Monitoring Respirable Crystalline Silica

At DustWatch we are always concerned about the health and safety of our clients.  Have a look at these articles regarding Monitoring Respirable Crystalline Silica.

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Silver Membranes in Monitoring Respirable Crystalline Silica – Sterlitech 

“Crystalline silica, most commonly found in the form of quartz, is a basic component of the earth; it’s found in soil, sand granite, and other minerals. During many industrial processes, crystalline silica is released as particles that are 100 times smaller than beach sand.1 Due to their size, these mineral particles cannot easily be cleared by human lungs. Instead, they persist in the respiratory system and form scar tissue, contributing to serious health problems for those experiencing prolonged exposure. The associated silicosis and other forms of cancer are a threat to workers in mining, construction, and other industrial trades.2

There is a global awareness of this seriousness of this issue, and the World Health Organization has published assessment documents detailing the negative health effects of exposure. Here in the US, the Occupational Safety and Health Administration (OSHA) released a Final Rule on Occupational Exposure to Respirable Crystalline Silica, to provide guidance for the safety of industrial workers.3 The ruling published in March 2016 puts the responsibility on companies to create a low-risk environment, with enforcement in the form of fines (potentially over $12,000 per day) going into effect for some industries starting in September 2017.3 Beyond recommending proper personal protective equipment, ventilation systems, and replacement of silica when safer materials can be used, this ruling establishes a permissible exposure limit (PEL) at 50 μg/m3. This means that only 1/5th of the previously allowed PEL is now considered safe in the workplace.2

To monitor levels of crystalline silica, employers can take routine samples and have them analyzed in a lab. A portable sampler is used to collect air from the worker’s respirable area during a full shift. The dust captured on the filter is then analyzed using a standard method, such as NIOSH 7500.4 In this method, the filter is then dissolved and redeposited on a 0.45 micron silver membrane for measurement using x-ray diffraction. Silver membranes have become the standard for x-ray diffraction analysis due to their high sample-load capacity and characteristically low background noise during analysis.

The results of these analyses help employers understand whether they need to be taking more action to protect their workers. OSHA estimates that the steps advised in their ruling will save 600 lives and prevent 900 cases of silicosis every year.5 For now, companies in regulated industries are developing control plans and training workers to ensure compliance with the new rules. It remains to be seen what the full impact of enforcement will mean for their employees and their business.”

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Taylor & Francis Online – Crystalline Silica Dust and Respirable Particulate Matter During Indoor Concrete Grinding—Wet Grinding and Ventilated Grinding Compared with Uncontrolled Conventional Grinding

“The effectiveness of wet grinding (wet dust reduction method) and ventilated grinding (local exhaust ventilation method, LEV) in reducing the levels of respirable crystalline silica dust (quartz) and respirable suspended particulate matter (RSP) were compared with that of uncontrolled (no dust reduction method) conventional grinding. A field laboratory was set up to simulate concrete surface grinding using hand-held angle grinders in an enclosed workplace. A total of 34 personal samples (16 pairs side-by-side and 2 singles) and 5 background air samples were collected during 18 concrete grinding sessions ranging from 15–93 min. General ventilation had no statistically significant effect on operator’s exposure to dust. Overall, the arithmetic mean concentrations of respirable crystalline silica dust and RSP in personal air samples during: (i) five sessions of uncontrolled conventional grinding were respectively 61.7 and 611 mg/m 3 (ii) seven sessions of wet grinding were 0.896 and 11.9 mg/m3 and (iii) six sessions of LEV grinding were 0.155 and 1.99 mg/m3. Uncontrolled conventional grinding generated relatively high levels of respirable silica dust and proportionally high levels of RSP. Wet grinding was effective in reducing the geometric mean concentrations of respirable silica dust 98.2% and RSP 97.6%. LEV grinding was even more effective and reduced the geometric mean concentrations of respirable silica dust 99.7% and RSP 99.6%. Nevertheless, the average level of respirable silica dust (i) during wet grinding was 0.959 mg/m3 (38 times the American Conference of Governmental Industrial Hygienists [ACGIH] threshold limit value [TLV] of 0.025 mg/m 3 ) and (ii) during LEV grinding was 0.155 mg/m 3 (6 times the ACGIH TLV). Further studies are needed to examine the effectiveness of a greater variety of models, types, and sizes of grinders on different types of cement in different positions and also to test the simulated field lab experimentation in the field.”

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Dust Monitoring Equipment – providing equipment, services and training in dust fallout management to the mining industry.

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