First Name | Richard |
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Last Name | Shaughnessy, PhD |
Email Address | rjstulsau@aol.com |
Affiliation | Univ of Tulsa, Indoor Air Research |
Subject | Comment on proposed regulation |
Comment | I am pleased to see that efforts are being made to regulate devices that emit ozone into the indoor environment. The regulation to my understanding requires any indoor air cleaning device (IACD) to comply with an "emission concentration not exceeding 0.050 ppm O3". I assume this level is selected based on current health data, or lack thereof, on the effects of ozone at less than .050 ppm concentration in the space. In addition this coincides with the same level as prescribed by the FDA standard for medical devices. Herein, I would offer the following comments for consideration: 1) The FDA standard was set as an "accumulation level" within a space. It is important to note that the .050 ppm concentration limit is based on all sources which may contribute to the resultant indoor ozone concentration. This would include not only contribution from the use of the ozone generating IACD but also (primarily) that from outdoor air. It is well-established in the literature that typical indoor/outdoor ratios of ozone range from 0.2 to 0.7 (Weschler, 2000). The point being made is that the regulation proposed will limit the emission concentration, within a reasonably sized space, from the IACD to less than .050 ppm. To fully evaluate the indoor accumulation of ozone, one must consider not only contributions from indoor sources but also that from the outdoor environment. The broader scenario of including outdoor air sources should also be considered in the final evaluation as to resultant indoor ozone accumulation and whether or not it is below the 50 ppb level related to the FDA Standard (note:it is recognized that the authors of the CA regulation are only citing the FDA limit as one of the Standards currently in place; thus the information provided here is for reference purposes only). Still, the current proposed CA regulation is the first of its kind, with substance, on IACDs and goes beyond any other Standard on IACDs. This is unequivocally a step in the right direction. 2)Whereas the proposed emission concentration standard in the CA regulation is currently set at 0.050 ppm, I would hope that this limit is reviewed on a periodic basis to account for the abundance of ongoing research on the effects of ozone AND the byproducts of ozone indoor-initiated reactions. The continued research in this field may warrant more stringent ozone limits in the near future based not only on the harmful effects from breathing ozone, but also from the effects of the byproducts of indoor reactions resulting in irritants such as aldehydes, ketones, organic acids, and ultrafine particles. |
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Date and Time Comment Was Submitted | 2007-09-22 22:01:27 |
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