Ozone is a gas made up of three oxygen atoms (O3). It occurs naturally in small amounts in the upper atmosphere where it protects us from ultraviolet (UV) radiation (“good” ozone). Near the earth’s surface, “bad” ozone is created by chemical reactions in outdoor air pollution and some indoor sources. “Bad” ozone can cause health problems even at relatively low concentrations, including respiratory tract irritation, asthma, and even permanent lung damage.

Electronic products used indoors, including some air cleaners, can generate ozone during normal use.  Indoor ozone levels can be a large source of exposure because people spend about 90% of our time indoors. The US Food and Drug Administration (FDA) was the first to set a limit on ozone emissions from all medical devices at 0.05 ppm. In 2008, the California Air Resources Board (CARB) finalized a state regulation targeting ozone emissions from air cleaners. The CARB regulation requires all electronic air cleaners to be certified to emit less than 0.05 ppm according to the UL867 standard.

Now, UL has created a validation procedure (UL2998) to help the HVAC community and consumers find electronic air cleaners that emit zero ozone. CosaTron was the first company to achieve this important verification for their air purification systems. The verified products are listed in the UL SPOT database of sustainable products (www.ul.com/spot).