Indoor Air Chemistry
In indoor air, chemicals can react with one another to form other compounds that are more hazardous than the original chemicals. Increasing evidence has shown that ozone and hydroxyl radicals formed by other oxidants can react with alkenes (such as limonene found in citrus and fragrance formulations, as well as terpenes emitted by many wood products) to generate secondary pollutants, including formaldehyde, as well as hydroxy radicals that can react with organics to form other potentially toxic air pollutants. The toxicity of many of these secondary pollutants is well-established while for others it has yet to be evaluated (12, 13, 14, 15, 16). These reactions can be limited by employing carbon-based filters in locations where outdoor ozone concentrations commonly approach or exceed the National Ambient Air Quality Standards (NAAQS) promulgated by the U.S. EPA.