SAMPLING FOR RESPIRABLE CRYSTALLINE SILICA TO MEET THE

SAMPLING FOR RESPIRABLE CRYSTALLINE SILICA TO MEET THE 2016 U. S. OSHA FINAL RULE

SILICA IS A TOPIC IN THE U. S. SKC INC. is pleased to share the latest updates.

BUT FIRST LET’S LOOK AT SILICA THE COMPOUND Given the chemical formula for silica (Si. O 2), it is interesting to note: Oxygen is the most abundant element in the earth’s crust and silicon is the second most abundant. n Quartz, the most common form of crystalline silica, is the second most common mineral on the earth’s surface. It’s no wonder that exposures to respirable crystalline silica are widespread throughout the world. n

CRYSTALLINE SILICA: WHERE IT’S FOUND n n n Crystalline silica is naturally occurring in sand, gravel, and mineral ores. Quartz, the most common form, is found in almost every type of rock. Nearly all mining and quarrying activities involve exposures to crystalline silica.

CRYSTALLINE SILICA: WHERE IT’S USED n Due to its chemical and physical properties, crystalline silica is a prized mineral with a number of industrial applications. n n Major ingredient in building materials such as concrete, bricks, and stone Used as a molding material for metal casting in foundries Filler in plastics, rubber, and paint Raw material for glass manufacture along with porcelain and fine china

A NEW USE FOR SILICA: FRACKING n Silica sand is used to hold open the fissures created by hydraulic fracturing (fracking) so natural gas or oil can flow out of the shale and into the well.

CRYSTALLINE SILICA: WORKPLACE EXPOSURES n n n U. S. OSHA reports that 2. 2 million workers are exposed to respirable crystalline silica. The majority (1. 85 million) are in the construction industry. Exposures occur when workers cut, grind, crush, or drill silica-containing materials.

CRYSTALLINE SILICA: OTHER WORKPLACE EXPOSURES n n n n Abrasive blasting Foundry work Stonecutting Rock drilling Mining Tunneling Hydraulic fracturing

ACTIONS BY U. S. OSHA ON CRYSTALLINE SILICA In September 2013, U. S. OSHA published a Notice of Proposed Rulemaking (NPRM) for Occupational Exposure to Respirable Crystalline Silica. n This was the first update since the original Permissible Exposure Limit (PEL) was adopted in 1971. n On March 25, 2016, OSHA published the long-awaited final rule. n

WHAT’S NEW FOR SAMPLING IN THE SILICA FINAL RULE n n New Permissible Exposure Limit (PEL) and Action Level New Specifications for Respirable Dust Samplers Guidance on Sample Times to Meet the Limit of Quantification for Lab Analysis Guidance on Analytical Methods that are sensitive enough to measure silica at the new, lower levels

ORIGINAL PELs FROM 1971 WERE CALCULATED FORMULAS PEL FOR GENERAL INDUSTRY A formula based on the % silica in the air sample. For quartz: _____10____ % Quartz + 2 PEL is equivalent to 100 µg/m 3 when the material is pure quartz. PEL approaches 5 mg/m 3, (the PEL for Particulates Not Otherwise Classified) with a low percentage of quartz in the sample. PEL FOR CONSTRUCTION AND SHIPYARDS A formula based on obsolete method of collecting dust into impingers with analysis by particle counting. PEL is approximately equivalent to 250 µg/m 3.

NEW OSHA PEL PASSED IN 2016 50 µg/m 3 as an 8 -hour TWA for all forms of silica including quartz, cristobalite, and trydymite for all industry sectors covered by the rule n n 25 µg/m 3 action level (same as current TLV)

OSHA’S 1971 SPECIFICATIONS FOR RESPIRABLE DUST SAMPLERS n n n U. S. OSHA originally specified the use of a respirable dust sampler whose collection efficiency curve had a 50% (median) cut-point of 3. 5 µm. NOTE: The 50% cut-point is the size of the dust that the sampler collects with 50% efficiency. U. S. OSHA has historically used the 10 -mm nylon Dorr-Oliver cyclone to meet this 1971 criteria.

NEW SAMPLER SPECIFICATIONS PASSED IN 2016 In their proposed and final rules, OSHA acknowledges that the 1971 specifications for respirable dust samplers (50% cut-point of 3. 5 µm) are obsolete. n OSHA now requires that respirable crystalline silica sampling be done using a device that meets the specifications in ISO Standard 7708 entitled Air Quality Particle Size Fraction Definitions for Health-related Sampling. n

ISO STANDARD 7708 n n This is the standard that ACGIH, NIOSH, CEN, and most countries around the world have already adopted. The collection efficiency curve for respirable dust samplers in this standard includes a 50% (median) cut-point of 4 µm.

COMPARISON: NEW AND OLD OSHA SPECIFICATIONS n n Samplers with a 4 -µm cut-point collect more contaminant mass than those with 3. 5 -µm cutpoint. So they are more conservative/protective of worker health. n A simple explanation: If you were collecting particles 3. 5 µm and smaller in the past and then change to collecting particles 4 µm and smaller, you will collect more particles. Also you will collect bigger particles which weigh more, thus, more contaminant mass.

RESPIRABLE DUST SAMPLERS: TO MEET ISO/CEN & OSHA CRITERIA OPTION #1: TRADITIONAL CYCLONES

CYCLONE SAMPLERS: TO MEET ISO & OSHA CRITERIA 10 -mm NYLON DORROLIVER CYCLONE: n Listed in OSHA Final Rule on page 16439 n Listed in NIOSH respirable dust methods n Designated flow rate is 1. 7 L/min (This seems strange because it is the same flow rate as that used for 1971 criteria).

DORR-OLIVER CYCLONE ADVANTAGES AND DISADVANTAGES n n n Advantage: Long history of use in the U. S. by compliance officers Disadvantage: Nylon construction creates static electricity concerns. Disadvantage: Orientation bias (AIHA Journal 56, November 1995) n Disadvantage: Dust sticks to cassette top with closed-face operation. (ASTM, STP 1565, 2013)

CYCLONE SAMPLERS: TO MEET ISO & OSHA CRITERIA SKC ALUMINUM CYCLONE: n n Listed in OSHA Final Rule on page 16439 Listed in NIOSH respirable dust methods Published performance (J. Aerosol Science, 29, 1998) Designated flow rate is 2. 5 L/min SKC 225 -01 -02

SKC ALUMINUM CYCLONE DESIGN FEATURES n n n Metal construction eliminates static electricity concerns. Open-face sample collection enhances collection. Calibration adapter offers user convenience. IMPORTANT NOTE FOR MINING: n Aluminum is considered a spark hazard in underground mines. So choose another sampler such as the GS-3 cyclone for this application.

CYCLONE SAMPLERS: TO MEET ISO & OSHA CRITERIA SKC GS-3: n n n . Listed in OSHA SILICA NPRM on page 267 Published performance (J. Aerosol Science, 28, 1997). Designated flow rate is 2. 75 L/min SKC 225 -100

GS-3 CYCLONE DESIGN FEATURES Developed at West Virginia University to overcome problems evidenced with 10 -mm nylon cyclone: n n n . Conductive plastic construction eliminates static electricity concerns. 3 inlet slits overcome orientation bias Open-face sample collection using 3 -piece cassette enhances collection and eliminates particles sticking to the top of a 2 -piece cassette. SKC 225 -100/103

IMPORTANT NOTE ON FLOW RATE n n n All cyclones are not created equal! Each cyclone has different operating specifications and performance criteria. Be sure you know the flow rate specified before using any cyclone.

TECH TIP: CASSETTE MATERIAL n n n In a March 2013 JOEH article by NIOSH, cassette wall losses were noted when using cyclones with typical cassettes made of clear styrene. * NIOSH recommends the use of 37 -mm black conductive cassettes made of polypropylene. 3 -piece polypropylene cassettes are available from SKC as SKC 225 -309. * Ashley & Harper (2013) Analytical Performance Issues, Journal of Occupational and Environmental Hygiene, 10: 3

RESPIRABLE DUST SAMPLERS: TO MEET ISO 7708 & OSHA CRITERIA NEW OPTIONS

NEW SAMPLERS: FOR ISO 7708 & OSHA CRITERIA n On Page 16439, OSHA notes: The new silica rule “will permit employers to use ANY sampling device that conforms to the ISO/CEN convention. ”

NEW SAMPLERS: FOR ISO 7708 & OSHA CRITERIA Page 16439 goes on to say that in addition to traditional cyclones: “There also personal impactors available for use at flow rates from 2 to 8 L/min that have been shown to conform closely with the ISO/CEN convention. ”

PERSONAL IMPACTORS FROM SKC: PPI SAMPLERS n Shown here are SKC PPI samplers designed to precisely match the ISO 7708/CEN/OSHA collection efficiency curve for respirable dust with a 4 -µm median cutpoint.

SKC PPI DESIGN: 4 INLETS OF DIFFERENT SIZES n Inlet n Impaction Plate Exhaust with Final Filter n Each of the 4 inlets is uniquely sized to achieve a designated cut-point. As such, each inlet functions as a separate impactor. The performance of each impactor matches part of the collection efficiency curve. Dust collected on final filter closely matches the entire curve.

USERS ASKED SKC DELIVERED n Reusable Aluminum n n n Disposable Antistatic Plastic SKC originally produced the PPI only in reusable aluminum. But users asked SKC to produce the PPI sampler in a single-use plastic model. This design eliminates the need for sampler assembly and cleaning. Filters in either model should be pre- & post-weighed by the lab if necessary.

PPI SAMPLER PERFORMANCE COMPARED TO CRITERIA

SKC RESPIRABLE PPI: FLOW RATE OPTIONS n 2 L/min: 225 -385 n 8 L/min: 225 -384 n Single-use, disposable PPI models are available for use at either 2, 4, or 8 L/min. Available empty or preloaded with filters. A calibration adapter is available for disposable models. 4 L/min: 225 -387

PPI FUNCTIONALITY n n n The disposable PPI looks like a traditional 37 -mm filter cassette. But the inlet section has 4 internal, pre-oiled impactor plates that scrub out larger particles. The respirable dust is then collected onto the filter in the outlet section for analysis.

WHY THE HIGHER FLOW RATE RESPIRABLE PPI SAMPLERS? NIOSH reported that for a working environment with an airborne concentration of respirable silica near the current TLV of 25 µg/m 3, the amount of sample collected with current respirable dust samplers (at typical flow rates of 2 L/min) might not be enough for quantitative analysis. (Harper, et al. Ann. Occup. Hyg. , 2010. )

PUMP PARTNERS: RESPIRABLE PPI SAMPLERS n 2 or 4 -L/min models can be partnered with SKC XR 5000 or new Air. Chek Touch pump. n 8 -L/min model can be partnered with the SKC Leland Legacy pump.

GUIDANCE ON SAMPLE TIMES FOR QUANTIFICATION BY LAB n n Page 16440 of the OSHA Final Rule includes a handy chart for guidance on sample times that will result in collection of at least 10 µg which is the limit of quantification for quartz by OSHA Method ID 142. Ex. , Using the SKC Aluminum Cyclone at 2. 5 L/min If sampling at PEL levels of 50 µg/m 3 for 4 hours, 30 µg of quartz will be collected (3 x the limit of quantification). If sampling at the action level of 25 µg/m 3 for 4 hours, 15 µg of quartz will be collected.

ANALYTICAL METHODS: OSHA SPECIFICATIONS n n U. S. OSHA reports on page 16445 that both X-ray diffraction (XRD) and Infrared Spectroscopy (IR) methods can detect and quantify crystalline silica in amounts below the final rule’s 25 -µg action level. Visible absorption spectrophometry (VIS) methods are NOT sensitive enough and are no longer used.

THANK YOU FOR YOUR ATTENTION! Please email skctech@skcinc. com with technical queries or contact your local SKC office for silica sampling equipment! WWW. SKCINC. COM