If the guy is using just O3, at pretty much any concentration, it`s not doing a complete disinfection job what so ever. At least thats how I understood the subject explained at fime. Medizone`s blend has found the sweet spot. The guy probably has no scrubbing tech to convert back into o2. Hope he`s wearing a Scot air pack when he opens that trailer door to air out. just my 2 cents...