Measurement of area and personal breathing zone concentrations of diesel particulate matter (DPM) during oil and gas extraction operations, including hydraulic fracturing

ABSTRACT

Diesel engines serve many purposes in modern oil and gas extraction activities. Diesel particulate matter (DPM) emitted from diesel engines is a complex aerosol that may cause adverse health effects depending on exposure dose and duration. This study reports on personal breathing zone (PBZ) and area measurements for DPM (expressed as elemental carbon) during oil and gas extraction operations including drilling, completions (which includes hydraulic fracturing), and servicing work.

Researchers at the National Institute for Occupational Safety and Health (NIOSH) collected 104 full-shift air samples (49 PBZ and 55 area) in Colorado, North Dakota, Texas, and New Mexico during a four-year period from 2008–2012. The arithmetic mean (AM) of the full shift TWA PBZ samples was 10 µg/m³; measurements ranged from 0.1–52 µg/m³. The geometric mean (GM) for the PBZ samples was 7 µg/m³. The AM of the TWA area measurements was 17 µg/m³ and ranged from 0.1–68 µg/m³. The GM for the area measurements was 9.5 µg/m³. Differences between the GMs of the PBZ samples and area samples were not statistically different (P > 0.05).

Neither the Occupational Safety and Health Administration (OSHA), NIOSH, nor the American Conference of Governmental Industrial Hygienists (ACGIH) have established occupational exposure limits (OEL) for DPM. However, the State of California, Department of Health Services lists a time-weighted average (TWA) OEL for DPM as elemental carbon (EC) exposure of 20 µg/m³. Five of 49 (10.2%) PBZ TWA measurements exceeded the 20 µg/m³ EC criterion. These measurements were collected on Sandmover and Transfer Belt (T-belt) Operators, Blender and Chemical Truck Operators, and Water Transfer Operators during hydraulic fracturing operations.

Recommendations to minimize DPM exposures include elimination (locating diesel-driven pumps away from well sites), substitution, (use of alternative fuels), engineering controls using advanced emission control technologies, administrative controls (configuration of well sites), hazard communication, and worker training.

KEYWORDS:

• Diesel exhaust
• diesel particulate matter
• elemental carbon
• exposure assessment
• hydraulic fracturing
• oil and gas extraction

Acknowledgments

The authors thank our industry partners and especially their employees for their demonstrated leadership in occupational health and safety for agreeing to participate in the NIOSH Field Effort to Assess Chemical Exposures in Oil and Gas Workers. We extend our deep and sincere appreciation to Mr. Rick Ingram (BP, Houston, TX and the National STEPS Network) for his support of the NIOSH Field Effort and his longstanding and determined efforts promoting worker health and safety in upstream oil and gas extraction. We recognize all past and present members of the NIOSH NORA Oil and Gas Extraction Sector Council for their dedication to occupational health and safety leadership and their efforts protecting U.S. onshore E&P workers.

We thank CDR Bradley King, Ph.D., CIH, CAPT. Jennifer Lincoln, Ph.D., CSP, NIOSH Western States Office, Arthur Miller, Ph.D. NIOSH Spokane Office of Mining Research, Robert Park, MS, NIOSH, Educational and Information Division, and Kevin Renton, MS, ROH, National Institute for Occupational Health, Johannesburg, South Africa for their critical reviews, insights, and thoughtful comments on drafts of the article.