Different carpet materials vary considerably in their ability to remove ozone from indoor environments, as well as in their emissions of aldehydes. Researchers at Portland State University and the University of Arizona tested new carpet samples in a glass chamber and measured ozone removal and emissions of aldehydes, both primary (from the carpet itself) and secondary (emitted after reactions with ozone). Ozone removal capacity under steady-state conditions ranged from 40% for polyester fiber carpets to 65% for wool. Total emissions of carbonyls (including aldehydes) increased in the presence of ozone, and varied on average by a factor of 2-4, between fiber types. Emissions of formaldehyde (highly toxic by inhalation), in particular, varied between 3 and 16 mg/m2/hr even without ozone addition. While this data is not sufficient to make general recommendations about fiber types, the authors noted that some fiber materials offer neither the benefit of high ozone removal nor that of low carbonyl emissions.