A study of the size distributions and the chemical characterization of airborne particles in the vicinity of a large integrated steelworks

An atmospheric measurement campaign took place in the spring of 2006 to characterize the emission of particles from an integrated iron and steelmaking site. During the measurement campaign, the PM10 daily limit value of 50 mu g m(-3) was not exceeded during any day. However, excursions in PM10 concentrations occurred over periods of a few hours which were associated with wind passing over the steelworks' site. Measurements with an Aerosol Time-of Flight Mass Spectrometer (ATOFMS) showed six particle classes associated with emissions from steelmaking processes. Two of these were iron-rich, one showing internal mixing with nitrate, the other internally mixed with phosphate, which subsequent analysis identified as arising from the ironmaking sector and the hot and cold mills as the dominant sources, respectively. Other ATOFMS classes were rich in lead, zinc, and nickel, which were also associated with steelmaking sources. A Micro Orifice Uniform Deposit Impactor (MOUDI), used to measure particle size distributions over periods of 19-42 hours, showed two characteristic size distributions for iron, one bimodal with modes at 0.45 mu m and 4 mu m, the other unimodal centered at 6 mu m. In the former case, the smaller mode exhibited a peak for lead at the same particle size and in the case of the larger mode, phosphate and calcium also showed a peak at 4 mu m diameter, consistent with the ATOFMS findings. An additional particle type with a unimodal size distribution centered at about 1.2 mu m, with internally mixed Pb, Zn, and Cl but not Fe was also found.