¹California Air Resources Board, California Environmental Protection Agency

Correspondence: Thomas J. Phillips, CARB/RD, P.O. Box 2815, Sacramento, CA 95812. Tel.: 916-322-7145. Fax: 916-322-4357. E-mail: tphillip@arb.ca.gov

¹Presented at: ISEA 7th Annual Meeting, November 2-5, 1997, Research Triangle Park, NC.

²Disclaimer: The statements and conclusions in this report are those of the authors and not necessarily those of the California Air Resources Board. The mention of commercial products, their source, or their use in connection with material reported herein is not to be construed as either actual or implied endorsement of such products.

Received 30 April 1998; Accepted 27 July 1998.

Abstract

Ozone emissions were measured above a "personal air purifier" (PAP) designed to be worn on a lapel, shirt pocket, or neck strap. The device is being marketed as a negative ion generator that purifies the air. However, it also produces ozone within the person's immediate breathing zone. In order to assess worst-case potential human exposure to ozone at the mouth and nose, we measured ozone concentrations in separate tests at 1, 3, 5, and 6 in. above each of two PAPs in a closed office. One PAP was new, and one had been used slightly for 3 months. Temperature, relative humidity, atmospheric pressure, room ozone concentration, and outdoor ozone concentration also were measured concurrently during the tests. Average ozone levels measured directly above the individual PAPs ranged from 65–71 ppb at 6 in. above the device to 268–389 ppb at 1 in. above the device. Ozone emission rates from the PAPs were estimated to be 1.7–1.9 g/minute. When house dust was sprinkled on the top grid of the PAPs, one showed an initial peak of 522 ppb ozone at 1 in., and then returned to the 200–400 ppb range. Room ozone levels increased by only 0–5 ppb during the tests. Even when two PAPs were left operating over a weekend, room ozone levels did not noticeably increase beyond background room ozone levels. These results indicate that this "PAP," even without significant background ozone, can potentially elevate the user's exposures to ozone levels greater than the health-based air quality standards for outdoor air in California (0.09 ppm, 1-hour average) and the United States (0.08 ppm, 8-hour average).