Characterization of process air emissions in automotive production plants.

During manufacturing, particles produced from industrial processes become airborne. These airborne emissions represent a challenge from an industrial hygiene and environmental standpoint. A study was undertaken to characterize the particles associated with a variety of manufacturing processes found in the auto industry. Air particulates were collected in five automotive plants covering ten manufacturing processes in the areas of casting, machining, heat treatment and assembly. Collection procedures provided information on air concentration, size distribution, and chemical composition of the airborne particulate matter for each process and insight into the physical and chemical processes that created those particles.

Dry deposition of sulfur dioxide or nitric acid to oak, elm and pine leaves.

To improve our knowledge of atmospheric inputs to forests, experiments were performed in the field to measure the dry deposition of SO2 and HNO3 to oak, elm, and pine leaves. A tree branch was enclosed in a Teflon chamber, through which SO2 or HNO3 flowed. The dry deposition characteristics of SO2 and HNO3 were very different. The SO2 deposition occurred primarily through stomatal openings for the oak and pine leaves, and equal stomatal and cuticular deposition was observed for the elm leaves. The deposited SO2 could not be removed from the branch by extracting in water or by revolatilization. In contrast, over 90% of HNO3 dry deposition occurred to the cuticle. Most of the deposited HNO3 could be extracted from the leaves. Revolatilization of HNO3 was negligible from an active branch, but increased from a dormant or detached branch. A deposition velocity was derived from the ratio of the flux of the gas to the leaves and the gas concentration in the chamber. Deposition velocities ranged from 0.02 to 0.11 cm s(-1) for SO2 and from 0.2 to 1.2 cm s(-1) for HNO3 to individual leaf surfaces.