Devices marketed as air cleaners or air purifiers are not always good for your health, a report to the California Air Resources Board (ARB) recently stated. According to the report, there are devices that intentionally generate ozone, a key component of smog, resulting in indoor ozone concentrations above health-based state and federal ambient air quality standards. The ARB report covers four devices that were tested according to manufacturer instructions in a small furnished room under common residential temperature and humidity conditions. ARB found that each device tested emitted ozone at levels that exceed health-based standards. One model produced room concentrations more than 4.5 times the health-based state ambient air quality standard for ozone. At elevated levels, ozone can exacerbate asthma, cause lung damage and lead to difficulty in breathing. For more information on what ozone generations to potentially avoid, visit www.arb.ca.gov/research/indoor/ozone.htm.