For instance, a plug-in air freshener was turned on for 24 h in a large climate chamber (30m3; AER=0.55h−1), then briefly exposedto 74 ppb ozone for 25min and followed bymonitoring of terpenes and the formation of formaldehyde, 4-AMCH (4-acetyl-1-methylcyclohexene),and nopinone (Liu et al., 2004).