Crystalline silica or quartz is one of the most common minerals on Earth. When finely powdered silica gets in the air it becomes a significant health hazard. Respirable quartz is associated with the development of silicosis, lung cancer, pulmonary tuberculosis and other airway diseases.
The National Institute for Occupational Safety and Health (NIOSH) has estimated that at least 1.7 million U.S. workers are exposed to respirable crystalline silica in a variety of industries and occupations, including construction, sandblasting and mining (1991 data). Other industries with significant exposure include building construction and medical and dental laboratories. To help safeguard workers, the Occupational Safety and Health Administration (OSHA) enforces strict regulatory limits on the emission of respirable crystalline silica in the work place.
Monitoring silica dust in the workplace typically is done by collecting samples over a period of hours on a special air filter and using X-ray diffraction (XRD) to determine the amount of silica present in the sample. To be effective, monitoring requires accurate measurements of micrograms of silica on the filters, which in turn requires precise calibration of the measurement system. NIOSH has identified calibration errors as a significant factor in inconsistent results from different laboratories.
To help environmental laboratories perform these demanding calibrations, NIST has developed a series of Standard Reference Materials (SRMs) with precisely measured quantities of respirable quartz deposited on typical filters. The NIST materials cover the range between 5 micrograms and 1000 micrograms of quartz per filter, the typical range encountered in the field, and can be used to validate the accuracy of lab measurements needed to meet OSHA regulations. The reduction to ash technique must be used to prepare the quartz-on-filter specimens for XRD measurements. Details on SRM series 2950--2958, "Respirable Alpha Quartz on Filter Media" are available at https://srmors.nist.gov/tables/view_table.cfm?table=105-10.htm.
A related series of reference materials using cristobalite, the second-most important form of respirable crystalline silica, also is being developed. Standard Reference Materials are among the most widely distributed and used products from NIST. The agency prepares, analyzes and distributes well over a thousand different materials that are used throughout the world to check the accuracy of instruments and test procedures.
Michael Baum | EurekAlert!
A materials scientist’s dream come true
21.08.2018 | Friedrich-Alexander-Universität Erlangen-Nürnberg
Novel sensors could enable smarter textiles
17.08.2018 | University of Delaware
There are currently great hopes for solid-state batteries. They contain no liquid parts that could leak or catch fire. For this reason, they do not require cooling and are considered to be much safer, more reliable, and longer lasting than traditional lithium-ion batteries. Jülich scientists have now introduced a new concept that allows currents up to ten times greater during charging and discharging than previously described in the literature. The improvement was achieved by a “clever” choice of materials with a focus on consistently good compatibility. All components were made from phosphate compounds, which are well matched both chemically and mechanically.
The low current is considered one of the biggest hurdles in the development of solid-state batteries. It is the reason why the batteries take a relatively long...
New design tool automatically creates nanostructure 3D-print templates for user-given colors
Scientists present work at prestigious SIGGRAPH conference
Most of the objects we see are colored by pigments, but using pigments has disadvantages: such colors can fade, industrial pigments are often toxic, and...
Scientists at the University of California, Los Angeles present new research on a curious cosmic phenomenon known as "whistlers" -- very low frequency packets...
Scientists develop first tool to use machine learning methods to compute flow around interactively designable 3D objects. Tool will be presented at this year’s prestigious SIGGRAPH conference.
When engineers or designers want to test the aerodynamic properties of the newly designed shape of a car, airplane, or other object, they would normally model...
Researchers from TU Graz and their industry partners have unveiled a world first: the prototype of a robot-controlled, high-speed combined charging system (CCS) for electric vehicles that enables series charging of cars in various parking positions.
Global demand for electric vehicles is forecast to rise sharply: by 2025, the number of new vehicle registrations is expected to reach 25 million per year....
17.08.2018 | Event News
08.08.2018 | Event News
27.07.2018 | Event News
21.08.2018 | Power and Electrical Engineering
21.08.2018 | Life Sciences
21.08.2018 | Medical Engineering