[Fiber emissions from weathered asbestos cement products. 2. Physical-chemical properties of liberated asbestos fibers]. / Zu faserigen Emissionen aus abgewitterten Asbestzement-Produkten. 2. Physikalisch-chemische Eigenschaften der freigesetzten Asbestfasern.

It could be already shown that fibrous particulates can be emitted from weathered and corroded surfaces of asbestos-cement-(AC)-products and that these fibers increase the total ambient air concentration after having been dispersed in the atmosphere. In this investigation we studied the influence of the polluted atmosphere on physical and chemical properties of asbestos fibers in the corroded surface layer. It was found, that in a part of these asbestos fibers the magnesium was partly leached and that the fibers were strongly contaminated by deposited air pollutants.

[Fiber emissions from weathered asbestos cement products. 1. Fiber release in ambient air]. / Zu faserigen Emissionen aus abgewitterten Asbestzement-Produkten. 1. Faserfreisetzung in die Aussenluft.

Emissions of fibrous aerosols were measured on buildings with weathered and corroded asbestos-cement-plates (roofing and facade shingles) by means of an already published equipment and procedure. The measured emission factors for asbestos fibers longer than 5 microns were in the range of 10(6) to 10(8) fibers/m2.h. They depended on the type of the AC-plates as well as on their age and corrosion intensity.

Measurement of inorganic fibrous particulates in ambient air and indoors with the scanning electron microscope.

In the Federal Republic of Germany, the concentration of inorganic fibrous particles in the ambient air is measured by scanning electron microscopy (SEM) in accordance with draft guideline VDI 3492. Fibres of length greater than or equal to 2.5 microns are counted at a magnification of X2000. The concentrations and fibre dimensions of asbestos fibres and other mineral fibres were determined for 231 ambient air samples, 219 indoor air samples taken during asbestos removal and 21 taken at workplaces. In the ambient air measurements in rural and urban areas, the average concentration of other inorganic fibres was greater than 1000 fibres of length greater than or equal to 5 microns per m3. On the average, only about 100 or fewer asbestos fibres of length greater than or equal to 5 microns per m3 were observed. These 'asbestos fibres' from ambient air had low aspect ratios. They differed substantially from asbestos fibres measured in the ambient air close to sources of asbestos emissions, indoors during asbestos removal or at workplaces. Furthermore, the size distribution of these 'asbestos fibres' was similar to that of 'other inorganic fibres'. We suggest, therefore, that a substantial portion of the 'asbestos fibres' observed by SEM analysis in ambient air samples from rural and urban areas should be classified instead as 'other mineral fibres'.

[Measurement of the fibrous dusts in West Germany. Fiber concentration in the vicinity of objects and buildings with asbestos-containing building materials]. / Immissionsmessungen von faserigen Stäuben in der Bundesrepublik Deutschland. Faserige Immissionen in der Umgebung von Objekten und Gebäuden mit asbesthaltigem Baumaterial.

Ambient air concentrations of fibrous dusts were measured in the vicinity of buildings with weathered and corroded asbestos-cement (AC)-products during 1983-1985. The concentrations of the total dust (TSP) were higher (mean value of 150 micrograms/m3) than the background concentrations. The mean value of ambient air asbestos concentrations lay at 750 fibers/3 for long asbestos fibers (longer than 5 microns). The maximum values were in the range of 10(3) fibers/m3. About 37% of the measured asbestos fiber concentrations (long fibers) were in the range above 500 fibers/m3; 12% of all long asbestos fiber concentrations were higher than 1000 fibers/m3. In the case of a proposed preventive concentration limit of 400 long asbestos fibers/m3, the asbestos fibers released from the corroded surfaces of AC-products on buildings, mean additional health risk not only for the house residents but in some cases also for the general population.