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Updated: December 02, 2005
Why NELAC Standards are Necessary for the Certification of Field Samplers!
The fundamental premise of the need for certification of field samplers is to assure the collection of defensible samples for compliance determination purposes. Field sampling includes all measurement-related activities performed in the field (versus activities performed in a laboratory). For some methods this involves sample collection, for others the entire measurement is performed in the field. For field sampling, the collection of samples or measurement takes place in the uncontrolled environment of the field, in which there is a minimum (if any) level of management oversight and quality assurance.
In this situation the sampler is faced with technical challenges that must be overcome to collect the proper sample or perform the measurement according to the method. It follows, then, that the measurement results are directly related to the ability of the field sampler to obtain a 'proper' sample or perform other field measurement activities. Depending on the sampling effort required, the level of effort may range from one person conducting the sampling to a crew of ten or more, depending on the complexity and the need for simultaneous sampling.
EPA's Emission Measurement Center, Office of Air and Radiation, has developed draft criteria for certification of field samplers. Certification is awarded based on years of experience, appropriate study/continuing education requirements, plus passing exams on knowledge of the methods.
With this background in mind, the following is a list of arguments for the need to certify field samplers: (Note: This narrative assumes that accreditation of testing firms involved with field measurement is included under NELAC.)
- Field sampler competence must be demonstrated since sampling methods are not amenable to performance evaluation testing.
- Sends a message that environmental field sample collection and measurement is as important as laboratory analyses.
- Is in concert with EPA's EMMC approach of consolidating under NELAC all program offices involved with collection of environmental compliance-based data.
- All stakeholders including sources are more assured of the accuracy and certainty in the compliance data.
- Certification is awarded based on years of experience, appropriate study/continuing education requirements, plus passing exams on knowledge of the methods. (EPA air programs, as noted above, are actively involved in this approach).
- The resulting compliance data will have fewer errors resulting from human error due to lack of knowledge and/or experience with methods.
- Integrity and representativeness of samples are better assured.
- NELAC standards for certification would help assure consistency in the application of field sampling methods from State to State.
- NELAC standards would define a "quality standard" to which all field samplers should aspire.
Dan Bivins
bivins.dan@epa.gov
919-541-5244