First Name | Glenn |
---|---|
Last Name | Morrison |
Email Address | gcm@umr.edu |
Affiliation | University of Missouri-Rolla |
Subject | Proposed regulation of indoor air cleaning devices |
Comment | The California Air Resources Board (ARB) has proposed to regulate ozone emitting air cleaners. The effect of this regulation is to reduce consumer exposure to ozone, a criteria pollutant recognized to be associated with morbidity and mortality. The regulation has the further benefit of reducing exposure to the byproducts of ozone reactions with surfaces and some gas-phase compounds. I support the California Air Resource Board’s efforts to reduce Californian’s exposure to ozone and its byproducts. Ozone is a very reactive compound that oxidizes compounds present in the air and on indoor surfaces, releasing a wide variety of chemicals. Commercial efforts to chemically improve indoor air with ozone have been misguided at best, dangerous at their worst. The fact that ozone can react rapidly to remove a small number of organic compounds have led manufacturers of ozone generating “air cleaners” to claim that their products effectively destroy organic pollutants . The reaction rates with most indoor odors are far too small to effect any significant change in exposure. For those compounds that are “destroyed”, such as the “terpenes” used to as scents, the chemical products of these reactions appear to be worse than the original scent. Ozone also reacts with surfaces with adverse outcomes. In early work, Weschler et al. (1992) showed that adding ozone to a chamber with carpet actually INCREASES the total mass concentration of inhalable compounds. Ozone has been consistently shown to increase indoor concentrations of aldehydes, ketones and carboxylic acids due to reactions with materials that would be present in almost any indoor environment. Most of these materials are themselves benign and “natural”, including natural terpenes used as scent and triglycerides derived from vegetable oils. In the attached file, I briefly review the chemistry of ozone in indoor environments. The growing literature on this subject shows us that a substantial fraction of ozone injected into indoor environments will raise indoor levels of reaction products that are troubling. Given the clear benefits of reducing ozone exposure, and the suspected and known hazards associated with ozone reaction products, every effort should be made to reduce and eliminate ozone emissions from consumer devices. The ARB regulation is a step in the right direction. However, I echo the sentiments expressed by Richard Corsi of the University of Texas, Austin: I hope that the Air Resources Board reviews their proposed 50 ppb limit and considers a lower value in the near future. |
Attachment | www.arb.ca.gov/lists/iacd07/22-response_to_carb_regulation_review.pdf |
Original File Name | Response to CARB regulation_review.pdf |
Date and Time Comment Was Submitted | 2007-09-25 16:00:33 |
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