Polycyclic aromatic hydrocarbons in the work atmosphere. I. Determination in an aluminum reduction plant.

The content of polycyclic aromatic hydrocarbons (PAH) in a Søderberg prebaked aluminum reduction plant and an anode plant was studied. Both stationary and personal sampling were used, and the samples were analyzed by glass capillary gas chromatography. In many samples more than 30 PAH and heterocyclic compounds were identified. Comparison of the results from the different plants revealed that the atmospheric PAH content was significantly higher in the Søderberg plant than in the others. However, the relative distribution of PAH components (PAH profile) was relatively constant in the prebaked and the anode baking plant, and different in the Søderberg plant. As a consequence of the variation in the pollution level among the different job categories, personal sampling showed a broader range of PAH concentrations than the stationary method.

Polycyclic aromatic hydrocarbons in the work atmosphere. II. Determination in a coke plant.

The content of polycyclic aromatic hydrocarbons (PAH) in the work atmosphere of a coke plant was investigated on two occasions. Stationary, mobile, and personal sampling were used, and the samples were analyzed by glass capillary gas chromatography. Up to 39 PAH and heterocyclic compounds were indentified in the samples. By personal sampling, the occupational exposure to PAH was determined to vary between 5 and 1,000 mg/m3. A study of the occurrence of PAH on particulate matter revealed that 98% of the PAH was respirable. No significant variation in the relative distribution of the PAH components (PAH profile) was observed during the two sampling periods. The PAH profile for the coke plant was similar to that of a Søderberg aluminum plant, but different from that of a Søderberg paste plant.

Polycyclic aromatic hydrocarbons in the work atmosphere: Determination of area-specific concentrations and job-specific exposure in a vertical pin Søderberg aluminum plant.

Polycyclic aromatic hydrocarbons (PAH) and particulates in the work atmospheres of the potrooms and anode paste plant of an aluminum reduction plant were determined by stationary and personal sampling and a glass capillary gas chromatographic method. The relative distribution of PAH (PAH profile), the fraction of PAH on particulates, and the ratio between particulate and gaseous PAH were also determined. The PAH profile was found to be similar to that found for another aluminum plant. The PAH fraction of particulate matter was generally between 1 and 4%, and the ratio between particulate and gaseous PAH in the potrooms varied from 0.2 to 1. The occupational exposures were determined from an analysis of a total of 167 personal samples. For most job categories, the geometric mean of the exposure values was higher than 40 microg/m3, spike pulling having the highest exposure of the categories measured.

Occurrence of fibrous sodium aluminumtetrafluoride particles in potrooms of the primary aluminum industry.

Inorganic fibrous particles have been found in the work environment of the primary aluminum industry. Based on scanning electron microscopic analysis, the concentrations ranged from 9 to 720 fibers/cc. The fibers were generally thinner than 0.1 micron in diameter and shorter than 5 microns. By electron microscopy, energy dispersive X-ray microanalysis, and selected area electron diffraction the fibers were identified as sodium aluminumtetrafluoride.

Introduction of a sink-diffusion model to describe the interaction between volatile organic compounds (VOCs) and material surfaces.

A sink-diffusion model to describe the interaction between material surfaces and volatile organic compounds (VOCs) in indoor air has been introduced. The model is based on adsorption/desorption on the material surfaces and diffusion into the materials. Test chamber experiments with exposure of nylon carpet and polyvinyl chloride (PVC) covering against alpha-pinene and toluene were used to validate the model and to make comparisons with a sink model based on the Langmuir adsorption isotherm. The results showed that the sink-diffusion model gave a better description of the desorption curve than the Langmuir model. The model predictions improved with increasing sorption effect. The Langmuir model gave good predictions of relative weak sorption effects, whereas the sink-diffusion model improved the predictions for stronger sorption effects. In this case, nylon carpet showed substantial stronger sorption than PVC covering and alpha-pinene showed stronger sorption than toluene. Controlled field experiments with combinations of building materials and a mixture of VOCs, encountered in real indoor environments, are needed to further validate the sink-diffusion model.

A screening assessment of emissions of volatile organic compounds and particles from heated indoor dust samples.

This paper characterizes and compares emissions during heating of different dust samples relevant to the indoor environment. Characterization includes emission of volatile organic compounds when dust samples were heated to 150 and 250 degrees C (gas chromatograph-mass spectrometer), weight loss during heating to 450 degrees C (thermogravimetric analysis), and the number of particles emitted during heating towards 200 degrees C (condensation nucleus counting). Element analyses were performed for non-heated dust (inductively coupled plasma discharge instrument). Emissions of volatile organic compounds from heated dust from different sources were surprisingly similar. However, the temperature at which the emission of volatiles started varied with the dust source. For most of the samples studied, the emissions were considerable already at 150 degrees C, and increased in number of peaks and peak area at 250 degrees C. Particle emissions started around 70 degrees C regardless of the dust source. Particle emissions seemed to be affected by the content of organic material.

Chamber testing of adsorption of volatile organic compounds (VOCs) on material surfaces.

A simple test chamber method to quantify adsorption and desorption of organic compounds on material surfaces is described. Important environmental parameters such as temperature, relative humidity and air velocity were varied and controlled independently around typical indoor values. Experiments were performed with alpha-pinene and toluene in concentrations of 160-300 micrograms/m3. The measurements show adsorption on and desorption from wool carpet, nylon carpet, polyvinyl chloride (PVC) floor coverings, cotton curtain material and the empty chamber. The ranking of the materials, with respect to their sorption capacity, is as mentioned above. The adsorption of alpha-pinene was higher than the adsorption of toluene for all the materials. Air velocity was not found to influence the sorption of alpha-pinene and toluene on wool carpet, tested with air velocities at 0, 10 and 20 cm/s. The experiments were carried out during both the adsorption and the desorption phase. The uncertainty of the experiments was lowest during the desorption phase. Based on the results obtained, it can be recommended that sorption experiments should be performed as desorption phase experiments. A one-sink model, based on the Langmuir adsorption isotherm, appears adequate to describe the results.

Heating of indoor dust causes reduction in its ability to stimulate release of IL-8 and TNFalpha in vitro compared to non-heated dust.

UNLABELLED: Dust is a major contaminant of the indoor air environment and may affect human health. Indoor dust accumulates on surfaces including heaters and light fixtures, and will be heated when these devices are used. Heat treatment of the dust may change its biologic properties and in this study we simulated the heat treatment with a dust-heating model (50-250 degrees C). The residual and the non-heated dust from seven samples were tested in cultures of fresh peripheral blood mononuclear cells and in A549 cell culture using the release of TNFalpha and IL-8, respectively, as effect indicators. The endotoxin-content and the particle size distribution of the residual and the non-heated dust suspensions were determined for some of the samples. We found that the residual dust had less ability to induce the release of TNFalpha and IL-8. The cytokine decline pattern was similar for all the dust tested and could partly be explained by the reduction in endotoxin content or possibly by inhibitory decomposition products. No correlation was found between the measured particle size distribution and the decreased cytokine levels. The results in this study suggest that the residual dust promotes reduced cytokine response and thereby a possibly lower inflammation reaction in the airways if suspended and inhaled compared with the non-heated dust. PRACTICAL IMPLICATIONS: Accumulation of indoor dust on electric heaters and light fixtures may produce a bad odor when switched on in the cold season and some people claim respiratory distress during such events. To investigate to what extent the residuals of heated indoor dust represent a health hazard, we measured the effect in cell cultures before and after heat treatment of the dust. The in vitro results imply that the residual dust will cause a lower proinflammatory response in the airways if suspended and inhaled compared with non-heated dust. This is partly explained by heat destruction of inflammatory components in the dust.