It’s important to distinguish between Atmospheric Hydroxyls like are produced by the HiTech are Biological or in vivo Hydroxyls which are produced inside the body.  It is the in vivo hydroxyls that are produced by the body’s immune system that are damaging to DNA.  Our skin and mucosal tissue (eyes, sinuses, mouth, throat, lungs) are in no way harmed by atmospheric hydroxyls as humans have been exposed to them since we’ve been on the earth, and they don’t penetrate beyond the epidermis or mucosal outer layers of cells in the body.  When you walk outside on a sunny day you are exposed to 500,000 - 2,000,000 atmospheric hydroxyls per cubic centimeter.