Dust Removes Ozone From Indoor Air

The squalene and cholesterol that are major constituents of dust found in a test of Danish homes and day-care centers could lessen the amount of potentially harmful indoor ozone, Charles J. Weschler of the University of Medicine & Dentistry of New Jersey and coworkers report (Environ. Sci. Technol., DOI: 10.1021/es103894r). The presence of squalene, which is the most abundant skin-surface lipid, indicates that human skin flakes are a significant fraction of the settled dust in these settings. The amount of cholesterol found indicates that cooking emissions also contribute significantly to indoor dust. Both compounds react with ozone and therefore help remediate indoor air. “If squalene in dust redistributes to other indoor surfaces, it may make an even larger contribution to the removal of indoor ozone than we estimate,” Weschler says. Some of the oxidation products, however, could be irritants. “What one person sheds may be an allergy trigger or source of harmful microbes for someone else,” Weschler notes. This study is a “potent reminder that humans leave a part of themselves in the settings they occupy.”