Dithiothreitol‐Measured Oxidative Potential of Reference Materials of Mineral Dust: Implications for the Toxicity of Mineral Dust Aerosols in the Atmosphere.

Oxidative stress is a mechanism that might raise the toxicity of mineral dust aerosols. We evaluated the oxidative potential (OP) of four reference materials (RMs) of mineral dusts using dithiothreitol assay. The OP of the water‐soluble fraction of the dust RMs accounts for 40%–70% of the OP of the total fraction. The values of total and water‐soluble OP normalized by the surface area of insoluble particles showed agreement among the different dust RMs. The surface area of insoluble dust particles was therefore inferred as an important factor affecting the OP of mineral dust. Using the relation between total OP and the surface area of insoluble particles of the dust RMs, we estimated the total OPs of fine and coarse atmospheric mineral dust aerosols assuming a typical particle size distribution of Asian dust aerosols observed in Japan. Mass‐normalized total OPs were estimated at 44 and 23 pmol min−1 μg−1 for fine and coarse atmospheric mineral dust particles. They closely approximate the values observed for urban aerosols in Japan, which suggests that mineral dust plume advection can lead to a marked increase in human exposure to redox‐active aerosols, even far downwind from mineral dust source regions. Plain Language Summary: Mineral dust aerosols in the atmosphere are mostly soil particles swept up from arid and semi‐arid land surfaces. They can be transported long distances in the atmosphere and can affect air quality throughout large areas, even far downwind from source regions. Inhalation and exposure to mineral dust aerosols adversely affect human health. Although the mechanisms of mineral dust aerosol toxicity remain unknown, oxidative stress has been implicated as a mechanism leading eventually to adverse health effects. The oxidative potential (OP) of aerosol particles is defined as the capability of aerosol particles to induce oxidative stress. To investigate the OP of mineral dust aerosols, we evaluated the OPs of reference materials of mineral dusts using a cell‐free assay called dithiothreitol assay. Then we estimated the OPs of mineral dust aerosols in the atmosphere. The intrinsic OP estimated for a long‐range transported mineral dust aerosol in the atmosphere was very similar to that of urban aerosols. This finding suggests that mineral dust plume advection can engender a marked increase in human exposure to toxic aerosols, consequently inducing oxidative stress even in areas far downwind from mineral dust source regions. Key Points: The oxidative potential (OP) of mineral dust reference materials is characterized using dithiothreitol assayThe surface area of insoluble particles strongly affects the OP of mineral dustThe intrinsic OP of atmospheric mineral dust aerosols is comparable to that of urban aerosols [ABSTRACT FROM AUTHOR]