A study was made of chemical and morphological properties of respirable dusts collected at three iron foundries, one aluminum foundry and one copper smelter. Cascade impactors, cyclones and closed cassettes were used for dust sampling at fixed stations. Analyses included scanning and transmission electron microscopy with energy dispersive x-ray analysis, x-ray photoelectron spectroscopy, secondary ion mass spectrometry, x-ray diffractometry, infrared spectrophotometry and atomic absorption spectroscopy. Ferrous foundries used sand molds without organic resins to cast gray brass and ductile iron. Average dust levels were 1.5 to 1.7mg/m3 (diameter greater than 10 microns), 0.8 to 2.5mg/m3 (diameter 1 to 10 microns) and 0.1 to 2.9mg/m3 (smaller particles). Quartz (14808607) concentrations were 0.08 to 0.1mg/m3 in cascade impactor samples and included calcium (7440702), iron (7439896), zirconium (7440677), fluorine (7782414), zinc (7440666), manganese (7439965), copper (7440508), cobalt (7440484), chromium (7440473), arsenic (7440382) and vanadium (7440622). Significant levels of lead (7439921) were noted in particles smaller than 1 micron from one iron foundry. At the aluminum (7429905) foundry, cassette sampling gave an average 2.6mg/m3 total inspirable dust; respirable dust in cyclone sampling was 1.1mg/m3. Granulometric fractions yielded sodium-fluoride (7681494), chlorine (7782505) and zinc. Manganese was noted in particles smaller than 1 micron. Copper smelter total dust levels were similar to those in the aluminum foundry. Arsenic, lead and copper levels in inhalable dusts were 0.02, 0.23, and 0.26mg/m3, respectively, compared with threshold limit values of 0.05, 0.15 and 1.0mg/m3. Lead occurred mostly as lead-sulfate (7446142). Quartz levels were around 5% in respirable dust.