The Art of Air Sampling

Therese Dunphy

August 1, 2009

Knowing when, how, and why to challenge citations stemming from air sampling can save your site not only current penalties but also potential future litigation.

by Daniel J. Pubal


When the Mine Safety and Health Administration (MSHA) or the Occupational Safety and Health Administration (OSHA) conducts air sampling, the results for the site can include short-term abatement problems as well as long-term liability implications. Employees, and even their family members, can sometimes use those results to support claims for disability and negligence against operators. Often times, there are ways to reduce this potential liability at the initial sampling stage, when agencies and the laboratories they use have been known to make significant mistakes.

When an agency decides to perform air sampling, take steps to protect your rights. Involve your most knowledgeable safety managers and engineers in the process. Insist on side-by-side sampling by your independent industrial hygienist. Take the same photos and/or videos as the agency. Don’t deviate from normal conditions by arbitrarily making changes in production activities. Ensure engineering controls are properly set up and working up to specifications.

The government’s overexposure numbers may appear black and white, but those numbers may actually be shades of gray because they are not backed by good science and proper sampling techniques. There are limitations in sampling equipment and laboratory processes. Not all overexposures can withstand close scrutiny. Knowing the limitations of sampling can help determine when and how to challenge MSHA and OSHA overexposures.

MSHA mandates in 56/57.5002 that mine operators survey for dust, mist, fume, and gases. An initial survey of those operations with air contaminants is essential to avoid citations. Don’t wait for MSHA to vigorously pursue air sampling at your mining or milling sites. If you encounter overexposures, immediately take steps to protect workers. It is not enough to simply make respirators available for use. An operator must develop a respiratory protection program and mandate the use of respirators while evaluating and implementing engineering controls.

Before donning a respirator (and annually thereafter), employees must have medical monitoring, fit testing, and training. In the case of silica, provide medical examinations for employees who may be exposed to respirable crystalline silica, as recommended by the National Institute for Occupational Safety and Health (NIOSH), and have X-rays read by a specialist in dust diseases. NIOSH recommends more frequent X-rays for workers with more years of exposure. When required by 30 CFR 56/57.5005, a respirator program must contain all of the elements of the ANSI Z88.2-1969 Practices for Respiratory Protection. If MSHA’s survey finds an overexposure, and there is no respiratory protection program (or if numerous deficiencies exist), then expect significantly higher penalties.

After the results are in, good reasons may exist to challenge MSHA’s sampling results. Consider a challenge when: (1) overexposures are out of line with previous surveys or side-by-side sampling, (2) a single overexposure is so high that only sampling or lab error can account for the error, (3) overexposures are low, bordering on the permissible exposure limits. Where previous surveys were in compliance and no changes in conditions occurred, perhaps MSHA is mistaken. A borderline overexposure may not stand if sampling errors, calibration, and/or lab errors exist.

MSHA dust sampling consists of a battery-operated air pump and a sampling head worn on the worker in the breathing zone. The sampling head contains a filter-cassette in which the respirable dust is collected. Prior to passing through the filter, the sampled air passes through a nylon cyclone, a size-selective device which removes the larger non-respirable particles. Cyclones used for dust or silica must maintain proper orientation during sampling. A cyclone that tips over may dump additional non-respirable material into the cassette.

With any sampling, determine if the monitoring equipment was properly positioned. Look for indications that the sampling cassette was grounded and pulled in contaminants from sources other than the air. A cassette placed outside of the breathing zone (an area within 12 inches of the nose and mouth) is not a representative sample.

Fairly large overexposures in line with historic sampling may not be worth fighting. However, uncovering small errors of a few percentage points may be enough to vacate a borderline overexposure. In a recent OSHA case, an administrative law judge dismissed several lead overexposure citations. The administrative law judge held that the calibration device used with the inspector’s pumps produced an additional 2 percent error that had not been properly calculated. Additionally, the results were called into question when OSHA’s laboratory deviated from its published procedure while preparing samples for analysis. In an MSHA case, a violation was vacated where the inspector’s pump stopped during sampling.

When challenging an agency’s sampling results, a Freedom of Information Act request is a good place to begin. Obtain the laboratory’s certifications, sampling protocols, and procedures. Acquiring the inspector’s file will provide information on pre- and post-calibration, field survey notes, photos, and any worksheets prepared by the inspector. The inspector’s notes from the inspection may document problems and challenges encountered. Compare the inspection procedures and sample processing to the agency’s published industrial hygiene and laboratory protocols. Errors may creep into sampling results anywhere along the process. The old adage “garbage in, garbage out” applies to the science of air sampling. The difference between being in compliance versus accepting substantial citations and penalties is knowing how and when to challenge inaccurate sampling results.


Daniel J. Pubal is an associate at Patton Boggs LLP’s Washington, D.C., office where he advises clients on environmental, health, and safety issues, as well as litigation and dispute resolution. Pubal may be reached via phone at 202-457-6165 or via e-mail at

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