HOCl Fogging & Electrostatic Spraying

Hypochlorous (HOCl) fogging and electrostatic spraying (collectively referred to as “spraying”) has become the preferred method of disinfecting many environments because of its simple, nontoxic and nonirritating method of disinfecting for both ambient air and hard to reach surfaces. It also provides the benefit of covering larger areas in less time, while using less solution. 

Perhaps the most groundbreaking facet of HOCl spraying is the chemistry lesson behind its effectiveness. HOCl is the most effective member of the chlorine family, with none of the negative traits of chlorine bleach. The sodium hypochlorite ion in bleach carries a negative electrical charge, while HOCl carries no electrical charge. Because most pathogens carry a negative surface charge, this allows it to efficiently penetrate the protective wall of viruses, bacteria, or fungi.

In addition to the neutrality of HOCl’s electrical charge, it also has a neutral pH. This neutrality, as well as its relatively low molecular weight, allows it to effectively penetrate the protective wall of a negatively charged germ, attach quickly and render it ineffective. Furthermore, because spraying atomizes the HOCl into an ultrafine mist, it begins disinfecting and killing pathogens in a matter of seconds. 

The speed at which HOCl begins working, as well as the power and convenience of the spraying delivery system to disinfect large areas quickly, helps businesses communicate a message to both customers and staff that their good health is their highest priority.

Tests using ATP (adenosine triphosphate) meters to measure the reduction in bacteria on surfaces using foggers and electrostatic sprayers have shown BOTH to be extremely effective. The measured differences were negligible. 

However, there are differences in these delivery systems that should be taken into consideration before deciding which is best for your business. In short, foggers do not change the charge of the liquid and dispense in smaller microns to act as a better aerosol, while electrostatic sprayers change the charge to positive and use larger microns, resulting in extended coverage of the given surface. Let’s look at each more closely.

Fogging with HOCl

Fogging gives businesses an added tool to combat lingering aerosols in their facilities in a cost effective and time saving manner. 

When the solution is atomized via fogging, ultra-low volume particles of 20 to 50 microns are created that linger in the air for an extended period of time—encouraging prolonged contact with airborne pathogens.

 “I did some research on HOCl fogging and realized that it was pretty much the only thing I could do to make sure that any viral particles that are in the air or that potentially hit a no-touch or low-touch area are eradicated,” Dr. Sarah Raymond, DDS shared.

After sharing her research and knowledge on HOCl fogging with her dental team, they became believers, too, and now love taking turns using the disinfecting fogger.  “We use the fogger twice a day—at lunchtime and at the end of the day—and it takes 3 to 4 minutes, tops, to fog the entire office,” she shared, adding that the tank holds just over a gallon of solution and only needs to be refilled about once a week. “We can easily change the angle of the nozzle and the force of it allows us to reach every corner very quickly just by standing in the doorway. This fogger beats every mark and exceeds my expectations.”

While fogging may be foreign to most dentists in the states, it has been used effectively in South Korea for many years to naturally and safely disinfect schools, medical offices, and cruise ships. Early on in the pandemic, it was even reported that workers at drive-through coronavirus testing stations in South Korea would step into a portable booth called a “Clean Zone,” where they were showered in a hypochlorous acid disinfectant. 

“I think part of the reason why my office is thriving, even in the face of this pandemic, is that my team feels safe…which then trickles down to my patients,” Dr. Raymond shared. "We practice in a small community, so word is getting out as patients tell each other what I’m doing in the office to ensure their safety. And because of that, I now have new patients banging down my door.”

HOCl Fogging Study

1. HOCl in the 20-200 ppm range in a liquid or fog is effective against Norovirus and other similar viruses.  It has achieved at least a 3 Log reduction and often a 5 Log reduction (see below). 
   
   
2. NV is a small, non-enveloped virus, which is harder to kill than Human Coronavirus.  Enveloped viruses are the easiest to kill.
   
   
3. Generally, glutaraldehyde and sodium hypochlorite (used to make HOCl) are known to be effective against nonenveloped RNA viruses, such as NVs, whereas detergents and most lipophilic disinfectants (e.g., quaternary ammonium compounds) have been reported to have WEAKER virucidal activity (2, 16)
   
   
4. Quaternary Ammonium is a low level disinfectant.  It is at least a step or two down from a Hospital-Grade Disinfectant.
   
   
5. Fog disinfection with HOCl always achieved greater than 3 log10 reductions and mostly >5 log10 reductions. 

Applied and Environmental Microbiology Study -Appl Environ Microbiol. 2007 Jul; 73(14): 4463–4468.
Published online 2007 May 4. doi: 10.1128/AEM.02839-06
Evaluation of Liquid- and Fog-Based Application of Hypochlorous Acid Solution for Surface Inactivation of Human Norovirus▿

Electrostatic Spraying with HOCl

In a recent study performed by EMist, HOCl was applied as an 85 micron positively (+) charged electrostatic spray combined with routine cleaning.

Outcomes proved that HOCl applied using an electrostatic sprayer provided additional efficacy.