Olav Bjørseth

Sorption behaviour of volatile organic compounds on material surfaces — The influence of combinations of compounds and materials compared to sorption of single compounds on single materials

Abstract The sorption of volatile organic compounds (VOC) on material surfaces was evaluated by chamber testing. The sorption of single VOCs was compared to the sorption of the combination of the VOCs and the sorption of single material surfaces was compared to the sorption of the combination of material surfaces. The sorption compounds were α-pinene and toluene, and the material surfaces were wool carpet and nylon carpet. The sink effect of the chambers and the effect of the loading of the materials were evaluated separately. The results show that the loading has no influence by itself. Relatively high loading minimises the sink effects of the test chamber and is therefore recommended. The presence of two chemical compounds at the same time gives correspondingly higher sorption compared to experiments with one compound at a time. The results indicate that the desorbed masses of individual compounds are additive, making prediction of the desorbed mass of combinations of compounds possible. The combination of two materials at the same time leads to higher sorption than one single material. The results indicate that the effect was additive, even if the results for α-pinene are not completely clear. There is a need for further research to investigate the sorption behaviour of combinations of materials as well as other combinations of common indoor compounds. A one-sink model, based on a linear Langmuir adsorption isotherm, appears adequate to describe the results.

Emissions from heated indoor dust

Settled indoor dust was collected from a university building, and the fine fraction was heated in the temperature range of 50-250 degrees C. Emissions of compounds were analysed and identified in a system consisting of a thermal desorption unit coupled to a gas chromatograph-mass spectrometer (GC-MS). The heating took place in both an oxidative (air) and an inert (He) atmosphere. The results indicate that oxidation of adsorbed compounds occurred, as well as decomposition of the dust itself. The emission in air started somewhere between 150 and 200 degrees C, with aldehydes and ketones as the main compounds. When heated in the inert atmosphere, semivolatile organic compounds (SVOCs) were emitted at temperatures above 150 degrees C. These compounds were not found in the air system, probably due to oxidation. Based on the obtained results we recommend that the temperature of hot surfaces in indoor environments should be kept below 150 degrees C to avoid oxidation of indoor dust and minimise the emissions.

Physical changes of indoor dust caused by hot surface contact

Abstract The aim of this study was to achieve a better understanding of the physical changes of indoor dust as a result of heating. Indoor dust was collected from an office building, and the fine fraction was heated in the temperature range 50–250°C. Characterisation of the dust was performed before and after contact with hot surface with respect to particle size and shape (electron microscope), specific surface area (nitrogen adsorption method), number of particles (optical particle counting, condensation nucleus counting) and weight loss (thermogravimetric analysis). Heat treatment induces a significant increase in the number of emitted sub-micron particles, probably dominated by condensation particles. This occurs even at low temperatures, (50–100°C), which are often present in an indoor environment. Size, shape and specific surface area of the residual dust show only minor differences from non-heated dust. Emitted volatile organic compounds from the same experiments have been reported in a previous study and biological effects are currently being studied.

Emissions from heated indoor dust: an approach for sample preparation and in vitro toxicity testing

A model was established to collect emissions from dust heated at 150°C and 250°C. These emissions were tested in vitro using lung epithelial cells (A549) and peripheral blood mononuclear cells (PBMCs). The volatile emissions and particles from the dust were either used for direct exposure or extracted in cell culture medium. A condensate of high-boiling point components was also tested. The direct exposure of 150°C and 250°C emissions to cells on inserts caused reduced viability and increased detachment in both cell cultures. Smoke and condensate extracts of emissions from dust heated at 250°C reduced proliferation and mitochondrial activity of A549 cells. The condensate, but not the smoke extract, reduced the viability of PBMCs. The results show that emitted compounds from heated dust have biological effects in vitro starting at 150°C. This study is a platform on which a standardized method for collecting and testing such emissions can be developed.

Sampling Petroleum Oil Mist and Vapor; Comparison of Methods

The sampling efficiency of four methods for sampling petroleum oil mist and vapor were compared. The four methods most frequently used in Scandinavia are (1) double glass fiber filter in 37 mm diameter clear styrene acrylonitrile (SAN) cassettes; (2) a single glass fiber filter followed by a membrane filter in the same type of filter cassette; (3) the IOM filter cassette with 25-mm double glass fiber filters; and (4) a glass tube filled with glass wool. The vapor was collected on charcoal tubes connected downstream to the sampling line after the filter cassette. The devices were tested with two petroleum oils with different boiling points. Results show that the IOM cassette had the highest sampling efficiency, and the SAN cassette with 37 mm diameter double glass fiber filters the lowest efficiency. The differences in sampling efficiency between the methods for sampling oil mist were statistically significant at the 5% level except the difference between method (2) and method (3) for the low boiling oil. ...