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Note the high elimination rate and short OH• exposure time for E. coli and Coronavirus. Even black mold, which is extremely difficult to eliminate, was subdued after only 72 hours. Keep in mind, OH• treatment is a continuous process; microorganisms won’t be able to get a foothold or propagate when OH• is abundant.

Hydroxyl Radical Safety

Hydroxyl radicals are naturally occurring within our atmosphere, and as such, humans, animals, and plants have all evolved in and thrive in this hydroxyl-rich environment. In fact, according to the National Institute of Environment Health Sciences (NIEHS), “[There is] no science or research indicating that hydroxyl radical generation is harmful to humans. This applies to both naturally occurring and man-made generation.”

Benefits of Hydroxyl Radicals

In the practice of industrial hygiene, the mantra for dealing with hazardous environments is “Destroy, Dilute, PPE.” This means your priority should be destroying the toxic substance if possible. If destruction is not possible, then diluting it to an acceptable level is the next best solution. Finally, if neither option works, providing and requiring personnel to wear PPE is the remaining option.

While diluting and providing PPE are options, they aren’t good answers; both have associated costs. For example, dilution doesn’t change the volume of toxic substances that are released into the environment, it simply reduces the concentration within an immediate area while increasing heating and cooling costs. PPE, which must be provided and worn, must be properly cared for and disposed of. There is also an increased risk of the equipment not be used or worn appropriately, resulting in dangerous health and safety issues.

With the use of hydroxyls, which sanitize indoor environments and remove VOCs and odors, the destruction of hazards elements is possible.

Other benefits include:

• Continuous workspace sanitization in manned spaces.
• Improved employee health and safety.
• A reduction in the time needed to perform sanitization tasks.
• Increased production availability.
• Increased product quality.
• Decreased contamination from viruses, bacteria, mold, and endotoxins.
• Increased profitability.

Why Haven’t You Heard About Hydroxyl Radicals Before?

There are three key reasons why you might not have heard of hydroxyl radicals.

Reason 1

Hydroxyl generators capable of producing the necessary volumes of OH• required to properly sanitize areas were only developed and commercialized within the past several years. Before that, photocatalytic hydroxyl generators were not effective enough to solve sanitation and VOCs issues on a large scale.

Reason 2

Early OH• generator companies lacked sufficient experience and knowledge of commercial and industrial applications. They had difficulty speaking the language of manufacturing, industrial, and facility customers, and they struggled to develop branding and a message that properly educated customers on the technology.

Reason 3

In the beginning, OH• generator companies engaged with early adopter facilities, and these facilities often required confidentiality agreements to maintain their competitive advantage. This slowed the adoption of this technology.

Hydroxyl Radical Effectiveness Experiment

In January of 2023, I conducted an experiment to demonstrate the effectiveness of hydroxyl radicals using packages of blackberries. Two packages were selected from a local supermarket from the same display case, so they were likely picked, packed, and shipped at the same time and under the same conditions.

One blackberry package was placed in a room with a photolytic hydroxyl radical generator running. The other package was placed in a comparable room, but without a generator. Both rooms had temperature and humidity reading devices to show the two samples remained under similar conditions.

The experiment ran for nine days, and by the sixth day, the blackberries in the non-hydroxyl treated room were showing early signs of mold growth, and over the next three days, it continued to spread until most of the blackberries in the package were affected.

In the hydroxyl-treated room, the blackberries didn’t show signs of mold until the seventh day, however, the mold did not spread to any other blackberries in the package. The mold that appeared on these blackberries was also different in appearance than the non-hydroxyl treated blackberries. As shown in Figure 4, the mold was greyish and not fuzzy, instead of white and fuzzy. It appeared the hydroxyl-treated mold was dead.