As a haboob dust storm passed through Big Spring, TX, 33 airborne dust samples were collected in a 1567-cm surface layer. Samples were dried, weighed, and then the size distributions were analyzed with an ultrasonic sieve and a vertical settling aerosol tube. The maximum measured dust concentration was 0.0013 kg m -3. The total horizontal particle flux was 84,960 kg km -2 h -1, within which the flux of particles 20-10 μm in diameter was 17,790 kg km -2 h -1. Vertical distributions of dust concentration decrease with height by a power function. The mean diameters of the dust particles were between 23 and 35 μm, whereas the 95th percentile diameters were from 8 to 14 μm. Particles smaller than 10 μm in diameter were from 1.5% to 10.76% of the total mass fluxes. Vertical distributions of the mean and the 95th percentile diameters showed a natural logarithmic function of height. The dust particles were unimodally distributed with a peak diameter of 40 μm in the 550 cm flow layer, whereas above 550 cm the peak diameter was 20 μm. The airborne dust was from moderately to poorly sorted and became less well sorted with the increasing height.