This is the second of a two-article series on disinfecting services in the midst of COVID-19 and our eventual return to our offices. Last month, I offered advice on how to select a company to provide these services, how they should protect themselves and you and how to avoid unnecessary services and costs from the unscrupulous. This month provides a general guide to your provider’s services.
Chemicals
Disinfecting is the application of a chemical to kill or deactivate any contaminant on a surface, be it a virus, bacteria, fungus or inorganic substance that may make people sick. The Environmental Protection Agency (EPA) has a list of the acceptable chemicals for this purpose. When a company offers you disinfecting services, they should tell you what product they are proposing to use and why. They should also provide a Safety Data Sheet (SDS, formerly MSDS) from the manufacturer. The Occupational Safety and Health Administration (OSHA) requires they have this with them when they are working, but I would be suspicious of a company that does not provide it with their proposal.
The two most common ones on the EPA’s list are:
• Quaternary ammonium compounds (the most common). They are contained in most household disinfectant products, as well as many commercial restoration or janitorial products. They are effective and cost-effective, but leave behind a residue that needs to be cleaned.
• Hydrogen peroxide-based compounds. These are the alternative for areas where chemical residues may be an issue (supermarkets, pharmacies, pet food stores, daycare centers). If cost were no factor, these would be used more often.
Methods of Delivery
Most companies are advertising disinfecting services withiout saying what they are going to do or how they will apply the products. The following are the most common methods of delivery. The correct process is a combination rather than the use of any of them alone.
ULV Fogging
Ultra-low volume (ULV) fogging covers a wide area with minimal product. But it does not give the best coverage on surfaces or enough dwell time of the chemical to be effective. Biohazard teams use this as a first step to get any particulate that may be floating in the air to settle; that’s about it.
Electrostatic Spraying
This electrically charges the chemical’s molecules, making them attract like a magnet to surfaces. It gives better surface coverage than ULV fogging or hand-to-surface wiping but is not enough on its own.
Hand to Surface Wiping
This should be part of any protocol. Experienced workers will know the few rules that need to be followed. It is not damp wiping; it must be wet wiping. You must leave enough disinfectant to stay wet for the recommended time. Cloths should be changed often and never reused, or the virus could spread.
Airless Sprayers
These emit a high volume on surfaces, which is good for dwell time.. This is good for disinfecting a stadium, where there is a high volume of surfaces that are very durable. You would not use this in an office environment with papers and electrical/computer components.
UV Lights
Rather than using chemicals, some companies use ultraviolet (UV) lights to destroy the virus. While effective, it is hard to reach all surfaces and these may miss areas that are not directly exposed (the backside of a door handle). UV lights are effective for treating masks, so you can reuse them if the light hits both sides. There are a large variety of units and the powerful ones are very expensive. They also don’t claim to destroy all of the virus, only to reduce it. If there is dirt or residue on the surface, it may not be effective.
Standard Operating Procedure
One possible standard operating procedure to treat an office space as a proactive additional measure before re-occupancy would include: ULV fogging followed by hand-to-surface wet-wiping in offices and cubicle areas and electrostatic spray followed by hand-to-surface wet-wiping in traffic areas, lunchrooms, bathrooms and other congregating spaces. Hand-to-surface wet-wiping is done on high touch-prone surfaces such as doorknobs, light switches, elevator buttons, desktops, keyboards, phones, cabinet doors, tops of low walls and walls in traffic areas (knee to shoulder height).
Dwell Time
Dwell time refers to how long the chemical should stay wet on a surface for it to effectively kill or neutralize any contaminants. The average dwell time for most quaternary compounds is 10 minutes — the surface has to be wet for 10 minutes for it to be effective. It is not what will be accomplished with a damp wipe or ULV fogging alone.
Surface Preparation
If dirt/dust/debris/residue is on the surface, you cannot effectively disinfect it. Wiping the surface makes sure that the residue is removed, while leaving a coating of the chemical to dwell on the surface. Unfortunately, this does mean that some residue will remain that will have to be cleaned up later, but it is better than ineffective disinfecting.
Hiring an outside company to do a one-time process is not the end-all. A vigilant protocol of daily disinfectant wipe downs of touch-prone surfaces in high traffic areas is the most effective process to limit the spread of the virus. The best way to protect yourself is to wear a mask, limit direct physical contact and wash hands often. Recent studies saying most transmission is person-to-person as opposed to person-to-surface-to-person.
Jeffrey Gross, CR (jgross@maxons.com) is the chief operating officer at Maxons Restorations, Inc., a restoration firm in New York City.
