Insight of the size dependent bioavailability and health risk assessment of arsenic in resuspended fly ash from power plants

•Fly ash samples were classified with different sizes by a self-made resuspension device.•The bioavailability of arsenic in fly ash increased with the decrease of particle size.•The ingestion and inhalation bioavailability of arsenic relied on non-specifically sorbed and specifically-sorbed fractions.•∑CR values of the samples from the power plants exceeded acceptable threshold or even tolerable risk level.