Safety Tidbit 3.33 - Respirable Dust

Safety Tidbit 3.33 – Respirable Dust

Reference:      OSHA Respirable Crystalline Silica Standard

                        Thoracic and respirable particle definitions for human health risk assessment

This week I attended the Central PA Safety Conference at the Nittany Lion Inn in State College. This local venue conference is always fun as I get to see friends that I may not have seen in a while but more importantly, the conversations and networking that happens. A few of us were discussing sampling for respirable crystalline silica and I mentioned that we a PA OSHA use the aluminum SKC cyclone, but I am looking at other means that have a higher flow rate to accommodate specific short duration task evaluation. The discussion led to a few other particle samplers then the everyone paused when one asked if OSHA will accept the newer sampling methods.

I pulled up the OSHA website to see what guidance was available in the standard. Luckily, the answer was easy to find. In the definitions section of the RCS standard OSHA specifies: “Respirable crystalline silica means quartz, cristobalite, and/or tridymite contained in airborne particles that are determined to be respirable by a sampling device designed to meet the characteristics for respirable-particle size-selective samplers specified in the International Organization for Standardization (ISO) 7708:1995: Air Quality-Particle Size Fraction Definitions for Health-Related Sampling.” Therefore, if the method meets the ISO 7708-1995 specifications for respirable-particle samplers we’re golden (and of course, you must use the sampler the way the manufacturer demands).

After a quick internet search for the samplers, all the samplers we were discussing met the ISO 7708-1995 requirements. Remember, sampling for respirable dust requires the pump to calibrated to the specified airflow (e.g. 1.7, 2.2, 2.5, 4, 8 liters per minute) so the dust collected meets the aerodynamic diameter. OSHA typically will use the Dorr-Oliver nylon cyclone with a median cut point of 3.5 microns however the SKC cyclone’s cut point is 4 microns. Both meet the ISO 7708:1995 requirements but the SKC cyclone results tends to be a bit more protective as they collect a slightly larger sample size. The next problem: can you find a pump that will pull enough air and can still be worn by the worker.

Hope this was helpful and thanks for reading my Safety Tidbits! Comments and questions are always welcome. ~ Bryan

P.S. If you have an interesting safety or health question please let me know.