Like other household appliances (hairdryers, mixers and electric fans), the Honeywell Electronic Air Cleaner, and any other high efficiency electronic air cleaner, will produce trace levels of ozone when they are running. In extensive testing of electronic air cleaners performance both in test chambers and in actual homes, under normal operating conditions, ozone levels measured are in the range of .005 to .020 parts per million (PPM), well below indoor safety levels set by the Food and Drug Administration (FDA). For outdoor air, levels above .120 are considered excessively stressing to people with a respiratory illness or who are sensitive to ozone. In general, levels below .080 are considered acceptable for outdoors, but these levels are often exceeded in some urban areas. The FDA sets a level of .050 with a 24 hour a day exposure as the maximum indoor ozone concentration acceptable An electronic air cleaner can be expected to add about .005 PPM ozone to the steady state indoor level. As the electronic air cleaner loads with dirt, the level of ozone produced further decreases Odor perception for ozone varies quite a bit among people. Some people can smell levels as low as .003 PPM, but most people can smell a level of .020 PPM, which is well below the FDA standard. The smell of ozone is does not necessarily indicate that the level of ozone is above normal, or even near the recommended limit set by the FDA.