problem associated with the cleaning and disinfection procedure is the reliance on the operator to repeatedly ensure adequate selection, formulation, distribution, and contact time.” In the case of spraying disinfectant solution, this can mean under applying, rushed procedures, or outright missed spots. Any amount of inconsistency in the disinfection process could lead to pathogens and bacteria remaining on surfaces, which would make any person coming into contact with that space vulnerable to receiving infection, thus defeating the entire purpose of the operation.

Further, these inconsistencies can be compounded with untrained technicians. To capitalise on the hype and demand for better disinfection protocols brought on by the pandemic, some companies have tried to quickly implement electrostatic spraying into their practices. However, due to the hasty nature of such measures, the training procedures are often skirted or ignored altogether. And if proper techniques are not adhered to, then the act of using electrostatic sprayers equates to little more than hygiene theatre — looks as though it solves the problem, but, in actuality, doesn’t do anything.

Harmful Chemical Residue from Electrostatic Sprayers

As is common with any manual disinfection process, electrostatic sprayers require the use of chemical solutions. These solutions can be quite effective at destroying various types of dangerous bacteria. However, those pathogens aren’t the only thing to which these chemicals can be harmful.

Of most importance, humans can be adversely affected. This applies directly to the staff who performs the disinfection using electrostatic sprayers. Thus, depending on the level and degree of disinfectant used, the operators must wear more intensive layers of personal protective equipment. According to the EPA, when spraying high vapour pressure chemicals, such as hydrogen peroxide, technicians should “use half face respirators with chemical specific cartridges and N95 filters.” 

Protecting team members is a top priority for any disinfection crew, and the use of chemical solutions only adds to the difficulty of this task. So while this requires the purchase of PPE and the needed replacement cartridges and filters, that isn’t the only cost-increasing measure that must be taken to safeguard a team. Due to the nature of using chemicals, further intensive training may be necessary to not only instruct the crew on how to safely apply the solutions, but to also prepare them for what measures must be taken should they suffer from an unexpected exposure.

Of course, the risk of exposure to the harmful chemicals associated with electrostatic spraying isn’t reserved solely for those who apply the disinfectant — we also must consider those who will use the space post-procedure. Chemical solutions must “dwell” on the applied surface for a specific amount of time to achieve proper disinfectant, and depending on the type of chemical used, that dwell time can stretch up to 10 minutes or more. Longer dwell requirements mean a greater period of time where, if the space is unmonitored, a passer-by could become exposed to the chemicals. Further, this obligatory dwell time means that the space cannot be used immediately after disinfecting – some electrostatic spraying companies recommend waiting one to two hours after treatment before entering the area, which could be problematic for places such as hospitals, where busy operating rooms need to be turned over as quickly as possible.

The fact that electrostatic sprayers are using water-based chemical solutions also limits the areas where they can be used or, depending on the location, requires the technician to practice greater caution during the application process. For one, because the disinfectant goes on wet, it cannot be used on electronics, which can be easily damaged by water or liquids of any sort. Think, for example, about the amount of electrical equipment in a standard operating room — monitors, cables, life-saving tools, and so on — and how these items, vital for medical professionals to perform their duties, could remain susceptible to viruses and infectious diseases simply because they are unable to be properly disinfected with an electrostatic sprayer.

Further on the note of location limitations, when working in areas of proximity to food preparation — kitchens, cafeterias, etc. — technicians must practice extreme care so the chemicals do not come into contact with any countertops, dishes, or the food itself. And due to the aerosolised nature of electrostatic sprayers, there is only so much control that one can maintain to ensure that no rogue droplets miss their intended target and unexpectedly land elsewhere.

The Answer: Autonomous UV-C Disinfection

In theory, electrostatic spraying is an effective means of disinfecting locations and surfaces, and, in a vacuum — i.e., the chemical solution interacting with a single, intended spot — one could have confidence in a proper disinfection. However, as laid out above, many factors limit the potential benefits and could cause more headaches than their worth.

Of course, true disinfection can be achieved quickly, efficiently, and safely by using an autonomous UV-C disinfection robot, such as the recently developed OhmniClean.

By using automation, you diminish concerns over human error, because the device can drive and navigate any room all by itself. So, if you’re needing to disinfect the front and backside of an object — chairs, trashcans, medical equipment, etc. — the robot can get both sides without any extended effort from a staff member. This not only ensures that proper disinfection takes place, but also allows the crew to attend to other duties and cleaning responsibilities. And with OhmniClean’s real-time, auditable reports — which include in-room position tracking — you’ll have legitimate results that prove a true disinfection was accomplished.

Additionally, the complex nature of electrostatic spraying requires skilled technicians, which could necessitate a bit of a learning curve during the initial stage. But not all disinfection systems are too complicated to use. OhmniClean has been specifically designed for a super easy onboarding process, where new team members can be trained on its operation in less than ten minutes, allowing you to start disinfecting in no time at all.

And while achieving a clean environment is important and, ultimately, the primary goal of any disinfection practice, we must not forget about the safety of both those performing the disinfection, as well as those who may be using the space after the process has taken place. As stated, the chemical liquid that electrostatic sprayers use can be dangerous, and depending on the type of solution that is being used for disinfection, technicians are required to wear varying degrees of personal protective equipment — masks, respirators, gloves, and so forth. From there, because the chemical residue must remain on the surfaces for upwards of ten minutes or more, it could potentially cause harm for any passersby who happen to come in contact with it.

However, with UV disinfection, there is no residue left behind — once the disinfection process is complete, there is no longer any risk of harmful exposure. And while exposure to UV light can have deleterious effects, OhmniClean is built with a multitude of safety mechanisms to protect both staff and members of the general public. This includes remote motion sensors for automatic shutdown if anyone approaches.

Disinfection is more important than ever, and now that the public has a heightened awareness of cleanliness and the various means used to disinfect, we must make sure the technology we use in this new normal lives up to its billing. So while electrostatic disinfection spraying may leave quite a bit to be desired, it’s good to know that other options are available and accessible. Whether you’re looking for better disinfection at a hospital, school, hotel, restaurant, or other business, it’s clear that autonomous UV-C is the most effective way to ensure that true disinfection is achieved.

About Robots4Good

A leading provider of robots as a service, Robots4Good is the exclusive supplier of OhmniLabs robots and services in Australia and New Zealand for business, manufacturing, schools, hospitals, disability and aged care settings.