Ozone is considered a toxic gas by the EPA, and its adverse effects include lung damage, exacerbated asthma symptoms and, at high levels of exposure, an increased risk of death. One 2006 study in the journal Environmental Science and Technology found that upon three hours of exposure to ozone, surfaces such as carpet chemicals and cooking-oil residue on kitchen countertops reacted with ozone to produce formaldehyde, a suspected carcinogen, and other products. Another 2005 study by researchers at the University of Texas found that when an ozone machine was turned on in the presence of a pine-oil cleaner, it produced “significant increases” in so-called ultrafine particles, a pollutant that is of concern to health experts because of the particles’ ability to penetrate deeply into the lungs. The results “add evidence to the potentially harmful effects of ozone generation in residential environments,” the study said. Jeffrey Siegel, a researcher at the University of Texas at Austin, has found that these ozone reactions can occur from very low levels of the gas. Dr. Siegel’s studies have mainly focused on air ionizers. In one study, he tested several popular ion generators in the presence or absence of a household air freshener. When the freshener was present, he contends that the small amounts of ozone from the machines resulted in the creation of ultrafine particles. “Every single one of the ion generators we tested was a net producer of particles, so they ended up generating more particles than they could remove,” he says. Dr. Siegel declined to name the brands of ionizers in the test.
The Wall Street Journal
Air Purifiers Draw Scrutiny