Region I 1997 Performance Audit Program

Region I conducts an audit program to assess the performance of Ambient Air Monitoring Networks to provide operators of these Networks with technical assistance to maintain and improve overall data quality. The audit procedures used in Region I are adapted from Volume II, of the U.S. EPA Quality Assurance handbook for Air Pollution Measurements. Gaseous pollutant audits are conducted by introducing a known concentration of a specific pollutant (traceable to the National Institute of Standards and Technology, NIST) into the monitor's sample intake, recording the response of the audited instrument, and comparing the instrument's response to the actual or known concentration. Mass Flow and Volumetric Flow controlled instruments for Particulate Matter less than 10 microns in size (PM10) are audited by attaching a reference flow device to the monitor which restricts air flow to a known rate. The known air flow rate is then compared with the rate of flow indicated by the sampler. These on site performance audits are conducted by EPA Region I, Ecosystem Assessment Branch in Lexington. The total number of Audits have been significantly decreased due to diminished travel funds and an augmented workload focusing on the PAMS program.

A total of 77 audits were conducted in the six New England States on instruments that measure Ozone (O3), Sulfur Dioxide (SO2), Particulate Matter less than 10 microns in size (PM10) and Carbon Monoxide (CO).

Of the 41 O3 audits conducted in 1997, all passed the audit. Region I's O3 audits continue to focus on costal O3 sites due to the concern that O3 may be transported up the coast and peak O3 levels are usually experienced at these sites.

Twenty-six PM10 audits were conducted with no failures in 1997. Of the 10 CO audits conducted in 1997, all passed.

1997 CT ME MA NH RI VT
O3 118 9 9 2 2
CO 12 2 2 1 2
PM10115 2 2 3 3

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Steven McDougall / swmcd@theworld.com / 1998 September 27