How should I sample to comply with OSHA’s silica dust standard?

“So, silica…”dusty

This was how many conversations started while exhibiting at conference  last week. OSHA released its rule for occupational exposure to respirable crystalline silica back in March and many are still looking to understand how it will affect their business and employees.

The new rule goes into effect on June 23, 2016 and most business will have between one to five years to comply depending on industry. The new standard reduces the permissible exposure limit (PEL) for respirable crystalline silica to 50 micrograms per cubic meter of air, averaged over an 8-hour shift. This is a reduction is two to five times lower than the previous PEL.

The new lower permissible exposure limit may change how you are currently monitoring. To meet the new standard there has to be a large enough sample to get the maximum limit of 12.5 micrograms/m3  which is 25% of the new permissible exposure limit (PEL). Simply speaking, you must take in a larger air sample for measurements taken over a shorter time period.  For a four hour measurement, you have to double the flow rate, which means you need a bigger pump to pull in more volume and a medium flow cyclone.

Silica sampling best practices:

  • There are six existing sampling methods, but the top three methods tend to be: NIOSH 7500 , NIOSH 7602, and NIOSH 7603.
  • Draw a large enough sample to obtain a maximum limit of detection of 12.5 micrograms per cubic meter (i.e., 25% of 50 micrograms per cubic meter)
  • Use a constant flow control pump that will keep the flow rate at +/- 5% of set flow.
  • Observe the cyclone flow rate specification for meeting the ACGIH size selection curve (50% at 4 microns).
  • A medium flow cyclone can meet the detecting limit in an 8 hour sample and still be comfortable to wear.

If you are looking to monitor for silica dust, please consult with an industrial hygienist before conducting any sampling program. We can help provide you with equipment to do so:

Sensidyne Gilian 10i Personal Air Sampling Pump for High Flow Applications (5-10 LPM)

Sensidyne Gilian 12 Personal Air Sampling Pump for Powerful High Flow Applications (4-12 LPM)

Sensidyne Gilian GilAir Plus Universal Air Sampling Pump (25-5000 cc/min)

If you want more information about OSHA’s crystalline silica rule, we have a free guidebook available.

RAECO LIC LLC is an authorized national distributor of Sensidyne and the premiere Midwest U.S. distributor for measurement, detection, and analysis instrumentation.

 

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