Documents airborne dust 13 results

"There are currently no exposure limits specific to engineered nanomaterial nor any national or international consensus standards on measurement techniques for nanomaterials in the workplace. However, facilities engaged in the production and use of engineered nanomaterials have expressed an interest in learning whether the potential for worker exposure exists. To assist with answering this question, the National Institute for Occupational Safety and Health established a nanotechnology field research team whose primary goal was to visit facilities and evaluate the potential for release of nanomaterials and worker exposure. The team identified numerous techniques to measure airborne nanomaterials with respect to particle size, mass, surface area, number concentration, and composition. However, some of these techniques lack specificity and field portability and are difficult to use and expensive when applied to routine exposure assessment. This article describes the nanoparticle emission assessment technique (NEAT) that uses a combination of measurement techniques and instruments to assess potential inhalation exposures in facilities that handle or produce engineered nanomaterials. The NEAT utilizes portable direct-reading instrumentation supplemented by a pair of filter-based air samples (source-specific and personal breathing zone). The use of the filter-based samples are crucial for identification purposes because particle counters are generally insensitive to particle source or composition and make it difficult to differentiate between incidental and process-related nanomaterials using number concentration alone. Results from using the NEAT at 12 facilities are presented in the companion article (Part B) in this issue. "

"This criteria document on particles in ambient air has been prepared at the Institute of Environmental Medicine, Karolinska Institutet, at the request of the Swedish Environmental Protection Agency. Although each chapter has main authors, the work has been a joint effort, and all conclusions and recommendations have been thoroughly discussed by the group. Besides the authors, the group included Carl-Elis Boström and Titus Kyrklund from the Swedish Environmental Protection Agency. Furthermore, a draft of the document was discussed with a reference group including Bertil Forsberg, Hans-Christen Hansson, Thomas Sandström, and Katarina Victorin. The main focus of the document is on effects other than cancer since particles in the ambient air were recently evaluated as a risk factor for cancer by the Institute of Environmental Medicine. In general, literature published through 1998 is reviewed, with occasional inclusion of important work published thereafter. However, the chapter on epidemiologic studies was prepared earlier and primarily relates to reports published through 1997."

"The use of manufactured nanomaterials (MNMs)1 has increased at a constant pace over the recent years. Their applications range from scratch resistant or self-cleaning surface coatings, via enforced polymers to enhanced cosmetics. Besides the tremendous new opportunities offered by these novel materials, concerns have been raised because of potential adverse health effects that may arise if MNMs are taken up by the human body. While human exposure to MNMs may in principle occur during any stage of the material's lifecycle, it is most likely in workplaces, where these materials are produced or handled in large quantities or over long periods of time. Inhalation is considered as the most critical uptake route, because the small particles are able to penetrate deep into the lung and deposit in the gas exchange region. Inhalation exposure to airborne nanomaterials therefore needs to be assessed in view of worker protection. ..."

"Background:Coal-fired thermal power plants (TPPs) in Mongolia use various types of asbestos-containing materials (ACMs) in thermal insulation of piping systems, furnaces, and other products.Objective:To investigate the occupational exposure of insulation workers to airborne asbestos in Mongolian power plants.Methods:Forty-seven air samples were collected from four power plants in Mongolia during the progress of insulation work. The samples were analyzed by phase contrast microscopy (PCM) and transmission electron microscopy (TEM).Results:The average phase contrast microscopy equivalent (PCME) asbestos fiber concentration was 0·93 f/cm3. Sixteen of the 41 personal and one of the area samples exceeded the United States Occupational Safety and Health Administration (US OSHA) short-term exposure limit of 1·0 f/cm3. If it is assumed that the short-term samples collected are representative of full-shift exposure, then the exposures are approximately 10 times higher than the US OSHA 8-hour permissible exposure limit of 0·1 f/cm3.Conclusion:Power plant insulation workers are exposed to airborne asbestos at concentrations that exceed the US OSHA Permissible Exposure Limit. Action to mitigate the risks should be taken in Mongolia."

Background To determine dimensions of airborne fibers in the U.S. refractory ceramic fiber (RCF) manufacturing industry, fibers collected through personal air sampling for employees at RCF manufacturing and processing operations have been measured. Methods Data were derived from transmission electron microscopy analyses of 118 air samples collected over a 20-year period. Results Characteristics of sized fibers include: diameter measurements of <60; 0.19 to 1.0 m, of which 75% are less than 0.6 m; and length ranging from < 0.6 to > 20 m, with 68% of fibers between 2.4 and 20 m. Conclusions Exposures in RCF manufacturing include airborne fibers with dimensions (diameter < 0.1-0.4 m, length < 10 m) historically associated with biological effects in pleural tissues. Air sampling data and a review of studies relating fiber size to pleural effects in animals and humans support the belief that information on fiber dimensions is essential for studies with synthetic vitreous fibers.