Ozone emissions from a "personal air purifier"

Ozone emissions were measured above a "personal air purifier" (PAP) designe d to be worn on a lapel, shirt pocket, or neck strap. The device is being m arketed as a negative ion generator that purifies the air. However, it also produces ozone within the person's immediate breathing zone. In order to a ssess worst-case potential human exposure to ozone at the mouth and nose, w e measured ozone concentrations in separate tests at 1, 3, 5, and 6 in. abo ve each of two PAPs in a closed office. One PAP was new, and one had been u sed slightly for 3 months. Temperature, relative humidity, atmospheric pres sure, room ozone concentration, and outdoor ozone concentration also were m easured concurrently during the tests. Average ozone levels measured direct ly above the individual PAPs ranged from 65-71 ppb at 6 in. above the devic e to 268-389 ppb at 1 in, above the device. Ozone emission rates from the P APs were estimated to be 1.7-1.9 mu g/minute. Wen 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 incre ased by only 0-5 ppb during the tests. Even when two PAPs were left operati ng over a weekend, room ozone levels did not noticeably increase beyond bac kground room ozone levels. These results indicate that this "PAP," even wit hout significant background ozone, can potentially elevate the user's expos ures to ozone levels greater than the health-based air quality standards fo r outdoor air in California (0.09 ppm, 1-hour average) and the United State s (0.08 ppm, 8-hour average).