@DickDastardly ...
The free radicals the FRG unit produces are mainly hydroxyl radicals and ozone. The amount of each will vary depending upon the humidity of the air going in, more hydroxyl radicals in moist air (less ozone), and more ozone in dry air. Even in 99% humidity it will still produce some ozone, according to the documentation I have already linked to from Purifloh.
https://purifloh.com/wp-content/uploads/2020/07/57SGH10618MA_Application_Final_11655641_1-1.pdf
Ozone is a pollutant and toxic gas at very minor levels, because the damage it does to virus, bacteria, particulates etc, is the damage it would do to the lining of your lungs if you breath it.
From NASA .... "According to the Environmental Protection Agency, exposure to ozone levels of greater than 70 parts per billion for 8 hours or longer is unhealthy
[1]. Such concentrations occur in or near cities during periods where the atmosphere is warm and stable. The harmful effects can include throat and lung irritation or aggravation of asthma or emphysema. "
https://ozonewatch.gsfc.nasa.gov/facts/SH.html
Ozone generators produce ozone in hundreds of ppm, which is thousands of times the safe limit for humans/animals/plants. The FRG unit looks like a very good producer of free radicals, mainly ozone in dry air, so I would expect it to produce high levels of ozone in dry air, just as advertised.