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"OZONE Generator" or Machines That Generate OZONE?D. Douglas Hoffman, IAQ/Environmental Consultant There has been much discussion about ozone and it's relative safety in the workplace. OSHA (Occupational Safety and Health Administration) has determined that a safe level of ozone in the workplace could include amounts of accumulated ozone not higher than .10 ppm while the EPA (Environmental Protection Agency) has set the bar at .08 ppm1. This fact alone highlights the controversy around the subject of ozone, even at recognized safe levels, in occupied space. Consequently, the question often arises "How can the EPA set a safety standard of accumulated ozone on one hand and yet take such a strong stance against it on the other?" This apparent contradiction is easily understood when you carefully read the EPA position statement and define the words they use to explain their position Reading from their own documentation, the EPA states "Often the vendors of ozone generators (my emphasis, ddh) make statements and distribute material that lead the public to believe that these devices are always safe and effective in controlling indoor air pollution. For almost a century, health professionals have refuted these claims (Sawyer, et. al 1913; Salls, 1927; Boeniger, 1995; American Lung Association, 1997; Al-Ahmady, 1997)." NOTE the use of the term "ozone generates". There is a significant difference between ozone generators and air purifiers that generate ozone. It is to that issue that I address this article. For clarification, there exists an entire class of ozone producing machines called "ozone generators". For years these machines have been used for fire restoration, hotel clean-up, and other odor control with little or no concern over their use because they were used, primarily, in UN-occupied space. These ozone generators, produced by manufacturers like Biozone, Zontec, and other companies, were never intended for occupied space. They were designed for use, on the contrary, in UN-occupied space where higher levels of ozone are not a health concern (because no humans or animals are present) but desired for the intended purpose of their use-to control IAQ contaminants. In contrast, there are certainly other machines that produce ozone but should not be considered "ozone generators". Simply by virtue of the fact that they generate ozone DOES NOT make them an "ozone generator", otherwise the "ozone generator" terminology could be applied to washing machines, copiers, ceiling fans, refrigerators, and any other device that produces ozone as a by-product of a running motor. I don't believe the EPA is interested in excluding those kinds of ozone producers from our occupied living space! Remember, even the EPA has established levels of ozone in OCCUPIED space to which these types of devices conform. In other words, running 15 ceiling fans, the refrigerator, and washing machine in your home will not produce enough ozone to exceed the EPA .05 ppm standard. SO, when the EPA discourages the use of "ozone generators", they are talking about machines that produce ozone levels far above their own EPA standard. Notice their own studied conclusions, "In an EPA study, several different devices were placed in a home environment, in various rooms, with doors alternately opened and closed, and with the central ventilation system fan alternately turned on and off. The results showed that some ozone generators, (again, my emphasis, ddh), when run at a high setting with interior doors closed, would frequently produce concentrations of 0.20 - 0.30 ppm. A powerful unit set on high with the interior doors opened achieved values of 0.12 to 0.20 ppm in adjacent rooms. When units were not run on high, and interior doors were open, concentrations generally did not exceed public health standards (US EPA, 1995)." There is another subject in this arena worth visiting. When you read anything regarding "the harmful affects of ozone" you should be aware that those studies, even when commissioned by EPA, are often based on machines which produce ozone ONLY and at levels exceeding government guidelines. Again, from the EPA's own documentation, "For example, in a laboratory experiment that mixed ozone with chemicals from new carpet, ozone reduced many of these chemicals, including those which can produce new carpet odor. However, in the process, the reaction produced a variety of aldehydes, and the total concentration of organic chemicals in the air increased rather than decreased after the introduction of ozone (Weschler, et. al., 1992b)." Notice again, most of the studies that have been done in laboratory conditions have been done with the introduction of ozone ONLY. Even the EPA realizes that laboratory conditions do not accurately simulate actual living environments. They go on to say, in the same paragraph, "Given the complexity of the chemical reactions that occur, additional research is needed to more completely understand the complex interactions of indoor chemicals in the presence of ozone." I couldn't agree more. IAQ problems are complex and laboratory studies, for the most part, have been rather simplistic. When considering IAQ solutions, consider the multiple-strategies approach. Certainly the EPA draws a positive conclusion by stating "The public is advised to use proven methods of controlling indoor air pollution. These methods include eliminating or controlling pollutant sources, increasing outdoor air ventilation, and using proven methods of air cleaning." Good ventilation, good filtration, source removal, and good common sense about what we introduce into our indoor living environments is a sound approach. Adding to this multiple-strategies solution could also include air purifiers that combine multiple technologies (including trace levels of ozone) and processes (hydroxyls and ionization) to more nearly simulate what are found outside to purify the air. By bringing these technologies indoors and using a common sense approach regarding all methods of cleaning the air we breathe, you can safely fix this complex problem with a complex solution. That's the way I see it. D. Douglas Hoffman is a member of the Advisory Board for the National Indoor Air Quality Institute and author of the book Mold-Free Construction™ (www.MoldFreeConstruction.com) There is more information available concerning his credentials at www.MyMoldGuy.com 1. From http://www.epa.gov/iaq/pubs/ozonegen.html#table%201
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