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New Developments Simplify Air Sampling at Fracking Sites

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September/October 2015

The American Petroleum Institute (API) reported that there are approximately 35,000 wells fractured hydraulically or “fracked” in the U.S. each year.1 Work activities at fracking sites can produce both gaseous and particulate airborne chemical hazards. To address concerns of worker exposure to these hazards, U.S. OSHA and NIOSH have issued hazard alerts on target compounds in fracking and have published guidance documents and journal articles to assist health and safety professionals. Readers may wish to consult two key documents found on the OSHA website:

    1. OSHA-NIOSH Hazard Alert: Worker Exposure to Silica during Hydraulic Fracturing at www.osha.gov
    2. Hydraulic Fracturing and Flowback Hazards Other than Respirable Silica at www.osha.gov/Publications

This article will discuss new developments in sampling technology that can simplify the health and safety professional’s job of taking air samples for designated compounds at fracking sites.

Respirable Crystalline Silica Issue: Silica sand is often added to fracturing fluids to serve as a proppant, i.e. to hold open fractures in shale rock following a fracturing treatment. U.S. NIOSH has published reports noting that occupational exposure levels of respirable crystalline silica at fracking sites have sometimes exceeded exposure limits by more than 10 times.2

New Developments: Size-selective cyclones sampling at flows of approximately 2 L/min have been used historically to sample silica onto PVC filters. In recent years, there have been two significant developments for sampling respirable dust, including silica.

    1. New Impaction-based Parallel Particle Impactor (PPI) Samplers
    1. Available in a single-use plastic model, these smaller and lighter weight samplers provide greater comfort for wearers. A key benefit is that unlike cyclones, there is no tipping hazard with PPI Samplers. PPI Samplers can be turned upside down during use or transport without invalidating the sample.
    1. 2. Higher Flow Respirable Dust Samplers
      1. Given lower occupational exposure limits, NIOSH has raised concerns that sampling flow rates near 2 L/min do not collect enough silica onto the filter for quantitative analysis.

    1. New respirable dust samplers have been developed with higher flow rates to provide a solution to NIOSH concerns. PPI Samplers (described previously) are available at flow rates of 2, 4, and 8 L/min. New cyclones have also emerged that are used at higher flows. The GK2.69 Cyclone is operated at 4.2 L/min to trap respirable dust. The GK4.162 RASCAL Cyclone is operated at 8.5 to 9 L/min. These new higher flow samplers allow for quantitative analysis of silica, even with shorter sample periods.



PPI Samplers


GK4.162 RASCAL Cyclone

VOCs (Including Benzene)


    1.  In 2014, the NIOSH Science Blog at http://blogs.cdc.gov/niosh-science-blog/2014/08/21/flowback-2 reported on worker exposures during oil and gas extraction flowback and production testing activities. In particular, NIOSH noted that workers gauging tanks can be exposed to higher than recommended levels of benzene. Other activities that may lead to high exposures to VOCs include opening hatches and performing maintenance on equipment in the flowback process.



VOC Chek Passive Sampler
New Developments:

    1.  Since the 1980s, passive samplers have provided a simple and effective option for sampling organic vapors. There are more recent developments of interest to professionals.


      1. U.S. OSHA has published validated sampling and analytical methods for designated VOCs using passive samplers. These methods bring a higher level of user confidence in results and the ability to withstand government scrutiny.
      2. The new OSHA methods allow for the use of passive samplers for both short-term and full-shift sampling of VOCs. For example, OSHA Method 1005 for benzene specifies a minimum sample time of only 10 minutes when using the SKC VOC Chek® Sampler 575-002 or the 3M 3520 Organic Vapor Monitor. Passive samplers have been developed for (sub) ppb-level sampling of VOCs for environmental or fenceline monitoring. SKC ULTRA® Passive Samplers use thermal desorption for highly sensitive laboratory analysis to achieve ultra-low detection limits.
      3. 3520 Organic Vapor Monitor. Passive samplers have been developed for (sub) ppb-level sampling VOCs for environmental or fenceline monitoring. SKC ULTRAâ Passive Samplers use thermal desorption for highly sensitive laboratory analysis to achieve ultra-low detection limits.



    1.  Methanol is used as an additive to fracking fluids because of its useful properties as a corrosion and scale inhibitor and friction reducer. Traditional active air sampling methods for methanol using sorbent tubes can be burdensome to both workers and professionals at fracking sites. For example, OSHA Method 91 requires the assembly of two sorbent tubes in series for the collection of methanol and the sample time is limited.

New Developments:

    1.  A new passive sampler for methanol has been validated by research chemists at SKC. The SKC VOC Chek Passive Sampler 575-007 can be used for measuring methanol exposures from 15 minutes to 8 hours at 20 to 400 ppm (80% relative humidity and 71.6 ºF [22 ºC]). No reverse diffusion was evidenced over a full-shift sample, and there was good sample stability when stored at ambient temperatures for one week or for longer at reduced temperatures.



    1.  Bacteria found underground can create a number of problems in hydraulic fracturing including metal corrosion and reduced drilling efficiency. Biocides, including glutaraldehyde, are used to solve bacteria problems.

New Developments:

    1.  As with compounds mentioned previously, new passive samplers have been developed to allow for easy air sampling of aldehydes, including glutaraldehyde. The SKC UMEX 100 Passive Sampler uses a 2,4-DNPH treated paper tape inside a badge housing to trap glutaraldehyde for laboratory analysis by high-performance liquid chromatography. The UME® 100 Passive Sampler can also be used for formaldehyde and other select aldehydes.


    1. From site preparation to production and transport, hydraulic fracturing operations can produce a number of air contaminants of potential concern to worker and public health. New developments in air sampling technology help to simplify the burden for health and safety professionals while providing high-quality exposure data.


    1. References

      1. American Petroleum Institute (API), Water Management Associated with Hydraulic Fracturing, Publication API HF2, 2010 (www.techstreet.com/api products/1701646)
      2. Esswein, E. et al., “Occupational Exposures to Respirable Crystalline Silica During Hydraulic Fracturing,” Journal of Occupational and Environmental Hygiene, 10, 2013, pp. 347-356 (http://doi.org/5kv)
      3. Lee, T. et al., “Performance of High Flow Rate Samplers for Respirable Particle Collection,” Annals of Occupational Hygiene, 54, 2010, pp. 697-709 (http://doi.org/c2v97b)


    1. Author: Debbie Dietrich, CIH, is Vice President of Sales and Marketing and Corporate Industrial Hygienist at SKC Inc. She can be reached at ddietrich@skcinc.com.



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