Ozone is a source of indoor air pollution. In another of the EPA’s studies and releases on “ozone generators that are sold as air cleaners” (www.epa.gov/iaq/pubs/ozonegen.html) there is a lot of good resource materials that can be considered unbiased. “There is a large body of written material on ozone and the use of ozone indoors. However, much of this material makes claims or draws conclusions without substantiation and sound science. In developing Ozone Generators that are Sold as Air Cleaners, the EPA reviewed a wide assortment of this literature, including information provided by a leading manufacturer of ozone generating devices. In keeping with EPA’s policy of insuring that the information it provides is based on sound science, only peer reviewed, scientifically supported findings and conclusions were relied upon in developing this document.” (U.S. EPA) It goes on to explain how ozone is harmful: “The same chemical properties that allow high concentrations of ozone to react with organic material outside the body give it the ability to react with similar organic material that makes up the body, and potentially cause harmful health consequences. When inhaled, ozone can damage the lungs (see - “Ozone and Your Health” - www.epa.gov/airnow/brochure.html). Relatively low amounts can cause chest pain, coughing, shortness of breath, and, throat irritation. Ozone may also worsen chronic respiratory diseases such as asthma and compromise the ability of the body to fight respiratory infections. People vary widely in their susceptibility to ozone. Healthy people, as well as those with respiratory difficulty, can experience breathing problems when exposed to ozone. Exercise during exposure to ozone causes a greater amount of ozone to be inhaled, and increases the risk of harmful respiratory effects. Recovery from the harmful effects can occur following short-term exposure to low levels of ozone, but health effects may become more damaging and recovery less certain at higher levels or from longer exposures (US EPA, 1996a, 1996b). Manufacturers and vendors of ozone devices often use misleading terms to describe ozone. Terms such as “energized oxygen” or “pure air” suggest that ozone is a healthy kind of oxygen. Ozone is a toxic gas with vastly different chemical and toxicological properties from oxygen.” It sums things up later when it says, “Are Ozone Generators Effective in Controlling Indoor Air Pollution? Available scientific evidence shows that at concentrations that do not exceed public health standards, ozone has little potential to remove indoor air contaminants. Some manufacturers or vendors suggest that ozone will render almost every chemical contaminant harmless by producing a chemical reaction whose only by-products are carbon dioxide, oxygen and water. This is misleading.” Also, “There is evidence to show that at concentrations that do not exceed public health standards, ozone is not effective at removing many odor-causing chemicals.” “If used at concentrations that do not exceed public health standards, ozone applied to indoor air does not effectively remove viruses, bacteria, mold, or other biological pollutants.” Finally, “If I Follow Manufacturers’ Directions, Can I be Harmed? Results of some controlled studies show that concentrations of ozone considerably higher than these standards are possible even when a user follows the manufacturer’s operating instructions.” Scientific studies that lead to these conclusions are included in this document and I would encourage anyone questioning the use of ozone as an air purification device or element of such effect to do the research first, making sure that they understand not only these facts, but the personal facts that only they can get answered by their doctor (sensitivities for example). I should probably include the EPA’s recommendations for care that are also included in that document: "What Other Methods Can Be Used to Control Indoor Air Pollution? The three most common approaches to reducing indoor air pollution, in order of effectiveness, are: Source Control: Eliminate or control the sources of pollution; Ventilation: Dilute and exhaust pollutants through outdoor air ventilation, and Air Cleaning: Remove pollutants through proven air cleaning methods. Of the three, the first approach – source control – is the most effective. This involves minimizing the use of products and materials that cause indoor pollution, employing good hygiene practices to minimize biological contaminants (including the control of humidity and moisture, and occasional cleaning and disinfection of wet or moist surfaces), and using good housekeeping practices to control particles. The second approach – outdoor air ventilation – is also effective and commonly employed. Ventilation methods include installing an exhaust fan close to the source of contaminants, increasing outdoor air flows in mechanical ventilation systems, and opening windows, especially when pollutant sources are in use. The third approach – air cleaning – is not generally regarded as sufficient in itself, but is sometimes used to supplement source control and ventilation. Air filters, electronic particle air cleaners and ionizers are often used to remove airborne particles, and gas adsorbing material is sometimes used to remove gaseous contaminants when source control and ventilation are inadequate. " I wish anyone dealing with these problems and pollutants the absolute best. I would encourage anyone that has a problem to talk to their doctor, and, when applicable, talk to a professional that can help define the condition(s) of the indoor environment in which they live. The reason I say all of this is that you don’t want to put anything in writing that may end up putting you in a weird position if someone occupies or handles the space inappropirately and then wants to turn around and come after you because you gave them the advise. If you don’t feel comfortable writing a protocol for remediation then you may want to advise them to either hire a indoor environmental professional or a remediation professional that is qualified to help them. Keep it simple and advisive without putting yourself in a position of responsibility, especially when dealing with ozone on mold.