Aerosol-borne quinones and reactive oxygen species generation by particulate matter extracts.

The mass loadings of quinones and their ability to generate reactive oxygen species (ROS) were investigated in total suspended particulate samples collected in Fresno, CA, over a 12-month period. Particles were collected on Teflon filters and were analyzed for the presence of 12 quinones containing one to four aromatic rings by gas chromatography with mass spectrometry. Measured levels are generally greater than mass loadings reported at other locations. The mass loadings were highest during winter months and were strongly anticorrelated with temperature. ROS generation was investigated by measuring the rate of hydrogen peroxide production from the reaction of laboratory standards and ambient samples with dithiothreitol (DTT). ROS generation from ambient samples shows a strong positive correlation with the mass loadings of the three most reactive quinones and may account for all of the ROS formed in the DTT test.