Air monitoring of solvent exposed workers with passive samplers in comparison to “biological monitoring (BM)"†

A study was performed comparing ambient air monitoring (AM) and biological monitoring (BM) in order to evaluate the reliability of passive sampling (PS) in occupational medicine.

Five groups of persons (total number = 188) exposed to tetrachloroethene, isopropanol, toluene, xylene and styrene at the workplace were examined.

AM was performed over several hours using one or two brands of passive samplers (Monitor 3500 and/or ORSA 5). BM includes the determination of the solvent and specific metabolites resp. in blood or urine samples taken at the end of workshift. On the basis of our results we recommend that PS can supply relevant data for the estimation of external exposure to several solvents like chlorinated‐ and aromatic‐hydrocarbons.     

Derivation of the reduced life cycle of <Emphasis Type="Italic">Thecoscyphus zibrowii</Emphasis> Werner, 1984 (Cnidaria,Scyphozoa)

The species Thecoscyphus zibrowii Werner, 1984 has an exceptional life cycle, which lacks a medusa stage but develops an extraordinary structure (egg sac) for reproduction. Investigation of the life cycle, as well as anatomical and histological studies of the different developmental stages of T. zibrowii were performed to provide evidence for a possible homology of the egg sac with the medusa stage and to determine whether the reduced metagenesis of T. zibrowii is derived from strobilation. The egg sac showed several characteristics, which were compared to those of coronate medusae. The ectodermis of the egg sac had a plate-like appearance and was completely ciliated as is typical for coronate medusae. The number and the location of the gonads were similar to those of coronate medusae. The cnidocysts were significantly larger in the egg sac than in the polyp. A size difference of cnidocysts in the medusa and the polyp stage is known for several Coronatae. Characteristics of egg sac formation were compared to characteristics of strobilation. The formation of the early operculum was similar in T. zibrowii and N. eumedusoides. The constriction of egg sac and strobila occurred in the same mode and the gastric cavities of two egg sacs stayed in contact in a similar fashion to the gastric cavities of the strobila discs. The developmental zones of cnidoblasts of the egg sac and polyp were separated during the formation of the egg sac which showed a similar developmental gradient to a strobila. The existence of all of these consistent characteristics makes it very likely that the egg sac structure was homologous to a medusa. The species T. zibrowii would therefore be derived from a metagenetic ancestor. This species has reduced the medusa generation to the greatest extent within the Nausithoidae and has demonstrated thus far the endpoint of a regressive evolution of the medusa generation.     

Lagrangian dispersion modeling of vehicular emissions from a highway in complex terrain

Transit traffic through the Austrian Alps is of major concern in government policy. Pollutant burdens resulting from such traffic are discussed widely in Austrian politics and have already led to measures to restrict traffic on transit routes. In the course of an environmental assessment study, comprehensive measurements were performed. These included air quality observations using passive samplers, a differential optical absorption spectroscopy system, a mobile and a fixed air quality monitoring station, and meteorological observations. As was evident from several previous studies, dispersion modeling in such areas of complex terrain and, moreover, with frequent calm wind conditions, is difficult to handle. Further, in the case presented here, different pollutant sources had to be treated simultaneously (e.g., road networks, exhaust chimneys from road tunnels, and road tunnel portals). No appropriate system for modeling all these factors has so far appeared in the literature. A prognostic wind field model coupled with a Lagrangian dispersion model is thus presented here and is designed to treat all these factors. A comparison of the modeling system with results from passive samplers and from a fixed air quality monitoring station proved the ability of the model to provide reasonable figures for concentration distributions along the A10.     

Modelling of Air Quality with CAMx: A Case Study in Switzerland

The three-dimensional Eulerian model CAMx (Comprehensive Air QualityModel with Extensions) was applied for the first time to simulate bothgaseous and particulate photochemical air pollution in Switzerland during July 28–30, 1993. The meteorological input data were prepared using the Systems Applications International Mesoscale Model (SAIMM). The CAMx model results were compared with the measurements carried out at ground level andfrom airborne measuring platforms within the frame of the Swiss POLLUMET research programme. In general, the CAMx performance for gaseous species wasfound to be better than that of the previously used Urban Airshed Model (UAM)and the Variable Grid Urban Airshed Model (UAM-V). The most significant improvement for the gaseous species is in the prediction of HNO₃ concentrations, due to the inclusion of aerosol chemistry. Aerosol species such as NO₃ ^-, NH₄ ⁺, SO₄ ^2-, and secondary organic aerosols were calculated in one particle size range (0.04–2.5 m) and compared with a few measurements available. Although July 29 was reasonably well simulated, overestimated wind speeds by SAIMM for July 30 caused a too fast transport of pollutants. Similarly to measurements, significant spatial correlation of the secondarily formed aerosols with ozone and formaldehyde is found in the afternoon.