Aerosol oxidative potential determined by the dithiothreitol assay (OP_DTT) has been linked to adverse cardiorespiratory health endpoints in large population epidemiological studies in metropolitan Atlanta. Although bulk measurements of PM2.5 OP_DTT are becoming more common, size resolved measurements are rare and provide unique insights on the sources and atmospheric processes that contribute to observed OP_DTT levels. Water-soluble OP_DTT size distributions are unimodal with a peak at 1 to 2.5 µm due to contributions from fine mode organic components plus coarse mode transition metal ions. In contrast, water-insoluble OP_DTT is bimodal with a fine and coarse mode; the fine mode is consistent with DTT active organic species associated with solid soot (or elemental carbon) surfaces and the coarse mode with transition metal ions with mineral-tire-brake dust surfaces. These size differences for OP means the main two chemical components that drive OP (organic versus transition metal ions) are largely externally mixed and may deposit in different locations in the respiratory system. This talk will present typical urban aerosol OP_DTT size distributions and discuss sources and processes that affect overall OP_DTT levels.

Aerosol oxidative potential size distributions: A contrast between water-soluble and insoluble components

254th National Meeting (2017)

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