Hydroxyl generators were introduced to the disaster restoration industry in 2008 as a new and disruptive technology, and have stimulated many questions and discussions throughout the years. While contractors will quickly confirm how effective they are, there are still a variety of questions.

  • Is it true you need 60% humidity?
  • How long do the ultraviolet (UV) optics last?
  • What size area do the machines really cover?
  • How do we know if they’re actually safe?
  • Are all hydroxyl generators basically the same?
  • Etc, etc, etc!

The Myths

Myth #1: All hydroxyl generators require 60% humidity to be effective.

To start, there is a statement in the industry that all hydroxyl generators require 60% humidity to be effective. This is a myth and would render hydroxyl generators useless in many parts of the United States and Canada. Hydroxyl generators using the patented technology will be effective with humidity as low as 5%. Contractors should never have to add humidity for their hydroxyl generators to work, particularly since this is counterproductive to most projects they are on. It is true that humidity plays a part in the chemical reactions that occur to create hydroxyl radicals (and oxy and peroxy radicals). However, any change in humidity will not have a noticeable effect on the generator’s ability to eliminate odours and certainly won’t determine if the machines work or not.

Myth #2: You need a strong fan to blow the hydroxyl radicals as far as possible before they’re gone since their half-life is a fraction of a second.

This is false, and would never work if this strategy had to be used on projects.  Instead, the patented technology is able to continuously create new hydroxyl radicals outside the chamber of the machine.  The science behind how this works is quite complex, but chemists refer to this as a chain reaction or a cascade effect. This means new hydroxyl radicals, as well as oxy and peroxy radicals, are being created outside the machine and throughout the treatment space due to a multitude of chemical reactions. The ability to create this chain reaction is a critical element of the patented technology, and allows contractors to eliminate odours that have been adsorbed in both the contents and structure. Additional air movers are often helpful to distribute hydroxyls into hard to reach areas. Many contractors have been very creative in reaching difficult areas, but those detailed tips are best in a different article.

Myth #3: There isn’t any documented, real-world research you can use to prove to a homeowner or adjuster that hydroxyl generators actually work and are safe.

That’s false; there is significant documentation out there and this is easily accessible! Testing has been performed over the years by reputable third-party companies like Underwriters Laboratory (UL), Lovelace Respiratory Research Institute, the FDA, Comparative Biosciences, and Wonder Makers Environmental. Results provide information that show how many hydroxyls are produced and how much ozone is produced.

These studies were only performed on the patented technology, and are powerful tools to confirm both the safety and efficacy.  They will certainly help answer the questions that may be received from both customers and adjusters.

Myth #4: While there are now different brands of hydroxyl generators, they are basically the same.

This is also false. There are two types of hydroxyl generators in the disaster restoration industry, and they use very different processes to create hydroxyls; as a result, the strength and capabilities are very different.

One uses high-powered UV light with multiple wavelengths to generate hydroxyls that exit the machine and create a chain reaction throughout the treatment space. This technology is unique because it enables the treatment of not just the air, but more importantly, the contents and structure where the odours have been adsorbed. They are very powerful and it is important to follow the manufacturer’s operating instructions restricting usage in small, occupied areas. These generators are used in conjunction with an air mover.

The other process used to produce hydroxyls is called photocatalytic oxidation (PCO), which is primarily used for residential air purifiers and many different brands can be found online. The PCO process uses a titanium dioxide coated surface and low-powered UV light, whereby only the VOCs in the air that pass through the machine and come in contact with this coated surface can be treated. This PCO process does not produce hydroxyls that exit the machine, and therefore cannot eliminate the odours that have been adsorbed by the contents and structure.  As you can see, while the name hydroxyl generators are the same, the differences are significant.

Hydroxyl radical Generators