EPA: Electrostatic Spray Application Update

EPA is providing notice of its intention to expedite reviews for addition of the electrostatic spray method of application for currently registered or new product registrations that are on EPA’s Disinfectant List N or would qualify for List N.


Recently, there has been increased interest in the application of antimicrobial disinfectants on List N via electrostatic spray given the need to disinfect large indoor spaces to reduce the risk of exposure to the virus that causes COVID-19.

Electrostatic sprayers work by charging the antimicrobial liquid as it passes through a nozzle.  The positively charged antimicrobial droplets are attracted to negatively charged environmental surfaces allowing for improved coverage on hard, non-porous environmental surfaces. 

Per the EPA, “Spray droplet particle size (regardless of the ability to change nozzles that impact particle size) should be limited to a volume median diameter (VMD) ≥40 µm.”

In EPA’s ‘Standard Operating Procedures for Residential Pesticide Exposure Assessment’ (2012) foggers are defined as having a droplet size of 15 – 60 µm. This definition is for total-release foggers that have a wider droplet size distribution than electrostatic sprayers. According to the WHO Guidance on ‘Space Spray Application of Insecticides for Vector and Public Health Pest Control’ (2003), it is generally accepted that droplets should be generated at 10-30 μm so that, even with some evaporation and after some time, they remain in the correct range for optimal airborne suspension and insect impact. An electrostatic sprayer that has a droplet size of ≥40 µm volume median diameter would not be considered a fogger.

water droplet

What is EMist’s sprayer droplet size?
EMist sprayers use a very specialized and precise spray tip. The EM360 electrostatic sprayer tip produces an average droplet size or variable mean diameter of 85 microns. The EPIX360 electrostatic sprayer tip produces an average droplet size or variable mean diameter of 75 microns. With these average droplet sizes there is much less “drift”, better surface coverage, improved surface dwell time, and the least possible suspension of liquids.

What is electrostatic spray technology?
Electrostatics is a branch of physics that studies the phenomena and properties of stationary or slow-moving electric charges (Electrostatics, 2016). Electrostatic phenomena is easily demonstrated when lint is attracted to clothes, or when dust clings to a TV screen. These descriptions are examples of Coulomb’s law. Coulomb’s law states that opposite electrical charges attract and like charges repel. Electrostatic spraying has been used for many decades in painting and agriculture. EMist uses this same process to apply a charge to the liquid droplets as they are formed and just before the droplets leave the spray nozzle. These “super-charged” droplets then actively seek out negative or neutral surfaces. What’s more, as the droplets leave the nozzle, the charged droplets repel one another, keeping them from coming together and forming larger droplets. Interestingly, because of the electrostatic charge, droplets “wrap” around surfaces providing an even, consistent surface coverage.

What are the EMist disinfectant sprayers?
The EMist sprayers are the most powerful, efficient and cost-effective disinfection sprayers on the market. The sprayers place an electrostatic charge to disinfectants as the chemical leaves the spray nozzle, which causes the chemical droplets to cling to virtually any surface.

Which disinfectants do you recommend?
The EMist electrostatic sprayers can apply any water-soluble chemical. We recommend the use of EPA-registered disinfectant products. A list of EPA registered products that have qualified for use against COVID-19 can be found here. We recommend EPA-approved organic, nontoxic, biodegradable and safe liquid disinfectants. You can find them by clicking here and then typing “hypochlorous” in the search box.

How does using an EMist sprayer save on labor costs as compared to “wipe-and-go” disinfecting method?
EMist is a better way to apply disinfectants. Using the system decreases the amount of labor and chemical by up to 50%. The system allows the chemistry to achieve proper contact time for maximum kill claims stated by the EPA registered chemical. The current “wipe-and-go” disinfecting method introduces human error with the potential of missing high/low touch surfaces, minimizing kill claims by chemicals with reduced, inconsistent contact times and introducing the potential for cross-contamination by touching every surface. It also has the potential to expose workers to surface pathogens due to touching surfaces.

Cordless vs. corded?
Just as is true in most industries, there are pros and cons between using a cordless or corded electrostatic sprayer. A corded electrostatic sprayer restricts mobility and keeps you tethered to a wall outlet and because there are electrical cords involved, they create a tripping hazard. As well, most corded electrostatic sprayers recommend the use of a GFCI (ground fault circuit interrupter) power outlet. On the other hand, a cordless electrostatic sprayer is not tethered to a wall outlet for power. That means you can take the electrostatic sprayer to where the work needs to be done rather than relying on wall outlets at the work site. Since the electrostatic sprayer has no cord, a cordless sprayer offers greater flexibility and portability. When spraying big projects, multi-story buildings, tight spaces, a cordless sprayer allows you to maneuver and move about freely without the hazard of tripping or tangling a cord. Portability is a clear advantage for any user that needs to move about frequently. Additionally, nearly every power tool on the market today comes with a lithium ion battery. These batteries are capable of holding a lot of power that doesn’t diminish over time if the sprayer is not in use. Corded electrostatic sprayers are no match to cordless electrostatic sprayers when it comes to maneuverability and convenience. EMist cordless electrostatic sprayers will last a long time before their power starts to diminish.

Are surfaces positive, negative or neutral?

Most surface areas are neutral (uncharged) or negative. Electrostatic application for surface disinfection is a method of applying EPA-registered disinfectants to a target surface area by utilizing the electrostatic force of attraction. Simply put, the electrostatic system places an electrical charge on the droplets and disperses them across a target surface area, providing a comprehensive, even coverage. This provides a consistent and uniform coverage in which the droplets adhere to vertical, horizontal and three-dimensional surfaces. As proven in the agriculture and automotive industries, this electrostatic application process takes less time to achieve the desired effect, while substantially reducing chemical costs. (Laryea and No, 2004 and 2005; Matthews, 1992)

Does electrostatically applied disinfectant perform better?

In both third-party testing and real-world settings, clinical studies have shown electrostatic application methodology can provide efficacy and significant improvements within environmental services terminal cleaning procedures. In the American Journal of Infection Control, a study for decontaminating the operating room environment was presented. It was found that using persistent technology with a quaternary ammonium and trichloromelamine solution using a 40-micron electrostatic applicator will significantly reduce colony-forming units (CFUs) remaining after standard terminal cleaning (Sutton, 2015). A study performed in the laboratory setting with an 85-micron electrostatic applicator utilizing a hydrogen peroxide and sliver based product for efficacy against S. Aureus, P. Aeruginosa, MRSA, and C. Difficile showed an average of 99.999% reduction of vegetative bacteria (S. aureus, P. aeruginosa, and MRSA) and an average 99% reduction of spore-forming bacteria (C. difficile) as labeled on the product for surfaces (Ebron, 2014). Other healthcare system studies have shown a significant decrease in hospital re-admission rates, turnaround times for patient discharge/transfer rooms, chemical consumption, and in labor. (Blake G. and Whiteley, B., 2015)

Which disinfectants can be used with EMist?

Any water-soluble chemical can be used in the EMist electrostatic sprayers. However, we prefer “safe and green” disinfectants. Obviously, a perfect disinfectant would offer complete and full microbiological sterilization, without harming people/animals, would be inexpensive, and noncorrosive. However, most disinfectants are potentially harmful and even toxic to humans/animals. One such solution is Hypochlorous acid (HOCl)HOCL works very well against pathogens like Methicillin-Resistant Staphylococcus Aureus and Pseudomonas Aeroginosa. Though very powerful, HOCL is 100 percent safe for humans, chemical-free, non-toxic and all-natural. It has been used in the medical field for over a century. Before antibiotics were available, HOCL was used to irrigate and disinfect wounds in World War I. Today, it is used in everyday settings such as daycare centers, hospitals, and even produce sections in grocery stores.

Which disinfectants does EMist recommend for COVID-19?

We recommend the EPA’s list of disinfectants for use against SARS-CoV-2, the cause of COVID-19. The list can be found here.

Link: https://www.epa.gov/pesticide-registration/expedited-review-adding-electrostatic-spray-application-directions-use