Hydroxyl radicals are short-lived molecules that are extremely reactive and will attack most cellular components. Oxidative stress due to *HO exposure is believed to be linked to neurodegenerative and cardiovascular diseases.  Photoionization (PCO) utilizes numerous UV bulbs, a metal (titanium or potassium) compound supported on media (such as granular carbon) and humidity to create *HO oxidant and treat facility exhaust.  Another technology, hydroxyl radical fogging, is performed by misting water and ozone to create *HO in a contained, unmanned area such as a wet well or pump station.  For both PCO and *HO fogging applications, personnel safety issues must be considered.
 
Though the equipment itself may appear similar to that of air ionization, ozone generators commonly operate at 30,000-40,000 volts, whereas Aerisa's ionizers operate at less than 3,000 volts to negate O₃ production.  The OSHA standard for O₃ is 0.10 ppm average over an 8-hour work shift--that's not much more than background concentrations, which can be 0.07 ppm or higher.  Exhaust O₃ treatment systems must also use instrumentation and controls to minimize the residual concentration of this greenhouse gas.  Ozone attacks natural rubber, nitrile, nylon, and mild steel-- this too must be considered.